content/browser/browser_shutdown_profile_dumper.cc

   1 // Copyright 2013 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 "content/browser/browser_shutdown_profile_dumper.h"
   6
   7 #include "base/base_switches.h"
   8 #include "base/command_line.h"
   9 #include "base/files/file_path.h"
  10 #include "base/files/file_util.h"
  11 #include "base/logging.h"
  12 #include "base/synchronization/waitable_event.h"
  13 #include "base/threading/thread.h"
  14 #include "base/threading/thread_restrictions.h"
  15 #include "base/trace_event/trace_event.h"
  16 #include "base/trace_event/trace_event_impl.h"
  17 #include "content/public/common/content_switches.h"
  18
  19 namespace content {
  20
  21 BrowserShutdownProfileDumper::BrowserShutdownProfileDumper(
  22     const base::FilePath& dump_file_name)
  23     : dump_file_name_(dump_file_name),
  24       blocks_(0),
  25       dump_file_(NULL) {
  26 }
  27
  28 BrowserShutdownProfileDumper::~BrowserShutdownProfileDumper() {
  29   WriteTracesToDisc();
  30 }
  31
  32 static float GetTraceBufferPercentFull() {
  33   base::trace_event::TraceLogStatus status =
  34       base::trace_event::TraceLog::GetInstance()->GetStatus();
  35   return 100 * static_cast<float>(static_cast<double>(status.event_count) /
  36                                   status.event_capacity);
  37 }
  38
  39 void BrowserShutdownProfileDumper::WriteTracesToDisc() {
  40   // Note: I have seen a usage of 0.000xx% when dumping - which fits easily.
  41   // Since the tracer stops when the trace buffer is filled, we'd rather save
  42   // what we have than nothing since we might see from the amount of events
  43   // that caused the problem.
  44   DVLOG(1) << "Flushing shutdown traces to disc. The buffer is "
  45            << GetTraceBufferPercentFull() << "% full.";
  46   DCHECK(!dump_file_);
  47   dump_file_ = base::OpenFile(dump_file_name_, "w+");
  48   if (!IsFileValid()) {
  49     LOG(ERROR) << "Failed to open performance trace file: "
  50                << dump_file_name_.value();
  51     return;
  52   }
  53   WriteString("{\"traceEvents\":");
  54   WriteString("[");
  55
  56   // TraceLog::Flush() requires the calling thread to have a message loop.
  57   // As the message loop of the current thread may have quit, start another
  58   // thread for flushing the trace.
  59   base::WaitableEvent flush_complete_event(false, false);
  60   base::Thread flush_thread("browser_shutdown_trace_event_flush");
  61   flush_thread.Start();
  62   flush_thread.message_loop()->PostTask(
  63       FROM_HERE,
  64       base::Bind(&BrowserShutdownProfileDumper::EndTraceAndFlush,
  65                  base::Unretained(this),
  66                  base::Unretained(&flush_complete_event)));
  67
  68   bool original_wait_allowed = base::ThreadRestrictions::SetWaitAllowed(true);
  69   flush_complete_event.Wait();
  70   base::ThreadRestrictions::SetWaitAllowed(original_wait_allowed);
  71 }
  72
  73 void BrowserShutdownProfileDumper::EndTraceAndFlush(
  74     base::WaitableEvent* flush_complete_event) {
  75   base::trace_event::TraceLog::GetInstance()->SetDisabled();
  76   base::trace_event::TraceLog::GetInstance()->Flush(
  77       base::Bind(&BrowserShutdownProfileDumper::WriteTraceDataCollected,
  78                  base::Unretained(this),
  79                  base::Unretained(flush_complete_event)));
  80 }
  81
  82 // static
  83 base::FilePath BrowserShutdownProfileDumper::GetShutdownProfileFileName() {
  84   const base::CommandLine& command_line =
  85       *base::CommandLine::ForCurrentProcess();
  86   base::FilePath trace_file =
  87       command_line.GetSwitchValuePath(switches::kTraceShutdownFile);
  88
  89   if (!trace_file.empty())
  90     return trace_file;
  91
  92   // Default to saving the startup trace into the current dir.
  93   return base::FilePath().AppendASCII("chrometrace.log");
  94 }
  95
  96 void BrowserShutdownProfileDumper::WriteTraceDataCollected(
  97     base::WaitableEvent* flush_complete_event,
  98     const scoped_refptr<base::RefCountedString>& events_str,
  99     bool has_more_events) {
 100   if (!IsFileValid()) {
 101     flush_complete_event->Signal();
 102     return;
 103   }
 104   if (blocks_) {
 105     // Blocks are not comma separated. Beginning with the second block we
 106     // start therefore to add one in front of the previous block.
 107     WriteString(",");
 108   }
 109   ++blocks_;
 110   WriteString(events_str->data());
 111
 112   if (!has_more_events) {
 113     WriteString("]");
 114     WriteString("}");
 115     CloseFile();
 116     flush_complete_event->Signal();
 117   }
 118 }
 119
 120 bool BrowserShutdownProfileDumper::IsFileValid() {
 121   return dump_file_ && (ferror(dump_file_) == 0);
 122 }
 123
 124 void BrowserShutdownProfileDumper::WriteString(const std::string& string) {
 125   WriteChars(string.data(), string.size());
 126 }
 127
 128 void BrowserShutdownProfileDumper::WriteChars(const char* chars, size_t size) {
 129   if (!IsFileValid())
 130     return;
 131
 132   size_t written = fwrite(chars, 1, size, dump_file_);
 133   if (written != size) {
 134     LOG(ERROR) << "Error " << ferror(dump_file_)
 135                << " in fwrite() to trace file '" << dump_file_name_.value()
 136                << "'";
 137     CloseFile();
 138   }
 139 }
 140
 141 void BrowserShutdownProfileDumper::CloseFile() {
 142   if (!dump_file_)
 143     return;
 144   base::CloseFile(dump_file_);
 145   dump_file_ = NULL;
 146 }
 147
 148 }  // namespace content