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| * The Initial Developer of the Original Code is |
| * Netscape Communications Corporation. |
| * Portions created by the Initial Developer are Copyright (C) 1998 |
| * the Initial Developer. All Rights Reserved. |
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| |
| #include "nsISupports.idl" |
| |
| /** |
| * |
| * nsIMemory: interface to allocate and deallocate memory. Also provides |
| * for notifications in low-memory situations. |
| * |
| * The frozen exported symbols NS_Alloc, NS_Realloc, and NS_Free |
| * provide a more efficient way to access XPCOM memory allocation. Using |
| * those symbols is preferred to using the methods on this interface. |
| * |
| * A client that wishes to be notified of low memory situations (for |
| * example, because the client maintains a large memory cache that |
| * could be released when memory is tight) should register with the |
| * observer service (see nsIObserverService) using the topic |
| * "memory-pressure". There are three specific types of notications |
| * that can occur. These types will be passed as the |aData| |
| * parameter of the of the "memory-pressure" notification: |
| * |
| * "low-memory" |
| * This will be passed as the extra data when the pressure |
| * observer is being asked to flush for low-memory conditions. |
| * |
| * "heap-minimize" |
| * This will be passed as the extra data when the pressure |
| * observer is being asked to flush because of a heap minimize |
| * call. |
| * |
| * "alloc-failure" |
| * This will be passed as the extra data when the pressure |
| * observer has been asked to flush because a malloc() or |
| * realloc() has failed. |
| * |
| * @status FROZEN |
| */ |
| |
| [scriptable, uuid(59e7e77a-38e4-11d4-8cf5-0060b0fc14a3)] |
| interface nsIMemory : nsISupports |
| { |
| /** |
| * Allocates a block of memory of a particular size. If the memory |
| * cannot be allocated (because of an out-of-memory condition), null |
| * is returned. |
| * |
| * @param size - the size of the block to allocate |
| * @result the block of memory |
| */ |
| [noscript, notxpcom] voidPtr alloc(in size_t size); |
| |
| /** |
| * Reallocates a block of memory to a new size. |
| * |
| * @param ptr - the block of memory to reallocate |
| * @param size - the new size |
| * @result the reallocated block of memory |
| * |
| * If ptr is null, this function behaves like malloc. |
| * If s is the size of the block to which ptr points, the first |
| * min(s, size) bytes of ptr's block are copied to the new block. |
| * If the allocation succeeds, ptr is freed and a pointer to the |
| * new block returned. If the allocation fails, ptr is not freed |
| * and null is returned. The returned value may be the same as ptr. |
| */ |
| [noscript, notxpcom] voidPtr realloc(in voidPtr ptr, |
| in size_t newSize); |
| |
| /** |
| * Frees a block of memory. Null is a permissible value, in which case |
| * nothing happens. |
| * |
| * @param ptr - the block of memory to free |
| */ |
| [noscript, notxpcom] void free(in voidPtr ptr); |
| |
| /** |
| * Attempts to shrink the heap. |
| * @param immediate - if true, heap minimization will occur |
| * immediately if the call was made on the main thread. If |
| * false, the flush will be scheduled to happen when the app is |
| * idle. |
| * @return NS_ERROR_FAILURE if 'immediate' is set an the call |
| * was not on the application's main thread. |
| */ |
| void heapMinimize(in boolean immediate); |
| |
| /** |
| * This predicate can be used to determine if we're in a low-memory |
| * situation (what constitutes low-memory is platform dependent). This |
| * can be used to trigger the memory pressure observers. |
| */ |
| boolean isLowMemory(); |
| }; |
| |