Benchmark: `--save-all-traces` argument

apps/benchmark/benchmark_app.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.

[ppi, 2015/10/12 19:32:50]

nits about the commit message:

please break the first line at 80 characters
please make the first line an imperative statement: "trace all events ..."
rather than "tracing all events ..."

 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <memory>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "apps/benchmark/event.h"
 #include "apps/benchmark/measurements.h"
@@ skipping 25 matching lines @@
 
   // mojo:ApplicationDelegate:
   void Initialize(mojo::ApplicationImpl* app) override {
     // Parse command-line arguments.
     if (!GetRunArgs(app->args(), &args_)) {
       LOG(ERROR) << "Failed to parse the input arguments.";
       mojo::ApplicationImpl::Terminate();
       return;
     }
 
-    // Calculate a list of trace categories we want to collect: a union of all
-    // categories targeted in measurements.
-    std::set<std::string> category_set;
-    for (const Measurement& measurement : args_.measurements) {
-      std::vector<std::string> categories;
-      base::SplitString(measurement.target_event.categories, ',', &categories);
-      category_set.insert(categories.begin(), categories.end());
+    // Trace all categories when results will be written in a file. No need
+    // to compute the categories string in that case (using "*" instead).
+    std::string categories_str = "*";
+    if (!args_.write_output_file) {

[ppi, 2015/10/12 19:30:52]

I'd argue that we should record all categories indiscriminately. --save_traces
should continue to save exactly the same trace that is being processed in a
benchmark run, otherwise it won't be that useful in debugging benchmarking
issues.

+      categories_str = ComputeCategoriesStr();
     }
-    std::vector<std::string> unique_categories(category_set.begin(),
-                                               category_set.end());
-    std::string categories_str = JoinString(unique_categories, ',');
 
     // Connect to trace collector, which will fetch the trace events produced by
     // the app being benchmarked.
     tracing::TraceCollectorPtr trace_collector;
     app->ConnectToService("mojo:tracing", &trace_collector);
     trace_collector_client_.reset(
         new TraceCollectorClient(this, trace_collector.Pass()));
     trace_collector_client_->Start(categories_str);
 
     // Start tracing the application with 1 sec of delay.
     base::MessageLoop::current()->PostDelayedTask(
-        FROM_HERE,
-        base::Bind(&BenchmarkApp::StartTracedApplication,
-            base::Unretained(this), app),
+        FROM_HERE, base::Bind(&BenchmarkApp::StartTracedApplication,
+                              base::Unretained(this), app),
         base::TimeDelta::FromSeconds(1));
   }
 
+  // Calculate a list of trace categories we want to collect: a union of all
+  // categories targeted in measurements.
+  std::string ComputeCategoriesStr() {
+    std::set<std::string> category_set;
+    for (const Measurement& measurement : args_.measurements) {
+      std::vector<std::string> categories;
+      base::SplitString(measurement.target_event.categories, ',', &categories);
+      category_set.insert(categories.begin(), categories.end());
+    }
+    std::vector<std::string> unique_categories(category_set.begin(),
+                                               category_set.end());
+    return JoinString(unique_categories, ',');
+  }
+
   void StartTracedApplication(mojo::ApplicationImpl* app) {
     // Record the time origin for measurements just before connecting to the app
     // being benchmarked.
     time_origin_ = base::TimeTicks::FromInternalValue(MojoGetTimeTicksNow());
     traced_app_connection_ = app->ConnectToApplication(args_.app);
 
     // Post task to stop tracing when the time is up.
     base::MessageLoop::current()->PostDelayedTask(
         FROM_HERE,
         base::Bind(&BenchmarkApp::StopTracing, base::Unretained(this)),
@@ skipping 61 matching lines @@
 };
 }  // namespace
 }  // namespace benchmark
 
 MojoResult MojoMain(MojoHandle application_request) {
   mojo::ApplicationRunnerChromium runner(new benchmark::BenchmarkApp);
   auto ret = runner.Run(application_request);
   fflush(nullptr);
   return ret;
 }