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87 lines
2.7 KiB
C++
87 lines
2.7 KiB
C++
#pragma once
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#if defined(OS_LINUX)
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#include <variant>
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#include <Client/IConnections.h>
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#include <Common/Fiber.h>
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#include <Common/Epoll.h>
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#include <Common/TimerDescriptor.h>
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#include <Common/AsyncTaskExecutor.h>
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namespace DB
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{
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/// Class for nonblocking packet receiving. It runs connection->receivePacket
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/// in fiber and sets special read callback which is called when
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/// reading from socket blocks. When read callback is called,
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/// socket and receive timeout are added in epoll and execution returns to the main program.
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/// So, you can poll this epoll file descriptor to determine when to resume
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/// packet receiving.
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class PacketReceiver : public AsyncTaskExecutor
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{
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public:
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explicit PacketReceiver(Connection * connection_);
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bool isPacketReady() const { return !is_read_in_process && !is_timeout_expired && !exception; }
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Packet getPacket() { return std::move(packet); }
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bool hasException() const { return exception.operator bool(); }
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std::exception_ptr getException() const { return exception; }
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bool isTimeoutExpired() const { return is_timeout_expired; }
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Poco::Timespan getTimeout() const { return timeout; }
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void setTimeout(const Poco::Timespan & timeout_)
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{
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timeout_descriptor.setRelative(timeout_);
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timeout = timeout_;
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}
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int getFileDescriptor() const { return epoll.getFileDescriptor(); }
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private:
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bool checkBeforeTaskResume() override;
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void afterTaskResume() override {}
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void processAsyncEvent(int fd, Poco::Timespan socket_timeout, AsyncEventTimeoutType, const std::string &, uint32_t) override;
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void clearAsyncEvent() override;
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void processException(std::exception_ptr e) override { exception = e; }
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struct Task : public AsyncTask
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{
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explicit Task(PacketReceiver & receiver_) : receiver(receiver_) {}
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PacketReceiver & receiver;
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void run(AsyncCallback async_callback, SuspendCallback suspend_callback) override;
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};
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/// When epoll file descriptor is ready, check if it's an expired timeout.
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/// Return false if receive timeout expired and socket is not ready, return true otherwise.
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bool checkTimeout();
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Connection * connection;
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int socket_fd = -1;
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Packet packet;
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/// We use timer descriptor for checking socket timeouts.
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TimerDescriptor timeout_descriptor;
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Poco::Timespan timeout;
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bool is_timeout_expired = false;
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/// In read callback we add socket file descriptor and timer descriptor with receive timeout
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/// in epoll, so we can return epoll file descriptor outside for polling.
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Epoll epoll;
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/// If and exception occurred in fiber resume, we save it and rethrow.
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std::exception_ptr exception;
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bool is_read_in_process = false;
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};
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}
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#endif
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