1 // Copyright 2016 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_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_ 6 #define MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_ 7 8 #include <map> 9 10 #include "base/callback.h" 11 #include "base/containers/stack_container.h" 12 #include "base/macros.h" 13 #include "base/memory/ref_counted.h" 14 #include "base/sequence_checker.h" 15 #include "base/synchronization/waitable_event.h" 16 #include "mojo/public/cpp/bindings/bindings_export.h" 17 #include "mojo/public/cpp/system/core.h" 18 #include "mojo/public/cpp/system/wait_set.h" 19 20 namespace mojo { 21 22 // SyncHandleRegistry is a sequence-local storage to register handles that want 23 // to be watched together. 24 // 25 // This class is thread unsafe. 26 class MOJO_CPP_BINDINGS_EXPORT SyncHandleRegistry 27 : public base::RefCounted<SyncHandleRegistry> { 28 public: 29 // Returns a sequence-local object. 30 static scoped_refptr<SyncHandleRegistry> current(); 31 32 using HandleCallback = base::Callback<void(MojoResult)>; 33 34 // Registers a |Handle| to be watched for |handle_signals|. If any such 35 // signals are satisfied during a Wait(), the Wait() is woken up and 36 // |callback| is run. 37 bool RegisterHandle(const Handle& handle, 38 MojoHandleSignals handle_signals, 39 const HandleCallback& callback); 40 41 void UnregisterHandle(const Handle& handle); 42 43 // Registers a |base::WaitableEvent| which can be used to wake up 44 // Wait() before any handle signals. |event| is not owned, and if it signals 45 // during Wait(), |callback| is invoked. Note that |event| may be registered 46 // multiple times with different callbacks. 47 void RegisterEvent(base::WaitableEvent* event, const base::Closure& callback); 48 49 // Unregisters a specific |event|+|callback| pair. 50 void UnregisterEvent(base::WaitableEvent* event, 51 const base::Closure& callback); 52 53 // Waits on all the registered handles and events and runs callbacks 54 // synchronously for any that become ready. 55 // The method: 56 // - returns true when any element of |should_stop| is set to true; 57 // - returns false when any error occurs. 58 bool Wait(const bool* should_stop[], size_t count); 59 60 private: 61 friend class base::RefCounted<SyncHandleRegistry>; 62 63 using EventCallbackList = base::StackVector<base::Closure, 1>; 64 using EventMap = std::map<base::WaitableEvent*, EventCallbackList>; 65 66 SyncHandleRegistry(); 67 ~SyncHandleRegistry(); 68 69 void RemoveInvalidEventCallbacks(); 70 71 WaitSet wait_set_; 72 std::map<Handle, HandleCallback> handles_; 73 EventMap events_; 74 75 // |true| iff this registry is currently dispatching event callbacks in 76 // Wait(). Used to allow for safe event registration/unregistration from event 77 // callbacks. 78 bool is_dispatching_event_callbacks_ = false; 79 80 // Indicates if one or more event callbacks was unregistered during the most 81 // recent event callback dispatch. 82 bool remove_invalid_event_callbacks_after_dispatch_ = false; 83 84 SEQUENCE_CHECKER(sequence_checker_); 85 86 DISALLOW_COPY_AND_ASSIGN(SyncHandleRegistry); 87 }; 88 89 } // namespace mojo 90 91 #endif // MOJO_PUBLIC_CPP_BINDINGS_SYNC_HANDLE_REGISTRY_H_ 92