зеркало из https://github.com/mozilla/pjs.git
bug 118061 First version of nsRecyclingAllocator r=dveditz sr=sfraser
This commit is contained in:
dp%netscape.com
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a39dd81ba9
Коммит
10f15d75f3
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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* 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
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2001, 2002
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Suresh Duddi <dp@netscape.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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/*
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* nsRecyclingAllocator
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include "nsRecyclingAllocator.h"
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#include "nsITimer.h"
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#define NS_SEC_TO_MS(s) ((s) * 1000)
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void
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nsRecyclingAllocator::nsRecycleTimerCallback(nsITimer *aTimer, void *aClosure)
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{
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nsRecyclingAllocator *obj = (nsRecyclingAllocator *) aClosure;
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if (!obj->mTouched)
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{
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#ifdef DEBUG_dp
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printf("DEBUG: nsRecyclingAllocator not touched: %d allocations avaliable\n", obj->mNAllocations);
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#endif
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if (obj->mNAllocations)
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obj->FreeUnusedBuckets();
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}
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else
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{
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// Clear touched so the next time the timer fires we can test whether
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// the allocator was used or not.
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obj->Untouch();
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}
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}
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nsRecyclingAllocator::nsRecyclingAllocator(PRUint32 nbucket, PRUint32 recycleAfter)
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: mNBucket(nbucket), mRecycleTimer(nsnull), mRecycleAfter(recycleAfter), mTouched(0),
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mNAllocations(0)
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{
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NS_ASSERTION(mNBucket <= NS_MAX_BUCKETS, "Too many buckets. This will affect the allocator's performance.");
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if (mNBucket > NS_MAX_BUCKETS)
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{
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mNBucket = NS_MAX_BUCKETS;
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}
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mMemBucket = (nsMemBucket *) calloc(mNBucket, sizeof(nsMemBucket));
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if (!mMemBucket)
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mNBucket = 0;
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else
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{
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for (PRUint32 i = 0; i < mNBucket; i++)
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mMemBucket[i].available = 1;
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// Setup timer for releasing memory
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// If this fails, then we wont have a timer to release unused memory. We can live with that.
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(void) NS_NewTimer(&mRecycleTimer, nsRecycleTimerCallback, this,
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NS_SEC_TO_MS(mRecycleAfter), NS_PRIORITY_LOWEST, NS_TYPE_REPEATING_SLACK);
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}
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}
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nsRecyclingAllocator::~nsRecyclingAllocator()
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{
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// Cancel and destroy recycle timer
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if (mRecycleTimer) {
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mRecycleTimer->Cancel();
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NS_RELEASE(mRecycleTimer);
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}
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// Free all memory held, if any
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if (mNAllocations)
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for (PRUint32 i = 0; i < mNBucket; i++)
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{
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PRBool claimed = Claim(i);
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// ASSERT that we claimed the bucked. If we cannot, then the bucket is in use.
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// We dont attempt to free this ptr.
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// This will most likely cause a leak of this memory.
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NS_ASSERTION(claimed, "~nsRecycledAllocator: Bucket memory still in use.");
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// Free bucket memory if not in use
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if (claimed && mMemBucket[i].ptr)
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free(mMemBucket[i].ptr);
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}
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}
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// Allocation and free routines
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void*
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nsRecyclingAllocator::Malloc(PRUint32 bytes, PRBool zeroit)
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{
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PRInt32 availableBucketIndex = -1;
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PRUint32 i;
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PRUint32 size;
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void *ptr;
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// Mark that we are using. This will prevent any
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// timer based release of unused memory.
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Touch();
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for (i = 0; i < mNBucket; i++)
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{
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size = mMemBucket[i].size;
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ptr = mMemBucket[i].ptr;
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// Dont look at buckets with no memory allocated or less memory than
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// what we need.
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// Can we do this check without claiming the bucket? I think we can
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// because the next thing we do is try claim this bucket.
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if (!ptr || size < bytes)
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continue;
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// Try Claim a bucket. If we cant, skip it.
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if (!Claim(i))
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continue;
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if (size == bytes)
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{
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// Let go of any freeAllocatedBucket that we claimed
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if (availableBucketIndex >= 0)
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Unclaim(availableBucketIndex);
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memset(ptr, bytes, 0);
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return ptr;
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}
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// Meanwhile, remember a free allocated bucket.
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// At this point we know the bucket is not in use and it has more
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// than what we need
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if (availableBucketIndex < 0)
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availableBucketIndex = i;
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else
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{
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// See if this bucket is closer to what we need
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if (size < mMemBucket[availableBucketIndex].size)
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{
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Unclaim(availableBucketIndex);
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availableBucketIndex = i;
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}
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else
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// Undo our claim as availableBucketIndex does better than this one
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Unclaim(i);
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}
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}
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// See if we have an allocated bucket
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if (availableBucketIndex >= 0) {
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ptr = mMemBucket[availableBucketIndex].ptr;
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memset(ptr, bytes, 0);
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return ptr;
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}
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// We dont have that memory already
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// Allocate.
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ptr = zeroit ? calloc(1, bytes) : malloc(bytes);
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// Take care of no memory and no free slot situation
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if (!ptr || mNAllocations == (PRInt32)mNBucket)
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return ptr;
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// Find a free unallocated bucket and store allocation
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for (i = 0; i < mNBucket; i++)
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{
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// If bucket cannot be calimed, continue search.
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if (!Claim(i))
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continue;
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if (!mMemBucket[i].ptr)
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{
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// Found free slot. Store it
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mMemBucket[i].ptr = ptr;
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mMemBucket[i].size = bytes;
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PR_AtomicIncrement(&mNAllocations);
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return ptr;
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}
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// This is an already allocated bucket. Cant use this one.
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Unclaim(i);
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}
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#ifdef DEBUG_dp
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// Warn if we are failing over to malloc and not storing it
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// This says we have a misdesigned memory pool. The intent was
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// once the pool was full, we would never fail over to calloc.
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printf("nsRecyclingAllocator::malloc %d - FAILOVER 0x%p Memory pool has sizes: ",
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bytes, ptr);
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for (i = 0; i < mNBucket; i++)
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{
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printf("%d ", mMemBucket[i].size);
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}
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printf("\n");
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#endif
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return ptr;
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}
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void
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nsRecyclingAllocator::Free(void *ptr)
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{
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// Mark that we are using the allocator. This will prevent any
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// timer based release of unused memory.
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Touch();
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for (PRUint32 i = 0; i < mNBucket; i++)
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{
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if (mMemBucket[i].ptr == ptr)
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{
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// Ah ha. One of the slots we allocated.
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// Nothing to do. Mark it unused.
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Unclaim(i);
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return;
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}
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}
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// Failover to free
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free(ptr);
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}
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/* FreeUnusedBuckets
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*
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* Frees any bucket memory that isn't in use
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*/
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void
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nsRecyclingAllocator::FreeUnusedBuckets()
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{
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#ifdef DEBUG_dp
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printf("DEBUG: nsRecyclingAllocator::FreeUnusedBuckets: ");
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#endif
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if (!mNAllocations)
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return;
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for (PRUint32 i = 0; i < mNBucket; i++)
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{
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if (Claim(i))
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{
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if (mMemBucket[i].ptr)
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{
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#ifdef DEBUG_dp
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printf("%d ", mMemBucket[i].size);
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#endif
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free(mMemBucket[i].ptr);
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mMemBucket[i].ptr = nsnull;
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mMemBucket[i].size = 0;
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PR_AtomicDecrement(&mNAllocations);
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}
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Unclaim(i);
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}
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}
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#ifdef DEBUG_dp
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printf("\n");
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#endif
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}
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@ -0,0 +1,151 @@
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/* -*- Mode: C; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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||||
/* ***** BEGIN LICENSE BLOCK *****
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||||
* 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
|
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* the License. You may obtain a copy of the License at
|
||||
* http://www.mozilla.org/MPL/
|
||||
*
|
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* Software distributed under the License is distributed on an "AS IS" basis,
|
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
|
||||
* for the specific language governing rights and limitations under the
|
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* 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
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* Netscape Communications Corporation.
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* Portions created by the Initial Developer are Copyright (C) 2001, 2002
|
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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* Suresh Duddi <dp@netscape.com>
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
|
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
|
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* in which case the provisions of the GPL or the LGPL are applicable instead
|
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* 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.
|
||||
*
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* ***** END LICENSE BLOCK ***** */
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/*
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* nsRecyclingAllocator
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*
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* This allocator is useful when we cycle through a small set of allocations
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* repeatedly with minimal overlap. For eg. something we do for every gif
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* file read (or) buffers required for decompression of every file from jar.
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*
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* What this does is keeps around the first set of memory allocated and
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* reuses it subsequently. If all buckets are full, this falls back to
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* malloc/free
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*
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* Uses a timer to release all memory allocated if not used for more than
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* 10 secs automatically.
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*
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* This allocator is thread safe.
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*
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* CAVEATS: As the number of buckets increases, this allocators performance
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* will drop. As a general guideline, dont use this for more
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* than NS_MAX_BUCKETS (10)
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*/
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#ifndef nsRecyclingAllocator_h__
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#define nsRecyclingAllocator_h__
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#include "nscore.h"
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#include "pratom.h"
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#define NS_DEFAULT_RECYCLE_TIMEOUT 10 // secs
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#define NS_MAX_BUCKETS 10
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class nsITimer;
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class NS_COM nsRecyclingAllocator {
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protected:
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struct nsMemBucket {
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void *ptr;
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PRUint32 size;
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// Is this bucket available ?
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// 1 : free
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// 0 or negative : in use
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// This is an int because we use atomic inc/dec to operate on it
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PRInt32 available;
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};
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PRUint32 mNBucket;
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nsMemBucket *mMemBucket;
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nsITimer *mRecycleTimer;
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PRUint32 mRecycleAfter;
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// mTouched : says if the allocator touched any bucket
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// If allocator didn't touch any bucket over a time
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// time interval, timer will call FreeUnusedBuckets()
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PRInt32 mTouched;
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// mNAllocations: says how many buckets still have memory.
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// If all buckets were freed the last time
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// around and allocator didn't touch any bucket, then
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// there is nothing to be freed.
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PRInt32 mNAllocations;
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public:
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nsRecyclingAllocator(PRUint32 nbucket, PRUint32 recycleAfter = NS_DEFAULT_RECYCLE_TIMEOUT);
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~nsRecyclingAllocator();
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// Allocation and free routines
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void* Malloc(PRUint32 size, PRBool zeroit = PR_FALSE);
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void Free(void *ptr);
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void* Calloc(PRUint32 items, PRUint32 size)
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{
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return Malloc(items * size, PR_TRUE);
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}
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// FreeUnusedBuckets - Frees any bucket memory that isn't in use
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void FreeUnusedBuckets();
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protected:
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// Timer callback to trigger unused memory
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static void nsRecycleTimerCallback(nsITimer *aTimer, void *aClosure);
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// Bucket handling
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PRBool Claim(PRUint32 i)
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{
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PRBool claimed = (PR_AtomicDecrement(&mMemBucket[i].available) == 0);
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// Undo the claim, if claim failed
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if (!claimed)
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Unclaim(i);
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return claimed;
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}
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void Unclaim(PRUint32 i) { PR_AtomicIncrement(&mMemBucket[i].available); }
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// Touch will mark that someone used this allocator
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// Timer based release will free unused memory only if allocator
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// was not touched for mRecycleAfter seconds.
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void Touch() {
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if (!mTouched)
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PR_AtomicSet(&mTouched, 1);
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}
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void Untouch() {
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PR_AtomicSet(&mTouched, 0);
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}
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friend void nsRecycleTimerCallback(nsITimer *aTimer, void *aClosure);
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};
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#endif // nsRecyclingAllocator_h__
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