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