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 chromeos {
  14
  15 enum ProcessOutputType {
  16   PROCESS_OUTPUT_TYPE_OUT,
  17   PROCESS_OUTPUT_TYPE_ERR,
  18   PROCESS_OUTPUT_TYPE_EXIT
  19 };
  20
  21 typedef base::Callback<void(ProcessOutputType, const std::string&)>
  22       ProcessOutputCallback;
  23
  24 // Observes output on |out_fd| and invokes |callback| when some output is
  25 // detected. It assumes UTF8 output.
  26 // If output is detected in |stop_fd|, the watcher is stopped.
  27 // This class should live on its own thread because running class makes
  28 // underlying thread block. It deletes itself when watching is stopped.
  29 class CHROMEOS_EXPORT ProcessOutputWatcher {
  30  public:
  31   // Verifies that fds that we got are properly set.
  32   static bool VerifyFileDescriptor(int fd);
  33
  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   // Reads data from fd, and when it's done, invokes callback function.
  50   void ReadFromFd(ProcessOutputType type, int* fd);
  51
  52   // Checks if the read buffer has any trailing incomplete UTF8 characters and
  53   // returns the read buffer size without them.
  54   size_t OutputSizeWithoutIncompleteUTF8();
  55
  56   // Processes new |read_buffer_| state and notifies observer about new process
  57   // output.
  58   void ReportOutput(ProcessOutputType type, size_t new_bytes_count);
  59
  60   // It will just delete this.
  61   void OnStop();
  62
  63   char read_buffer_[256];
  64   // Maximum read buffer content size.
  65   size_t read_buffer_capacity_;
  66   // Current read bufferi content size.
  67   size_t read_buffer_size_;
  68
  69   int out_fd_;
  70   int stop_fd_;
  71   int max_fd_;
  72
  73   // Callback that will be invoked when some output is detected.
  74   ProcessOutputCallback on_read_callback_;
  75
  76   DISALLOW_COPY_AND_ASSIGN(ProcessOutputWatcher);
  77 };
  78
  79 }  // namespace chromeos
  80
  81 #endif  // CHROMEOS_PROCESS_PROXY_PROCESS_OUTPUT_WATCHER_H_