base/mac/dispatch_source_mach.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 BASE_MAC_DISPATCH_SOURCE_MACH_H_
   6 #define BASE_MAC_DISPATCH_SOURCE_MACH_H_
   7
   8 #include <dispatch/dispatch.h>
   9
  10 #include "base/base_export.h"
  11 #include "base/macros.h"
  12
  13 namespace base {
  14
  15 // This class encapsulates a MACH_RECV dispatch source. When this object is
  16 // destroyed, the source will be cancelled and it will wait for the source
  17 // to stop executing work. The source can run on either a user-supplied queue,
  18 // or it can create its own for the source.
  19 class BASE_EXPORT DispatchSourceMach {
  20  public:
  21   // Creates a new dispatch source for the |port| and schedules it on a new
  22   // queue that will be created with |name|. When a Mach message is received,
  23   // the |event_handler| will be called.
  24   DispatchSourceMach(const char* name,
  25                      mach_port_t port,
  26                      void (^event_handler)());
  27
  28   // Creates a new dispatch source with the same semantics as above, but rather
  29   // than creating a new queue, it schedules the source on |queue|.
  30   DispatchSourceMach(dispatch_queue_t queue,
  31                      mach_port_t port,
  32                      void (^event_handler)());
  33
  34   // Cancels the source and waits for it to become fully cancelled before
  35   // releasing the source.
  36   ~DispatchSourceMach();
  37
  38   // Resumes the source. This must be called before any Mach messages will
  39   // be received.
  40   void Resume();
  41
  42  private:
  43   // Cancels the source, after which this class will no longer receive Mach
  44   // messages. Calling this more than once is a no-op.
  45   void Cancel();
  46
  47   // The dispatch queue used to service the source_.
  48   dispatch_queue_t queue_;
  49
  50   // A MACH_RECV dispatch source.
  51   dispatch_source_t source_;
  52
  53   // Semaphore used to wait on the |source_|'s cancellation in the destructor.
  54   dispatch_semaphore_t source_canceled_;
  55
  56   DISALLOW_COPY_AND_ASSIGN(DispatchSourceMach);
  57 };
  58
  59 }  // namespace base
  60
  61 #endif  // BASE_MAC_DISPATCH_SOURCE_MACH_H_