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/* 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, You can obtain one at https://mozilla.org/MPL/2.0/. */
#ifndef BASEALLOC_H
#define BASEALLOC_H
#include "Mutex.h"
// The base allocator is a simple memory allocator used internally by
// mozjemalloc for its own structures.
class BaseAlloc {
public:
constexpr BaseAlloc() {};
void Init() MOZ_REQUIRES(gInitLock);
void* alloc(size_t aSize);
void* calloc(size_t aNumber, size_t aSize);
Mutex mMutex;
struct Stats {
size_t mMapped = 0;
size_t mCommitted = 0;
};
Stats GetStats() MOZ_EXCLUDES(mMutex) {
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mStats.mMapped >= mStats.mCommitted);
return mStats;
}
private:
// Allocate fresh pages to satsify at least minsize.
bool pages_alloc(size_t minsize) MOZ_REQUIRES(mMutex);
// BaseAlloc uses bump-pointer allocation from mNextAddr. In general
// mNextAddr <= mNextDecommitted <= mPastAddr.
//
// If an allocation would cause mNextAddr > mPastAddr then a new chunk is
// required (from pages_alloc()). Else-if an allocation would case
// mNextAddr > mNextDecommitted then some of the memory is decommitted and
// pages_committ() is needed before the memory can be used.
uintptr_t mNextAddr MOZ_GUARDED_BY(mMutex) = 0;
uintptr_t mNextDecommitted MOZ_GUARDED_BY(mMutex) = 0;
// Address immediately past the current chunk of pages.
uintptr_t mPastAddr MOZ_GUARDED_BY(mMutex) = 0;
Stats mStats MOZ_GUARDED_BY(mMutex);
};
extern BaseAlloc sBaseAlloc;
// A specialization of the base allocator with a free list.
template <typename T>
struct TypedBaseAlloc {
static T* sFirstFree;
static size_t size_of() { return sizeof(T); }
static T* alloc() {
{
MutexAutoLock lock(sBaseAlloc.mMutex);
T* ret = sFirstFree;
if (ret) {
sFirstFree = *(T**)ret;
return ret;
}
}
return (T*)sBaseAlloc.alloc(size_of());
}
static void dealloc(T* aNode) {
MutexAutoLock lock(sBaseAlloc.mMutex);
*(T**)aNode = sFirstFree;
sFirstFree = aNode;
}
};
template <typename T>
T* TypedBaseAlloc<T>::sFirstFree = nullptr;
template <typename T>
struct BaseAllocFreePolicy {
void operator()(T* aPtr) { TypedBaseAlloc<T>::dealloc(aPtr); }
};
#endif /* ! BASEALLOC_H */
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