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// Copyright 2016 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/macros.h"
#include "base/memory/ref_counted.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/lock.h"
#include "components/metrics/public/interfaces/call_stack_profile_collector.mojom.h"
namespace service_manager {
class InterfaceProvider;
namespace metrics {
// ChildCallStackProfileCollector collects stacks at startup, caching them
// internally until a CallStackProfileCollector interface is available. If a
// CallStackProfileCollector is provided via the InterfaceProvider supplied to
// SetParentProfileCollector, the cached stacks are sent via that interface. All
// future stacks received via callbacks supplied by GetProfilerCallback are sent
// via that interface as well.
// If no CallStackProfileCollector is provided via InterfaceProvider, any cached
// stacks and all future stacks received via callbacks supplied by
// GetProfilerCallback are flushed. In typical usage this should not happen
// because the browser is expected to always supply a CallStackProfileCollector.
// This class is only necessary if a CallStackProfileCollector is not available
// at the time the profiler is created. Otherwise the CallStackProfileCollector
// can be used directly.
// To use, create as a leaky lazy instance:
// base::LazyInstance<metrics::ChildCallStackProfileCollector>::Leaky
// g_call_stack_profile_collector = LAZY_INSTANCE_INITIALIZER;
// Then, invoke CreateCompletedCallback() to generate the CompletedCallback to
// pass when creating the StackSamplingProfiler.
// When the mojo InterfaceProvider becomes available, provide it via
// SetParentProfileCollector().
class ChildCallStackProfileCollector {
// Get a callback for use with StackSamplingProfiler that provides completed
// profiles to this object. The callback should be immediately passed to the
// StackSamplingProfiler, and should not be reused between
// StackSamplingProfilers. This function may be called on any thread.
base::StackSamplingProfiler::CompletedCallback GetProfilerCallback(
const CallStackProfileParams& params);
// Sets the CallStackProfileCollector interface from |parent_collector|. This
// function MUST be invoked exactly once, regardless of whether
// |parent_collector| is null, as it flushes pending data in either case.
void SetParentProfileCollector(
metrics::mojom::CallStackProfileCollectorPtr parent_collector);
friend class ChildCallStackProfileCollectorTest;
// Bundles together a set of collected profiles and the collection state for
// storage, pending availability of the parent mojo interface. |profiles|
// is not const& because it must be passed with std::move.
struct ProfilesState {
const CallStackProfileParams& params,
base::TimeTicks start_timestamp,
base::StackSamplingProfiler::CallStackProfiles profiles);
ProfilesState& operator=(ProfilesState&&);
CallStackProfileParams params;
base::TimeTicks start_timestamp;
// The sampled profiles.
base::StackSamplingProfiler::CallStackProfiles profiles;
using CallStackProfile = base::StackSamplingProfiler::CallStackProfile;
void Collect(const CallStackProfileParams& params,
base::TimeTicks start_timestamp,
std::vector<CallStackProfile> profiles);
// This object may be accessed on any thread, including the profiler
// thread. The expected use case for the object is to be created and have
// GetProfilerCallback before the message loop starts, which prevents the use
// of PostTask and the like for inter-thread communication.
base::Lock lock_;
// Whether to retain profiles when the interface is not set. Remains true
// until the invocation of SetParentProfileCollector(), at which point it is
// false for the rest of the object lifetime.
bool retain_profiles_ = true;
// The task runner associated with the parent interface.
scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
// The interface to use to collect the stack profiles provided to this
// object. Initially null until SetParentProfileCollector() is invoked, at
// which point it may either become set or remain null. If set, stacks are
// collected via the interface, otherwise they are ignored.
mojom::CallStackProfileCollectorPtr parent_collector_;
// Profiles being cached by this object, pending a parent interface to be
// supplied.
std::vector<ProfilesState> profiles_;
} // namespace metrics