| // Copyright 2019 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef PLATFORM_IMPL_SOCKET_HANDLE_WAITER_H_ |
| #define PLATFORM_IMPL_SOCKET_HANDLE_WAITER_H_ |
| |
| #include <condition_variable> |
| #include <functional> |
| #include <memory> |
| #include <mutex> |
| #include <unordered_map> |
| #include <vector> |
| |
| #include "platform/api/time.h" |
| #include "platform/base/error.h" |
| #include "platform/base/macros.h" |
| #include "platform/impl/socket_handle.h" |
| |
| namespace openscreen { |
| |
| // The class responsible for calling platform-level method to watch UDP sockets |
| // for available read data. Reading from these sockets is handled at a higher |
| // layer. |
| class SocketHandleWaiter { |
| public: |
| using SocketHandleRef = std::reference_wrapper<const SocketHandle>; |
| |
| enum Flags { |
| kReadable = 1, |
| kWriteable = 2, |
| }; |
| |
| class Subscriber { |
| public: |
| virtual ~Subscriber() = default; |
| |
| // Provides a socket handle to the subscriber which has data waiting to be |
| // processed. |
| virtual void ProcessReadyHandle(SocketHandleRef handle, uint32_t flags) = 0; |
| }; |
| |
| explicit SocketHandleWaiter(ClockNowFunctionPtr now_function); |
| virtual ~SocketHandleWaiter() = default; |
| |
| // Start notifying |subscriber| whenever |handle| has an event. May be called |
| // multiple times, to be notified for multiple handles, but should not be |
| // called multiple times for the same handle. |
| void Subscribe(Subscriber* subscriber, SocketHandleRef handle); |
| |
| // Stop receiving notifications for one of the handles currently subscribed |
| // to. |
| void Unsubscribe(Subscriber* subscriber, SocketHandleRef handle); |
| |
| // Stop receiving notifications for all handles currently subscribed to, or |
| // no-op if there are no subscriptions. |
| void UnsubscribeAll(Subscriber* subscriber); |
| |
| // Called when a handle will be deleted to ensure that deletion can proceed |
| // safely. |
| void OnHandleDeletion(Subscriber* subscriber, |
| SocketHandleRef handle, |
| bool disable_locking_for_testing = false); |
| |
| OSP_DISALLOW_COPY_AND_ASSIGN(SocketHandleWaiter); |
| |
| // Gets all socket handles to process, checks them for readable data, and |
| // handles any changes that have occured. |
| Error ProcessHandles(Clock::duration timeout); |
| |
| protected: |
| struct ReadyHandle { |
| SocketHandleRef handle; |
| uint32_t flags; |
| }; |
| |
| // Waits until data is available in one of the provided sockets or the |
| // provided timeout has passed - whichever is first. If any sockets have data |
| // available, they are returned. |
| virtual ErrorOr<std::vector<ReadyHandle>> AwaitSocketsReadable( |
| const std::vector<SocketHandleRef>& socket_fds, |
| const Clock::duration& timeout) = 0; |
| |
| private: |
| struct SocketSubscription { |
| Subscriber* subscriber = nullptr; |
| Clock::time_point last_updated = Clock::time_point::min(); |
| }; |
| |
| struct HandleWithSubscription { |
| ReadyHandle ready_handle; |
| // Reference to the original subscription in the unordered map, so |
| // we can keep track of when we updated this socket handle. |
| SocketSubscription* subscription; |
| }; |
| |
| // Call the subscriber associated with each changed handle. Handles are only |
| // processed until |timeout| is exceeded. Must be called with |mutex_| held. |
| void ProcessReadyHandles(std::vector<HandleWithSubscription>* handles, |
| Clock::duration timeout); |
| |
| // Guards against concurrent access to all other class data members. |
| std::mutex mutex_; |
| |
| // Blocks deletion of handles until they are no longer being watched. |
| std::condition_variable handle_deletion_block_; |
| |
| // Set of handles currently being deleted, for ensuring handle_deletion_block_ |
| // does not exit prematurely. |
| std::vector<SocketHandleRef> handles_being_deleted_; |
| |
| // Set of all socket handles currently being watched, mapped to the subscriber |
| // that is watching them. |
| std::unordered_map<SocketHandleRef, SocketSubscription, SocketHandleHash> |
| handle_mappings_; |
| |
| const ClockNowFunctionPtr now_function_; |
| }; |
| |
| } // namespace openscreen |
| |
| #endif // PLATFORM_IMPL_SOCKET_HANDLE_WAITER_H_ |