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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();
+};
+