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