Make Tracing Service not use outgoing InterfaceProvider, update conventions

services/tracing/public/cpp/provider.cc

+// 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 "services/tracing/public/cpp/provider.h"
+
+#include <utility>
+
+#include "base/callback.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/platform_thread.h"
+#include "base/time/time.h"
+#include "base/trace_event/trace_config.h"
+#include "base/trace_event/trace_event.h"
+#include "services/shell/public/cpp/connection.h"
+#include "services/shell/public/cpp/connector.h"
+#include "services/tracing/public/cpp/switches.h"
+
+namespace tracing {
+namespace {
+
+// Controls access to |g_tracing_singleton_created|, which can be accessed from
+// different threads.
+base::LazyInstance<base::Lock>::Leaky g_singleton_lock =
+    LAZY_INSTANCE_INITIALIZER;
+
+// Whether we are the first TracingImpl to be created in this mojo
+// application. The first TracingImpl in a physical mojo application connects
+// to the mojo:tracing service.
+//
+// If this is a ContentHandler, it will outlive all its served Applications. If
+// this is a raw mojo application, it is the only Application served.
+bool g_tracing_singleton_created = false;
+
+}
+
+Provider::Provider()
+    : binding_(this), tracing_forced_(false), weak_factory_(this) {}
+
+Provider::~Provider() {
+  StopTracing();
+}
+
+void Provider::Initialize(shell::Connector* connector, const std::string& url) {
+  {
+    base::AutoLock lock(g_singleton_lock.Get());
+    if (g_tracing_singleton_created)
+      return;
+    g_tracing_singleton_created = true;
+  }
+
+  // This will only set the name for the first app in a loaded mojo file. It's
+  // up to something like CoreServices to name its own child threads.
+  base::PlatformThread::SetName(url);
+
+  mojom::FactoryPtr factory;
+  connector->ConnectToInterface("mojo:tracing", &factory);
+  mojom::ProviderPtr provider;
+  Bind(GetProxy(&provider));
+  factory->CreateRecorder(std::move(provider));
+#ifdef NDEBUG
+  if (base::CommandLine::ForCurrentProcess()->HasSwitch(
+          tracing::kEarlyTracing)) {
+    ForceEnableTracing();
+  }
+#else
+  ForceEnableTracing();
+#endif
+}
+
+void Provider::Bind(mojom::ProviderRequest request) {
+  if (!binding_.is_bound()) {
+    binding_.Bind(std::move(request));
+  } else {
+    LOG(ERROR) << "Cannot accept two connections to TraceProvider.";
+  }
+}
+
+void Provider::StartTracing(const std::string& categories,
+                            mojom::RecorderPtr recorder) {
+  DCHECK(!recorder_);
+  recorder_ = std::move(recorder);
+  tracing_forced_ = false;
+  if (!base::trace_event::TraceLog::GetInstance()->IsEnabled()) {
+    base::trace_event::TraceLog::GetInstance()->SetEnabled(
+        base::trace_event::TraceConfig(categories,
+                                       base::trace_event::RECORD_UNTIL_FULL),
+        base::trace_event::TraceLog::RECORDING_MODE);
+  }
+}
+
+void Provider::StopTracing() {
+  if (recorder_) {
+    base::trace_event::TraceLog::GetInstance()->SetDisabled();
+
+    base::trace_event::TraceLog::GetInstance()->Flush(
+        base::Bind(&Provider::SendChunk, base::Unretained(this)));
+  }
+}
+
+void Provider::ForceEnableTracing() {
+  base::trace_event::TraceLog::GetInstance()->SetEnabled(
+      base::trace_event::TraceConfig("*", base::trace_event::RECORD_UNTIL_FULL),
+      base::trace_event::TraceLog::RECORDING_MODE);
+  tracing_forced_ = true;
+  base::MessageLoop::current()->task_runner()->PostTask(
+      FROM_HERE,
+      base::Bind(&Provider::DelayedStop, weak_factory_.GetWeakPtr()));
+}
+
+void Provider::DelayedStop() {
+  // We use this indirection to account for cases where the Initialize method
+  // takes more than one second to finish; thus we start the countdown only when
+  // the current thread is unblocked.
+  base::MessageLoop::current()->task_runner()->PostDelayedTask(
+      FROM_HERE,
+      base::Bind(&Provider::StopIfForced, weak_factory_.GetWeakPtr()),
+      base::TimeDelta::FromSeconds(1));
+}
+
+void Provider::StopIfForced() {
+  if (!tracing_forced_) {
+    return;
+  }
+  base::trace_event::TraceLog::GetInstance()->SetDisabled();
+  base::trace_event::TraceLog::GetInstance()->Flush(
+      base::Callback<void(const scoped_refptr<base::RefCountedString>&,
+                          bool)>());
+}
+
+void Provider::SendChunk(
+    const scoped_refptr<base::RefCountedString>& events_str,
+    bool has_more_events) {
+  DCHECK(recorder_);
+  // The string will be empty if an error eccured or there were no trace
+  // events. Empty string is not a valid chunk to record so skip in this case.
+  if (!events_str->data().empty()) {
+    recorder_->Record(mojo::String(events_str->data()));
+  }
+  if (!has_more_events) {
+    recorder_.reset();
+  }
+}
+
+}  // namespace tracing