base/test/trace_to_file.cc

   1 // Copyright (c) 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/test/trace_to_file.h"
   6
   7 #include "base/base_switches.h"
   8 #include "base/bind.h"
   9 #include "base/command_line.h"
  10 #include "base/files/file_util.h"
  11 #include "base/run_loop.h"
  12 #include "base/trace_event/trace_event_impl.h"
  13
  14 namespace base {
  15 namespace test {
  16
  17 TraceToFile::TraceToFile() : started_(false) {
  18 }
  19
  20 TraceToFile::~TraceToFile() {
  21   EndTracingIfNeeded();
  22 }
  23
  24 void TraceToFile::BeginTracingFromCommandLineOptions() {
  25   DCHECK(CommandLine::InitializedForCurrentProcess());
  26   DCHECK(!started_);
  27
  28   if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kTraceToFile))
  29     return;
  30
  31   // Empty filter (i.e. just --trace-to-file) turns into default categories in
  32   // TraceEventImpl
  33   std::string filter = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
  34       switches::kTraceToFile);
  35
  36   FilePath path;
  37   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kTraceToFileName)) {
  38     path = FilePath(CommandLine::ForCurrentProcess()
  39                         ->GetSwitchValuePath(switches::kTraceToFileName));
  40   } else {
  41     path = FilePath(FILE_PATH_LITERAL("trace.json"));
  42   }
  43
  44   BeginTracing(path, filter);
  45 }
  46
  47 void TraceToFile::BeginTracing(const FilePath& path,
  48                                const std::string& categories) {
  49   DCHECK(!started_);
  50   started_ = true;
  51   path_ = path;
  52   WriteFileHeader();
  53
  54   trace_event::TraceLog::GetInstance()->SetEnabled(
  55       trace_event::TraceConfig(categories, trace_event::RECORD_UNTIL_FULL),
  56       trace_event::TraceLog::RECORDING_MODE);
  57 }
  58
  59 void TraceToFile::WriteFileHeader() {
  60   const char str[] = "{\"traceEvents\": [";
  61   WriteFile(path_, str, static_cast<int>(strlen(str)));
  62 }
  63
  64 void TraceToFile::AppendFileFooter() {
  65   const char str[] = "]}";
  66   AppendToFile(path_, str, static_cast<int>(strlen(str)));
  67 }
  68
  69 void TraceToFile::TraceOutputCallback(const std::string& data) {
  70   bool ret = AppendToFile(path_, data.c_str(), static_cast<int>(data.size()));
  71   DCHECK(ret);
  72 }
  73
  74 static void OnTraceDataCollected(
  75     Closure quit_closure,
  76     trace_event::TraceResultBuffer* buffer,
  77     const scoped_refptr<RefCountedString>& json_events_str,
  78     bool has_more_events) {
  79   buffer->AddFragment(json_events_str->data());
  80   if (!has_more_events)
  81     quit_closure.Run();
  82 }
  83
  84 void TraceToFile::EndTracingIfNeeded() {
  85   if (!started_)
  86     return;
  87   started_ = false;
  88
  89   trace_event::TraceLog::GetInstance()->SetDisabled();
  90
  91   trace_event::TraceResultBuffer buffer;
  92   buffer.SetOutputCallback(
  93       Bind(&TraceToFile::TraceOutputCallback, Unretained(this)));
  94
  95   RunLoop run_loop;
  96   trace_event::TraceLog::GetInstance()->Flush(
  97       Bind(&OnTraceDataCollected, run_loop.QuitClosure(), Unretained(&buffer)));
  98   run_loop.Run();
  99
 100   AppendFileFooter();
 101 }
 102
 103 }  // namespace test
 104 }  // namespace base