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/command_line.h"
   9 #include "base/debug/trace_event_impl.h"
  10 #include "base/files/file_util.h"
  11 #include "base/run_loop.h"
  12
  13 namespace base {
  14 namespace test {
  15
  16 TraceToFile::TraceToFile() : started_(false) {
  17 }
  18
  19 TraceToFile::~TraceToFile() {
  20   EndTracingIfNeeded();
  21 }
  22
  23 void TraceToFile::BeginTracingFromCommandLineOptions() {
  24   DCHECK(CommandLine::InitializedForCurrentProcess());
  25   DCHECK(!started_);
  26
  27   if (!CommandLine::ForCurrentProcess()->HasSwitch(switches::kTraceToFile))
  28     return;
  29
  30   // Empty filter (i.e. just --trace-to-file) turns into default categories in
  31   // TraceEventImpl
  32   std::string filter = CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
  33       switches::kTraceToFile);
  34
  35   FilePath path;
  36   if (CommandLine::ForCurrentProcess()->HasSwitch(switches::kTraceToFileName)) {
  37     path = FilePath(CommandLine::ForCurrentProcess()
  38                         ->GetSwitchValuePath(switches::kTraceToFileName));
  39   } else {
  40     path = FilePath(FILE_PATH_LITERAL("trace.json"));
  41   }
  42
  43   BeginTracing(path, filter);
  44 }
  45
  46 void TraceToFile::BeginTracing(const FilePath& path,
  47                                const std::string& categories) {
  48   DCHECK(!started_);
  49   started_ = true;
  50   path_ = path;
  51   WriteFileHeader();
  52
  53   debug::TraceLog::GetInstance()->SetEnabled(
  54       debug::CategoryFilter(categories),
  55       debug::TraceLog::RECORDING_MODE,
  56       debug::TraceOptions(debug::RECORD_UNTIL_FULL));
  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   int ret = AppendToFile(path_, data.c_str(), static_cast<int>(data.size()));
  71   DCHECK_NE(-1, ret);
  72 }
  73
  74 static void OnTraceDataCollected(
  75     Closure quit_closure,
  76     debug::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   debug::TraceLog::GetInstance()->SetDisabled();
  90
  91   debug::TraceResultBuffer buffer;
  92   buffer.SetOutputCallback(
  93       Bind(&TraceToFile::TraceOutputCallback, Unretained(this)));
  94
  95   RunLoop run_loop;
  96   debug::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