Kotlin Coroutine API

pom.xml

@@ -1,4 +1,5 @@
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-v4_0_0.xsd">
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-v4_0_0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>io.lettuce</groupId>
@@ -73,6 +74,8 @@
         <rxjava3.version>3.0.5</rxjava3.version>
         <reactive-streams-tck.version>1.0.3</reactive-streams-tck.version>
         <slf4j.version>1.7.25</slf4j.version>
+        <kotlin.version>1.4.0</kotlin.version>
+        <kotlinx-coroutines.version>1.3.9</kotlinx-coroutines.version>
 
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <!-- You need a running redis+sentinel for all tests, therefore disabled by default -->
@@ -84,8 +87,8 @@
         <connection>scm:git:https://github.com/lettuce-io/lettuce-core.git</connection>
         <developerConnection>scm:git:https://github.com/lettuce-io/lettuce-core.git</developerConnection>
         <url>http://github.com/lettuce-io/lettuce-core</url>
-      <tag>HEAD</tag>
-  </scm>
+        <tag>HEAD</tag>
+    </scm>
 
     <distributionManagement>
         <snapshotRepository>
@@ -182,6 +185,27 @@
             <optional>true</optional>
         </dependency>
 
+        <dependency>
+            <groupId>org.jetbrains.kotlin</groupId>
+            <artifactId>kotlin-stdlib</artifactId>
+            <version>${kotlin.version}</version>
+            <optional>true</optional>
+        </dependency>
+
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-coroutines-reactive</artifactId>
+            <version>${kotlinx-coroutines.version}</version>
+            <optional>true</optional>
+        </dependency>
+
+        <dependency>
+            <groupId>org.jetbrains.kotlinx</groupId>
+            <artifactId>kotlinx-coroutines-jdk8</artifactId>
+            <version>${kotlinx-coroutines.version}</version>
+            <optional>true</optional>
+        </dependency>
+
         <!-- OS-native transports -->
 
         <dependency>
@@ -578,14 +602,48 @@
                 </executions>
             </plugin>
 
+            <plugin>
+                <groupId>org.jetbrains.kotlin</groupId>
+                <artifactId>kotlin-maven-plugin</artifactId>
+                <version>${kotlin.version}</version>
+                <configuration>
+                    <args>
+                        <arg>-Xopt-in=kotlin.RequiresOptIn</arg>
+                        <arg>-Xopt-in=io.lettuce.core.ExperimentalLettuceCoroutinesApi</arg>
+                    </args>
+                    <sourceDirs>${project.basedir}/src/main/kotlin</sourceDirs>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <phase>process-sources</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+
+                    <execution>
+                        <id>test-compile</id>
+                        <goals>
+                            <goal>test-compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
+                <executions>
+                    <execution>
+                        <id>compile</id>
+                        <phase>compile</phase>
+                        <goals>
+                            <goal>compile</goal>
+                        </goals>
+                    </execution>
+                </executions>
                 <configuration>
-                    <compilerArgument>-Xlint:all,-deprecation,-unchecked</compilerArgument>
-                    <testCompilerArgument>-Xlint:none</testCompilerArgument>
-                    <showWarnings>true</showWarnings>
-                    <showDeprecation>false</showDeprecation>
                     <source>1.8</source>
                     <target>1.8</target>
                 </configuration>
@@ -884,7 +942,7 @@
                                     <arguments>
                                         <argument>-Xmx2G</argument>
                                         <argument>-classpath</argument>
-                                        <classpath />
+                                        <classpath/>
                                         <argument>org.openjdk.jmh.Main</argument>
                                         <argument>.*</argument>
                                         <argument>-tu</argument>
@@ -958,7 +1016,9 @@
                                 <phase>process-resources</phase>
                                 <configuration>
                                     <target>
-                                        <copy failonerror="false" file="${project.build.directory}/generated-docs/index.pdf" tofile="target/site/reference/pdf/lettuce-reference.pdf" />
+                                        <copy failonerror="false"
+                                              file="${project.build.directory}/generated-docs/index.pdf"
+                                              tofile="target/site/reference/pdf/lettuce-reference.pdf"/>
                                     </target>
                                 </configuration>
                                 <goals>
@@ -1025,9 +1085,9 @@
                                 <toclevels>3</toclevels>
                                 <numbered>true</numbered>
                                 <ext-doc>https://raw.githubusercontent.com/wiki/lettuce-io/lettuce-core/</ext-doc>
-                                <allow-uri-read />
-                                <docinfo />
-                                <toc2 />
+                                <allow-uri-read/>
+                                <docinfo/>
+                                <toc2/>
                                 <icons>font</icons>
                                 <source-highlighter>coderay</source-highlighter>
                             </attributes>

src/main/asciidoc/kotlin-api.asciidoc

@@ -0,0 +1,38 @@
+= Kotlin API
+
+=== Suspendable API based on either reactive or async operations
+
+Example for retrieving commands and using it:
+
+[source,kt]
+----
+val cmd1: RedisSuspendableCommands<String, String> = connection.async().asSuspendable()
+val cmd2: RedisSuspendableCommands<String, String> = connection.reactive().asSuspendable()
+
+val foo1 = cmd1.set("foo", "bar")
+val foo2 = cmd2.keys("fo*")
+----
+
+=== Extensions for existing APIs
+
+==== Transactions DSL
+
+Example for sync:
+
+[source,kt]
+----
+val result: TransactionResult? = connection.sync().multi {
+    set("foo", "bar")
+    get("foo")
+}
+----
+
+Example for async with coroutines:
+
+[source,kt]
+----
+val result: TransactionResult? = connection.async().multi {
+    set("foo", "bar").await()
+    get("foo").await()
+}
+----

src/main/kotlin/io/lettuce/core/ExperimentalLettuceCoroutinesApi.kt

@@ -0,0 +1,25 @@
+package io.lettuce.core
+
+import kotlin.RequiresOptIn.Level.WARNING
+import kotlin.annotation.AnnotationRetention.BINARY
+import kotlin.annotation.AnnotationTarget.*
+
+/**
+ * @author sokomishalov
+ */
+@RequiresOptIn(level = WARNING)
+@Retention(BINARY)
+@Target(
+        CLASS,
+        ANNOTATION_CLASS,
+        PROPERTY,
+        FIELD,
+        LOCAL_VARIABLE,
+        VALUE_PARAMETER,
+        CONSTRUCTOR,
+        FUNCTION,
+        PROPERTY_GETTER,
+        PROPERTY_SETTER,
+        TYPEALIAS
+)
+annotation class ExperimentalLettuceCoroutinesApi

src/main/kotlin/io/lettuce/core/api/async/RedisAsyncCommandsExtensions.kt

@@ -0,0 +1,36 @@
+package io.lettuce.core.api.async
+
+import io.lettuce.core.ExperimentalLettuceCoroutinesApi
+import io.lettuce.core.TransactionResult
+import io.lettuce.core.api.coroutines.RedisSuspendableCommands
+import io.lettuce.core.api.coroutines.async.RedisSuspendableAsyncCommandsImpl
+import kotlinx.coroutines.future.await
+
+
+/**
+ * Extension for [RedisAsyncCommands] to create [RedisSuspendableCommands]
+ *
+ * @author Mikhael Sokolov
+ * @since 6.0
+ */
+@ExperimentalLettuceCoroutinesApi
+fun <K, V> RedisAsyncCommands<K, V>.asSuspendable(): RedisSuspendableCommands<K, V> {
+    return RedisSuspendableAsyncCommandsImpl(this)
+}
+
+/**
+ * Allows to create transaction DSL block with [RedisAsyncCommands].
+ *
+ * @author Mikhael Sokolov
+ * @since 6.0
+ */
+@ExperimentalLettuceCoroutinesApi
+suspend inline fun <K, V> RedisAsyncCommands<K, V>.multi(action: RedisAsyncCommands<K, V>.() -> Unit): TransactionResult? {
+    multi().await()
+    runCatching {
+        action.invoke(this)
+    }.onFailure {
+        discard()
+    }
+    return exec().await()
+}