Java: Pub & Sub = <3

java/client/src/main/java/glide/api/BaseClient.java

@@ -97,6 +97,7 @@
 import static redis_request.RedisRequestOuterClass.RequestType.PfAdd;
 import static redis_request.RedisRequestOuterClass.RequestType.PfCount;
 import static redis_request.RedisRequestOuterClass.RequestType.PfMerge;
+import static redis_request.RedisRequestOuterClass.RequestType.Publish;
 import static redis_request.RedisRequestOuterClass.RequestType.RPop;
 import static redis_request.RedisRequestOuterClass.RequestType.RPush;
 import static redis_request.RedisRequestOuterClass.RequestType.RPushX;
@@ -179,13 +180,15 @@
 import glide.api.commands.HashBaseCommands;
 import glide.api.commands.HyperLogLogBaseCommands;
 import glide.api.commands.ListBaseCommands;
+import glide.api.commands.PubSubBaseCommands;
 import glide.api.commands.ScriptingAndFunctionsBaseCommands;
 import glide.api.commands.SetBaseCommands;
 import glide.api.commands.SortedSetBaseCommands;
 import glide.api.commands.StreamBaseCommands;
 import glide.api.commands.StringBaseCommands;
 import glide.api.commands.TransactionsBaseCommands;
 import glide.api.models.GlideString;
+import glide.api.models.PubSubMessage;
 import glide.api.models.Script;
 import glide.api.models.commands.ExpireOptions;
 import glide.api.models.commands.GetExOptions;
@@ -225,33 +228,37 @@
 import glide.api.models.commands.stream.StreamReadOptions;
 import glide.api.models.commands.stream.StreamTrimOptions;
 import glide.api.models.configuration.BaseClientConfiguration;
+import glide.api.models.configuration.BaseSubscriptionConfiguration;
+import glide.api.models.exceptions.ConfigurationError;
 import glide.api.models.exceptions.RedisException;
 import glide.connectors.handlers.CallbackDispatcher;
 import glide.connectors.handlers.ChannelHandler;
+import glide.connectors.handlers.MessageHandler;
 import glide.connectors.resources.Platform;
 import glide.connectors.resources.ThreadPoolResource;
 import glide.connectors.resources.ThreadPoolResourceAllocator;
 import glide.ffi.resolvers.RedisValueResolver;
-import glide.managers.BaseCommandResponseResolver;
+import glide.managers.BaseResponseResolver;
 import glide.managers.CommandManager;
 import glide.managers.ConnectionManager;
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ConcurrentLinkedDeque;
 import java.util.concurrent.ExecutionException;
-import java.util.function.BiFunction;
+import java.util.function.Supplier;
 import java.util.stream.Collectors;
-import lombok.AllArgsConstructor;
 import lombok.NonNull;
 import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.lang3.NotImplementedException;
 import response.ResponseOuterClass.ConstantResponse;
 import response.ResponseOuterClass.Response;
 
 /** Base Client class for Redis */
-@AllArgsConstructor
 public abstract class BaseClient
         implements AutoCloseable,
                 BitmapBaseCommands,
@@ -265,13 +272,44 @@ public abstract class BaseClient
                 HyperLogLogBaseCommands,
                 GeospatialIndicesBaseCommands,
                 ScriptingAndFunctionsBaseCommands,
-                TransactionsBaseCommands {
+                TransactionsBaseCommands,
+                PubSubBaseCommands {
 
     /** Redis simple string response with "OK" */
     public static final String OK = ConstantResponse.OK.toString();
 
-    protected final ConnectionManager connectionManager;
-    protected final CommandManager commandManager;
+    // Members below are effectively-final, but since we use a static async method as a constructor,
+    // we can't set them in a standard constructor. They all set in `buildClient` method below.
+    // All made protected to simplify testing.
+    protected CommandManager commandManager;
+    protected ConnectionManager connectionManager;
+    protected ConcurrentLinkedDeque<PubSubMessage> messageQueue;
+    protected Optional<BaseSubscriptionConfiguration> subscriptionConfiguration = Optional.empty();
+
+    /** Helper which extracts data from received {@link Response}s from GLIDE. */
+    private static final BaseResponseResolver responseResolver =
+            new BaseResponseResolver(RedisValueResolver::valueFromPointer);
+
+    /** Helper which extracts data with binary strings from received {@link Response}s from GLIDE. */
+    private static final BaseResponseResolver binaryResponseResolver =
+            new BaseResponseResolver(RedisValueResolver::valueFromPointerBinary);
+
+    /** Create a client instance and init private fields. */
+    protected static <T extends BaseClient> T buildClient(
+            Supplier<T> constructor,
+            ConnectionManager connectionManager,
+            CommandManager commandManager,
+            MessageHandler messageHandler,
+            BaseSubscriptionConfiguration subscriptionConfiguration) {
+        T client = constructor.get();
+        client.connectionManager = connectionManager;
+        client.commandManager = commandManager;
+        client.messageQueue = messageHandler.getQueue();
+        if (subscriptionConfiguration != null) {
+            client.subscriptionConfiguration = Optional.of(subscriptionConfiguration);
+        }
+        return client;
+    }
 
     /**
      * Async request for an async (non-blocking) Redis client.
@@ -281,31 +319,81 @@ public abstract class BaseClient
      * @param <T> Client type.
      * @return a Future to connect and return a RedisClient.
      */
-    protected static <T> CompletableFuture<T> CreateClient(
-            BaseClientConfiguration config,
-            BiFunction<ConnectionManager, CommandManager, T> constructor) {
+    protected static <T extends BaseClient> CompletableFuture<T> CreateClient(
+            @NonNull BaseClientConfiguration config, Supplier<T> constructor) {
         try {
             ThreadPoolResource threadPoolResource = config.getThreadPoolResource();
             if (threadPoolResource == null) {
                 threadPoolResource =
                         ThreadPoolResourceAllocator.getOrCreate(Platform.getThreadPoolResourceSupplier());
             }
-            ChannelHandler channelHandler = buildChannelHandler(threadPoolResource);
+            MessageHandler messageHandler = buildMessageHandler(config);
+            ChannelHandler channelHandler = buildChannelHandler(threadPoolResource, messageHandler);
             ConnectionManager connectionManager = buildConnectionManager(channelHandler);
             CommandManager commandManager = buildCommandManager(channelHandler);
             // TODO: Support exception throwing, including interrupted exceptions
             return connectionManager
                     .connectToRedis(config)
-                    .thenApply(ignore -> constructor.apply(connectionManager, commandManager));
+                    .thenApply(
+                            ignored ->
+                                    buildClient(
+                                            constructor,
+                                            connectionManager,
+                                            commandManager,
+                                            messageHandler,
+                                            config.getSubscriptionConfiguration()));
         } catch (InterruptedException e) {
-            // Something bad happened while we were establishing netty connection to
-            // UDS
+            // Something bad happened while we were establishing netty connection to UDS
             var future = new CompletableFuture<T>();
             future.completeExceptionally(e);
             return future;
         }
     }
 
+    /**
+     * Tries to return a next pubsub message.
+     *
+     * @throws ConfigurationError If client is not subscribed to any channel or if client configured
+     *     with a callback.
+     * @return A message if any or <code>null</code> if there are no unread messages.
+     */
+    public PubSubMessage tryGetPubSubMessage() {
+        if (subscriptionConfiguration.isEmpty()) {
+            throw new ConfigurationError(
+                    "The operation will never complete since there was no pubsub subscriptions applied to the"
+                            + " client.");
+        }
+        if (subscriptionConfiguration.get().getCallback().isPresent()) {
+            throw new ConfigurationError(
+                    "The operation will never complete since messages will be passed to the configured"
+                            + " callback.");
+        }
+        return messageQueue.poll();
+    }
+
+    /**
+     * Returns a promise for a next pubsub message.
+     *
+     * @apiNote <b>Not implemented!</b>
+     * @throws ConfigurationError If client is not subscribed to any channel or if client configured
+     *     with a callback.
+     * @return A <code>Future</code> which resolved with the next incoming message.
+     */
+    public CompletableFuture<PubSubMessage> getPubSubMessage() {
+        if (subscriptionConfiguration.isEmpty()) {
+            throw new ConfigurationError(
+                    "The operation will never complete since there was no pubsub subscriptions applied to the"
+                            + " client.");
+        }
+        if (subscriptionConfiguration.get().getCallback().isPresent()) {
+            throw new ConfigurationError(
+                    "The operation will never complete since messages will be passed to the configured"
+                            + " callback.");
+        }
+        throw new NotImplementedException(
+                "This feature will be supported in a future release of the GLIDE java client");
+    }
+
     /**
      * Closes this resource, relinquishing any underlying resources. This method is invoked
      * automatically on objects managed by the try-with-resources statement.
@@ -318,15 +406,25 @@ public void close() throws ExecutionException {
         try {
             connectionManager.closeConnection().get();
         } catch (InterruptedException e) {
-            // suppressing the interrupted exception - it is already suppressed in the
-            // future
+            // suppressing the interrupted exception - it is already suppressed in the future
             throw new RuntimeException(e);
         }
     }
 
-    protected static ChannelHandler buildChannelHandler(ThreadPoolResource threadPoolResource)
+    protected static MessageHandler buildMessageHandler(BaseClientConfiguration config) {
+        if (config.getSubscriptionConfiguration() == null) {
+            return new MessageHandler(Optional.empty(), Optional.empty(), responseResolver);
+        }
+        return new MessageHandler(
+                config.getSubscriptionConfiguration().getCallback(),
+                config.getSubscriptionConfiguration().getContext(),
+                responseResolver);
+    }
+
+    protected static ChannelHandler buildChannelHandler(
+            ThreadPoolResource threadPoolResource, MessageHandler messageHandler)
             throws InterruptedException {
-        CallbackDispatcher callbackDispatcher = new CallbackDispatcher();
+        CallbackDispatcher callbackDispatcher = new CallbackDispatcher(messageHandler);
         return new ChannelHandler(callbackDispatcher, getSocket(), threadPoolResource);
     }
 
@@ -362,10 +460,7 @@ protected <T> T handleRedisResponse(
         boolean encodingUtf8 = flags.contains(ResponseFlags.ENCODING_UTF8);
         boolean isNullable = flags.contains(ResponseFlags.IS_NULLABLE);
         Object value =
-                encodingUtf8
-                        ? new BaseCommandResponseResolver(RedisValueResolver::valueFromPointer).apply(response)
-                        : new BaseCommandResponseResolver(RedisValueResolver::valueFromPointerBinary)
-                                .apply(response);
+                encodingUtf8 ? responseResolver.apply(response) : binaryResponseResolver.apply(response);
         if (isNullable && (value == null)) {
             return null;
         }
@@ -2705,6 +2800,18 @@ public CompletableFuture<Map<String, Object>> lcsIdxWithMatchLen(
         return commandManager.submitNewCommand(LCS, arguments, this::handleMapResponse);
     }
 
+    @Override
+    public CompletableFuture<String> publish(@NonNull String channel, @NonNull String message) {
+        return commandManager.submitNewCommand(
+                Publish,
+                new String[] {channel, message},
+                response -> {
+                    // Check, but ignore the number - it is never valid. A GLIDE bug/limitation TODO
+                    handleLongResponse(response);
+                    return OK;
+                });
+    }
+
     @Override
     public CompletableFuture<String> watch(@NonNull String[] keys) {
         return commandManager.submitNewCommand(Watch, keys, this::handleStringResponse);

java/client/src/main/java/glide/api/RedisClient.java

@@ -54,8 +54,6 @@
 import glide.api.models.commands.SortOptions;
 import glide.api.models.commands.function.FunctionRestorePolicy;
 import glide.api.models.configuration.RedisClientConfiguration;
-import glide.managers.CommandManager;
-import glide.managers.ConnectionManager;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
@@ -73,10 +71,6 @@ public class RedisClient extends BaseClient
                 ScriptingAndFunctionsCommands,
                 TransactionsCommands {
 
-    protected RedisClient(ConnectionManager connectionManager, CommandManager commandManager) {
-        super(connectionManager, commandManager);
-    }
-
     /**
      * Async request for an async (non-blocking) Redis client in Standalone mode.
      *

java/client/src/main/java/glide/api/RedisClusterClient.java

@@ -37,13 +37,15 @@
 import static redis_request.RedisRequestOuterClass.RequestType.Lolwut;
 import static redis_request.RedisRequestOuterClass.RequestType.Ping;
 import static redis_request.RedisRequestOuterClass.RequestType.RandomKey;
+import static redis_request.RedisRequestOuterClass.RequestType.SPublish;
 import static redis_request.RedisRequestOuterClass.RequestType.Sort;
 import static redis_request.RedisRequestOuterClass.RequestType.SortReadOnly;
 import static redis_request.RedisRequestOuterClass.RequestType.Time;
 import static redis_request.RedisRequestOuterClass.RequestType.UnWatch;
 
 import glide.api.commands.ConnectionManagementClusterCommands;
 import glide.api.commands.GenericClusterCommands;
+import glide.api.commands.PubSubClusterCommands;
 import glide.api.commands.ScriptingAndFunctionsClusterCommands;
 import glide.api.commands.ServerManagementClusterCommands;
 import glide.api.commands.TransactionsClusterCommands;
@@ -57,8 +59,6 @@
 import glide.api.models.configuration.RedisClusterClientConfiguration;
 import glide.api.models.configuration.RequestRoutingConfiguration.Route;
 import glide.api.models.configuration.RequestRoutingConfiguration.SingleNodeRoute;
-import glide.managers.CommandManager;
-import glide.managers.ConnectionManager;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.Map;
@@ -77,11 +77,8 @@ public class RedisClusterClient extends BaseClient
                 GenericClusterCommands,
                 ServerManagementClusterCommands,
                 ScriptingAndFunctionsClusterCommands,
-                TransactionsClusterCommands {
-
-    protected RedisClusterClient(ConnectionManager connectionManager, CommandManager commandManager) {
-        super(connectionManager, commandManager);
-    }
+                TransactionsClusterCommands,
+                PubSubClusterCommands {
 
     /**
      * Async request for an async (non-blocking) Redis client in Cluster mode.
@@ -780,6 +777,18 @@ public CompletableFuture<String> randomKey() {
                 RandomKey, new String[0], this::handleStringOrNullResponse);
     }
 
+    @Override
+    public CompletableFuture<String> spublish(@NonNull String channel, @NonNull String message) {
+        return commandManager.submitNewCommand(
+                SPublish,
+                new String[] {channel, message},
+                response -> {
+                    // Check, but ignore the number - it is never valid. A GLIDE bug/limitation TODO
+                    handleLongResponse(response);
+                    return OK;
+                });
+    }
+
     @Override
     public CompletableFuture<String[]> sort(
             @NonNull String key, @NonNull SortClusterOptions sortClusterOptions) {

java/client/src/main/java/glide/api/commands/PubSubBaseCommands.java

@@ -0,0 +1,27 @@
+/** Copyright Valkey GLIDE Project Contributors - SPDX Identifier: Apache-2.0 */
+package glide.api.commands;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Supports commands for the "Pub/Sub" group for standalone and cluster clients.
+ *
+ * @see <a href="https://redis.io/docs/latest/commands/?group=pubsub">Pub/Sub Commands</a>
+ */
+public interface PubSubBaseCommands {
+
+    /**
+     * Publishes message on pubsub channel.
+     *
+     * @see <a href="https://redis.io/docs/latest/commands/publish/">redis.io</a> for details.
+     * @param channel The Channel to publish the message on.
+     * @param message The message to publish.
+     * @return <code>OK</code>.
+     * @example
+     *     <pre>{@code
+     * Long receivers = client.publish("announcements", "The cat said 'meow'!").get();
+     * assert receivers > 0L;
+     * }</pre>
+     */
+    CompletableFuture<String> publish(String channel, String message);
+}

java/client/src/main/java/glide/api/commands/PubSubClusterCommands.java

@@ -0,0 +1,28 @@
+/** Copyright Valkey GLIDE Project Contributors - SPDX Identifier: Apache-2.0 */
+package glide.api.commands;
+
+import java.util.concurrent.CompletableFuture;
+
+/**
+ * Supports commands for the "Pub/Sub" group for a cluster client.
+ *
+ * @see <a href="https://redis.io/docs/latest/commands/publish/">Pub/Sub Commands</a>
+ */
+public interface PubSubClusterCommands {
+
+    /**
+     * Publishes message on pubsub channel in sharded mode.
+     *
+     * @since Redis 7.0 and above.
+     * @see <a href="https://redis.io/docs/latest/commands/spublish/">redis.io</a> for details.
+     * @param channel The Channel to publish the message on.
+     * @param message The message to publish.
+     * @return <code>OK</code>.
+     * @example
+     *     <pre>{@code
+     * Long receivers = client.spublish("announcements", "The cat said 'meow'!").get();
+     * assert receivers > 0L;
+     * }</pre>
+     */
+    CompletableFuture<String> spublish(String channel, String message);
+}