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@ -32,12 +32,8 @@ |
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*/ |
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/// A completion queue implements a producer-consumer queue, with two main
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/// methods:
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///
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/// - Next
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/// - AsyncNext XXX
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///
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/// A completion queue implements a concurrent producer-consumer queue, with two
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/// main methods, \a Next and \a AsyncNext.
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#ifndef GRPCXX_COMPLETION_QUEUE_H |
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#define GRPCXX_COMPLETION_QUEUE_H |
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@ -81,35 +77,67 @@ class Server; |
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class ServerBuilder; |
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class ServerContext; |
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// grpc_completion_queue wrapper class
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// This class is a thin wrapper around \a grpc_completion_queue (see
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// \a src/core/surface/completion_queue.h).
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class CompletionQueue : public GrpcLibrary { |
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public: |
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/// Default constructor. Implicitly creates a \a grpc_completion_queue
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/// instance.
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CompletionQueue(); |
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/// Wrap \a take, taking ownership of the instance.
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///
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/// \param take The completion queue instance to wrap. Ownership is taken.
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explicit CompletionQueue(grpc_completion_queue* take); |
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/// Destructor. Destroys the owned wrapped completion queue / instance.
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~CompletionQueue() GRPC_OVERRIDE; |
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// Tri-state return for AsyncNext: SHUTDOWN, GOT_EVENT, TIMEOUT
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/// Tri-state return for AsyncNext: SHUTDOWN, GOT_EVENT, TIMEOUT.
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enum NextStatus { SHUTDOWN, GOT_EVENT, TIMEOUT }; |
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// Nonblocking (until deadline) read from queue.
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// Cannot rely on result of tag or ok if return is TIMEOUT
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/// Read from the queue, blocking up to \a deadline (or the queue's shutdown).
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/// Both \a tag and \a ok are updated upon success (if an event is available
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/// within the \a deadline). A \a tag points to an arbitrary location usually
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/// employed to uniquely identify an event.
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///
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/// \param tag[out] Upon sucess, updated to point to the event's tag.
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/// \param ok[out] Upon sucess, true if read a regular event, false otherwise.
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/// \param deadline[in] How long to block in wait for an event.
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///
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/// \return The type of event read.
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template <typename T> |
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NextStatus AsyncNext(void** tag, bool* ok, const T& deadline) { |
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TimePoint<T> deadline_tp(deadline); |
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return AsyncNextInternal(tag, ok, deadline_tp.raw_time()); |
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} |
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// Blocking read from queue.
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// Returns false if the queue is ready for destruction, true if event
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/// Read from the queue, blocking until an event is available or the queue is
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/// shutting down.
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///
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/// \param tag[out] Updated to point to the read event's tag.
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/// \param ok[out] true if read a regular event, false otherwise.
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///
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/// \return true if read a regular event, false if the queue is shutting down.
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bool Next(void** tag, bool* ok) { |
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return (AsyncNextInternal(tag, ok, gpr_inf_future(GPR_CLOCK_REALTIME)) != |
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SHUTDOWN); |
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} |
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// Shutdown has to be called, and the CompletionQueue can only be
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// destructed when false is returned from Next().
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/// Request the shutdown of the queue.
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///
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/// \warning This method must be called at some point. Once invoked, \a Next
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/// will start to return false and \a AsyncNext will return \a
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/// NextStatus::SHUTDOWN. Only once either one of these methods does that
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/// (that is, once the queue has been \em drained) can an instance of this
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/// class be destroyed.
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void Shutdown(); |
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/// Returns a \em raw pointer to the underlying \a grpc_completion_queue
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/// instance.
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///
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/// \warning Remember that the returned instance is owned. No transfer of
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/// owership is performed.
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grpc_completion_queue* cq() { return cq_; } |
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private: |
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@ -147,27 +175,29 @@ class CompletionQueue : public GrpcLibrary { |
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NextStatus AsyncNextInternal(void** tag, bool* ok, gpr_timespec deadline); |
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// Wraps grpc_completion_queue_pluck.
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// Cannot be mixed with calls to Next().
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/// Wraps \a grpc_completion_queue_pluck.
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/// \warning Must not be mixed with calls to \a Next.
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bool Pluck(CompletionQueueTag* tag); |
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// Does a single polling pluck on tag
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/// Performs a single polling pluck on \a tag.
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void TryPluck(CompletionQueueTag* tag); |
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grpc_completion_queue* cq_; // owned
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}; |
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/// An interface allowing implementors to process and filter event tags.
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class CompletionQueueTag { |
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public: |
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virtual ~CompletionQueueTag() {} |
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// Called prior to returning from Next(), return value
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// is the status of the operation (return status is the default thing
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// to do)
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// If this function returns false, the tag is dropped and not returned
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// from the completion queue
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// Called prior to returning from Next(), return value is the status of the
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// operation (return status is the default thing to do). If this function
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// returns false, the tag is dropped and not returned from the completion
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// queue
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virtual bool FinalizeResult(void** tag, bool* status) = 0; |
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}; |
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/// A specific type of completion queue used by the processing of notifications
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/// by servers.
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class ServerCompletionQueue : public CompletionQueue { |
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private: |
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friend class ServerBuilder; |
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