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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sw=2 et tw=80:
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
#include "gc/MallocedBlockCache.h"
#include "mozilla/MemoryChecking.h"
using js::PointerAndUint7;
using js::gc::MallocedBlockCache;
MallocedBlockCache::~MallocedBlockCache() { clear(); }
// This is the fallback path for MallocedBlockCache::alloc. Do not call this
// directly, since it doesn't handle all cases by itself. See ::alloc for
// further comments.
PointerAndUint7 MallocedBlockCache::allocSlow(size_t size) {
// We're never expected to handle zero-sized blocks.
MOZ_ASSERT(size > 0);
size = js::RoundUp(size, STEP);
size_t i = size / STEP;
MOZ_ASSERT(i > 0);
// Too large to cache; go straight to js_malloc.
if (MOZ_UNLIKELY(i >= NUM_LISTS)) {
void* p = js_malloc(size);
// If p is nullptr, that fact is carried into the PointerAndUint7, and the
// caller is expected to check that.
return PointerAndUint7(p, OVERSIZE_BLOCK_LIST_ID);
}
// The block is of cacheable size, but we expect the relevant list to be
// empty, because ::alloc will have handled the case where it wasn't.
MOZ_ASSERT(i >= 1 && i < NUM_LISTS);
// Check that i is the right list
MOZ_ASSERT(i * STEP == size);
MOZ_RELEASE_ASSERT(lists[i].empty());
// And so we have to hand the request off to js_malloc.
void* p = js_malloc(size);
if (MOZ_UNLIKELY(!p)) {
return PointerAndUint7(nullptr, 0); // OOM
}
return PointerAndUint7(p, i);
}
void MallocedBlockCache::preen(double percentOfBlocksToDiscard) {
MOZ_ASSERT(percentOfBlocksToDiscard >= 0.0 &&
percentOfBlocksToDiscard <= 100.0);
MOZ_ASSERT(lists[OVERSIZE_BLOCK_LIST_ID].empty());
for (size_t listID = 1; listID < NUM_LISTS; listID++) {
MallocedBlockVector& list = lists[listID];
size_t numToFree =
size_t(float(list.length()) * (percentOfBlocksToDiscard / 100.0));
MOZ_RELEASE_ASSERT(numToFree <= list.length());
while (numToFree > 0) {
void* block = list.popCopy();
MOZ_ASSERT(block);
js_free(block);
numToFree--;
}
}
}
void MallocedBlockCache::clear() {
MOZ_ASSERT(lists[OVERSIZE_BLOCK_LIST_ID].empty());
for (size_t i = 1; i < NUM_LISTS; i++) {
MallocedBlockVector& list = lists[i];
for (void*& block : list) {
MOZ_ASSERT(block);
js_free(block);
block = nullptr; // for safety
}
list.clear();
}
}
size_t MallocedBlockCache::sizeOfExcludingThis(
mozilla::MallocSizeOf mallocSizeOf) const {
MOZ_ASSERT(lists[OVERSIZE_BLOCK_LIST_ID].empty());
size_t nBytes = 0;
for (const MallocedBlockVector& list : lists) {
nBytes += list.sizeOfExcludingThis(mallocSizeOf);
// The payload size of each block in `list` is the same. Hence, we could
// possibly do better here (measure once and multiply by the length) if we
// believe that the metadata size for each block is also the same.
for (void* block : list) {
MOZ_ASSERT(block);
nBytes += mallocSizeOf(block);
}
}
return nBytes;
}