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89 lines
2.8 KiB
C++
89 lines
2.8 KiB
C++
// Copyright 2015 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/trace_event/heap_profiler_allocation_context.h"
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#include <cstring>
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#include "base/hash.h"
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#include "base/macros.h"
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namespace base {
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namespace trace_event {
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bool operator < (const StackFrame& lhs, const StackFrame& rhs) {
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return lhs.value < rhs.value;
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}
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bool operator == (const StackFrame& lhs, const StackFrame& rhs) {
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return lhs.value == rhs.value;
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}
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bool operator != (const StackFrame& lhs, const StackFrame& rhs) {
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return !(lhs.value == rhs.value);
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}
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Backtrace::Backtrace() = default;
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bool operator==(const Backtrace& lhs, const Backtrace& rhs) {
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if (lhs.frame_count != rhs.frame_count) return false;
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return std::equal(lhs.frames, lhs.frames + lhs.frame_count, rhs.frames);
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}
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bool operator!=(const Backtrace& lhs, const Backtrace& rhs) {
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return !(lhs == rhs);
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}
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AllocationContext::AllocationContext(): type_name(nullptr) {}
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AllocationContext::AllocationContext(const Backtrace& backtrace,
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const char* type_name)
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: backtrace(backtrace), type_name(type_name) {}
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bool operator==(const AllocationContext& lhs, const AllocationContext& rhs) {
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return (lhs.backtrace == rhs.backtrace) && (lhs.type_name == rhs.type_name);
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}
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bool operator!=(const AllocationContext& lhs, const AllocationContext& rhs) {
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return !(lhs == rhs);
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}
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} // namespace trace_event
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} // namespace base
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namespace std {
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using base::trace_event::AllocationContext;
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using base::trace_event::Backtrace;
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using base::trace_event::StackFrame;
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size_t hash<StackFrame>::operator()(const StackFrame& frame) const {
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return hash<const void*>()(frame.value);
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}
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size_t hash<Backtrace>::operator()(const Backtrace& backtrace) const {
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const void* values[Backtrace::kMaxFrameCount];
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for (size_t i = 0; i != backtrace.frame_count; ++i) {
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values[i] = backtrace.frames[i].value;
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}
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return base::PersistentHash(values, backtrace.frame_count * sizeof(*values));
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}
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size_t hash<AllocationContext>::operator()(const AllocationContext& ctx) const {
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size_t backtrace_hash = hash<Backtrace>()(ctx.backtrace);
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// Multiplicative hash from [Knuth 1998]. Works best if |size_t| is 32 bits,
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// because the magic number is a prime very close to 2^32 / golden ratio, but
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// will still redistribute keys bijectively on 64-bit architectures because
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// the magic number is coprime to 2^64.
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size_t type_hash = reinterpret_cast<size_t>(ctx.type_name) * 2654435761;
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// Multiply one side to break the commutativity of +. Multiplication with a
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// number coprime to |numeric_limits<size_t>::max() + 1| is bijective so
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// randomness is preserved.
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return (backtrace_hash * 3) + type_hash;
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}
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} // namespace std
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