IMemoryManager Class Reference

#include <IMemoryManager.h>

Inheritance diagram for IMemoryManager:

Public Types
enum	{ kDefaultIID = IID_IMEMORYMANAGER }
enum	PurgeLevel {   kNoPurge = -1, kSwitchingDocuments = 0, kSwitchingApplications = 1, kLowMemory1 = 2,   kLowMemory2 = 3, kLowMemory3 = 4, kReleaseEverything = 5, kMaxMemoryLevel = 5 }
enum	MemoryState { kNormalMemoryState = 0, kConstrainedMemoryState = 1, kLowMemoryState = 2 }

Public Member Functions
virtual void	Init ()=0
virtual void	PurgeObjects (PurgeLevel purgeLevel)=0
virtual void	CheckMemoryState ()=0
virtual bool16	MemoryPanic ()=0
virtual bool16	CheckMemory (bool16 showAlerts=kFalse)=0
virtual bool16	MemoryIsLow ()=0
virtual bool16	MemoryIsFailing ()=0
virtual void	RegisterAdviseMemoryStateNotification (AdviseMemoryStateNotificationFunction func, void *refPtr)=0
virtual void	UnregisterAdviseMemoryStateNotification (AdviseMemoryStateNotificationFunction func, void *refPtr)=0
virtual uint32	GetPurgeCount () const =0
virtual uint32	GetPurgeTime () const =0
virtual bool16	PurgeInProgress () const =0
virtual bool16	HandleAllocationFailure (size_t blockSize)=0
virtual void	ResetFailureHandler ()=0
Register and de-register purge handlers
virtual void	RegisterMemoryNotification (MemoryNotificationFunction func, void *refPtr)=0
virtual void	RegisterNewMemoryNotification (NewMemoryNotificationFunction func, void *refPtr, bool16 bGrowZoneFailSafe)=0
virtual void	UnregisterMemoryNotification (MemoryNotificationFunction func, void *refPtr)=0
virtual void	UnregisterNewMemoryNotification (NewMemoryNotificationFunction func, void *refPtr)=0
Public Member Functions inherited from IPMUnknown
virtual IPMUnknown *	QueryInterface (PMIID interfaceID) const =0
virtual void	AddRef () const =0
virtual void	Release () const =0

Detailed Description

The memory manager keeps track of the memory load, and acts as a central handler for memory issues.

Member Enumeration Documentation

enum IMemoryManager::MemoryState

Load on memory

Enumerator
kNormalMemoryState	Normal state, there is plenty of memory
kConstrainedMemoryState	Heap is relatively full, around 10-20% free (a good time to fix sizes of caches)
kLowMemoryState	Heap is very full, less than 5% free (a good time to reduce memory footprint)

enum IMemoryManager::PurgeLevel

Every purge request has a priority attached to it, which is the PurgeLevel.

Enumerator
kNoPurge	Used to indicate no purge is necessary
kSwitchingDocuments	Called when document focus changes, releases document oriented caches
kSwitchingApplications	Called when the application is being switched out, releases temporary memory
kLowMemory1	Called when memory is getting tight
kLowMemory2	Called when memory is getting more tight
kLowMemory3	Called when memory is getting even more tight
kReleaseEverything	Called when a memory request is about to fail. Release all caches.
kMaxMemoryLevel	Attempt to free up memory by unloading plug-ins. Called only on the Mac, when a plug-in fails to load. Purge handlers will not get this level.

Member Function Documentation

virtual bool16 IMemoryManager::CheckMemory ( bool16  showAlerts = kFalse )

pure virtual

If CheckMemory() returns kFalse the application should quit asap.

virtual void IMemoryManager::CheckMemoryState ( )

pure virtual

Checks available memory and notifies registered memory state clients so thay can make caching algorithm adjustments.

virtual uint32 IMemoryManager::GetPurgeCount ( ) const

pure virtual

Return the number of times PurgeObjects has been called

virtual uint32 IMemoryManager::GetPurgeTime ( ) const

pure virtual

Returns the cumulative time spent in PurgeObjects

virtual bool16 IMemoryManager::HandleAllocationFailure ( size_t  blockSize )

pure virtual

Called when an allocation fails. It will attempt to free some memory by calling the purge handlers. Returns true if it made any progress and the caller should retry the allocation, false if no progress was made and we should give up.

Parameters

blockSize

[IN] - the size of the block that the allocator failed to allocate.

virtual bool16 IMemoryManager::MemoryIsFailing ( )

pure virtual

If MemoryIsFailing() returns kTrue the application should quit asap

virtual bool16 IMemoryManager::MemoryIsLow ( )

pure virtual

If MemoryIsLow returns kTrue certain methods and commands will not work.

virtual bool16 IMemoryManager::MemoryPanic ( )

pure virtual

Tries to free the last memory reserves. The memory manager maintains a reserve emergency block of memory that can be freed in order to satisfy memory requests when all other attempts have failed. These blocks will be reacquired as soon as the application judges the memory state has improved.

Returns

kTrue if it released any emergency block and the caller should retry, kFalse if no emergency blocks were available

virtual bool16 IMemoryManager::PurgeInProgress ( ) const

pure virtual

Returns true if a memory purge is in progress for the calling thread. Note that the function can return false, but other threads can be purging. Reserved for internal use only.

virtual void IMemoryManager::PurgeObjects ( PurgeLevel  purgeLevel )

pure virtual

Tries to free some memory. Calls out to the purge handlers and requests them to free up memory. PurgeObjects is called by the new fail handler.

Parameters

purgeLevel,the

priority level of the request

virtual void IMemoryManager::RegisterAdviseMemoryStateNotification ( AdviseMemoryStateNotificationFunction  func, void *  refPtr  )

pure virtual

Register a memory state notification function.

Parameters

func	the memory state notification function to register
refPtr	the pointer to pass the function when it's called

virtual void IMemoryManager::RegisterMemoryNotification ( MemoryNotificationFunction  func, void *  refPtr  )

pure virtual

Register a purge handler.

Parameters

func	the memory notification function to register
refPtr	the pointer to pass the function when it's called

virtual void IMemoryManager::RegisterNewMemoryNotification ( NewMemoryNotificationFunction  func, void *  refPtr, bool16  bGrowZoneFailSafe  )

pure virtual

Register a purge handler.

Parameters

func	the memory notification function to register
refPtr	the pointer to pass the function when it's called

virtual void IMemoryManager::ResetFailureHandler ( )

pure virtual

Resets the failure handler into its initial state. Called after the failure handler was invoked (one or more times) in order to reset the purge level back to normal. Reserved for internal use only.

virtual void IMemoryManager::UnregisterAdviseMemoryStateNotification ( AdviseMemoryStateNotificationFunction  func, void *  refPtr  )

pure virtual

De-register a memory state notification function.

Parameters

func	the memory state notification function to de-register
refPtr	the pointer to pass the function when it's called

virtual void IMemoryManager::UnregisterMemoryNotification ( MemoryNotificationFunction  func, void *  refPtr  )

pure virtual

De-register a purge handler.

Parameters

func	the memory notification function to register
refPtr	the pointer to pass the function when it's called

virtual void IMemoryManager::UnregisterNewMemoryNotification ( NewMemoryNotificationFunction  func, void *  refPtr  )

pure virtual

De-register a purge handler.

Parameters

func	the memory notification function to register
refPtr	the pointer to pass the function when it's called