| // -*- 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: |
| constexpr PageHeapAllocator() = default; |
| |
| // 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) { |
| #ifndef NDEBUG |
| memset(static_cast<void*>(p), 0xAA, sizeof(T)); |
| #endif |
| *(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_; |
| }; |
| |
| // STL-compatible allocator which forwards allocations to a PageHeapAllocator. |
| // |
| // Like PageHeapAllocator, this requires external synchronization. To avoid multiple |
| // separate STLPageHeapAllocator<T> from sharing the same underlying PageHeapAllocator<T>, |
| // the |LockingTag| template argument should be used. Template instantiations with |
| // different locking tags can safely be used concurrently. |
| template <typename T, class LockingTag> |
| class STLPageHeapAllocator { |
| public: |
| typedef size_t size_type; |
| typedef ptrdiff_t difference_type; |
| typedef T* pointer; |
| typedef const T* const_pointer; |
| typedef T& reference; |
| typedef const T& const_reference; |
| typedef T value_type; |
| |
| template <class T1> struct rebind { |
| typedef STLPageHeapAllocator<T1, LockingTag> other; |
| }; |
| |
| STLPageHeapAllocator() { } |
| STLPageHeapAllocator(const STLPageHeapAllocator&) { } |
| template <class T1> STLPageHeapAllocator(const STLPageHeapAllocator<T1, LockingTag>&) { } |
| ~STLPageHeapAllocator() { } |
| |
| pointer address(reference x) const { return &x; } |
| const_pointer address(const_reference x) const { return &x; } |
| |
| size_type max_size() const { return size_t(-1) / sizeof(T); } |
| |
| void construct(pointer p, const T& val) { ::new(p) T(val); } |
| void construct(pointer p) { ::new(p) T(); } |
| void destroy(pointer p) { p->~T(); } |
| |
| // There's no state, so these allocators are always equal |
| bool operator==(const STLPageHeapAllocator&) const { return true; } |
| bool operator!=(const STLPageHeapAllocator&) const { return false; } |
| |
| pointer allocate(size_type n, const void* = 0) { |
| if (!underlying_.initialized) { |
| underlying_.allocator.Init(); |
| underlying_.initialized = true; |
| } |
| |
| CHECK_CONDITION(n == 1); |
| return underlying_.allocator.New(); |
| } |
| void deallocate(pointer p, size_type n) { |
| CHECK_CONDITION(n == 1); |
| underlying_.allocator.Delete(p); |
| } |
| |
| private: |
| struct Storage { |
| constexpr Storage() = default; |
| PageHeapAllocator<T> allocator; |
| bool initialized; |
| }; |
| static inline Storage underlying_; |
| }; |
| |
| } // namespace tcmalloc |
| |
| #endif // TCMALLOC_PAGE_HEAP_ALLOCATOR_H_ |