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// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/40284755): Remove this and spanify to fix the errors.
#pragma allow_unsafe_buffers
#endif
#include "base/trace_event/heap_profiler_allocation_context.h"
#include <algorithm>
#include <array>
#include <cstring>
#include "base/containers/span.h"
#include "base/hash/hash.h"
namespace base::trace_event {
bool operator<(const StackFrame& lhs, const StackFrame& rhs) {
return lhs.value < rhs.value;
}
bool operator==(const StackFrame& lhs, const StackFrame& rhs) {
return lhs.value == rhs.value;
}
Backtrace::Backtrace() = default;
bool operator==(const Backtrace& lhs, const Backtrace& rhs) {
if (lhs.frame_count != rhs.frame_count) {
return false;
}
return std::equal(lhs.frames, lhs.frames + lhs.frame_count, rhs.frames);
}
AllocationContext::AllocationContext() : type_name(nullptr) {}
AllocationContext::AllocationContext(const Backtrace& backtrace,
const char* type_name)
: backtrace(backtrace), type_name(type_name) {}
} // namespace base::trace_event
namespace std {
using base::trace_event::AllocationContext;
using base::trace_event::Backtrace;
using base::trace_event::StackFrame;
size_t hash<StackFrame>::operator()(const StackFrame& frame) const {
return hash<const void*>()(frame.value.get());
}
size_t hash<Backtrace>::operator()(const Backtrace& backtrace) const {
std::array<const void*, Backtrace::kMaxFrameCount> values;
for (size_t i = 0; i != backtrace.frame_count; ++i) {
values[i] = backtrace.frames[i].value;
}
return base::PersistentHash(
base::as_bytes(base::span(values).first(backtrace.frame_count)));
}
size_t hash<AllocationContext>::operator()(const AllocationContext& ctx) const {
size_t backtrace_hash = hash<Backtrace>()(ctx.backtrace);
// Multiplicative hash from [Knuth 1998]. Works best if |size_t| is 32 bits,
// because the magic number is a prime very close to 2^32 / golden ratio, but
// will still redistribute keys bijectively on 64-bit architectures because
// the magic number is coprime to 2^64.
size_t type_hash = reinterpret_cast<size_t>(ctx.type_name) * 2654435761;
// Multiply one side to break the commutativity of +. Multiplication with a
// number coprime to |numeric_limits<size_t>::max() + 1| is bijective so
// randomness is preserved.
return (backtrace_hash * 3) + type_hash;
}
} // namespace std
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