nsIMemory.idl
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- /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
- /* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is mozilla.org code.
- *
- * 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.
- *
- * Contributor(s):
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either of the GNU General Public License Version 2 or later (the "GPL"),
- * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
- #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();
- };