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130 lines
4.5 KiB
Plaintext
130 lines
4.5 KiB
Plaintext
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
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*
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* The contents of this file are subject to the Netscape Public
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* License Version 1.1 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.mozilla.org/NPL/
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*
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* Software distributed under the License is distributed on an "AS
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* IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
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* implied. See the License for the specific language governing
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* rights and limitations under the License.
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*
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* The Original Code is mozilla.org code.
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*
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* The Initial Developer of the Original Code is Netscape
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* Communications Corporation. Portions created by Netscape are
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* Copyright (C) 1998 Netscape Communications Corporation. All
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* Rights Reserved.
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*
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* Contributor(s):
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*/
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/**
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* <font color="#FF0000"><b> W A R N I N G
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* <p>This API is currently under review in preparation for making it an
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* officially supported part of the mozilla platform. Please submit comments
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* to porkjockeys@mozilla.org before 6/15/00. Until that time, it is not
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* advised to base commercial products on this API because it is subject to
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* change. Use at your own risk!
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* </b></font>
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*
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* @status UNDER_REVIEW
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*/
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#include "nsISupports.idl"
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interface nsIMemoryPressureObserver;
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/**
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* nsIMemory: interface to allocate and deallocate memory. Also provides
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* for notifications in low-memory situations.
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*/
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[scriptable, uuid(59e7e77a-38e4-11d4-8cf5-0060b0fc14a3)]
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interface nsIMemory : nsISupports
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{
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/**
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* Allocates a block of memory of a particular size. If the memory
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* cannot be allocated (because of an out-of-memory condition), null
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* is returned.
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*
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* @param size - the size of the block to allocate
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* @result the block of memory
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*/
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[noscript, notxpcom] voidPtr alloc(in size_t size);
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/**
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* Reallocates a block of memory to a new size.
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*
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* @param ptr - the block of memory to reallocate
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* @param size - the new size
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* @result the reallocated block of memory
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*
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* If ptr is null, this function behaves like malloc.
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* If s is the size of the block to which ptr points, the first
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* min(s, size) bytes of ptr's block are copied to the new block.
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* If the allocation succeeds, ptr is freed and a pointer to the
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* new block returned. If the allocation fails, ptr is not freed
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* and null is returned. The returned value may be the same as ptr.
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*/
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[noscript, notxpcom] voidPtr realloc(in voidPtr ptr,
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in size_t newSize);
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/**
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* Frees a block of memory. Null is a permissible value, in which case
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* nothing happens.
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*
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* @param ptr - the block of memory to free
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*/
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[noscript, notxpcom] void free(in voidPtr ptr);
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/**
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* Attempts to shrink the heap.
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*/
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void heapMinimize();
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/**
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* Allows a memory pressure observer to be registered to provide a
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* callback for low-memory situations, allowing unnecessary objects to
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* be freed (e.g. flushing caches). Observers will be called either
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* before alloc or realloc are about to return null, or when
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* heapMinimize is called.
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* @param obs - the observer to register
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*/
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void registerObserver(in nsIMemoryPressureObserver obs);
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/**
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* Allows a memory pressure observer to be unregistered.
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* @param obs - the observer to unregister
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*/
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void unregisterObserver(in nsIMemoryPressureObserver obs);
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/**
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* This predicate can be used to determine if we're in a low-memory
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* situation (what constitutes low-memory is platform dependent). This
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* can be used to trigger the memory flushers.
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*/
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boolean isLowMemory();
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};
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/**
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* nsIMemoryPressureObserver: interface for low-memory notification.
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*/
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[scriptable, uuid(fe6c8bd4-38e4-11d4-8cf5-0060b0fc14a3)]
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interface nsIMemoryPressureObserver : nsISupports
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{
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const unsigned long REASON_ALLOC_FAILURE = 0;
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const unsigned long REASON_HEAP_MINIMIZE = 1;
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/**
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* Called in response to a low-memory condition.
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* @param reason - either REASON_ALLOC_FAILURE when alloc or realloc
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* fails, or REASON_HEAP_MINIMIZE when heapMinimize is
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* called
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* @param requestedAmount - either the size requested by alloc or realloc,
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* or 0 if heapMinimize was called
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*/
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void flushMemory(in unsigned long reason,
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in size_t requestedAmount);
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};
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