subscribe_client.hpp

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#pragma once
 
/// @file userver/storages/redis/subscribe_client.hpp
/// @brief @copybrief storages::redis::SubscribeClient
 
#include <memory>
#include <string>
 
#include <userver/storages/redis/client_fwd.hpp>
#include <userver/storages/redis/impl/base.hpp>
#include <userver/storages/redis/impl/wait_connected_mode.hpp>
 
#include <userver/storages/redis/subscription_token.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace redis {
class SubscribeSentinel;
}  // namespace redis
 
namespace storages::redis {
 
/// @ingroup userver_clients
///
/// @brief Client that allows subscribing to Redis channel messages.
///
/// Usually retrieved from components::Redis component.
///
/// Callback for each received message is called only
/// after the execution of callback for previous message has finished. For
/// parallel message processing use the utils::Async().
///
/// @warning Messages can be received in any order due to Redis sharding.
/// Sometimes messages can be duplicated due to subscriptions rebalancing.
/// Some messages may be lost (it's a Redis limitation).
///
/// @warning The first callback execution can happen before `Subscribe()` or
/// `Psubscribe()` return as it happens in a separate task.
///
/// @note a good GMock-based mock for this class can be found here:
/// userver/storages/redis/mock_subscribe_client.hpp
class SubscribeClient {
 public:
  virtual ~SubscribeClient();
 
  virtual SubscriptionToken Subscribe(
      std::string channel, SubscriptionToken::OnMessageCb on_message_cb,
      const USERVER_NAMESPACE::redis::CommandControl& command_control) = 0;
 
  SubscriptionToken Subscribe(std::string channel,
                              SubscriptionToken::OnMessageCb on_message_cb) {
    return Subscribe(std::move(channel), std::move(on_message_cb), {});
  }
 
  virtual SubscriptionToken Psubscribe(
      std::string pattern, SubscriptionToken::OnPmessageCb on_pmessage_cb,
      const USERVER_NAMESPACE::redis::CommandControl& command_control) = 0;
 
  virtual size_t ShardsCount() const = 0;
 
  SubscriptionToken Psubscribe(std::string pattern,
                               SubscriptionToken::OnPmessageCb on_pmessage_cb) {
    return Psubscribe(std::move(pattern), std::move(on_pmessage_cb), {});
  }
 
  virtual SubscriptionToken Ssubscribe(
      std::string channel, SubscriptionToken::OnMessageCb on_message_cb,
      const USERVER_NAMESPACE::redis::CommandControl& command_control) = 0;
 
  SubscriptionToken Ssubscribe(std::string channel,
                               SubscriptionToken::OnMessageCb on_message_cb) {
    return Ssubscribe(std::move(channel), std::move(on_message_cb), {});
  }
};
 
}  // namespace storages::redis
 
USERVER_NAMESPACE_END