Manager: Memory Manager

Carbon will support the majority of the Memory Manager programming interface. Changes will primarily affect applications that use zones, system memory, or temporary memory. For example, temporary memory allocations in Mac OS X will be allocated in the application's address space. As a result, calling TempNewHandle will effectively be the same as calling NewHandle.

Carbon will not support current functions for accessing the system heap, but Apple will provide new routines to allocate shared and persistent memory. In addition, the virtual memory system in Mac OS X will introduce a number of changes in the addressing model.

The following Memory Manager functions are likely to change in Carbon: GZSaveHnd, MoreMasters, and TempNewHandle.

The following Memory Manager functions are still under evaluation: GetZone, HandleZone, InitZone, PtrZone, SetGrowZone, and SetZone. Please give us feedback on the importance of using subzones in your applications.

The following Memory Manager functions will not be supported in Carbon: MaxBlockSys, MaxMemSys, NewEmptyHandleSys, NewHandleSys, NewHandleSysClear, NewPtrSys, NewPtrSysClear, PurgeMemSys, PurgeSpaceSysContiguous, PurgeSpaceSysTotal, ReallocateHandleSys, RecoverHandleSys, RecoverMemSys, and SystemZone.

The following Virtual Memory functions are likely to change in Carbon: FlushMemory, MakeMemoryNonResident, MakeMemoryResident, and ReleaseMemoryData.

By adhering to the following guidelines, you can increase your application's compliance with Mac OS X memory management:

* Try to use memory only within your own application heap. Review the places where you allocate memory in the system heap.

* Do not pass pointers to data among applications through Apple events, Gestalt routines, or other means. For example, don't share Toolbox data structures between applications, because in Mac OS X, each application will run in its own protected address space.

* Do not use inline, hard-coded addresses.

* Do not use the following Memory Manager functions: EnterSupervisorMode, StripAddress, Translate24To32.

* Do not modify a field in a zone header to specify how many master pointer blocks are allocated by each call to the function MoreMasters. The Memory Manager will supply a new version of the MoreMasters function that allows you to specify the number of master pointer blocks to allocate. Note, however, that master pointer blocks do not need to be preallocated or optimized in the Mac OS X memory model, so the new function will provide the most benefit for applications running on previous versions of the Mac OS.

* Don't make assumptions about the layout of memory, such as the relative position of data stored in heaps, stacks, and other memory areas.

* Don't use the DisposePtr or DisposeHandle functions on pointers or handles allocated by Toolbox managers. For example, don't call the function DisposeHandle on a control allocated with the function NewControl--use DisposeControl instead.

* Because Mac OS X applications will run in a large, protected memory space, memory sizing routines such as MaxMem and FreeMem will work differently than they do now.

 ApplicationZone

 BlockMove

 BlockMoveData

 BlockMoveDataUncached

 BlockMoveUncached

 BlockZero

 BlockZeroUncached

 CompactMem

 CompactMemSys

 DebuggerEnter

 DebuggerExit

 DebuggerGetMax

 DebuggerLockMemory

 DebuggerPoll

 DebuggerUnlockMemory

 DeferUserFn

 DisposeHandle

 DisposePtr

 EmptyHandle

 EnterSupervisorMode

 FlushMemory

 FreeMem

 FreeMemSys

 GetApplLimit

 GetHandleSize

 GetPageState

 GetPhysical

 GetPtrSize

 GetZone

 GZSaveHnd

 HandAndHand

 HandleZone

 HandToHand

 HClrRBit

 HGetState

 HLock

 HLockHi

 HNoPurge

 HoldMemory

 HPurge

 HSetRBit

 HSetState

 HUnlock

 InitApplZone

 InitZone

 InlineGetHandleSize

 LockMemory

 LockMemoryContiguous

 LockMemoryForOutput

 MakeMemoryNonResident

 MakeMemoryResident

 MaxApplZone

 MaxBlock

 MaxBlockSys

 MaxMem

 MaxMemSys

 MemError

 MoreMasters

MoreMasters will have a longint parameter for specifying the number of master pointers to allocate in the block. Specifying a number less than 32 will result in 32 master pointers in the allocated block, the current standard allocation.

 MoveHHi

 NewEmptyHandle

 NewEmptyHandleSys

 NewHandle

 NewHandleClear

 NewHandleSys

 NewHandleSysClear

 NewPtr

 NewPtrClear

 NewPtrSys

 NewPtrSysClear

 PageFaultFatal

 PtrAndHand

 PtrToHand

 PtrToXHand

 PtrZone

 PurgeMem

 PurgeMemSys

 PurgeSpace

 ReallocateHandle

 ReallocateHandleSys

 RecoverHandle

 RecoverHandleSys

 ReleaseMemoryData

 ReserveMem

 ReserveMemSys

 SetApplBase

 SetApplLimit

 SetGrowZone

 SetHandleSize

 SetPtrSize

 SetZone

 StackSpace

 SystemZone

 TempDisposeHandle

 TempFreeMem

 TempHLock

 TempHUnlock

 TempMaxMem

 TempNewHandle

Temporary memory allocations will actually come from the applications's address space in Mac OS X. However, Carbon applications running under Mac OS 8.x will be able to get true temporary memory.

 TempTopMem

 TopMem

 UnholdMemory

 UnlockMemory