[GCS] Add MessagePublisher to GCS (#7771)

BUILD.bazel

@@ -983,6 +983,24 @@ cc_test(
     ],
 )
 
+cc_library(
+    name = "gcs_pubsub",
+    srcs = [
+        "src/ray/gcs/pubsub/redis_message_publisher.cc",
+    ],
+    hdrs = [
+        "src/ray/gcs/callback.h",
+        "src/ray/gcs/pubsub/message_publisher.h",
+        "src/ray/gcs/pubsub/redis_message_publisher.h",
+    ],
+    copts = COPTS,
+    deps = [
+        ":ray_common",
+        ":ray_util",
+        ":redis_client",
+    ],
+)
+
 cc_library(
     name = "gcs",
     srcs = glob(

src/ray/gcs/pubsub/message_publisher.h

@@ -0,0 +1,33 @@
+#ifndef RAY_GCS_PUBSUB_MESSAGE_PUBLISHER_H
+#define RAY_GCS_PUBSUB_MESSAGE_PUBLISHER_H
+
+#include <string>
+#include "ray/common/status.h"
+#include "ray/gcs/callback.h"
+#include "ray/util/io_service_pool.h"
+#include "ray/util/logging.h"
+
+namespace ray {
+
+namespace gcs {
+
+class MessagePublisher {
+ public:
+  virtual ~MessagePublisher() {}
+
+  virtual Status Init() = 0;
+
+  virtual void Shutdown() = 0;
+
+  virtual Status PublishMessage(const std::string &channel, const std::string &message,
+                                const StatusCallback &callback) = 0;
+
+ protected:
+  MessagePublisher() {}
+};
+
+}  // namespace gcs
+
+}  // namespace ray
+
+#endif  // RAY_GCS_PUBSUB_MESSAGE_PUBLISHER_H

src/ray/gcs/pubsub/redis_message_publisher.cc

@@ -0,0 +1,44 @@
+#include "ray/gcs/pubsub/redis_message_publisher.h"
+#include "ray/gcs/redis_context.h"
+
+namespace ray {
+
+namespace gcs {
+
+RedisMessagePublisher::RedisMessagePublisher(
+    const RedisClientOptions &options, std::shared_ptr<IOServicePool> io_service_pool)
+    : redis_client_(new RedisClient(options)),
+      io_service_pool_(std::move(io_service_pool)) {}
+
+Status RedisMessagePublisher::Init() {
+  auto io_services = io_service_pool_->GetAll();
+  Status status = redis_client_->Connect(io_services);
+  RAY_LOG(INFO) << "RedisMessagePublisher::Init finished with status "
+                << status.ToString();
+  return status;
+}
+
+void RedisMessagePublisher::Shutdown() {
+  redis_client_->Disconnect();
+  RAY_LOG(INFO) << "RedisMessagePublisher::Shutdown.";
+}
+
+Status RedisMessagePublisher::PublishMessage(const std::string &channel,
+                                             const std::string &message,
+                                             const StatusCallback &callback) {
+  std::vector<std::string> args = {"PUBLISH", channel, message};
+
+  RedisCallback pub_callback = nullptr;
+  if (callback) {
+    pub_callback = [callback](std::shared_ptr<CallbackReply> reply) {
+      callback(Status::OK());
+    };
+  }
+  // Select shard context by channel.
+  auto shard_context = redis_client_->GetShardContext(channel);
+  return shard_context->RunArgvAsync(args, pub_callback);
+}
+
+}  // namespace gcs
+
+}  // namespace ray

src/ray/gcs/pubsub/redis_message_publisher.h

@@ -0,0 +1,32 @@
+#ifndef RAY_GCS_PUBSUB_REDIS_MESSAGE_PUBLISHER_H
+#define RAY_GCS_PUBSUB_REDIS_MESSAGE_PUBLISHER_H
+
+#include "ray/gcs/pubsub/message_publisher.h"
+#include "ray/gcs/redis_client.h"
+
+namespace ray {
+
+namespace gcs {
+
+class RedisMessagePublisher : public MessagePublisher {
+ public:
+  RedisMessagePublisher(const RedisClientOptions &options,
+                        std::shared_ptr<IOServicePool> io_service_pool);
+
+  Status Init() override;
+
+  void Shutdown() override;
+
+  Status PublishMessage(const std::string &channel, const std::string &message,
+                        const StatusCallback &callback) override;
+
+ private:
+  std::shared_ptr<RedisClient> redis_client_;
+  std::shared_ptr<IOServicePool> io_service_pool_;
+};
+
+}  // namespace gcs
+
+}  // namespace ray
+
+#endif  // RAY_GCS_PUBSUB_REDIS_MESSAGE_PUBLISHER_H