mojo/shell/child_process_host.h

   1 // Copyright 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 #ifndef MOJO_SHELL_CHILD_PROCESS_HOST_H_
   6 #define MOJO_SHELL_CHILD_PROCESS_HOST_H_
   7
   8 #include "base/macros.h"
   9 #include "base/process/process_handle.h"
  10 #include "mojo/embedder/platform_channel_pair.h"
  11 #include "mojo/embedder/scoped_platform_handle.h"
  12 #include "mojo/shell/child_process.h"  // For |ChildProcess::Type|.
  13
  14 namespace mojo {
  15 namespace shell {
  16
  17 class Context;
  18
  19 // (Base) class for a "child process host". Handles launching and connecting a
  20 // platform-specific "pipe" to the child, and supports joining the child
  21 // process. Intended for use as a base class, but may be used on its own in
  22 // simple cases.
  23 //
  24 // This class is not thread-safe. It should be created/used/destroyed on a
  25 // single thread.
  26 //
  27 // Note: Does not currently work on Windows before Vista.
  28 class ChildProcessHost {
  29  public:
  30   class Delegate {
  31    public:
  32     virtual void WillStart() = 0;
  33     virtual void DidStart(bool success) = 0;
  34   };
  35
  36   ChildProcessHost(Context* context,
  37                    Delegate* delegate,
  38                    ChildProcess::Type type);
  39   virtual ~ChildProcessHost();
  40
  41   // |Start()|s the child process; calls the delegate's |DidStart()| (on the
  42   // thread on which |Start()| was called) when the child has been started (or
  43   // failed to start). After calling |Start()|, this object must not be
  44   // destroyed until |DidStart()| has been called.
  45   // TODO(vtl): Consider using weak pointers and removing this requirement.
  46   void Start();
  47
  48   // Waits for the child process to terminate, and returns its exit code.
  49   // Note: If |Start()| has been called, this must not be called until the
  50   // callback has been called.
  51   int Join();
  52
  53   embedder::ScopedPlatformHandle* platform_channel() {
  54     return &platform_channel_;
  55   }
  56
  57  protected:
  58   Context* context() const {
  59     return context_;
  60   }
  61
  62  private:
  63   bool DoLaunch();
  64   void DidLaunch(bool success);
  65
  66   Context* const context_;
  67   Delegate* const delegate_;
  68   const ChildProcess::Type type_;
  69
  70   base::ProcessHandle child_process_handle_;
  71
  72   embedder::PlatformChannelPair platform_channel_pair_;
  73
  74   // Platform-specific "pipe" to the child process. Valid immediately after
  75   // creation.
  76   embedder::ScopedPlatformHandle platform_channel_;
  77
  78   DISALLOW_COPY_AND_ASSIGN(ChildProcessHost);
  79 };
  80
  81 }  // namespace shell
  82 }  // namespace mojo
  83
  84 #endif  // MOJO_SHELL_CHILD_PROCESS_HOST_H_