/* * * Copyright 2015, Google Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the * distribution. * * Neither the name of Google Inc. nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ /// A completion queue implements a concurrent producer-consumer queue, with two /// main methods, \a Next and \a AsyncNext. #ifndef GRPCXX_COMPLETION_QUEUE_H #define GRPCXX_COMPLETION_QUEUE_H #include <grpc/support/time.h> #include <grpc++/impl/grpc_library.h> #include <grpc++/support/status.h> #include <grpc++/support/time.h> struct grpc_completion_queue; namespace grpc { template <class R> class ClientReader; template <class W> class ClientWriter; template <class R, class W> class ClientReaderWriter; template <class R> class ServerReader; template <class W> class ServerWriter; template <class R, class W> class ServerReaderWriter; template <class ServiceType, class RequestType, class ResponseType> class RpcMethodHandler; template <class ServiceType, class RequestType, class ResponseType> class ClientStreamingHandler; template <class ServiceType, class RequestType, class ResponseType> class ServerStreamingHandler; template <class ServiceType, class RequestType, class ResponseType> class BidiStreamingHandler; class UnknownMethodHandler; class Channel; class ClientContext; class CompletionQueueTag; class CompletionQueue; class RpcMethod; class Server; class ServerBuilder; class ServerContext; /// A thin wrapper around \a grpc_completion_queue (see / \a /// src/core/surface/completion_queue.h). class CompletionQueue : public GrpcLibrary { public: /// Default constructor. Implicitly creates a \a grpc_completion_queue /// instance. CompletionQueue(); /// Wrap \a take, taking ownership of the instance. /// /// \param take The completion queue instance to wrap. Ownership is taken. explicit CompletionQueue(grpc_completion_queue* take); /// Destructor. Destroys the owned wrapped completion queue / instance. ~CompletionQueue() GRPC_OVERRIDE; /// Tri-state return for AsyncNext: SHUTDOWN, GOT_EVENT, TIMEOUT. enum NextStatus { SHUTDOWN, ///< The completion queue has been shutdown. GOT_EVENT, ///< Got a new event; \a tag will be filled in with its ///< associated value; \a ok indicating its success. TIMEOUT ///< deadline was reached. }; /// Read from the queue, blocking up to \a deadline (or the queue's shutdown). /// Both \a tag and \a ok are updated upon success (if an event is available /// within the \a deadline). A \a tag points to an arbitrary location usually /// employed to uniquely identify an event. /// /// \param tag[out] Upon sucess, updated to point to the event's tag. /// \param ok[out] Upon sucess, true if read a regular event, false otherwise. /// \param deadline[in] How long to block in wait for an event. /// /// \return The type of event read. template <typename T> NextStatus AsyncNext(void** tag, bool* ok, const T& deadline) { TimePoint<T> deadline_tp(deadline); return AsyncNextInternal(tag, ok, deadline_tp.raw_time()); } /// Read from the queue, blocking until an event is available or the queue is /// shutting down. /// /// \param tag[out] Updated to point to the read event's tag. /// \param ok[out] true if read a regular event, false otherwise. /// /// \return true if read a regular event, false if the queue is shutting down. bool Next(void** tag, bool* ok) { return (AsyncNextInternal(tag, ok, gpr_inf_future(GPR_CLOCK_REALTIME)) != SHUTDOWN); } /// Request the shutdown of the queue. /// /// \warning This method must be called at some point. Once invoked, \a Next /// will start to return false and \a AsyncNext will return \a /// NextStatus::SHUTDOWN. Only once either one of these methods does that /// (that is, once the queue has been \em drained) can an instance of this /// class be destroyed. void Shutdown(); /// Returns a \em raw pointer to the underlying \a grpc_completion_queue /// instance. /// /// \warning Remember that the returned instance is owned. No transfer of /// owership is performed. grpc_completion_queue* cq() { return cq_; } private: // Friend synchronous wrappers so that they can access Pluck(), which is // a semi-private API geared towards the synchronous implementation. template <class R> friend class ::grpc::ClientReader; template <class W> friend class ::grpc::ClientWriter; template <class R, class W> friend class ::grpc::ClientReaderWriter; template <class R> friend class ::grpc::ServerReader; template <class W> friend class ::grpc::ServerWriter; template <class R, class W> friend class ::grpc::ServerReaderWriter; template <class ServiceType, class RequestType, class ResponseType> friend class RpcMethodHandler; template <class ServiceType, class RequestType, class ResponseType> friend class ClientStreamingHandler; template <class ServiceType, class RequestType, class ResponseType> friend class ServerStreamingHandler; template <class ServiceType, class RequestType, class ResponseType> friend class BidiStreamingHandler; friend class UnknownMethodHandler; friend class ::grpc::Server; friend class ::grpc::ServerContext; template <class InputMessage, class OutputMessage> friend Status BlockingUnaryCall(Channel* channel, const RpcMethod& method, ClientContext* context, const InputMessage& request, OutputMessage* result); NextStatus AsyncNextInternal(void** tag, bool* ok, gpr_timespec deadline); /// Wraps \a grpc_completion_queue_pluck. /// \warning Must not be mixed with calls to \a Next. bool Pluck(CompletionQueueTag* tag); /// Performs a single polling pluck on \a tag. void TryPluck(CompletionQueueTag* tag); grpc_completion_queue* cq_; // owned }; /// An interface allowing implementors to process and filter event tags. class CompletionQueueTag { public: virtual ~CompletionQueueTag() {} // Called prior to returning from Next(), return value is the status of the // operation (return status is the default thing to do). If this function // returns false, the tag is dropped and not returned from the completion // queue virtual bool FinalizeResult(void** tag, bool* status) = 0; }; /// A specific type of completion queue used by the processing of notifications /// by servers. Instantiated by \a ServerBuilder. class ServerCompletionQueue : public CompletionQueue { private: friend class ServerBuilder; ServerCompletionQueue() {} }; } // namespace grpc #endif // GRPCXX_COMPLETION_QUEUE_H