gecko-dev/modules/libjar/nsZlibAllocator.h

104 lines
3.2 KiB
C++

/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** 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) 2001
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either 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 ***** */
/*
* Allocator for zlib optimized for mozilla's use
*
*/
#define NBUCKETS 6
#define BY4ALLOC_ITEMS 320
class nsZlibAllocator;
extern nsZlibAllocator *gZlibAllocator;
class nsZlibAllocator {
public:
struct nsMemBucket {
void *ptr;
PRUint32 size;
// Is this bucket available ?
// 1 : free
// 0 or negative : in use
// This is an int because we use atomic inc/dec to operate on it
PRInt32 available;
};
nsMemBucket mMemBucket[NBUCKETS];
nsZlibAllocator() {
memset(mMemBucket, 0, sizeof(mMemBucket));
for (PRUint32 i = 0; i < NBUCKETS; i++)
mMemBucket[i].available = 1;
return;
}
~nsZlibAllocator() {
for (PRUint32 i = 0; i < NBUCKETS; i++)
{
PRBool claimed = Claim(i);
// ASSERT that we claimed the bucked. If we cannot, then the bucket is in use.
// We dont attempt to free this ptr.
// This will most likely cause a leak of this memory.
PR_ASSERT(claimed);
// Free bucket memory if not in use
if (claimed && mMemBucket[i].ptr)
free(mMemBucket[i].ptr);
}
}
// zlib allocators
void* zAlloc(PRUint32 items, PRUint32 size);
void zFree(void *ptr);
// Bucket handling.
PRBool Claim(PRUint32 i) {
PRBool claimed = (PR_AtomicDecrement(&mMemBucket[i].available) == 0);
// Undo the claim, if claim failed
if (!claimed)
Unclaim(i);
return claimed;
}
void Unclaim(PRUint32 i) { PR_AtomicIncrement(&mMemBucket[i].available); }
};