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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/trace_event/heap_profiler_allocation_context.h"
#include <cstring>
#include "base/hash.h"
#include "base/macros.h"
namespace base {
namespace trace_event {
// Constructor that does not initialize members.
AllocationContext::AllocationContext() {}
// static
AllocationContext AllocationContext::Empty() {
AllocationContext ctx;
for (size_t i = 0; i < arraysize(ctx.backtrace.frames); i++)
ctx.backtrace.frames[i] = nullptr;
ctx.type_id = 0;
return ctx;
}
bool operator==(const Backtrace& lhs, const Backtrace& rhs) {
// Pointer equality of the stack frames is assumed, so instead of doing a deep
// string comparison on all of the frames, a |memcmp| suffices.
return std::memcmp(lhs.frames, rhs.frames, sizeof(lhs.frames)) == 0;
}
bool operator==(const AllocationContext& lhs, const AllocationContext& rhs) {
return (lhs.backtrace == rhs.backtrace) && (lhs.type_id == rhs.type_id);
}
} // namespace trace_event
} // namespace base
namespace BASE_HASH_NAMESPACE {
using base::trace_event::AllocationContext;
using base::trace_event::Backtrace;
size_t hash<Backtrace>::operator()(const Backtrace& backtrace) const {
return base::SuperFastHash(reinterpret_cast<const char*>(backtrace.frames),
sizeof(backtrace.frames));
}
size_t hash<AllocationContext>::operator()(const AllocationContext& ctx) const {
size_t ctx_hash = hash<Backtrace>()(ctx.backtrace);
// 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. The type ID is assumed to be distributed randomly
// already so there is no need to hash it.
return (ctx_hash * 3) + static_cast<size_t>(ctx.type_id);
}
} // BASE_HASH_NAMESPACE
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