userver: userver/ugrpc/client/channels.hpp Source File
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channels.hpp
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1#pragma once
2
3/// @file userver/ugrpc/client/channels.hpp
4/// @brief Utilities for managing gRPC connections
5
6#include <grpcpp/channel.h>
7#include <grpcpp/completion_queue.h>
8#include <grpcpp/security/credentials.h>
9
10#include <userver/engine/deadline.hpp>
11#include <userver/engine/task/task_processor_fwd.hpp>
12
13#include <userver/ugrpc/client/impl/client_data.hpp>
14
15USERVER_NAMESPACE_BEGIN
16
17namespace ugrpc::client {
18
19namespace impl {
20
21[[nodiscard]] bool TryWaitForConnected(
22 grpc::Channel& channel, grpc::CompletionQueue& queue,
23 engine::Deadline deadline, engine::TaskProcessor& blocking_task_processor);
24
25[[nodiscard]] bool TryWaitForConnected(
26 impl::ChannelCache::Token& token, grpc::CompletionQueue& queue,
27 engine::Deadline deadline, engine::TaskProcessor& blocking_task_processor);
28
29} // namespace impl
30
31/// @brief Create a new gRPC channel (connection pool) for the endpoint
32///
33/// Channel creation is expensive, reuse channels if possible.
34///
35/// Each channel is fully thread-safe: it can be used across multiple threads,
36/// possibly from multiple clients and using multiple `CompletionQueue`
37/// instances at the same time.
38///
39/// @param blocking_task_processor task processor for blocking channel creation
40/// @param channel_credentials channel credentials
41/// @param endpoint string host:port
42/// @returns shared pointer to the gRPC channel
43std::shared_ptr<grpc::Channel> MakeChannel(
44 engine::TaskProcessor& blocking_task_processor,
45 std::shared_ptr<grpc::ChannelCredentials> channel_credentials,
46 const std::string& endpoint);
47
48/// @brief Wait until the channel state of `client` is `READY`. If the current
49/// state is already `READY`, returns `true` immediately. In case of multiple
50/// underlying channels, waits for all of them.
51/// @returns `true` if the state changed before `deadline` expired
52/// @note The wait operation does not support task cancellations
53template <typename Client>
54[[nodiscard]] bool TryWaitForConnected(
55 Client& client, engine::Deadline deadline,
56 engine::TaskProcessor& blocking_task_processor) {
57 return impl::TryWaitForConnected(
58 impl::GetClientData(client).GetChannelToken(),
59 impl::GetClientData(client).NextQueue(), deadline,
60 blocking_task_processor);
61}
62
63} // namespace ugrpc::client
64
65USERVER_NAMESPACE_END