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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "components/performance_manager/scenario_api/performance_scenarios.h"
#include <optional>
#include <utility>
#include "base/memory/read_only_shared_memory_region.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/structured_shared_memory.h"
#include "base/no_destructor.h"
#include "base/notreached.h"
#include "base/types/pass_key.h"
#include "components/performance_manager/scenario_api/performance_scenario_observer.h"
namespace performance_scenarios {
namespace {
// Global pointers to the shared memory mappings.
scoped_refptr<RefCountedScenarioMapping>& MappingPtrForScope(
ScenarioScope scope) {
static base::NoDestructor<scoped_refptr<RefCountedScenarioMapping>>
current_process_mapping;
static base::NoDestructor<scoped_refptr<RefCountedScenarioMapping>>
global_mapping;
switch (scope) {
case ScenarioScope::kCurrentProcess:
return *current_process_mapping;
case ScenarioScope::kGlobal:
return *global_mapping;
}
NOTREACHED();
}
// Returns the scenario state from `mapping`, or a default empty state if
// `mapping` is null (which can happen if no ScopedReadOnlyScenarioMemory exists
// or if the mapping failed). Takes a raw pointer instead of a scoped_ptr to
// avoid refcount churn.
const ScenarioState& GetScenarioStateFromMapping(
const RefCountedScenarioMapping* mapping) {
static constinit ScenarioState kDummyScenarioState;
return mapping ? mapping->data.ReadOnlyRef() : kDummyScenarioState;
}
} // namespace
// TODO(crbug.com/365586676): Currently these are only mapped into browser and
// renderer processes. The global scenarios should also be mapped into utility
// processes.
ScopedReadOnlyScenarioMemory::ScopedReadOnlyScenarioMemory(
ScenarioScope scope,
base::ReadOnlySharedMemoryRegion region)
: scope_(scope) {
using SharedScenarioState = base::StructuredSharedMemory<ScenarioState>;
std::optional<SharedScenarioState::ReadOnlyMapping> mapping =
SharedScenarioState::MapReadOnlyRegion(std::move(region));
if (mapping.has_value()) {
MappingPtrForScope(scope_) =
base::MakeRefCounted<RefCountedScenarioMapping>(
std::move(mapping.value()));
}
// The ObserverList must be created after mapping the memory, because it reads
// the scenario state in its constructor.
PerformanceScenarioObserverList::CreateForScope(
base::PassKey<ScopedReadOnlyScenarioMemory>(), scope_);
}
ScopedReadOnlyScenarioMemory::~ScopedReadOnlyScenarioMemory() {
PerformanceScenarioObserverList::DestroyForScope(
base::PassKey<ScopedReadOnlyScenarioMemory>(), scope_);
MappingPtrForScope(scope_).reset();
}
// static
scoped_refptr<RefCountedScenarioMapping>
ScopedReadOnlyScenarioMemory::GetMappingForTesting(ScenarioScope scope) {
return MappingPtrForScope(scope);
}
SharedAtomicRef<LoadingScenario> GetLoadingScenario(ScenarioScope scope) {
scoped_refptr<RefCountedScenarioMapping> mapping = MappingPtrForScope(scope);
return SharedAtomicRef<LoadingScenario>(
mapping, GetScenarioStateFromMapping(mapping.get()).loading);
}
SharedAtomicRef<InputScenario> GetInputScenario(ScenarioScope scope) {
scoped_refptr<RefCountedScenarioMapping> mapping = MappingPtrForScope(scope);
return SharedAtomicRef<InputScenario>(
mapping, GetScenarioStateFromMapping(mapping.get()).input);
}
bool CurrentScenariosMatch(ScenarioScope scope, ScenarioPattern pattern) {
return ScenariosMatch(
GetLoadingScenario(scope)->load(std::memory_order_relaxed),
GetInputScenario(scope)->load(std::memory_order_relaxed), pattern);
}
bool ScenariosMatch(LoadingScenario loading_scenario,
InputScenario input_scenario,
ScenarioPattern pattern) {
bool loading_matches =
pattern.loading.empty() || pattern.loading.Has(loading_scenario);
bool input_matches =
pattern.input.empty() || pattern.input.Has(input_scenario);
return loading_matches && input_matches;
}
} // namespace performance_scenarios
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