chromeos/process_proxy/process_output_watcher.h

   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 #ifndef CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_
   6 #define CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_
   7
   8 #include <string>
   9
  10 #include "base/callback.h"
  11 #include "chromeos/chromeos_export.h"
  12
  13 namespace {
  14
  15 const int kReadBufferSize = 256;
  16
  17 }  // namespace
  18
  19 namespace chromeos {
  20
  21 enum ProcessOutputType {
  22   PROCESS_OUTPUT_TYPE_OUT,
  23   PROCESS_OUTPUT_TYPE_ERR,
  24   PROCESS_OUTPUT_TYPE_EXIT
  25 };
  26
  27 typedef base::Callback<void(ProcessOutputType, const std::string&)>
  28       ProcessOutputCallback;
  29
  30 // This class should live on its own thread because running class makes
  31 // underlying thread block. It deletes itself when watching is stopped.
  32 class CHROMEOS_EXPORT ProcessOutputWatcher {
  33  public:
  34   ProcessOutputWatcher(int out_fd, int stop_fd,
  35                        const ProcessOutputCallback& callback);
  36
  37   // This will block current thread!!!!
  38   void Start();
  39
  40  private:
  41   // The object will destroy itself when it stops watching process output.
  42   ~ProcessOutputWatcher();
  43
  44   // Listens to output from supplied fds. It guarantees data written to one fd
  45   // will be reported in order that it has been written (this is not true across
  46   // fds, it would be nicer if it was).
  47   void WatchProcessOutput();
  48
  49   // Verifies that fds that we got are properly set.
  50   void VerifyFileDescriptor(int fd);
  51
  52   // Reads data from fd, and when it's done, invokes callback function.
  53   void ReadFromFd(ProcessOutputType type, int* fd);
  54
  55   // It will just delete this.
  56   void OnStop();
  57
  58   char read_buffer_[kReadBufferSize];
  59   ssize_t read_buffer_size_;
  60
  61   int out_fd_;
  62   int stop_fd_;
  63   int max_fd_;
  64
  65   // Callback that will be invoked when some output is detected.
  66   ProcessOutputCallback on_read_callback_;
  67
  68   DISALLOW_COPY_AND_ASSIGN(ProcessOutputWatcher);
  69 };
  70
  71 }  // namespace chromeos
  72
  73 #endif  // CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_