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- // -*- Mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*-
- // Copyright (c) 2008, Google Inc.
- // All rights reserved.
- //
- // Redistribution and use in source and binary forms, with or without
- // modification, are permitted provided that the following conditions are
- // met:
- //
- // * Redistributions of source code must retain the above copyright
- // notice, this list of conditions and the following disclaimer.
- // * Redistributions in binary form must reproduce the above
- // copyright notice, this list of conditions and the following disclaimer
- // in the documentation and/or other materials provided with the
- // distribution.
- // * Neither the name of Google Inc. nor the names of its
- // contributors may be used to endorse or promote products derived from
- // this software without specific prior written permission.
- //
- // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
- // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
- // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
- // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
- // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- // ---
- // Author: Sanjay Ghemawat <opensource@google.com>
- #ifndef TCMALLOC_PAGE_HEAP_ALLOCATOR_H_
- #define TCMALLOC_PAGE_HEAP_ALLOCATOR_H_
- #include <stddef.h> // for NULL, size_t
- #include "common.h" // for MetaDataAlloc
- #include "internal_logging.h" // for ASSERT
- namespace tcmalloc {
- // Simple allocator for objects of a specified type. External locking
- // is required before accessing one of these objects.
- template <class T>
- class PageHeapAllocator {
- public:
- // We use an explicit Init function because these variables are statically
- // allocated and their constructors might not have run by the time some
- // other static variable tries to allocate memory.
- void Init() {
- ASSERT(sizeof(T) <= kAllocIncrement);
- inuse_ = 0;
- free_area_ = NULL;
- free_avail_ = 0;
- free_list_ = NULL;
- // Reserve some space at the beginning to avoid fragmentation.
- Delete(New());
- }
- T* New() {
- // Consult free list
- void* result;
- if (free_list_ != NULL) {
- result = free_list_;
- free_list_ = *(reinterpret_cast<void**>(result));
- } else {
- if (free_avail_ < sizeof(T)) {
- // Need more room. We assume that MetaDataAlloc returns
- // suitably aligned memory.
- free_area_ = reinterpret_cast<char*>(MetaDataAlloc(kAllocIncrement));
- if (free_area_ == NULL) {
- Log(kCrash, __FILE__, __LINE__,
- "FATAL ERROR: Out of memory trying to allocate internal "
- "tcmalloc data (bytes, object-size)",
- kAllocIncrement, sizeof(T));
- }
- free_avail_ = kAllocIncrement;
- }
- result = free_area_;
- free_area_ += sizeof(T);
- free_avail_ -= sizeof(T);
- }
- inuse_++;
- return reinterpret_cast<T*>(result);
- }
- void Delete(T* p) {
- *(reinterpret_cast<void**>(p)) = free_list_;
- free_list_ = p;
- inuse_--;
- }
- int inuse() const { return inuse_; }
- private:
- // How much to allocate from system at a time
- static const int kAllocIncrement = 128 << 10;
- // Free area from which to carve new objects
- char* free_area_;
- size_t free_avail_;
- // Free list of already carved objects
- void* free_list_;
- // Number of allocated but unfreed objects
- int inuse_;
- };
- } // namespace tcmalloc
- #endif // TCMALLOC_PAGE_HEAP_ALLOCATOR_H_
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