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| 1 // Copyright 2017 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_EDK_SYSTEM_WATCHER_DISPATCHER_H_ |
| 6 #define MOJO_EDK_SYSTEM_WATCHER_DISPATCHER_H_ |
| 7 |
| 8 #include <map> |
| 9 #include <set> |
| 10 |
| 11 #include "base/macros.h" |
| 12 #include "base/memory/ref_counted.h" |
| 13 #include "base/synchronization/lock.h" |
| 14 #include "mojo/edk/system/dispatcher.h" |
| 15 #include "mojo/edk/system/handle_signals_state.h" |
| 16 #include "mojo/edk/system/system_impl_export.h" |
| 17 #include "mojo/public/c/system/watcher.h" |
| 18 |
| 19 namespace mojo { |
| 20 namespace edk { |
| 21 |
| 22 class Watch; |
| 23 |
| 24 // The dispatcher type which backs watcher handles. |
| 25 class WatcherDispatcher : public Dispatcher { |
| 26 public: |
| 27 // Constructs a new WatcherDispatcher which invokes |callback| when a |
| 28 // registered watch observes some relevant state change. |
| 29 explicit WatcherDispatcher(MojoWatcherCallback callback); |
| 30 |
| 31 // Methods used by watched dispatchers to notify watchers of events. |
| 32 void NotifyHandleState(Dispatcher* dispatcher, |
| 33 const HandleSignalsState& state); |
| 34 void NotifyHandleClosed(Dispatcher* dispatcher); |
| 35 |
| 36 // Method used by RequestContext (indirectly, via Watch) to complete |
| 37 // notification operations from a safe stack frame to avoid reentrancy. |
| 38 void InvokeWatchCallback(uintptr_t context, |
| 39 MojoResult result, |
| 40 const HandleSignalsState& state, |
| 41 MojoWatcherNotificationFlags flags); |
| 42 |
| 43 // Dispatcher: |
| 44 Type GetType() const override; |
| 45 MojoResult Close() override; |
| 46 MojoResult WatchDispatcher(scoped_refptr<Dispatcher> dispatcher, |
| 47 MojoHandleSignals signals, |
| 48 uintptr_t context) override; |
| 49 MojoResult CancelWatch(uintptr_t context) override; |
| 50 MojoResult Arm(uint32_t* num_ready_contexts, |
| 51 uintptr_t* ready_contexts, |
| 52 MojoResult* ready_results, |
| 53 MojoHandleSignalsState* ready_signals_states) override; |
| 54 |
| 55 private: |
| 56 friend class Watch; |
| 57 |
| 58 ~WatcherDispatcher() override; |
| 59 |
| 60 const MojoWatcherCallback callback_; |
| 61 |
| 62 // Guards access to the fields below. |
| 63 // |
| 64 // NOTE: This may be acquired while holding another dispatcher's lock, as |
| 65 // watched dispatchers call into WatcherDispatcher methods which lock this |
| 66 // when issuing state change notifications. WatcherDispatcher must therefore |
| 67 // take caution to NEVER acquire other dispatcher locks while this is held. |
| 68 base::Lock lock_; |
| 69 |
| 70 bool armed_ = false; |
| 71 bool closed_ = false; |
| 72 |
| 73 // A mapping from context to Watch. |
| 74 std::map<uintptr_t, scoped_refptr<Watch>> watches_; |
| 75 |
| 76 // A mapping from watched dispatcher to Watch. |
| 77 std::map<Dispatcher*, scoped_refptr<Watch>> watched_handles_; |
| 78 |
| 79 // The set of all Watch instances which are currently ready to signal. This is |
| 80 // used for efficient arming behavior, as it allows for O(1) discovery of |
| 81 // whether or not arming can succeed and quick determination of who's |
| 82 // responsible if it can't. |
| 83 std::set<Watch*> ready_watches_; |
| 84 |
| 85 DISALLOW_COPY_AND_ASSIGN(WatcherDispatcher); |
| 86 }; |
| 87 |
| 88 } // namespace edk |
| 89 } // namespace mojo |
| 90 |
| 91 #endif // MOJO_EDK_SYSTEM_WATCHER_DISPATCHER_H_ |
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