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Multiprocessing Services Reference

Framework	CoreServices/CoreServices.h
Companion guide	Multiprocessing Services Programming Guide
Declared in	Multiprocessing.h MultiprocessingInfo.h

Overview

Multiprocessing Services is an API that lets you create preemptive tasks in your application that can run on one or more microprocessors. Unlike the cooperative threads created by the Thread Manager, Multiprocessing Services automatically divides processor time among the available tasks, so that no particular task can monopolize the system. This document is relevant to you if you want to add multitasking capability to your Mac OS applications.

In Mac OS X, Carbon supports Multiprocessing Services with the following restrictions:

Debugging functions are not implemented. Use the mach APIs provided by the system to implement debugging services.
Opaque notification IDs are local to your process; they are not globally addressable across processes.
Global memory allocation is not supported.

Functions by Task

Determining Multiprocessing Services And Processor Availability

Creating and Handling Message Queues

Creating and Handling Semaphores

Creating and Scheduling Tasks

Handling Critical Regions

Handling Event Groups

Handling Kernel Notifications

Accessing Per-Task Storage Variables

Memory Allocation Functions

Remote Calling Functions

Timer Services Functions

Exception Handling Functions

Debugger Support Functions

Functions

MPAllocate

Allocates a nonrelocatable memory block. (Deprecated. Use MPAllocateAligned instead.)

LogicalAddress MPAllocate (
   ByteCount size
);

Parameters

size: The size, in bytes, of the memory block to allocate.

Return Value

A pointer to the allocated memory. If the function cannot allocate the requested memory or the requested alignment, the returned address is NULL.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPAllocateAligned

Allocates a nonrelocatable memory block.

LogicalAddress MPAllocateAligned (
   ByteCount size,
   UInt8 alignment,
   OptionBits options
);

Parameters

size: The size, in bytes, of the memory block to allocate.
alignment: The desired alignment of the allocated memory block. See “Memory Allocation Alignment Constants” for a list of possible values to pass. Note that there will be a minimum alignment regardless of the requested alignment. If the requested memory block is 4 bytes or smaller, the block will be at least 4-byte aligned. If the requested block is greater than 4 bytes, the block will be at least 8-byte aligned.
options: Any optional information to use with this call. See “Memory Allocation Option Constants” for a list of possible values to pass.

Return Value

A pointer to the allocated memory. If the function cannot allocate the requested memory or the requested alignment, the returned address is NULL.

Discussion

The memory referenced by the returned address is guaranteed to be accessible by the application's cooperative task and any preemptive tasks that it creates, but not by other applications or their preemptive tasks. Any existing non-global heap blocks are freed when the application terminates. As with all shared memory, you must explicitly synchronize access to allocated heap blocks using a notification mechanism.

You can replicate the effect of the older MPAllocate function by calling MPAllocateAligned with 32-byte alignment and no options.

Also see the function MPFree.

Special Considerations

Mac OS X does not support allocation of global (cross address space) or resident memory with this function. In addition, passing the kMPAllocateNoGrowthMask constant in the options parameter has no effect in Mac OS X, since memory allocation is done with sparse heaps.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPAllocateTaskStorageIndex

Returns an index number to access per-task storage.

OSStatus MPAllocateTaskStorageIndex (
   TaskStorageIndex *taskIndex
);

Parameters

index: On return, index contains an index number you can use to store task data.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

A call to the function MPAllocateTaskStorageIndex returns an index number that is common across all tasks in the current process. You can use this index number in calls to MPSetTaskStorageValue and MPGetTaskStorageValue to set a different value for each task using the same index.

You can think of the task storage area as a two dimensional array cross-referenced by the task storage index number and the task ID. Note that since the amount of per-task storage is determined when the task is created, the number of possible index values associated with a task is limited.

Also see the function MPDeallocateTaskStorageIndex.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPArmTimer

Arms the timer to expire at a given time.

OSStatus MPArmTimer (
   MPTimerID timerID,
   AbsoluteTime *expirationTime,
   OptionBits options
);

Parameters

timerID: The ID of the timer you want to arm.
expirationTime: A pointer to a value that specifies when you want the timer to expire. Note that if you arm the timer with a time that has already passed, the timer expires immediately.
options: Any optional actions. See “Timer Option Masks” for a list of possible values.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the timer has already expired, the reset does not take place and the function returns kMPInsufficientResourcesErr.

Discussion

The expiration time is an absolute time, which you can generate by calling the Driver Services Library function UpTime. When the timer expires, a notification is sent to the notification mechanism specified in the last MPSetTimerNotify call. If the specified notification ID has become invalid, no action is taken when the timer expires. The timer itself is deleted when it expires unless you specified the kMPPreserveTimerID option in the options parameter.

Also see the function MPCancelTimer.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPBlockClear

Clears a block of memory.

void MPBlockClear (
   LogicalAddress address,
   ByteCount size
);

Parameters

address: The starting address of the memory block you want to clear.
size: The number of bytes you want to clear.

Discussion

As with all shared memory, your application must synchronize access to the memory blocks to avoid data corruption. MPBlockClear ensures the clearing stays within the bounds of the area specified by size, but the calling task can be preempted during the copying process.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPBlockCopy

Copies a block of memory.

void MPBlockCopy (
   LogicalAddress source,
   LogicalAddress destination,
   ByteCount size
);

Parameters

source: The starting address of the memory block you want to copy.
destination: The location to which you want to copy the memory block.
size: The number of bytes to copy.

Discussion

This function simply calls through to the Driver Services Library function BlockMoveData. Note that you should not make any assumptions about the state of the destination memory while this function is executing. In the intermediate state, values may be present that are neither the original nor the final ones. For example, this function may use the 'dcbz' instruction. If the underlying memory is not cacheable, if the memory is write-through instead of copy-back, or if the cache block is flushed for some reason, the 'dcbz' instruction will write zeros to the destination. You can avoid the use of the 'dcbz' instruction by calling BlockMoveDataUncached, but even that function makes no other guarantees about the memory block's intermediate state.

As with all shared memory, your application must synchronize access to the memory blocks to avoid data corruption. MPBlockCopy ensures the copying stays within the bounds of the area specified by size, but the calling task can be preempted during the copying process.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCancelTimer

Cancels an armed timer.

OSStatus MPCancelTimer (
   MPTimerID timerID,
   AbsoluteTime *timeRemaining
);

Parameters

timerID: The ID of the armed timer you want to cancel.
timeRemaining: On return, the timeRemaining contains the time remaining before the timer would have expired.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the timer has already expired, this function returns kMPInsufficientResourcesErr.

Discussion

Also see the function MPArmTimer.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCauseNotification

Signals a kernel notification.

OSStatus MPCauseNotification (
   MPNotificationID notificationID
);

Parameters

notificationID: The ID of the kernel notification you want to signal.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

You call this function to signal a kernel notification much as you would signal any simple notification (for example, MPNotifyQueue ).

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateCriticalRegion

Creates a critical region object.

OSStatus MPCreateCriticalRegion (
   MPCriticalRegionID *criticalRegion
);

Parameters

criticalRegion: On return, the criticalRegion contains the ID of the newly created critical region object.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Also see the function MPDeleteCriticalRegion.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateEvent

Creates an event group.

OSStatus MPCreateEvent (
   MPEventID *event
);

Parameters

event: On return, event contains the ID of the newly created event group.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Event groups are created from dynamically allocated internal resources. Other tasks may be competing for these resources so it is possible that this function will not be able to create an event group.

Also see the function MPDeleteEvent.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateNotification

Creates a kernel notification

OSStatus MPCreateNotification (
   MPNotificationID *notificationID
);

Parameters

notificationID: On return, notificationID points to the newly created kernel notification.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

After creating the kernel notification object, you can add simple notifications by calling the function MPModifyNotification.

Also see the function MPDeleteNotification.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateQueue

Creates a message queue.

OSStatus MPCreateQueue (
   MPQueueID *queue
);

Parameters

queue: On return, the variable contains the ID of the newly created message queue.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If a queue could not be created, MPCreateQueue returns kMPInsufficientResourcesErr.

Discussion

This call creates a message queue, which can be used to notify (that is, send) and wait for (that is, receive) messages consisting of three pointer-sized values in a preemptively safe manner.

Message queues are created from dynamically allocated internal resources. Other tasks may be competing for these resources so it is possible this function may not be able to create a queue.

See also the functions MPDeleteQueue and MPSetQueueReserve.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateSemaphore

Creates a semaphore.

OSStatus MPCreateSemaphore (
   MPSemaphoreCount maximumValue,
   MPSemaphoreCount initialValue,
   MPSemaphoreID *semaphore
);

Parameters

maximumValue: The maximum allowed value of the semaphore.
initialValue: The initial value of the semaphore.
semaphore: On return, semaphore contains the ID of the newly–created semaphore.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

If you want to create a binary semaphore, you can call the macro MPCreateBinarySemaphore (MPSemaphoreID *semaphore) instead, which simply calls MPCreateSemaphore with both maximumValue and initialValue set to 1.

Also see the function MPDeleteSemaphore.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateTask

Creates a preemptive task.

OSStatus MPCreateTask (
   TaskProc entryPoint,
   void *parameter,
   ByteCount stackSize,
   MPQueueID notifyQueue,
   void *terminationParameter1,
   void *terminationParameter2,
   MPTaskOptions options,
   MPTaskID *task
);

Parameters

entryPoint

A pointer to the task function. The task function should take a single pointer-sized parameter and return a value of type OSStatus.

parameter

The parameter to pass to the task function.

stackSize

The size of the stack assigned to the task. Note that you should be careful not to exceed the bounds of the stack, since stack overflows may not be detected. Specifying zero for the size will result in a default stack size of 4KB.

Note that in Mac OS X prior to version 10.1, this parameter is ignored, and all stacks have the default size of 512 KB. Versions 10.1 and later do not have this limitation.

notifyQueue

The ID of the message queue to which the system will send a message when the task terminates. You specify the first two values of the message in the parameters terminationParameter1 and terminationParameter2 respectively. The last message value contains the result code of the task function.

terminationParameter1

A pointer-sized value that is sent to the message queue specified by the parameter notifyQueue when the task terminates.

terminationParameter2

A pointer-sized value that is sent to the message queue specified by the parameter notifyQueue when the task terminates.

options

Optional attributes of the preemptive task. See “Task Creation Options” for a list of possible values.

task

On return, task points to the ID of the newly created task.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If MPCreateTask could not create the task because some critical resource was not available, the function returns kMPInsufficientResourcesErr. Usually this is due to lack of memory to allocate the internal data structures associated with the task or the stack. The function also returns kMPInsufficientResourcesErr if any reserved option bits are set.

Discussion

Tasks are created in the unblocked state, ready for execution. A task can terminate in the following ways:

By returning from its entry point
By calling MPExit
When specified as the target of an MPTerminateTask call
If a hardware-detected exception or programming exception occurs and no exception handler is installed
If the application calls ExitToShell

Task resources (its stack, active timers, internal structures related to the task, and so on) are reclaimed by the system when the task terminates. The task's address space is inherited from the process address space. All existing tasks are terminated when the owning process terminates.

To set the relative processor weight to be assigned to a task, use the function MPSetTaskWeight.

See also the function MPTerminateTask.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCreateTimer

Creates a timer.

OSStatus MPCreateTimer (
   MPTimerID *timerID
);

Parameters

timerID: On return, the timerID contains the ID of the newly created timer.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

You can use a timer to notify an event, queue, or semaphore after a specified amount of time has elapsed.

Timer objects are created from dynamically-allocated internal resources. Other tasks may be competing for these resources so it is possible this function may not be able to create one.

To specify the notification mechanism to signal, use the function MPSetTimerNotify.

Also see the functions MPDeleteTimer and MPArmTimer.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCurrentTaskID

Obtains the task ID of the currently-executing preemptive task

MPTaskID MPCurrentTaskID (
   void
);

Return Value

The task ID of the current preemptive task. See the description of the MPTaskID data type.

Discussion

Returns the ID of the current preemptive task. If called from a cooperative task, this function returns an ID which is different than the ID of any preemptive task. Nonpreemptive processes may or may not have different task IDs for each application; future implementations of this API may behave differently in this regard.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDataToCode

Designates the specified block of memory as executable code.

void MPDataToCode (
   LogicalAddress address,
   ByteCount size
);

Parameters

address: The starting address of the memory block you want to designate as code.
size: The size of the memory block.

Discussion

Since processors need to differentiate between code and data in memory, you should call this function to tag any executable code that your tasks may generate.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.
Not available to 64-bit applications.

Declared In

Multiprocessing.h

MPDeallocateTaskStorageIndex

Frees an index number used to access per-task storage

OSStatus MPDeallocateTaskStorageIndex (
   TaskStorageIndex taskIndex
);

Parameters

index: The index number you want to deallocate.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Also see the function MPAllocateTaskStorageIndex.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDelayUntil

Blocks the calling task until a specified time.

OSStatus MPDelayUntil (
   AbsoluteTime *expirationTime
);

Parameters

expirationTime: The time to unblock the task.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

You cannot call this function from a cooperative task.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDeleteCriticalRegion

Removes the specified critical region object.

OSStatus MPDeleteCriticalRegion (
   MPCriticalRegionID criticalRegion
);

Parameters

criticalRegion: The critical region object you want to remove.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Calling this function unblocks all tasks waiting to enter the critical region and their respective MPEnterCriticalRegion calls will return with the result code kMPDeletedErr.

Also see the function MPCreateCriticalRegion.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDeleteEvent

Removes an event group.

OSStatus MPDeleteEvent (
   MPEventID event
);

Parameters

event: The ID of the event group you want to remove.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

After deletion, the event ID becomes invalid, and all internal resources associated with the event group are reclaimed. Calling this function unblocks all tasks waiting on the event group and their respective MPWaitForEvent calls will return with the result code kMPDeletedErr.

Also see the function MPCreateEvent.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDeleteNotification

Removes a kernel notification.

OSStatus MPDeleteNotification (
   MPNotificationID notificationID
);

Parameters

notificationID: The ID of the notification you want to remove.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Also see the function MPCreateNotification.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDeleteQueue

Deletes a message queue.

OSStatus MPDeleteQueue (
   MPQueueID queue
);

Parameters

queue: The ID of the message queue you want to delete.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

After calling MPDeleteQueue, the specified queue ID becomes invalid, and all internal resources associated with the queue (including queued messages) are reclaimed. Any tasks waiting on the queue are unblocked and their respective MPWaitOnQueue calls will return with the result code kMPDeletedErr.

Also see the function MPCreateQueue.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDeleteSemaphore

Removes a semaphore.

OSStatus MPDeleteSemaphore (
   MPSemaphoreID semaphore
);

Parameters

semaphore: The ID of the semaphore you want to remove.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Calling this function unblocks all tasks waiting on the semaphore and the tasks’ respective MPWaitOnSemaphore calls will return with the result code kMPDeletedErr.

Also see the function MPCreateSemaphore.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDeleteTimer

Removes a timer.

OSStatus MPDeleteTimer (
   MPTimerID timerID
);

Parameters

timerID: The ID of the timer you want to remove.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

After deletion, the timer ID becomes invalid, and all internal resources associated with the timer are reclaimed.

Also see the function MPCreateTimer.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPDisposeTaskException

Removes a task exception.

OSStatus MPDisposeTaskException (
   MPTaskID task,
   OptionBits action
);

Parameters

task: The task whose exception you want to remove.
action: Any actions to perform on the task. For example, you can enable single-stepping when the task resumes, or you can pass the exception on to another handler. See “Task Exception Disposal Constants” for a listing of possible values.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the specified action is invalid or unsupported, or if the specified task is not suspended, this function returns kMPInsufficientResourcesErr.

Discussion

This function removes the task exception and allows the task to resume operation. If desired, you can enable single-stepping or branch-stepping, or propagate the exception instead.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPEnterCriticalRegion

Attempts to enter a critical region.

OSStatus MPEnterCriticalRegion (
   MPCriticalRegionID criticalRegion,
   Duration timeout
);

Parameters

criticalRegion: The ID of the critical region you want to enter.
timeout: The maximum time to wait for entry before timing out. See “Timer Duration Constants” for a list of constants you can use to specify the wait interval.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

If another task currently occupies the critical region, the current task is blocked until the critical region is released or until the designated timeout expires. Otherwise the task enters the critical region and MPEnterCriticalRegion increments the region’s use count.

Once a task enters a critical region it can make further calls to MPEnterCriticalRegion without blocking (its use count increments for each call). However, each call to MPEnterCriticalRegion must be balanced by a call to MPExitCriticalRegion ; otherwise the region is not released for use by other tasks.

Note that you can enter a critical region from a cooperative task. Each cooperative task is treated as unique and different from any preemptive task. If you call this function from a cooperative task, you should specify only kDurationImmediate for the timeout length; other waits will cause the task to block.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPExit

Allows a task to terminate itself

void MPExit (
   OSStatus status
);

Parameters

status: An application-defined value that indicates termination status. This value is sent to the termination message queue in place of the task’s result code.

Discussion

When called from within a preemptive task, the task terminates, and the value indicated by the parameter status is sent to the termination message queue you specified in MPCreateTask. Note that you cannot call MPExit from outside a preemptive task.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPExitCriticalRegion

Exits a critical region.

OSStatus MPExitCriticalRegion (
   MPCriticalRegionID criticalRegion
);

Parameters

criticalRegion: The ID of the critical region you want to exit.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the task does not own the critical region specified by criticalRegion, MPExitCriticalRegion returns kMPInsufficientResourcesErr.

Discussion

This function decrements the use count of the critical region object. When the use count reaches zero, ownership of the critical region object is released (which allows another task to use the critical region).

Also see the function MPEnterCriticalRegion.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPExtractTaskState

Extracts state information from a suspended task.

OSStatus MPExtractTaskState (
   MPTaskID task,
   MPTaskStateKind kind,
   void *info
);

Parameters

task: The task whose state information you want to obtain.
kind: The kind of state information you want to obtain. See “Task State Constants” for a listing of possible values.
info: A pointer to a data structure to hold the state information. On return, the data structure holds the desired state information. The format of the data structure varies depending on the state information you want to retrieve. See the header file MachineExceptions.h for the formats of the various state information structures.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If you attempt to extract state information for a running task, this function returns kMPInsufficientResourcesErr.

Discussion

You can use this function to obtain register contents or exception information about a particular task.

Also see the function MPSetTaskState.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPFree

Frees memory allocated by MPAllocateAligned.

void MPFree (
   LogicalAddress object
);

Parameters

object: A pointer to the memory you want to release.

Discussion

Also see the function MPAllocateAligned.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPGetAllocatedBlockSize

Returns the size of a memory block.

ByteCount MPGetAllocatedBlockSize (
   LogicalAddress object
);

Parameters

object: The address of the memory block whose size you want to determine.

Return Value

The size of the allocated memory block, in bytes.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPGetNextCpuID

Obtains the next CPU ID in the list of physical processors of the specified memory coherence group.

OSStatus MPGetNextCpuID (
   MPCoherenceID owningCoherenceID,
   MPCpuID *cpuID
);

Parameters

owningCoherenceID: The ID of the memory coherence group whose physical processor IDs you want to obtain. Pass kMPInvalidIDErr, as only one coherence group, internal RAM, is currently defined.
cpuID: On return, cpuID points to the ID of the next physical processor.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

By iterating on this function (after calling MPProcessors , for example), you can obtain the IDs of all the processors available on the host computer. Generally, you would only use this function in diagnostic programs.

Availability

Available in Mac OS X v10.4 and later.

Declared In

MultiprocessingInfo.h

MPGetNextTaskID

Obtains the next task ID in the list of available tasks.

OSStatus MPGetNextTaskID (
   MPProcessID owningProcessID,
   MPTaskID *taskID
);

Parameters

owningProcessID: The ID of the process (typically the application) that owns the tasks. This ID is the same as the process ID handled by the Code Fragment Manager.
taskID: On return, taskID points to ID of the next task in the list of tasks.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

By iterating on this function, you can obtain the IDs of all the tasks in a given process. These tasks may be running, ready, or blocked. Generally you would only use this function in diagnostic programs.

Availability

Available in Mac OS X v10.4 and later.

Declared In

MultiprocessingInfo.h

MPGetTaskStorageValue

Gets the storage value stored at a specified index number.

TaskStorageValue MPGetTaskStorageValue (
   TaskStorageIndex taskIndex
);

Parameters

index: The index number of the storage value you want to obtain.

Return Value

The value stored at the specified index number. See the description of the TaskStorageValue data type.

Discussion

Calling this function from within a task effectively reads a value in a two-dimensional array cross-referenced by task storage index value and the task ID.

Note that since this function does not return any status information, it may not be immediately obvious whether the returned storage value is valid.

Also see the function MPSetTaskStorageValue.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPModifyNotification

Adds a simple notification to a kernel notification.

OSStatus MPModifyNotification (
   MPNotificationID notificationID,
   MPOpaqueID anID,
   void *notifyParam1,
   void *notifyParam2,
   void *notifyParam3
);

Parameters

notificationID: The ID of the kernel notification you want to add to..
anID: The ID of the simple notification (semaphore, message group, or event group) you want to add to the kernel notification.
notifyParam1: If anID specifies an event group, this parameter should contain the flags to set in the event group when MPCauseNotification is called. If anID specifies a message queue, this parameter should contain the first pointer-sized value of the message to be sent to the message queue when MPCauseNotification is called.
notifyParam2: If anID specifies a message queue, this parameter should contain the second pointer-sized value of the message to be sent to the message queue when MPCauseNotification is called. Pass NULL if you don’t need this parameter.
notifyParam3: If anID specifies a message queue, this parameter should contain the third pointer-sized value of the message sent to the message queue when MPCauseNotification is called. Pass NULL if you don’t need this parameter.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

You specify the parameters for the simple notifications just as if you were calling the MPSetTimerNotify function.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPModifyNotificationParameters

OSStatus MPModifyNotificationParameters (
   MPNotificationID notificationID,
   MPOpaqueIDClass kind,
   void *notifyParam1,
   void *notifyParam2,
   void *notifyParam3
);

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Availability

Available in Mac OS X v10.1 and later.

Declared In

Multiprocessing.h

MPNotifyQueue

Sends a message to the specified message queue.

OSStatus MPNotifyQueue (
   MPQueueID queue,
   void *param1,
   void *param2,
   void *param3
);

Parameters

queue: The queue ID of the message queue you want to notify.
param1: The first pointer-sized value of the message to send.
param2: The second pointer-sized value of the message to send.
param3: The third pointer-sized value of the message to send.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

This function sends a message to the specified queue, which consist of the three parameters, param1, param2, and param3. The system does not interpret the three values which comprise the text of the message. If tasks are waiting on the specified queue, the first waiting task is unblocked and the task’s MPWaitOnQueue function completes.

Depending on the queue mode, the system either allocates messages dynamically or assigns them to memory reserved for the queue. In either case, if no more memory is available for messages MPNotifyQueue returns kMPInsufficientResourcesErr.

You can call this function from an interrupt handler if messages are reserved on the queue. For more information about queueing modes and reserving messages, see MPSetQueueReserve.

Also see the function MPWaitOnQueue.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPProcessors

Returns the number of processors on the host computer.

ItemCount MPProcessors (
   void
);

Return Value

The number of physical processors on the host computer.

Discussion

See also the function MPProcessorsScheduled.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPProcessorsScheduled

Returns the number of active processors available on the host computer.

ItemCount MPProcessorsScheduled (
   void
);

Return Value

The number of active processors available on the host computer.

Discussion

The number of active processors is defined as the number of processors scheduled to run tasks. This number varies while the system is running. Advanced power management facilities may stop or start scheduling processors in the system to control power consumption or to maintain a proper operating temperature.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPRegisterDebugger

Registers a debugger.

OSStatus MPRegisterDebugger (
   MPQueueID queue,
   MPDebuggerLevel level
);

Parameters

queue: The ID of the queue to which you want exception messages and other information to be sent.
level: The level of this debugger with respect to other debuggers. Exceptions and informational messages are sent first to the debugger with the highest level. If more than one debugger attempts to register at a particular level, only the first debugger is registered. Other attempts return an error.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

In Mac OS X, this function is available but is not implemented. Use system debugging services to write a debugger for Mac OS X.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPRemoteCall

Calls a non-reentrant function and blocks the current task.

void * MPRemoteCall (
   MPRemoteProcedure remoteProc,
   void *parameter,
   MPRemoteContext context
);

Parameters

remoteProc: A pointer to the application-defined function you want to call. See MPRemoteProcedure for more information about the form of this function.
parameter: A pointer to a parameter to pass to the application-defined function. For example, this value could point to a data structure or a memory location.
context: This parameter is ignored; specify kMPOwningProcessRemoteContext.

Return Value

The value that your remote procedure callback returned.

Discussion

You use this function to execute code on your application’s main task. The remoteProc function is scheduled on the application’s main run loop and run in the default mode (kCFRunloopDefaultMode). If you call this function from your application’s main task, the remoteProc function is executed immediately in the current mode without blocking the task; otherwise, calling this function blocks the current task until the remote call completes.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPRemoteCallCFM

Calls a non-reentrant function and blocks the current task.

void * MPRemoteCallCFM (
   MPRemoteProcedure remoteProc,
   void *parameter,
   MPRemoteContext context
);

Parameters

remoteProc: A pointer to the application-defined CFM (Code Fragment Manager) function you want to call. See MPRemoteProcedure for more information about the form of this function.
parameter: A pointer to a parameter to pass to the application-defined function. For example, this value could point to a data structure or a memory location.
context: This parameter is ignored; specify kMPOwningProcessRemoteContext.

Return Value

The value that your remote procedure callback returned.

Discussion

Availability

Available in Mac OS X v10.4 and later.

Declared In

Multiprocessing.h

MPSetEvent

Merges event flags into a specified event group.

OSStatus MPSetEvent (
   MPEventID event,
   MPEventFlags flags
);

Parameters

event: The ID of the event group you want to set.
flags: The flags you want to merge into the event group.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

The flags are logically ORed with the current flags in the event group. This procedure is an atomic operation to ensure that multiple updates do not get lost. If tasks are waiting on this event group, the first waiting task is unblocked.

Note that you can call this function from an interrupt handler.

Also see the function MPWaitForEvent.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSetExceptionHandler

Sets an exception handler for a task.

OSStatus MPSetExceptionHandler (
   MPTaskID task,
   MPQueueID exceptionQ
);

Parameters

task: The task to associate with the exception handler.
exceptionQ: The message queue to which an exception message will be sent.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

When an exception handler is set and an exception occurs, the task is suspended and a message is sent to the message queue specified by exceptionQ. The message contains the following information:

The first pointer-sized value contains the ID of the task in which the exception occurred.
The second pointer-sized value contains the type of exception that occurred. See the header file MachineExceptions.h for a listing of exception types.
The last pointer-sized value is set to NULL (reserved for future use).

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSetQueueReserve

Reserves space for messages on a specified message queue.

OSStatus MPSetQueueReserve (
   MPQueueID queue,
   ItemCount count
);

Parameters

queue: The ID of the queue whose messages you want to reserve.
count: The number of messages to reserve.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

MPNotifyQueue allocates spaces for messages dynamically; that is, memory to hold the message is allocated for the queue at the time of the call. In most cases this method is both speed and storage efficient. However, it is possible that, due to lack of memory resources, space for the message may not be available at the time of the call; in such cases, MPNotifyQueue will return kInsufficientResourcesErr.

If you must have guaranteed message delivery, or if you need to call MPNotifyQueue from an interrupt handler, you should reserve space on the specified queue by calling MPSetQueueReserve. Because such allocated space is reserved for duration of the queue’s existence, you should avoid straining internal system resources by reserving messages only when absolutely necessary. Note that if you have reserved messages on a queue, additional space cannot be added dynamically if the number of messages exceeds the number reserved for that queue.

The number of reserved messages is set to count, lowering or increasing the current number of reserved messages as required. If count is set to zero, no messages are reserved for the queue, and space for messages is allocated dynamically.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSetTaskState

Sets state information for a suspended task.

OSStatus MPSetTaskState (
   MPTaskID task,
   MPTaskStateKind kind,
   void *info
);

Parameters

task: The task whose state information you want to set.
kind: The kind of state information you want to set. See “Task State Constants” for a listing of possible values. Note that some state information is read-only and cannot be changed using this function.
info: A pointer to a data structure holding the state information you want to set. The format of the data structure varies depending on the state information you want to set. See the header file MachineExceptions.h for the formats of the various state information structures.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If you specify kMPTaskState32BitMemoryException for the state information, this function returns kMPInsufficientResourcesErr, since the exception state information is read-only. Attempting to set state information for a running task will also return kMPInsufficientResourcesErr.

Discussion

You can use this function to set register contents or exception information for a particular task. However, some state information, such as the exception information (as specified by kMPTaskState32BitMemoryException) as well as the MSR, ExceptKind, DSISR, and DAR machine registers (specified under kMPTaskStateMachine) are read-only. Attempting to set the read-only machine registers will do nothing, while attempting to set the exception information will return an error.

Also see the function MPExtractTaskState.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSetTaskStorageValue

Sets the storage value for a given index number.

OSStatus MPSetTaskStorageValue (
   TaskStorageIndex taskIndex,
   TaskStorageValue value
);

Parameters

index: The index number whose storage value you want to set.
value: The value you want to set.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

Typically you use MPSetTaskStorageValue to store pointers to task-specific structures or data.

Calling this function from within a task effectively assigns a value in a two-dimensional array cross-referenced by task storage index value and the task ID.

Also see the function MPGetTaskStorageValue.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSetTaskType

Sets the type of the task.

OSStatus MPSetTaskType (
   MPTaskID task,
   OSType taskType
);

Return Value

The noErr result code. See “Multiprocessing Services Result Codes.”

Discussion

This function does nothing and should not be used.

Availability

Available in Mac OS X v10.1 and later.

Declared In

Multiprocessing.h

MPSetTaskWeight

Assigns a relative weight to a task, indicating how much processor time it should receive compared to other available tasks.

OSStatus MPSetTaskWeight (
   MPTaskID task,
   MPTaskWeight weight
);

Parameters

task: The ID of the task to which you want to assign a weighting.
weight: The relative weight to assign. This value can range from 1 to 10,000, with the default value being 100.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

The approximate processor share is defined as:

weight of the task / total weight of available tasks

For a set of ready tasks, the amount of CPU time dedicated to the tasks will be determined by the dynamically computed share. Note that the processor share devoted to tasks may deviate from the suggested weighting if critical tasks require attention. For example, a real-time task (such as a QuickTime movie) may require more than its relative weight of processor time, and the scheduler will adjust proportions accordingly.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSetTimerNotify

Sets the notification information associated with a timer.

OSStatus MPSetTimerNotify (
   MPTimerID timerID,
   MPOpaqueID anID,
   void *notifyParam1,
   void *notifyParam2,
   void *notifyParam3
);

Parameters

timerID: The ID of the timer whose notification information you want to set.
notificationID: The ID of the notification mechanism to associate with the timer. This value should be the ID of an event group, a message queue, or a semaphore.
notifyParam1: If anID specifies an event group, this parameter should contain the flags to set in the event group when the timer expires. If anID specifies a message queue, this parameter should contain the first pointer-sized value of the message to be sent to the message queue when the timer expires.
notifyParam2: If anID specifies a message queue, this parameter should contain the second pointer-sized value of the message to be sent to the message queue when the timer expires. Pass NULL if you don’t need this parameter.
notifyParam3: If anID specifies a message queue, this parameter should contain the third pointer-sized value of the message sent to the message queue when the timer expires. Pass NULL if you don’t need this parameter.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

When the timer expires, Multiprocessing Services checks the notification ID, and if it is valid, notifies the related notification mechanisms (that is, event groups, queues, or semaphores) you had specified in your MPSetTimerNotify calls.

You can specify multiple notification mechanisms by calling this function several times. For example, you can call MPSetTimerNotify to specify a message queue and then call it again to specify a semaphore. When the timer expires, a message is sent to the message queue and the appropriate semaphore is signaled. You cannot, however, specify more than one notification per notification mechanism (for example, if you call MPSetTimerNotify twice, specifying different messages or message queues in each call, the second call will overwrite the first). Note that if a call to MPSetTimerNotify returns an error, any previous calls specifying the same timer are still valid; previously set notifications will still be notified when the timer expires.

You can set the notification information at any time. If the timer is armed, it will modify the notification parameters dynamically. If the timer is disarmed, it will modify the notification parameters to be used for the next MPArmTimer call.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSignalSemaphore

Signals a semaphore.

OSStatus MPSignalSemaphore (
   MPSemaphoreID semaphore
);

Parameters

semaphore: The ID of the semaphore you want to signal.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the value of the semaphore was already at the maximum, MPSignalSemaphore returns kInsufficientResourcesErr.

Discussion

If tasks are waiting on the semaphore, the oldest (first queued) task is unblocked so that the corresponding MPWaitOnSemaphore call for that task completes. Otherwise, if the value of the semaphore is not already equal to its maximum value, it is incremented by one.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTaskIsPreemptive

Determines whether a task is preemptively scheduled.

Boolean MPTaskIsPreemptive (
   MPTaskID taskID
);

Parameters

taskID: The task you want to check. Pass kMPNoID or kInvalidID if you want to specify the current task.

Return Value

If true, the task is preemptively scheduled. If false, the task is cooperatively scheduled.

Discussion

If you have code that may be called from either cooperative or preemptive tasks, that code can call MPTaskIsPreemptive if its actions should differ depending on its execution environment.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTerminateTask

Terminates an existing task.

OSStatus MPTerminateTask (
   MPTaskID task,
   OSStatus terminationStatus
);

Parameters

task: The ID of the task you wish to terminate.
terminationStatus: A value of type OSStatus indicating termination status. This value is sent to the termination status message queue you specified in MPCreateTask in place of the task function’s result code.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the task to be terminated is already in the process of termination, MPTerminateTask returns kMPInsufficientResourcesErr. You do not need to take any additional action if this occurs.

Discussion

You should be very careful when calling MPTerminateTask. As defined, this call will asynchronously and abruptly terminate a task, potentially leaving whatever structures or resources it was operating upon in an indeterminate state. Mac OS X exacerbates this problem, as MP tasks can use many more system services that are not expecting client threads to asynchronously terminate, and these services do not take the rather complicated steps necessary to protect against, or recover from, such a situation.

However, there are situations in which calling MPTerminateTask is useful and relatively safe. One such situation is when your application or service is quitting and you know that the task you wish to terminate is waiting on an MP synchonization construct (queue, event, semaphore or critical region). While you could do this more cleanly by waking the task and causing it to exit on its own, doing so may not always be practical.

For example, suppose you have several service tasks performing background processing for your application. These service tasks wait on a queue, onto which the application places requests for processing. When the task is done with a request, it notifies another queue, which the application polls. Since the main application task is placing items on the shared queue, and receiving notifications when the requests are done, it can track whether or not there are outstanding requests being processed. If all outstanding requests have, in fact, been processed, it is relatively safe to terminate a task (or all tasks) waiting on the request queue.

You should not assume that the task has completed termination when this call returns; the proper way to synchronize with task termination is to wait on the termination queue (specified in MPCreateTask ) until a message appears. Because task termination is a multistage activity, it is possible for a preemptive task to attempt to terminate a task that is already undergoing termination. In such cases, MPTerminateTask returns kMPInsufficientResourcesErr.

Note that Multiprocessing Services resources (event groups, queues, semaphores, and critical regions) owned by a preemptive task are not released when that task terminates. If a task has a critical region locked when it terminates, the critical region remains in the locked state. Multiprocessing Services resources no longer needed should be explicitly deleted by the task that handles the termination message. All Multiprocessing Services resources created by tasks are released when their owning process (that is, the host application) terminates.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPThrowException

Throws an exception to a specified task.

OSStatus MPThrowException (
   MPTaskID task,
   MPExceptionKind kind
);

Parameters

task: The task to which the exception should be thrown.
kind: The type of exception to give to the task.

Return Value

A result code. See “Multiprocessing Services Result Codes.” If the task is already suspended or if the task is not defined to take thrown exceptions, the function returns kMPInsufficientResourcesErr.

Discussion

The exception is treated in the same manner as any other exception taken by a task. However, since it is asynchronous, it may not be presented immediately.

By convention, you should set the exception kind to kMPTaskStoppedErr if you want to suspend a task. In general, you should do so only if you are debugging and wish to examine the state of the task. Otherwise you should block the task using one of the traditional notification mechanisms (such as a message queue).

An exception can be thrown at any time, whether that task is running, eligible to be run (that is, ready), or blocked. The task is suspended and an exception message may be generated the next time the task is about to run. Note that this may never occur— for example, if the task is deadlocked or the resource it is waiting on is never released. If the task is currently blocked when this function is executed, kMPTaskBlockedErr is returned. If the task was suspended immediately at the conclusion of this function call the return value is kMPTaskStoppedErr.

In Mac OS X, this function is available but is not implemented.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPUnregisterDebugger

Unregisters a debugger.

OSStatus MPUnregisterDebugger (
   MPQueueID queue
);

Parameters

queue: The ID of the queue whose debugger you want to unregister.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

In Mac OS X, this function is available but is not implemented. Use system debugging services to write a debugger for Mac OS X.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPWaitForEvent

Retrieves event flags from a specified event group.

OSStatus MPWaitForEvent (
   MPEventID event,
   MPEventFlags *flags,
   Duration timeout
);

Parameters

event: The event group whose flags you want to retrieve.
flags: On return, flags contains the flags of the specified event group. Pass NULL if you do not need any flag information.
timeout: The maximum time to wait for events before timing out. See “Timer Duration Constants” for a list of constants you can use to specify the wait interval.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

This function obtains event flags from the specified event group. The timeout specifies how long to wait for events if none are present when the call is made. If any flags are set when this function is called, all the flags in the event group are moved to the flag field and the event group is cleared. This obtaining and clearing action is an atomic operation to ensure that no updates are lost. If multiple tasks are waiting on an event group, only one can obtain any particular set of flags.

If you call this function from a cooperative task, you should specify only kDurationImmediate for the timeout length; other waits will cause the task to block.

Also see the function MPSetEvent.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPWaitOnQueue

Obtains a message from a specified message queue.

OSStatus MPWaitOnQueue (
   MPQueueID queue,
   void **param1,
   void **param2,
   void **param3,
   Duration timeout
);

Parameters

queue: The ID of the message queue from which to receive the notification.
param1: On return, the first pointer-sized value of the notification message. Pass NULL if you do not need this portion of the message.
param2: On return, the second pointer-sized value of the notification message. Pass NULL if you do not need this portion of the message.
param3: On return, the third pointer-sized value of the notification message. Pass NULL if you do not need this portion of the message.
timeout: The time to wait for a notification before timing out. See “Timer Duration Constants” for a list of constants you can use to specify the wait interval.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

This function receives a message from the specified message queue. If no messages are currently available, the timeout specifies how long the function should wait for one. Tasks waiting on the queue are handled in a first in, first out manner; that is, the first task to wait on the queue receives the message from the MPNotifyQueue call.

After calling this function, when a message appears, it is removed from the queue and the three fields, param1, param2, and param3 are set to the values specified by the message text. Note these parameters are pointers to variables to be set with the message text.

If you call this function from a cooperative task, you should specify only kDurationImmediate for the timeout length; other waits will cause the task to block.

Also see the function MPNotifyQueue.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPWaitOnSemaphore

Waits on a semaphore

OSStatus MPWaitOnSemaphore (
   MPSemaphoreID semaphore,
   Duration timeout
);

Parameters

semaphore: The ID of the semaphore you want to wait on.
timeout: The maximum time the function should wait before timing out. See “Timer Duration Constants” for a list of constants you can use to specify the wait interval.

Return Value

A result code. See “Multiprocessing Services Result Codes.”

Discussion

If the value of the semaphore is greater than zero, the value is decremented and the function returns with noErr. Otherwise, the task is blocked awaiting a signal until the specified timeout is exceeded.

If you call this function from a cooperative task, you should specify only kDurationImmediate for the timeout length; other waits will cause the task to block.

Also see the function MPSignalSemaphore.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPYield

Allows a task to yield the processor to another task.

void MPYield (
   void
);

Discussion

This function indicates to the scheduler that another task can run. Other than possibly yielding the processor to another task or application, the call has no effect. Note that since tasks are preemptively scheduled, an implicit yield may occur at any point, whether or not this function is called.

In most cases you should not need to call this function. The most common use of MPYield is to release the processor when a task is in a loop in which further progress is dependent on other tasks, and the task cannot be blocked by waiting on a Multiprocessing Services resource. You should avoid such busy waiting whenever possible.

Note that you can call this function from an interrupt handler.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

_MPIsFullyInitialized

Indicates whether Multiprocessing Services is available for use.

Boolean _MPIsFullyInitialized (
   void
);

Return Value

If true, Multiprocessing Services is available for use; otherwise, false.

Declared In

Multiprocessing.h

Callbacks

MPRemoteProcedure

Defines a remote procedure call.

typedef void* (*MPRemoteProcedure) (
   void *parameter
);

For example, this is how you would declare the application-defined function if you were to name the function MyRemoteProcedure:

void* MyRemoteProcedure (
   void *parameter
);

Parameters

parameter: A pointer to the application-defined value you passed to the function MPRemoteCallCFM. For example, this value could point to a data structure or a memory location.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

TaskProc

Defines the entry point of a task.

typedef OSStatus (*TaskProc) (
   void *parameter
);

For example, this is how you would declare the application-defined function if you were to name the function MyTaskProc:

OSStatus MyTaskProc (
   void *parameter
);

Parameters

parameter: A pointer to the application-defined value you passed to the function MPCreateTask. For example, this value could point to a data structure or a memory location.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

Data Types

MPAddressSpaceID

typedef struct OpaqueMPAddressSpaceID * MPAddressSpaceID;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPAddressSpaceInfo

struct MPAddressSpaceInfo {
   PBVersion version;
   MPProcessID processID;
   MPCoherenceID groupID;
   ItemCount nTasks;
   UInt32 vsid[16];
};
typedef struct MPAddressSpaceInfo MPAddressSpaceInfo;

Availability

Available in Mac OS X v10.1 and later.

Declared In

MultiprocessingInfo.h

MPAreaID

typedef struct OpaqueMPAreaID * MPAreaID;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCoherenceID

Represents a memory coherence group.

typedef struct OpaqueMPCoherenceID * MPCoherenceID;

Discussion

A coherence group is the set of processors and other bus controllers that have cache-coherent access to memory. Mac OS 9 defines only one coherence group, which is all the processors that can access internal memory (RAM). Other coherence groups are possible; for example, a PCI card with its own memory and processors can comprise a coherence group.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPConsoleID

typedef struct OpaqueMPConsoleID * MPConsoleID;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCpuID

Represents a CPU ID.

typedef struct OpaqueMPCpuID * MPCpuID;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCriticalRegionID

Represents a critical region ID, which Multiprocessing Services uses to manipulate critical regions.

typedef struct OpaqueMPCriticalRegionID * MPCriticalRegionID;

Discussion

You obtain a critical region ID by calling the function MPCreateCriticalRegion.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPCriticalRegionInfo

struct MPCriticalRegionInfo {
   PBVersion version;
   MPProcessID processID;
   OSType regionName;
   ItemCount nWaiting;
   MPTaskID waitingTaskID;
   MPTaskID owningTask;
   ItemCount count;
};
typedef struct MPCriticalRegionInfo MPCriticalRegionInfo;

Availability

Available in Mac OS X v10.0 and later.

Declared In

MultiprocessingInfo.h

MPEventFlags

Represents event information for an event group.

typedef UInt32 MPEventFlags;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPEventID

Represents an event group ID, which Multiprocessing Services uses to manipulate event groups.

typedef struct OpaqueMPEventID * MPEventID;

Discussion

You obtain an event group ID by calling the function MPCreateEvent.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPEventInfo

struct MPEventInfo {
   PBVersion version;
   MPProcessID processID;
   OSType eventName;
   ItemCount nWaiting;
   MPTaskID waitingTaskID;
   MPEventFlags events;
};
typedef struct MPEventInfo MPEventInfo;

Availability

Available in Mac OS X v10.0 and later.

Declared In

MultiprocessingInfo.h

MPExceptionKind

Represents the kind of exception thrown.

typedef UInt32 MPExceptionKind;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPNotificationID

Represents a notification ID, which Multiprocessing Services uses to manipulate kernel notifications.

typedef struct OpaqueMPNotificationID * MPNotificationID;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPNotificationInfo

struct MPNotificationInfo {
   PBVersion version;
   MPProcessID processID;
   OSType notificationName;
   MPQueueID queueID;
   void * p1;
   void * p2;
   void * p3;
   MPEventID eventID;
   MPEventFlags events;
   MPSemaphoreID semaphoreID;
};
typedef struct MPNotificationInfo MPNotificationInfo;

Availability

Available in Mac OS X v10.0 and later.

Declared In

MultiprocessingInfo.h

MPOpaqueID

Represents a generic notification ID (that is, an ID that could be a queue ID, event ID, kernel notification ID, or semaphore ID).

typedef struct OpaqueMPOpaqueID * MPOpaqueID;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPOpaqueIDClass

typedef UInt32 MPOpaqueIDClass;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPPageSizeClass

typedef UInt32 MPPageSizeClass;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPProcessID

Represents a process ID.

typedef struct OpaqueMPProcessID * MPProcessID;

Discussion

Note that this process ID is identical to the process ID (or context ID) handled by the Code Fragment Manager.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPQueueID

Represents a queue ID, which Multiprocessing Services uses to manipulate message queues.

typedef struct OpaqueMPQueueID * MPQueueID;

Discussion

You obtain a queue ID by calling the function MPCreateQueue.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPQueueInfo

struct MPQueueInfo {
   PBVersion version;
   MPProcessID processID;
   OSType queueName;
   ItemCount nWaiting;
   MPTaskID waitingTaskID;
   ItemCount nMessages;
   ItemCount nReserved;
   void * p1;
   void * p2;
   void * p3;
};
typedef struct MPQueueInfo MPQueueInfo;

Availability

Available in Mac OS X v10.0 and later.

Declared In

MultiprocessingInfo.h

MPSemaphoreCount

Represents a semaphore count.

typedef ItemCount MPSemaphoreCount;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSemaphoreID

Represents a semaphore ID, which Multiprocessing Services uses to manipulate semaphores.

typedef struct OpaqueMPSemaphoreID * MPSemaphoreID;

Discussion

You obtain a semaphore ID by calling the function MPCreateSemaphore.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPSemaphoreInfo

struct MPSemaphoreInfo {
   PBVersion version;
   MPProcessID processID;
   OSType semaphoreName;
   ItemCount nWaiting;
   MPTaskID waitingTaskID;
   ItemCount maximum;
   ItemCount count;
};
typedef struct MPSemaphoreInfo MPSemaphoreInfo;

Availability

Available in Mac OS X v10.0 and later.

Declared In

MultiprocessingInfo.h

MPTaskID

Represents a task ID.

typedef struct OpaqueMPTaskID * MPTaskID;

Discussion

You obtain a task ID by calling the function MPCreateTask.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTaskInfo

Contains information about a task.

struct MPTaskInfo {
   PBVersion version;
   OSType name;
   OSType queueName;
   UInt16 runState;
   UInt16 lastCPU;
   UInt32 weight;
   MPProcessID processID;
   AbsoluteTime cpuTime;
   AbsoluteTime schedTime;
   AbsoluteTime creationTime;
   ItemCount codePageFaults;
   ItemCount dataPageFaults;
   ItemCount preemptions;
   MPCpuID cpuID;
   MPOpaqueID blockedObject;
   MPAddressSpaceID spaceID;
   LogicalAddress stackBase;
   LogicalAddress stackLimit;
   LogicalAddress stackCurr;
};
typedef struct MPTaskInfo MPTaskInfo;

Fields

version: The version of this data structure.
name: The name of the task.
queueName: A four-byte code indicating the status of the queue waiting on the task.
runState: The current state of the task (running, ready, or blocked).
lastCPU: The address of the last processor that ran this task.
weight: The weighting assigned to this task.
processID: The ID of the process that owns this task.
cpuTime: The accumulated CPU time used by the task.
schedTime: The time when the task was last scheduled.
creationTime: The time when the task was created.
codePageFaults: The number of page faults that occurred during code execution.
dataPageFaults: The number of page faults that occurred during data access.
preemptions: The number of times this task was preempted.
cpuID: The ID of the last processor that ran this task.
blockedObject: Reserved for use by Mac OS X.
spaceID: Address space ID of this task.
stackBase: The lowest memory address of the task’s stack.
stackLimit: The highest memory address of the task’s stack.
stackCurr: The current stack address.

Discussion

If you specify the kMPTaskStateTaskInfo constant when calling the function MPExtractTaskState , Multiprocessing Services returns state information in an MPTaskInfo structure.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTaskInfoVersion2

struct MPTaskInfoVersion2 {
   PBVersion version;
   OSType name;
   OSType queueName;
   UInt16 runState;
   UInt16 lastCPU;
   UInt32 weight;
   MPProcessID processID;
   AbsoluteTime cpuTime;
   AbsoluteTime schedTime;
   AbsoluteTime creationTime;
   ItemCount codePageFaults;
   ItemCount dataPageFaults;
   ItemCount preemptions;
   MPCpuID cpuID;
};
typedef struct MPTaskInfoVersion2 MPTaskInfoVersion2;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTaskStateKind

typedef UInt32 MPTaskStateKind;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTaskWeight

Represents the relative processor weighting of a task.

typedef UInt32 MPTaskWeight;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

MPTimerID

Represents a timer ID.

typedef struct OpaqueMPTimerID * MPTimerID;

Discussion

You obtain a timer ID by calling the function MPCreateTimer.

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

TaskStorageIndex

Represents a task storage index value used by functions described in “Accessing Per-Task Storage Variables.”

typedef ItemCount TaskStorageIndex;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

TaskStorageValue

Represents a task storage value used by functions described in “Accessing Per-Task Storage Variables.”

typedef LogicalAddress TaskStorageValue;

Availability

Available in Mac OS X v10.0 and later.

Declared In

Multiprocessing.h

Constants

Allocation constants

The maximum memory allocation size.

enum {
   kMPMaxAllocSize = 1024L * 1024 * 1024
};

Constants

kMPMaxAllocSize

The maximum allocation size: 1GB.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Task IDs

Use to specify no task ID.

enum {
   kMPNoID = kInvalidID
};

Constants

kMPNoID

No task ID.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Discussion

Used when calling MPTaskIsPreemptive if you want to specify the current task.

Data Structure Version Constants

Data structure version information constants.

enum {
   kMPQueueInfoVersion = 1L | (kOpaqueQueueID << 16),
   kMPSemaphoreInfoVersion = 1L | (kOpaqueSemaphoreID << 16),
   kMPEventInfoVersion = 1L | (kOpaqueEventID << 16),
   kMPCriticalRegionInfoVersion = 1L | (kOpaqueCriticalRegionID << 16),
   kMPNotificationInfoVersion = 1L | (kOpaqueNotificationID << 16),
   kMPAddressSpaceInfoVersion = 1L | (kOpaqueAddressSpaceID << 16)
};

Constants

kMPQueueInfoVersion

The MPQueueInfo structure version.

Available in Mac OS X v10.0 and later.

Declared in MultiprocessingInfo.h.

kMPSemaphoreInfoVersion

The MPSemaphoreInfo structure version.

Available in Mac OS X v10.0 and later.

Declared in MultiprocessingInfo.h.

kMPEventInfoVersion

The MPEventInfo structure version.

Available in Mac OS X v10.0 and later.

Declared in MultiprocessingInfo.h.

kMPCriticalRegionInfoVersion

The MPCriticalRegionInfo structure version.

Available in Mac OS X v10.0 and later.

Declared in MultiprocessingInfo.h.

kMPNotificationInfoVersion

The MPNotificationInfo structure version.

Available in Mac OS X v10.0 and later.

Declared in MultiprocessingInfo.h.

kMPAddressSpaceInfoVersion

The MPAddressSpaceInfo structure version.

Available in Mac OS X v10.1 and later.

Declared in MultiprocessingInfo.h.

Values for the MPOpaqueIDClass type

Constants indicating the source of a generic notification.

enum {
   kOpaqueAnyID = 0,
   kOpaqueProcessID = 1,
   kOpaqueTaskID = 2,
   kOpaqueTimerID = 3,
   kOpaqueQueueID = 4,
   kOpaqueSemaphoreID = 5,
   kOpaqueCriticalRegionID = 6,
   kOpaqueCpuID = 7,
   kOpaqueAddressSpaceID = 8,
   kOpaqueEventID = 9,
   kOpaqueCoherenceID = 10,
   kOpaqueAreaID = 11,
   kOpaqueNotificationID = 12,
   kOpaqueConsoleID = 13
};

Constants

kOpaqueAnyID

Any source.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueProcessID

A process.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueTaskID

A task.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueTimerID

A timer.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueQueueID

A queue.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueSemaphoreID

A semaphore.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueCriticalRegionID

A critical region.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueCpuID

A CPU.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueAddressSpaceID

An address space.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueEventID

An event.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueCoherenceID

A coherence group.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueAreaID

An area.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueNotificationID

A notification.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kOpaqueConsoleID

A console.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Memory Allocation Alignment Constants

Specify the alignment of the desired memory block when calling the MPAllocateAligned function.

enum {
   kMPAllocateDefaultAligned = 0,
   kMPAllocate8ByteAligned = 3,
   kMPAllocate16ByteAligned = 4,
   kMPAllocate32ByteAligned = 5,
   kMPAllocate1024ByteAligned = 10,
   kMPAllocate4096ByteAligned = 12,
   kMPAllocateMaxAlignment = 16,
   kMPAllocateAltiVecAligned = kMPAllocate16ByteAligned,
   kMPAllocateVMXAligned = kMPAllocateAltiVecAligned,
   kMPAllocateVMPageAligned = 254,
   kMPAllocateInterlockAligned = 255
};

Constants

kMPAllocateDefaultAligned

Use the default alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocate8ByteAligned

Use 8-byte alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocate16ByteAligned

Use 16-byte alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocate32ByteAligned

Use 32-byte alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocate1024ByteAligned

Use 1024-byte alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocate4096ByteAligned

Use 4096-byte alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateMaxAlignment

Use the maximum alignment (65536 byte).

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateAltiVecAligned

Use AltiVec alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateVMXAligned

Use VMX (now called AltiVec) alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateVMPageAligned

Use virtual memory page alignment. This alignment is set at runtime.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateInterlockAligned

Use interlock alignment, which is the alignment needed to allow the use of CPU interlock instructions (that is, lwarx and stwcx.) on the returned memory address. This alignment is set at runtime. In most cases you would never need to use this alignment.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Memory Allocation Option Constants

Specify optional actions when calling the MPAllocateAligned function.

enum {
   kMPAllocateClearMask = 0x0001,
   kMPAllocateGloballyMask = 0x0002,
   kMPAllocateResidentMask = 0x0004,
   kMPAllocateNoGrowthMask = 0x0010,
   kMPAllocateNoCreateMask = 0x0020
};

Constants

kMPAllocateClearMask

Zero out the allocated memory block.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateGloballyMask

Allocate memory from in memory space that is visible to all processes. Note that such globally-allocated space is not automatically reclaimed when the allocating process terminates. By default, MPAllocateAligned allocates memory from process-specific (that is, not global) memory.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateResidentMask

Allocate memory from resident memory only (that is, the allocated memory is not pageable).

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateNoGrowthMask

Do not attempt to grow the pool of available memory. Specifying this option is useful, as attempting to grow memory may cause your task to block until such memory becomes available.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPAllocateNoCreateMask

Do not attempt to create the pool if it does not yet exist.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

MPDebuggerLevel

Indicates the debugger level.

typedef UInt32 MPDebuggerLevel;
enum {
   kMPLowLevelDebugger = 0x00000000,
   kMPMidLevelDebugger = 0x10000000,
   kMPHighLevelDebugger = 0x20000000
};

Constants

kMPLowLevelDebugger

The low-level debugger.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

kMPMidLevelDebugger

The mid-level debugger.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

kMPHighLevelDebugger

The high-level debugger.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

Library Version Constants

Identifies the current library version.

enum {
   MPLibrary_MajorVersion = 2,
   MPLibrary_MinorVersion = 3,
   MPLibrary_Release = 1,
   MPLibrary_DevelopmentRevision = 1
};

Constants

MPLibrary_MajorVersion

Major version number.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

MPLibrary_MinorVersion

Minor version number.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

MPLibrary_Release

Release number.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

MPLibrary_DevelopmentRevision

Development revision number.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Remote Call Context Option Constants

Specify which contexts are allowed to execute the callback function when using MPRemoteCall.

enum {
   kMPAnyRemoteContext = 0,
   kMPOwningProcessRemoteContext = 1,
   kMPInterruptRemoteContext = 2,
   kMPAsyncInterruptRemoteContext = 3
};
typedef UInt8 MPRemoteContext;

Constants

kMPAnyRemoteContext

Any cooperative context can execute the function. Note that the called function may not have access to any of the owning context’s process-specific low-memory values.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPOwningProcessRemoteContext

Only the context that owns the task can execute the function.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPInterruptRemoteContext

Unsupported in Mac OS X.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

kMPAsyncInterruptRemoteContext

Unsupported in Mac OS X.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

Discussion

These constants are used to support older versions of Mac OS and are ignored in Mac OS X.

Task Creation Options

Specify optional actions when calling the MPCreateTask function.

enum {
   kMPCreateTaskSuspendedMask = 1L << 0,
   kMPCreateTaskTakesAllExceptionsMask = 1L << 1,
   kMPCreateTaskNotDebuggableMask = 1L << 2,
   kMPCreateTaskValidOptionsMask = kMPCreateTaskSuspendedMask | kMPCreateTaskTakesAllExceptionsMask | kMPCreateTaskNotDebuggableMask
};
typedef OptionBits MPTaskOptions;

Constants

kMPCreateTaskSuspendedMask

Unsupported in Mac OS X.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPCreateTaskTakesAllExceptionsMask

The task will take all exceptions, including those normally handled by the system, such as page faults.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPCreateTaskNotDebuggableMask

Unsupported in Mac OS X.

Available in Mac OS X v10.1 and later.

Declared in Multiprocessing.h.

kMPCreateTaskValidOptionsMask

Include all valid options for this task.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Task Exception Disposal Constants

Specify actions to take on an exception when passed in the action parameter of the MPDisposeTaskException function.

enum {
   kMPTaskPropagate = 0,
   kMPTaskResumeStep = 1,
   kMPTaskResumeBranch = 2,
   kMPTaskResumeMask = 0x0000,
   kMPTaskPropagateMask = 1 << kMPTaskPropagate,
   kMPTaskResumeStepMask = 1 << kMPTaskResumeStep,
   kMPTaskResumeBranchMask = 1 << kMPTaskResumeBranch
};

Constants

kMPTaskPropagate

The exception is propagated.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskResumeStep

The task is resumed and single step is enabled.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskResumeBranch

The task is resumed and branch stepping is enabled.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskResumeMask

Resume the task.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskPropagateMask

Propagate the exception to the next debugger level.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskResumeStepMask

Resume the task and enable single stepping.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskResumeBranchMask

Resume the task and enable branch stepping.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Task Information Structure Version Constant

Indicates the current version of the MPTaskInfo structure (returned as the first field).

enum {
   kMPTaskInfoVersion = 3
};

Constants

kMPTaskInfoVersion

The current version of the task information structure.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Task Run State Constants

Indicate the state of the task when returned as part of the MPTaskInfo data structure.

enum {
   kMPTaskBlocked = 0,
   kMPTaskReady = 1,
   kMPTaskRunning = 2
};

Constants

kMPTaskBlocked

The task is blocked..

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskReady

The task is ready for execution.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskRunning

The task is currently running.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Task State Constants

Specify what states you want to set or obtain when calling the MPExtractTaskState or MPSetTaskState functions.

enum {
   kMPTaskStateRegisters = 0,
   kMPTaskStateFPU = 1,
   kMPTaskStateVectors = 2,
   kMPTaskStateMachine = 3,
   kMPTaskState32BitMemoryException = 4,
   kMPTaskStateTaskInfo = 5
};

Constants

kMPTaskStateRegisters

The task’s general-purpose (GP) registers. The RegisterInformationPowerPC structure in MachineExceptions.h defines the format of this information.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskStateFPU

The task’s floating point registers. The FPUInformationPowerPC structure in MachineExceptions.h defines the format of this information.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskStateVectors

The task’s vector registers. The VectorInformationPowerPC structure in MachineExceptions.h defines the format of this information.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskStateMachine

The task’s machine registers. The MachineInformationPowerPC structure in MachineExceptions.h defines the format of this information. Note that the MSR, ExceptKind, DSISR, and DAR registers are read-only.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskState32BitMemoryException

The task’s exception information for older 32-bit memory exceptions (that is, memory exceptions on 32-bit CPUs). The MemoryExceptionInformation structure in MachineExceptions.h defines the format of this information. This exception information is read-only.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTaskStateTaskInfo

Static and dynamic information about the task, as described by the data structure MPTaskInfo. This task information is read-only.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Timer Duration Constants

Specify the maximum time a task should wait for an event to occur.

enum {
   kDurationImmediate = 0,
   kDurationForever = 0x7FFFFFFF,
   kDurationMillisecond = 1,
   kDurationMicrosecond = -1
};

Constants

kDurationImmediate

The task times out immediately, whether or not the event has occurred. If the event occurred, the return status is noErr. If the event did not occur, the return status is kMPTimeoutErr (assuming no other errors occurred).

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kDurationForever

The task waits forever. The blocking call waits until either the event occurs, or until the object being waited upon (such as a message queue) is deleted.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kDurationMillisecond

The task waits one millisecond before timing out.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kDurationMicrosecond

The task waits one microsecond before timing out.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Discussion

You can use these constants in conjunction with other values to indicate specific wait intervals. For example, to wait 1 second, you can pass kDurationMillisecond * 1000.

Timer Option Masks

Indicate optional actions when calling MPArmTimer.

enum {
   kMPPreserveTimerIDMask = 1L << 0,
   kMPTimeIsDeltaMask = 1L << 1,
   kMPTimeIsDurationMask = 1L << 2
};

Constants

kMPPreserveTimerIDMask

Specifying this mask prevents the timer from being deleted when it expires.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTimeIsDeltaMask

Specifying this mask indicates that the specified time should be added to the previous expiration time to form the new expiration time. You can use this mask to compensate for timing drift caused by the finite amount of time required to arm the timer, receive the notification, and so on.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

kMPTimeIsDurationMask

Specifying this mask indicates that the specified expiration time is of type Duration. You can use this mask to avoid having to call time conversion routines when specifying an expiration time.

Available in Mac OS X v10.0 and later.

Declared in Multiprocessing.h.

Result Codes

Result codes defined for Multiprocessing Services are listed below.

Result Code	Value	Description
`kMPIterationEndErr`	-29275	Available in Mac OS X v10.0 and later.
`kMPPrivilegedErr`	-29276	Available in Mac OS X v10.0 and later.
`kMPProcessCreatedErr`	-29288	Available in Mac OS X v10.0 and later.
`kMPProcessTerminatedErr`	-29289	Available in Mac OS X v10.0 and later.
`kMPTaskCreatedErr`	-29290	Available in Mac OS X v10.0 and later.
`kMPTaskBlockedErr`	-29291	The desired task is blocked. Available in Mac OS X v10.0 and later.
`kMPTaskStoppedErr`	-29292	The desired task is stopped. Available in Mac OS X v10.0 and later.
`kMPDeletedErr`	-29295	The desired notification the function was waiting upon was deleted. Available in Mac OS X v10.0 and later.
`kMPTimeoutErr`	-29296	The designated timeout interval passed before the function could take action. Available in Mac OS X v10.0 and later.
`kMPInsufficientResourcesErr`	-29298	Could not complete task due to unavailable Multiprocessing Services resources. Note that many functions return this value as a general error when the desired action could not be performed. Available in Mac OS X v10.0 and later.
`kMPInvalidIDErr`	-29299	Invalid ID value. For example, an invalid message queue ID was passed to `MPNotifyQueue`. Available in Mac OS X v10.0 and later.

Gestalt Constants

You can determine which system software calls are preemptively-safe for Multiprocessing Services by using the preemptive function attribute selectors defined in the Gestalt Manager. For more information, see Gestalt Manager Reference.

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