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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.
*
* 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();
};
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