More implicitness in kotlin (#277)

We had to rename ctx.run to ctx.runBlock in kotlin to avoid clashing with stdlib run extension method.

Author: slinkydeveloper

examples/src/main/kotlin/my/restate/sdk/examples/CounterKt.kt

@@ -10,9 +10,8 @@ package my.restate.sdk.examples
 
 import dev.restate.sdk.annotation.Handler
 import dev.restate.sdk.annotation.VirtualObject
-import dev.restate.sdk.common.StateKey
 import dev.restate.sdk.http.vertx.RestateHttpEndpointBuilder
-import dev.restate.sdk.kotlin.KtSerdes
+import dev.restate.sdk.kotlin.KtStateKey
 import dev.restate.sdk.kotlin.ObjectContext
 import kotlinx.serialization.Serializable
 import org.apache.logging.log4j.LogManager
@@ -24,7 +23,7 @@ import org.apache.logging.log4j.Logger
 class CounterKt {
 
   companion object {
-    private val TOTAL = StateKey.of<Long>("total", KtSerdes.json())
+    private val TOTAL = KtStateKey.json<Long>("total")
     private val LOG: Logger = LogManager.getLogger(CounterKt::class.java)
   }
 

sdk-api-kotlin/src/main/kotlin/dev/restate/sdk/kotlin/ContextImpl.kt

@@ -130,7 +130,7 @@ internal class ContextImpl internal constructor(private val syscalls: Syscalls)
     }
   }
 
-  override suspend fun <T : Any?> run(serde: Serde<T>, sideEffectAction: suspend () -> T): T {
+  override suspend fun <T : Any?> runBlock(serde: Serde<T>, block: suspend () -> T): T {
     val exitResult =
         suspendCancellableCoroutine { cont: CancellableContinuation<CompletableDeferred<ByteString>>
           ->
@@ -165,7 +165,7 @@ internal class ContextImpl internal constructor(private val syscalls: Syscalls)
     var actionReturnValue: T? = null
     var actionFailure: TerminalException? = null
     try {
-      actionReturnValue = sideEffectAction()
+      actionReturnValue = block()
     } catch (e: TerminalException) {
       actionFailure = e
     } catch (e: Error) {

sdk-api-kotlin/src/main/kotlin/dev/restate/sdk/kotlin/KtSerdes.kt

@@ -10,12 +10,21 @@ package dev.restate.sdk.kotlin
 
 import com.google.protobuf.ByteString
 import dev.restate.sdk.common.Serde
+import dev.restate.sdk.common.StateKey
 import java.nio.charset.StandardCharsets
 import kotlin.reflect.typeOf
 import kotlinx.serialization.KSerializer
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.serializer
 
+object KtStateKey {
+
+  /** Creates a json [StateKey]. */
+  inline fun <reified T> json(name: String): StateKey<T> {
+    return StateKey.of(name, KtSerdes.json())
+  }
+}
+
 object KtSerdes {
 
   /** Creates a [Serde] implementation using the `kotlinx.serialization` json module. */

sdk-api-kotlin/src/main/kotlin/dev/restate/sdk/kotlin/api.kt

@@ -114,9 +114,9 @@ sealed interface Context {
    * Errors occurring within this closure won't be propagated to the caller, unless they are
    * [TerminalException]. Consider the following code:
    * ```
-   * // Bad usage of try-catch outside the run
+   * // Bad usage of try-catch outside the runBlock
    * try {
-   *     ctx.run {
+   *     ctx.runBlock {
    *         throw IllegalStateException();
    *     };
    * } catch (e: IllegalStateException) {
@@ -125,9 +125,9 @@ sealed interface Context {
    *     // following the invocation retry policy.
    * }
    *
-   * // Good usage of try-catch outside the run
+   * // Good usage of try-catch outside the runBlock
    * try {
-   *     ctx.run {
+   *     ctx.runBlock {
    *         throw TerminalException("my error");
    *     };
    * } catch (e: TerminalException) {
@@ -138,16 +138,11 @@ sealed interface Context {
    * To propagate failures to the run call-site, make sure to wrap them in [TerminalException].
    *
    * @param serde the type tag of the return value, used to serialize/deserialize it.
-   * @param action closure to execute.
+   * @param block closure to execute.
    * @param T type of the return value.
-   * @return value of the run operation.
+   * @return value of the runBlock operation.
    */
-  suspend fun <T : Any?> run(serde: Serde<T>, sideEffectAction: suspend () -> T): T
-
-  /** Like [run] without a return value. */
-  suspend fun run(sideEffectAction: suspend () -> Unit) {
-    run(KtSerdes.UNIT, sideEffectAction)
-  }
+  suspend fun <T : Any?> runBlock(serde: Serde<T>, block: suspend () -> T): T
 
   /**
    * Create an [Awakeable], addressable through [Awakeable.id].
@@ -176,15 +171,74 @@ sealed interface Context {
    *
    * This instance is useful to generate identifiers, idempotency keys, and for uniform sampling
    * from a set of options. If a cryptographically secure value is needed, please generate that
-   * externally using [run].
+   * externally using [runBlock].
    *
-   * You MUST NOT use this [Random] instance inside a [run].
+   * You MUST NOT use this [Random] instance inside a [runBlock].
    *
    * @return the [Random] instance.
    */
   fun random(): RestateRandom
 }
 
+/**
+ * Execute a non-deterministic closure, recording the result value in the journal using
+ * [KtSerdes.json]. The result value will be re-played in case of re-invocation (e.g. because of
+ * failure recovery or suspension point) without re-executing the closure. Use this feature if you
+ * want to perform <b>non-deterministic operations</b>.
+ *
+ * <p>The closure should tolerate retries, that is Restate might re-execute the closure multiple
+ * times until it records a result.
+ *
+ * <h2>Error handling</h2>
+ *
+ * Errors occurring within this closure won't be propagated to the caller, unless they are
+ * [TerminalException]. Consider the following code:
+ * ```
+ * // Bad usage of try-catch outside the runBlock
+ * try {
+ *     ctx.runBlock {
+ *         throw IllegalStateException();
+ *     };
+ * } catch (e: IllegalStateException) {
+ *     // This will never be executed,
+ *     // but the error will be retried by Restate,
+ *     // following the invocation retry policy.
+ * }
+ *
+ * // Good usage of try-catch outside the runBlock
+ * try {
+ *     ctx.runBlock {
+ *         throw TerminalException("my error");
+ *     };
+ * } catch (e: TerminalException) {
+ *     // This is invoked
+ * }
+ * ```
+ *
+ * To propagate failures to the run call-site, make sure to wrap them in [TerminalException].
+ *
+ * @param block closure to execute.
+ * @param T type of the return value.
+ * @return value of the runBlock operation.
+ */
+suspend inline fun <reified T : Any> Context.runBlock(noinline block: suspend () -> T): T {
+  return this.runBlock(KtSerdes.json(), block)
+}
+
+/**
+ * Create an [Awakeable] using [KtSerdes.json] deserializer, addressable through [Awakeable.id].
+ *
+ * You can use this feature to implement external asynchronous systems interactions, for example you
+ * can send a Kafka record including the [Awakeable.id], and then let another service consume from
+ * Kafka the responses of given external system interaction by using [awakeableHandle].
+ *
+ * @return the [Awakeable] to await on.
+ * @see Awakeable
+ */
+suspend inline fun <reified T : Any> Context.awakeable(): Awakeable<T> {
+  return this.awakeable(KtSerdes.json())
+}
+
 /**
  * This interface extends [Context] adding access to the virtual object instance key-value state
  * storage.
@@ -233,7 +287,7 @@ class RestateRandom(seed: Long, private val syscalls: Syscalls) : Random() {
   private val r = Random(seed)
 
   override fun nextBits(bitCount: Int): Int {
-    check(!syscalls.isInsideSideEffect) { "You can't use RestateRandom inside ctx.run!" }
+    check(!syscalls.isInsideSideEffect) { "You can't use RestateRandom inside ctx.runBlock!" }
     return r.nextBits(bitCount)
   }
 
@@ -369,3 +423,13 @@ sealed interface AwakeableHandle {
    */
   suspend fun reject(reason: String)
 }
+
+/**
+ * Complete with success the [Awakeable] using [KtSerdes.json] serializer.
+ *
+ * @param payload the result payload.
+ * @see Awakeable
+ */
+suspend inline fun <reified T : Any> AwakeableHandle.resolve(payload: T) {
+  return this.resolve(KtSerdes.json(), payload)
+}

sdk-api-kotlin/src/test/kotlin/dev/restate/sdk/kotlin/AwakeableIdTest.kt

@@ -8,7 +8,6 @@
 // https://github.com/restatedev/sdk-java/blob/main/LICENSE
 package dev.restate.sdk.kotlin
 
-import dev.restate.sdk.common.CoreSerdes
 import dev.restate.sdk.core.AwakeableIdTestSuite
 import dev.restate.sdk.core.TestDefinitions
 import dev.restate.sdk.kotlin.KotlinCoroutinesTests.Companion.testDefinitionForService
@@ -17,7 +16,7 @@ class AwakeableIdTest : AwakeableIdTestSuite() {
 
   override fun returnAwakeableId(): TestDefinitions.TestInvocationBuilder =
       testDefinitionForService("ReturnAwakeableId") { ctx, _: Unit ->
-        val awakeable = ctx.awakeable(CoreSerdes.JSON_STRING)
+        val awakeable: Awakeable<String> = ctx.awakeable()
         awakeable.id
       }
 }

sdk-api-kotlin/src/test/kotlin/dev/restate/sdk/kotlin/RandomTest.kt

@@ -21,7 +21,7 @@ class RandomTest : RandomTestSuite() {
 
   override fun randomInsideSideEffect(): TestInvocationBuilder =
       testDefinitionForService<Unit, Int>("RandomInsideSideEffect") { ctx, _: Unit ->
-        ctx.run { ctx.random().nextInt() }
+        ctx.runBlock { ctx.random().nextInt() }
         throw IllegalStateException("This should not unreachable")
       }
 

sdk-api-kotlin/src/test/kotlin/dev/restate/sdk/kotlin/SideEffectTest.kt

@@ -8,7 +8,6 @@
 // https://github.com/restatedev/sdk-java/blob/main/LICENSE
 package dev.restate.sdk.kotlin
 
-import dev.restate.sdk.common.CoreSerdes
 import dev.restate.sdk.core.ProtoUtils.GREETER_SERVICE_TARGET
 import dev.restate.sdk.core.SideEffectTestSuite
 import dev.restate.sdk.core.TestDefinitions
@@ -23,15 +22,14 @@ class SideEffectTest : SideEffectTestSuite() {
 
   override fun sideEffect(sideEffectOutput: String): TestInvocationBuilder =
       testDefinitionForService("SideEffect") { ctx, _: Unit ->
-        val result = ctx.run(CoreSerdes.JSON_STRING) { sideEffectOutput }
+        val result = ctx.runBlock { sideEffectOutput }
         "Hello $result"
       }
 
   override fun consecutiveSideEffect(sideEffectOutput: String): TestInvocationBuilder =
       testDefinitionForService("ConsecutiveSideEffect") { ctx, _: Unit ->
-        val firstResult = ctx.run(CoreSerdes.JSON_STRING) { sideEffectOutput }
-        val secondResult =
-            ctx.run(CoreSerdes.JSON_STRING) { firstResult.uppercase(Locale.getDefault()) }
+        val firstResult = ctx.runBlock { sideEffectOutput }
+        val secondResult = ctx.runBlock { firstResult.uppercase(Locale.getDefault()) }
         "Hello $secondResult"
       }
 
@@ -42,8 +40,7 @@ class SideEffectTest : SideEffectTestSuite() {
               Component.Options(
                   Dispatchers.Unconfined + CoroutineName("CheckContextSwitchingTestCoroutine"))) {
                 handler("run") { ctx, _: Unit ->
-                  val sideEffectCoroutine =
-                      ctx.run(CoreSerdes.JSON_STRING) { coroutineContext[CoroutineName]!!.name }
+                  val sideEffectCoroutine = ctx.runBlock { coroutineContext[CoroutineName]!!.name }
                   check(sideEffectCoroutine == "CheckContextSwitchingTestCoroutine") {
                     "Side effect thread is not running within the same coroutine context of the handler method: $sideEffectCoroutine"
                   }
@@ -54,7 +51,7 @@ class SideEffectTest : SideEffectTestSuite() {
 
   override fun sideEffectGuard(): TestInvocationBuilder =
       testDefinitionForService<Unit, String>("SideEffectGuard") { ctx, _: Unit ->
-        ctx.run { ctx.send(GREETER_SERVICE_TARGET, KtSerdes.json(), "something") }
+        ctx.runBlock { ctx.send(GREETER_SERVICE_TARGET, KtSerdes.json(), "something") }
         throw IllegalStateException("This point should not be reached")
       }
 }

sdk-api-kotlin/src/test/kotlin/dev/restate/sdk/kotlin/StateMachineFailuresTest.kt

@@ -47,7 +47,7 @@ class StateMachineFailuresTest : StateMachineFailuresTestSuite() {
 
   override fun sideEffectFailure(serde: Serde<Int>): TestInvocationBuilder =
       testDefinitionForService("SideEffectFailure") { ctx, _: Unit ->
-        ctx.run(serde) { 0 }
+        ctx.runBlock(serde) { 0 }
         "Francesco"
       }
 }

sdk-api-kotlin/src/test/kotlin/dev/restate/sdk/kotlin/UserFailuresTest.kt

@@ -26,7 +26,7 @@ class UserFailuresTest : UserFailuresTestSuite() {
   ): TestInvocationBuilder =
       testDefinitionForService<Unit, Unit>("SideEffectThrowIllegalStateException") { ctx, _: Unit ->
         try {
-          ctx.run { throw IllegalStateException("Whatever") }
+          ctx.runBlock { throw IllegalStateException("Whatever") }
         } catch (e: Throwable) {
           if (e !is CancellationException && e !is TerminalException) {
             nonTerminalExceptionsSeen.addAndGet(1)
@@ -44,7 +44,7 @@ class UserFailuresTest : UserFailuresTestSuite() {
 
   override fun sideEffectThrowTerminalException(code: Int, message: String): TestInvocationBuilder =
       testDefinitionForService<Unit, Unit>("SideEffectThrowTerminalException") { ctx, _: Unit ->
-        ctx.run { throw TerminalException(code, message) }
+        ctx.runBlock<Unit> { throw TerminalException(code, message) }
         throw IllegalStateException("Not expected to reach this point")
       }
 }

sdk-core/src/test/java/dev/restate/sdk/core/RandomTestSuite.java

@@ -8,7 +8,7 @@
 // https://github.com/restatedev/sdk-java/blob/main/LICENSE
 package dev.restate.sdk.core;
 
-import static dev.restate.sdk.core.AssertUtils.containsOnlyExactErrorMessage;
+import static dev.restate.sdk.core.AssertUtils.*;
 import static dev.restate.sdk.core.ProtoUtils.*;
 
 import dev.restate.sdk.core.TestDefinitions.TestDefinition;
@@ -37,7 +37,7 @@ public Stream<TestDefinition> definitions() {
         this.randomInsideSideEffect()
             .withInput(startMessage(1).setDebugId(debugId), ProtoUtils.inputMessage())
             .assertingOutput(
-                containsOnlyExactErrorMessage(
-                    new IllegalStateException("You can't use RestateRandom inside ctx.run!"))));
+                containsOnly(
+                    errorMessageStartingWith(IllegalStateException.class.getCanonicalName()))));
   }
 }