mirror of https://github.com/grpc/grpc.git
Karthik Ravi Shankar
6 years ago
parent
40210d3b8a
commit
03b079499c
29 changed files with 532 additions and 99 deletions
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/*
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* |
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* Copyright 2015-2016 gRPC authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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* |
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*/ |
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/// A completion queue implements a concurrent producer-consumer queue, with
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/// two main API-exposed methods: \a Next and \a AsyncNext. These
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/// methods are the essential component of the gRPC C++ asynchronous API.
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/// There is also a \a Shutdown method to indicate that a given completion queue
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/// will no longer have regular events. This must be called before the
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/// completion queue is destroyed.
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/// All completion queue APIs are thread-safe and may be used concurrently with
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/// any other completion queue API invocation; it is acceptable to have
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/// multiple threads calling \a Next or \a AsyncNext on the same or different
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/// completion queues, or to call these methods concurrently with a \a Shutdown
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/// elsewhere.
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/// \remark{All other API calls on completion queue should be completed before
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/// a completion queue destructor is called.}
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#ifndef GRPCPP_IMPL_CODEGEN_COMPLETION_QUEUE_IMPL_H |
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#define GRPCPP_IMPL_CODEGEN_COMPLETION_QUEUE_IMPL_H |
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#include <grpc/impl/codegen/atm.h> |
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#include <grpcpp/impl/codegen/completion_queue_tag.h> |
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#include <grpcpp/impl/codegen/core_codegen_interface.h> |
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#include <grpcpp/impl/codegen/grpc_library.h> |
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#include <grpcpp/impl/codegen/status.h> |
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#include <grpcpp/impl/codegen/time.h> |
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struct grpc_completion_queue; |
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namespace grpc_impl { |
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class Channel; |
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class Server; |
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class ServerBuilder; |
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} // namespace grpc_impl
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namespace grpc { |
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template <class R> |
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class ClientReader; |
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template <class W> |
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class ClientWriter; |
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template <class W, class R> |
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class ClientReaderWriter; |
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template <class R> |
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class ServerReader; |
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template <class W> |
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class ServerWriter; |
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namespace internal { |
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template <class W, class R> |
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class ServerReaderWriterBody; |
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} // namespace internal
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class ChannelInterface; |
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class ClientContext; |
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class ServerContext; |
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class ServerInterface; |
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namespace internal { |
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class CompletionQueueTag; |
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class RpcMethod; |
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template <class ServiceType, class RequestType, class ResponseType> |
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class RpcMethodHandler; |
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template <class ServiceType, class RequestType, class ResponseType> |
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class ClientStreamingHandler; |
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template <class ServiceType, class RequestType, class ResponseType> |
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class ServerStreamingHandler; |
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template <class ServiceType, class RequestType, class ResponseType> |
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class BidiStreamingHandler; |
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template <class Streamer, bool WriteNeeded> |
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class TemplatedBidiStreamingHandler; |
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template <StatusCode code> |
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class ErrorMethodHandler; |
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template <class InputMessage, class OutputMessage> |
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class BlockingUnaryCallImpl; |
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template <class Op1, class Op2, class Op3, class Op4, class Op5, class Op6> |
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class CallOpSet; |
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} // namespace internal
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extern CoreCodegenInterface* g_core_codegen_interface; |
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} // namespace grpc
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namespace grpc_impl { |
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/// A thin wrapper around \ref grpc_completion_queue (see \ref
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/// src/core/lib/surface/completion_queue.h).
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/// See \ref doc/cpp/perf_notes.md for notes on best practices for high
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/// performance servers.
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class CompletionQueue : private ::grpc::GrpcLibraryCodegen { |
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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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: CompletionQueue(grpc_completion_queue_attributes{ |
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GRPC_CQ_CURRENT_VERSION, GRPC_CQ_NEXT, GRPC_CQ_DEFAULT_POLLING, |
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nullptr}) {} |
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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() { |
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::grpc::g_core_codegen_interface->grpc_completion_queue_destroy(cq_); |
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} |
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/// Tri-state return for AsyncNext: SHUTDOWN, GOT_EVENT, TIMEOUT.
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enum NextStatus { |
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SHUTDOWN, ///< The completion queue has been shutdown and fully-drained
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GOT_EVENT, ///< Got a new event; \a tag will be filled in with its
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///< associated value; \a ok indicating its success.
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TIMEOUT ///< deadline was reached.
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}; |
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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 successful event, false otherwise.
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///
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/// Note that each tag sent to the completion queue (through RPC operations
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/// or alarms) will be delivered out of the completion queue by a call to
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/// Next (or a related method), regardless of whether the operation succeeded
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/// or not. Success here means that this operation completed in the normal
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/// valid manner.
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///
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/// Server-side RPC request: \a ok indicates that the RPC has indeed
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/// been started. If it is false, the server has been Shutdown
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/// before this particular call got matched to an incoming RPC.
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///
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/// Client-side StartCall/RPC invocation: \a ok indicates that the RPC is
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/// going to go to the wire. If it is false, it not going to the wire. This
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/// would happen if the channel is either permanently broken or
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/// transiently broken but with the fail-fast option. (Note that async unary
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/// RPCs don't post a CQ tag at this point, nor do client-streaming
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/// or bidi-streaming RPCs that have the initial metadata corked option set.)
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///
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/// Client-side Write, Client-side WritesDone, Server-side Write,
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/// Server-side Finish, Server-side SendInitialMetadata (which is
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/// typically included in Write or Finish when not done explicitly):
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/// \a ok means that the data/metadata/status/etc is going to go to the
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/// wire. If it is false, it not going to the wire because the call
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/// is already dead (i.e., canceled, deadline expired, other side
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/// dropped the channel, etc).
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///
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/// Client-side Read, Server-side Read, Client-side
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/// RecvInitialMetadata (which is typically included in Read if not
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/// done explicitly): \a ok indicates whether there is a valid message
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/// that got read. If not, you know that there are certainly no more
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/// messages that can ever be read from this stream. For the client-side
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/// operations, this only happens because the call is dead. For the
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/// server-sider operation, though, this could happen because the client
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/// has done a WritesDone already.
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///
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/// Client-side Finish: \a ok should always be true
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///
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/// Server-side AsyncNotifyWhenDone: \a ok should always be true
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///
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/// Alarm: \a ok is true if it expired, false if it was canceled
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///
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/// \return true if got an event, false if the queue is fully drained and
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/// shut down.
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bool Next(void** tag, bool* ok) { |
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return (AsyncNextInternal(tag, ok, |
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::grpc::g_core_codegen_interface->gpr_inf_future( |
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GPR_CLOCK_REALTIME)) != SHUTDOWN); |
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} |
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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 a successful event, false otherwise
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/// See documentation for CompletionQueue::Next for explanation of ok
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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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::grpc::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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/// EXPERIMENTAL
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/// First executes \a F, then reads from the queue, blocking up to
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/// \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 f [in] Function to execute before calling AsyncNext on this queue.
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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
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/// 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, typename F> |
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NextStatus DoThenAsyncNext(F&& f, void** tag, bool* ok, const T& deadline) { |
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CompletionQueueTLSCache cache = CompletionQueueTLSCache(this); |
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f(); |
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if (cache.Flush(tag, ok)) { |
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return GOT_EVENT; |
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} else { |
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return AsyncNext(tag, ok, deadline); |
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} |
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} |
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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 if this completion queue
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/// is accessed with Next or AsyncNext. \a Next will not return false
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/// until this method has been called and all pending tags have been drained.
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/// (Likewise for \a AsyncNext returning \a NextStatus::SHUTDOWN .)
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/// Only once either one of these methods does that (that is, once the queue
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/// has been \em drained) can an instance of this class be destroyed.
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/// Also note that applications must ensure that no work is enqueued on this
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/// completion queue after this method is called.
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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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protected: |
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/// Private constructor of CompletionQueue only visible to friend classes
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CompletionQueue(const grpc_completion_queue_attributes& attributes) { |
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cq_ = ::grpc::g_core_codegen_interface->grpc_completion_queue_create( |
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::grpc::g_core_codegen_interface->grpc_completion_queue_factory_lookup( |
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&attributes), |
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&attributes, NULL); |
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InitialAvalanching(); // reserve this for the future shutdown
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} |
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private: |
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// Friend synchronous wrappers so that they can access Pluck(), which is
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// a semi-private API geared towards the synchronous implementation.
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template <class R> |
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friend class ::grpc::ClientReader; |
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template <class W> |
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friend class ::grpc::ClientWriter; |
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template <class W, class R> |
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friend class ::grpc::ClientReaderWriter; |
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template <class R> |
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friend class ::grpc::ServerReader; |
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template <class W> |
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friend class ::grpc::ServerWriter; |
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template <class W, class R> |
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friend class ::grpc::internal::ServerReaderWriterBody; |
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template <class ServiceType, class RequestType, class ResponseType> |
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friend class ::grpc::internal::RpcMethodHandler; |
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template <class ServiceType, class RequestType, class ResponseType> |
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friend class ::grpc::internal::ClientStreamingHandler; |
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template <class ServiceType, class RequestType, class ResponseType> |
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friend class ::grpc::internal::ServerStreamingHandler; |
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template <class Streamer, bool WriteNeeded> |
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friend class ::grpc::internal::TemplatedBidiStreamingHandler; |
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template <::grpc::StatusCode code> |
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friend class ::grpc::internal::ErrorMethodHandler; |
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friend class ::grpc_impl::Server; |
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friend class ::grpc::ServerContext; |
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friend class ::grpc::ServerInterface; |
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template <class InputMessage, class OutputMessage> |
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friend class ::grpc::internal::BlockingUnaryCallImpl; |
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// Friends that need access to constructor for callback CQ
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friend class ::grpc_impl::Channel; |
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// For access to Register/CompleteAvalanching
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template <class Op1, class Op2, class Op3, class Op4, class Op5, class Op6> |
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friend class ::grpc::internal::CallOpSet; |
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/// EXPERIMENTAL
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/// Creates a Thread Local cache to store the first event
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/// On this completion queue queued from this thread. Once
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/// initialized, it must be flushed on the same thread.
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class CompletionQueueTLSCache { |
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public: |
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CompletionQueueTLSCache(CompletionQueue* cq); |
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~CompletionQueueTLSCache(); |
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bool Flush(void** tag, bool* ok); |
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private: |
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CompletionQueue* cq_; |
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bool flushed_; |
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}; |
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NextStatus AsyncNextInternal(void** tag, bool* ok, gpr_timespec deadline); |
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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(::grpc::internal::CompletionQueueTag* tag) { |
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auto deadline = |
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::grpc::g_core_codegen_interface->gpr_inf_future(GPR_CLOCK_REALTIME); |
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while (true) { |
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auto ev = ::grpc::g_core_codegen_interface->grpc_completion_queue_pluck( |
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cq_, tag, deadline, nullptr); |
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bool ok = ev.success != 0; |
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void* ignored = tag; |
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if (tag->FinalizeResult(&ignored, &ok)) { |
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GPR_CODEGEN_ASSERT(ignored == tag); |
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return ok; |
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} |
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} |
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} |
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/// Performs a single polling pluck on \a tag.
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/// \warning Must not be mixed with calls to \a Next.
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///
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/// TODO: sreek - This calls tag->FinalizeResult() even if the cq_ is already
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/// shutdown. This is most likely a bug and if it is a bug, then change this
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/// implementation to simple call the other TryPluck function with a zero
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/// timeout. i.e:
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/// TryPluck(tag, gpr_time_0(GPR_CLOCK_REALTIME))
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void TryPluck(::grpc::internal::CompletionQueueTag* tag) { |
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auto deadline = |
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::grpc::g_core_codegen_interface->gpr_time_0(GPR_CLOCK_REALTIME); |
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auto ev = ::grpc::g_core_codegen_interface->grpc_completion_queue_pluck( |
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cq_, tag, deadline, nullptr); |
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if (ev.type == GRPC_QUEUE_TIMEOUT) return; |
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bool ok = ev.success != 0; |
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void* ignored = tag; |
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// the tag must be swallowed if using TryPluck
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GPR_CODEGEN_ASSERT(!tag->FinalizeResult(&ignored, &ok)); |
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} |
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/// Performs a single polling pluck on \a tag. Calls tag->FinalizeResult if
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/// the pluck() was successful and returned the tag.
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///
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/// This exects tag->FinalizeResult (if called) to return 'false' i.e expects
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/// that the tag is internal not something that is returned to the user.
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void TryPluck(::grpc::internal::CompletionQueueTag* tag, |
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gpr_timespec deadline) { |
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auto ev = ::grpc::g_core_codegen_interface->grpc_completion_queue_pluck( |
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cq_, tag, deadline, nullptr); |
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if (ev.type == GRPC_QUEUE_TIMEOUT || ev.type == GRPC_QUEUE_SHUTDOWN) { |
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return; |
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} |
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bool ok = ev.success != 0; |
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void* ignored = tag; |
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GPR_CODEGEN_ASSERT(!tag->FinalizeResult(&ignored, &ok)); |
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} |
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/// Manage state of avalanching operations : completion queue tags that
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/// trigger other completion queue operations. The underlying core completion
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/// queue should not really shutdown until all avalanching operations have
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/// been finalized. Note that we maintain the requirement that an avalanche
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/// registration must take place before CQ shutdown (which must be maintained
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/// elsehwere)
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void InitialAvalanching() { |
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gpr_atm_rel_store(&avalanches_in_flight_, static_cast<gpr_atm>(1)); |
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} |
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void RegisterAvalanching() { |
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gpr_atm_no_barrier_fetch_add(&avalanches_in_flight_, |
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static_cast<gpr_atm>(1)); |
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} |
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void CompleteAvalanching() { |
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if (gpr_atm_no_barrier_fetch_add(&avalanches_in_flight_, |
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static_cast<gpr_atm>(-1)) == 1) { |
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::grpc::g_core_codegen_interface->grpc_completion_queue_shutdown(cq_); |
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} |
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} |
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grpc_completion_queue* cq_; // owned
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gpr_atm avalanches_in_flight_; |
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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. Instantiated by \a ServerBuilder.
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class ServerCompletionQueue : public CompletionQueue { |
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public: |
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bool IsFrequentlyPolled() { return polling_type_ != GRPC_CQ_NON_LISTENING; } |
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protected: |
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/// Default constructor
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ServerCompletionQueue() : polling_type_(GRPC_CQ_DEFAULT_POLLING) {} |
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private: |
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/// \param completion_type indicates whether this is a NEXT or CALLBACK
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/// completion queue.
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/// \param polling_type Informs the GRPC library about the type of polling
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/// allowed on this completion queue. See grpc_cq_polling_type's description
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/// in grpc_types.h for more details.
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/// \param shutdown_cb is the shutdown callback used for CALLBACK api queues
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ServerCompletionQueue(grpc_cq_completion_type completion_type, |
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grpc_cq_polling_type polling_type, |
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grpc_experimental_completion_queue_functor* shutdown_cb) |
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: CompletionQueue(grpc_completion_queue_attributes{ |
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GRPC_CQ_CURRENT_VERSION, completion_type, polling_type, |
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shutdown_cb}), |
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polling_type_(polling_type) {} |
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grpc_cq_polling_type polling_type_; |
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friend class ::grpc_impl::ServerBuilder; |
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friend class ::grpc_impl::Server; |
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}; |
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} // namespace grpc_impl
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#endif // GRPCPP_IMPL_CODEGEN_COMPLETION_QUEUE_IMPL_H
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