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      1 // Copyright 2015 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_WAIT_SET_DISPATCHER_H_
      6 #define MOJO_EDK_SYSTEM_WAIT_SET_DISPATCHER_H_
      7 
      8 #include <stdint.h>
      9 
     10 #include <deque>
     11 #include <memory>
     12 #include <unordered_map>
     13 #include <utility>
     14 
     15 #include "base/macros.h"
     16 #include "base/synchronization/lock.h"
     17 #include "mojo/edk/system/awakable_list.h"
     18 #include "mojo/edk/system/dispatcher.h"
     19 #include "mojo/edk/system/system_impl_export.h"
     20 
     21 namespace mojo {
     22 namespace edk {
     23 
     24 class MOJO_SYSTEM_IMPL_EXPORT WaitSetDispatcher : public Dispatcher {
     25  public:
     26   WaitSetDispatcher();
     27 
     28   // Dispatcher:
     29   Type GetType() const override;
     30   MojoResult Close() override;
     31   MojoResult AddWaitingDispatcher(const scoped_refptr<Dispatcher>& dispatcher,
     32                                   MojoHandleSignals signals,
     33                                   uintptr_t context) override;
     34   MojoResult RemoveWaitingDispatcher(
     35       const scoped_refptr<Dispatcher>& dispatcher) override;
     36   MojoResult GetReadyDispatchers(uint32_t* count,
     37                                  DispatcherVector* dispatchers,
     38                                  MojoResult* results,
     39                                  uintptr_t* contexts) override;
     40   HandleSignalsState GetHandleSignalsState() const override;
     41   MojoResult AddAwakable(Awakable* awakable,
     42                          MojoHandleSignals signals,
     43                          uintptr_t context,
     44                          HandleSignalsState* signals_state) override;
     45   void RemoveAwakable(Awakable* awakable,
     46                       HandleSignalsState* signals_state) override;
     47   bool BeginTransit() override;
     48 
     49  private:
     50   // Internal implementation of Awakable.
     51   class Waiter;
     52 
     53   struct WaitState {
     54     WaitState();
     55     WaitState(const WaitState& other);
     56     ~WaitState();
     57 
     58     scoped_refptr<Dispatcher> dispatcher;
     59     MojoHandleSignals signals;
     60     uintptr_t context;
     61   };
     62 
     63   ~WaitSetDispatcher() override;
     64 
     65   HandleSignalsState GetHandleSignalsStateNoLock() const;
     66 
     67   // Signal that the dispatcher indexed by |context| has been woken up with
     68   // |result| and is now ready.
     69   void WakeDispatcher(MojoResult result, uintptr_t context);
     70 
     71   // Guards |is_closed_|, |waiting_dispatchers_|, and |waiter_|.
     72   //
     73   // TODO: Consider removing this.
     74   mutable base::Lock lock_;
     75   bool is_closed_ = false;
     76 
     77   // Map of dispatchers being waited on. Key is a Dispatcher* casted to a
     78   // uintptr_t, and should be treated as an opaque value and not casted back.
     79   std::unordered_map<uintptr_t, WaitState> waiting_dispatchers_;
     80 
     81   // Separate lock that can be locked without locking |lock_|.
     82   mutable base::Lock awoken_lock_;
     83   // List of dispatchers that have been woken up. Any dispatcher in this queue
     84   // will NOT currently be waited on.
     85   std::deque<std::pair<uintptr_t, MojoResult>> awoken_queue_;
     86   // List of dispatchers that have been woken up and retrieved.
     87   std::deque<uintptr_t> processed_dispatchers_;
     88 
     89   // Separate lock that can be locked without locking |lock_|.
     90   base::Lock awakable_lock_;
     91   // List of dispatchers being waited on.
     92   AwakableList awakable_list_;
     93 
     94   // Waiter used to wait on dispatchers.
     95   std::unique_ptr<Waiter> waiter_;
     96 
     97   DISALLOW_COPY_AND_ASSIGN(WaitSetDispatcher);
     98 };
     99 
    100 }  // namespace edk
    101 }  // namespace mojo
    102 
    103 #endif  // MOJO_EDK_SYSTEM_WAIT_SET_DISPATCHER_H_
    104