source: vbox/trunk/src/libs/xpcom18a4/xpcom/glue/nsMemory.h@ 31232

/* -*- 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 ***** */

#ifndef nsMemory_h__
#define nsMemory_h__

#include "nsIMemory.h"

#define NS_MEMORY_CONTRACTID "@mozilla.org/xpcom/memory-service;1"
#define NS_MEMORY_CLASSNAME  "Global Memory Service"
#define NS_MEMORY_CID                                \
{ /* 30a04e40-38e7-11d4-8cf5-0060b0fc14a3 */         \
    0x30a04e40,                                      \
    0x38e7,                                          \
    0x11d4,                                          \
    {0x8c, 0xf5, 0x00, 0x60, 0xb0, 0xfc, 0x14, 0xa3} \
}


/**
 * Static helper routines to manage memory. These routines allow easy access
 * to xpcom's built-in (global) nsIMemory implementation, without needing
 * to go through the service manager to get it. However this requires clients
 * to link with the xpcom DLL. 
 *
 * This class is not threadsafe and is intented for use only on the main
 * thread.
 */
class nsMemory
{
public:
    static NS_COM void*      Alloc(size_t size);
    static NS_COM void*      Realloc(void* ptr, size_t size);
    static NS_COM void       Free(void* ptr);
    static NS_COM nsresult   HeapMinimize(PRBool aImmediate);
    static NS_COM void*      Clone(const void* ptr, size_t size);
    static NS_COM nsIMemory* GetGlobalMemoryService();       // AddRefs
};

/** 
 * Macro to free all elements of an XPCOM array of a given size using
 * freeFunc, then frees the array itself using nsMemory::Free().  
 *
 * Note that this macro (and its wrappers) can be used to deallocate a
 * partially- or completely-built array while unwinding an error
 * condition inside the XPCOM routine that was going to return the
 * array.  For this to work on a partially-built array, your code
 * needs to be building the array from index 0 upwards, and simply
 * pass the number of elements that have already been built (and thus
 * need to be freed) as |size|.
 *
 * Thanks to <[email protected]> for suggesting this form, which
 * allows the macro to be used with NS_RELEASE / NS_RELEASE_IF in
 * addition to nsMemory::Free.
 * 
 * @param size      Number of elements in the array.  If not a constant, this 
 *                  should be a PRInt32.  Note that this means this macro 
 *                  will not work if size >= 2^31.
 * @param array     The array to be freed.
 * @param freeFunc  The function or macro to be used to free it. 
 *                  For arrays of nsISupports (or any class derived
 *                  from it), NS_IF_RELEASE (or NS_RELEASE) should be
 *                  passed as freeFunc.  For most (all?) other pointer
 *                  types (including XPCOM strings and wstrings),
 *                  nsMemory::Free should be used, since the
 *                  shared-allocator (nsMemory) is what will have been
 *                  used to allocate the memory.  
 */
#define NS_FREE_XPCOM_POINTER_ARRAY(size, array, freeFunc)                    \
    PR_BEGIN_MACRO                                                            \
        PRInt32 iter_ = PRInt32(size);                                        \
        while (--iter_ >= 0)                                                  \
            freeFunc((array)[iter_]);                                         \
        nsMemory::Free((array));                                              \
    PR_END_MACRO

// convenience macros for commonly used calls.  mmmmm.  syntactic sugar.

/** 
 * Macro to free arrays of non-refcounted objects allocated by the
 * shared allocator (nsMemory) such as strings and wstrings.  A
 * convenience wrapper around NS_FREE_XPCOM_POINTER_ARRAY.
 *
 * @param size      Number of elements in the array.  If not a constant, this 
 *                  should be a PRInt32.  Note that this means this macro 
 *                  will not work if size >= 2^31.
 * @param array     The array to be freed.
 */
#define NS_FREE_XPCOM_ALLOCATED_POINTER_ARRAY(size, array)                    \
    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), nsMemory::Free)

/**
 * Macro to free an array of pointers to nsISupports (or classes
 * derived from it).  A convenience wrapper around
 * NS_FREE_XPCOM_POINTER_ARRAY.
 *
 * Note that if you know that none of your nsISupports pointers are
 * going to be 0, you can gain a bit of speed by calling
 * NS_FREE_XPCOM_POINTER_ARRAY directly and using NS_RELEASE as your
 * free function.
 *
 * @param size      Number of elements in the array.  If not a constant, this 
 *                  should be a PRInt32.  Note that this means this macro 
 *                  will not work if size >= 2^31.
 * @param array     The array to be freed.
 */
#define NS_FREE_XPCOM_ISUPPORTS_POINTER_ARRAY(size, array)                    \
    NS_FREE_XPCOM_POINTER_ARRAY((size), (array), NS_IF_RELEASE)

/**
 * Helpful array length function for calculating the length of a
 * statically declared array.
 */

#define NS_ARRAY_LENGTH(array_) \
  (sizeof(array_)/sizeof(array_[0]))


#endif // nsMemory_h__