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/*
*
* Copyright 2015-2016, 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_IMPL_CODEGEN_COMPLETION_QUEUE_H
#define GRPCXX_IMPL_CODEGEN_COMPLETION_QUEUE_H
#include <grpc++/impl/codegen/grpc_library.h>
#include <grpc++/impl/codegen/status.h>
#include <grpc++/impl/codegen/time.h>
struct grpc_completion_queue;
namespace grpc {
template <class R>
class ClientReader;
template <class W>
class ClientWriter;
template <class W, class R>
class ClientReaderWriter;
template <class R>
class ServerReader;
template <class W>
class ServerWriter;
template <class W, class R>
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 ChannelInterface;
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 : private 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();
/// 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 W, class R>
friend class ::grpc::ClientReaderWriter;
template <class R>
friend class ::grpc::ServerReader;
template <class W>
friend class ::grpc::ServerWriter;
template <class W, class R>
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(ChannelInterface* 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
};
/// 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_IMPL_CODEGEN_COMPLETION_QUEUE_H
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