content/browser/tracing/trace_subscriber_stdio.cc

   1 // Copyright (c) 2012 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/tracing/trace_subscriber_stdio.h"
   6
   7 #include "base/bind.h"
   8 #include "base/debug/trace_event.h"
   9 #include "base/file_util.h"
  10 #include "base/logging.h"
  11 #include "base/threading/sequenced_worker_pool.h"
  12 #include "content/public/browser/browser_thread.h"
  13
  14 namespace content {
  15
  16 // All method calls on this class are done on a SequencedWorkerPool thread.
  17 class TraceSubscriberStdioImpl
  18     : public base::RefCountedThreadSafe<TraceSubscriberStdioImpl> {
  19  public:
  20   explicit TraceSubscriberStdioImpl(const base::FilePath& path)
  21       : path_(path),
  22         file_(0) {}
  23
  24   void OnStart() {
  25     DCHECK(!file_);
  26     trace_buffer_.SetOutputCallback(
  27         base::Bind(&TraceSubscriberStdioImpl::Write, this));
  28     file_ = file_util::OpenFile(path_, "w+");
  29     if (IsValid()) {
  30       LOG(INFO) << "Logging performance trace to file: " << path_.value();
  31       trace_buffer_.Start();
  32     } else {
  33       LOG(ERROR) << "Failed to open performance trace file: " << path_.value();
  34     }
  35   }
  36
  37   void OnData(const scoped_refptr<base::RefCountedString>& data_ptr) {
  38     trace_buffer_.AddFragment(data_ptr->data());
  39   }
  40
  41   void OnEnd() {
  42     trace_buffer_.Finish();
  43     CloseFile();
  44   }
  45
  46  private:
  47   friend class base::RefCountedThreadSafe<TraceSubscriberStdioImpl>;
  48
  49   ~TraceSubscriberStdioImpl() {
  50     CloseFile();
  51   }
  52
  53   bool IsValid() const {
  54     return file_ && (0 == ferror(file_));
  55   }
  56
  57   void CloseFile() {
  58     if (file_) {
  59       fclose(file_);
  60       file_ = 0;
  61     }
  62     // This is important, as it breaks a reference cycle.
  63     trace_buffer_.SetOutputCallback(
  64         base::debug::TraceResultBuffer::OutputCallback());
  65   }
  66
  67   void Write(const std::string& output_str) {
  68     if (IsValid()) {
  69       size_t written = fwrite(output_str.data(), 1, output_str.size(), file_);
  70       if (written != output_str.size()) {
  71         LOG(ERROR) << "Error " << ferror(file_) << " in fwrite() to trace file";
  72         CloseFile();
  73       }
  74     }
  75   }
  76
  77   base::FilePath path_;
  78   FILE* file_;
  79   base::debug::TraceResultBuffer trace_buffer_;
  80 };
  81
  82 TraceSubscriberStdio::TraceSubscriberStdio(const base::FilePath& path)
  83     : impl_(new TraceSubscriberStdioImpl(path)) {
  84   BrowserThread::PostBlockingPoolSequencedTask(
  85       __FILE__, FROM_HERE,
  86       base::Bind(&TraceSubscriberStdioImpl::OnStart, impl_));
  87 }
  88
  89 TraceSubscriberStdio::~TraceSubscriberStdio() {
  90 }
  91
  92 void TraceSubscriberStdio::OnEndTracingComplete() {
  93   BrowserThread::PostBlockingPoolSequencedTask(
  94       __FILE__, FROM_HERE,
  95       base::Bind(&TraceSubscriberStdioImpl::OnEnd, impl_));
  96 }
  97
  98 void TraceSubscriberStdio::OnTraceDataCollected(
  99     const scoped_refptr<base::RefCountedString>& data_ptr) {
 100   BrowserThread::PostBlockingPoolSequencedTask(
 101       __FILE__, FROM_HERE,
 102       base::Bind(&TraceSubscriberStdioImpl::OnData, impl_, data_ptr));
 103 }
 104
 105 }  // namespace content