Add guard for RestateContext.sideEffect await

slinkydeveloper · slinkydeveloper · commit 6b43985cbe07 · 2024-01-15T12:47:01.000+01:00
diff --git a/src/restate_context_impl.ts b/src/restate_context_impl.ts
@@ -82,6 +82,10 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
   // For example, this is illegal: 'ctx.sideEffect(() => {await ctx.get("my-state")})'
   static callContext = new AsyncLocalStorage<CallContext>();
 
+  // This is used to guard users against calling ctx.sideEffect without awaiting it.
+  // See https://github.com/restatedev/sdk-typescript/issues/197 for more details.
+  private executingSideEffect = false;
+
   constructor(
     public readonly id: Buffer,
     public readonly serviceName: string,
@@ -90,30 +94,35 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
     public readonly rand: Rand = new RandImpl(id)
   ) {}
 
-  public async get<T>(name: string): Promise<T | null> {
+  // DON'T make this function async!!! see sideEffect comment for details.
+  public get<T>(name: string): Promise<T | null> {
     // Check if this is a valid action
     this.checkState("get state");
 
     // Create the message and let the state machine process it
     const msg = this.stateMachine.localStateStore.get(name);
-    const result = await this.stateMachine.handleUserCodeMessage(
-      GET_STATE_ENTRY_MESSAGE_TYPE,
-      msg
-    );
 
-    // If the GetState message did not have a value or empty,
-    // then we went to the runtime to get the value.
-    // When we get the response, we set it in the localStateStore,
-    // to answer subsequent requests
-    if (msg.value === undefined && msg.empty === undefined) {
-      this.stateMachine.localStateStore.add(name, result as Buffer | Empty);
-    }
+    const getState = async (): Promise<T | null> => {
+      const result = await this.stateMachine.handleUserCodeMessage(
+        GET_STATE_ENTRY_MESSAGE_TYPE,
+        msg
+      );
 
-    if (!(result instanceof Buffer)) {
-      return null;
-    }
+      // If the GetState message did not have a value or empty,
+      // then we went to the runtime to get the value.
+      // When we get the response, we set it in the localStateStore,
+      // to answer subsequent requests
+      if (msg.value === undefined && msg.empty === undefined) {
+        this.stateMachine.localStateStore.add(name, result as Buffer | Empty);
+      }
+
+      if (!(result instanceof Buffer)) {
+        return null;
+      }
 
-    return jsonDeserialize(result.toString());
+      return jsonDeserialize(result.toString());
+    };
+    return getState();
   }
 
   public set<T>(name: string, value: T): void {
@@ -144,7 +153,8 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
     }
   }
 
-  private async invoke(
+  // DON'T make this function async!!! see sideEffect comment for details.
+  private invoke(
     service: string,
     method: string,
     data: Uint8Array
@@ -156,11 +166,9 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
       methodName: method,
       parameter: Buffer.from(data),
     });
-    const promise = this.stateMachine.handleUserCodeMessage(
-      INVOKE_ENTRY_MESSAGE_TYPE,
-      msg
-    );
-    return (await promise) as Uint8Array;
+    return this.stateMachine
+      .handleUserCodeMessage(INVOKE_ENTRY_MESSAGE_TYPE, msg)
+      .transform((v) => v as Uint8Array);
   }
 
   private async invokeOneWay(
@@ -184,33 +192,39 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
     return new Uint8Array();
   }
 
-  public async oneWayCall(
+  // DON'T make this function async!!! see sideEffect comment for details.
+  public oneWayCall(
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     call: () => Promise<any>
   ): Promise<void> {
     this.checkState("oneWayCall");
 
-    await RestateGrpcContextImpl.callContext.run(
+    return RestateGrpcContextImpl.callContext.run(
       { type: CallContexType.OneWayCall },
       call
     );
   }
 
-  public async delayedCall(
+  // DON'T make this function async!!! see sideEffect comment for details.
+  public delayedCall(
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     call: () => Promise<any>,
     delayMillis?: number
   ): Promise<void> {
     this.checkState("delayedCall");
 
     // Delayed call is a one way call with a delay
-    await RestateGrpcContextImpl.callContext.run(
+    return RestateGrpcContextImpl.callContext.run(
       { type: CallContexType.OneWayCall, delay: delayMillis },
       call
     );
   }
 
-  public async sideEffect<T>(
+  // DON'T make this function async!!!
+  // The reason is that we want the erros thrown by the initial checks to be propagated in the caller context,
+  // and not in the promise context. To understand the semantic difference, make this function async and run the
+  // UnawaitedSideEffectShouldFailSubsequentContextCall test.
+  public sideEffect<T>(
     fn: () => Promise<T>,
     retryPolicy: RetrySettings = DEFAULT_INFINITE_EXPONENTIAL_BACKOFF
   ): Promise<T> {
@@ -227,6 +241,8 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
         { errorCode: ErrorCodes.INTERNAL }
       );
     }
+    this.checkNotExecutingSideEffect();
+    this.executingSideEffect = true;
 
     const executeAndLogSideEffect = async () => {
       // in replay mode, we directly return the value from the log
@@ -302,7 +318,13 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
     };
 
     const sleep = (millis: number) => this.sleep(millis);
-    return executeWithRetries(retryPolicy, executeAndLogSideEffect, sleep);
+    return executeWithRetries(
+      retryPolicy,
+      executeAndLogSideEffect,
+      sleep
+    ).finally(() => {
+      this.executingSideEffect = false;
+    });
   }
 
   public sleep(millis: number): Promise<void> {
@@ -385,9 +407,20 @@ export class RestateGrpcContextImpl implements RestateGrpcContext {
     return context?.delay || 0;
   }
 
+  private checkNotExecutingSideEffect() {
+    if (this.executingSideEffect) {
+      throw new TerminalError(
+        `Invoked a RestateContext method while a side effect is still executing. 
+          Make sure you await the ctx.sideEffect call before using any other RestateContext method.`,
+        { errorCode: ErrorCodes.INTERNAL }
+      );
+    }
+  }
+
   private checkState(callType: string): void {
     const context = RestateGrpcContextImpl.callContext.getStore();
     if (!context) {
+      this.checkNotExecutingSideEffect();
       return;
     }
 
diff --git a/src/server/base_restate_server.ts b/src/server/base_restate_server.ts
@@ -149,9 +149,7 @@ export abstract class BaseRestateServer {
         method
       );
       // note that this log will not print all the keys.
-      rlog.info(
-        `Binding: ${url}  -> ${JSON.stringify(method, null, "\t")}`
-      );
+      rlog.info(`Binding: ${url}  -> ${JSON.stringify(method, null, "\t")}`);
     }
   }
 
@@ -264,11 +262,7 @@ export abstract class BaseRestateServer {
       ) as HostedGrpcServiceMethod<unknown, unknown>;
 
       rlog.info(
-        `Binding: ${url}  -> ${JSON.stringify(
-          registration.method,
-          null,
-          "\t"
-        )}`
+        `Binding: ${url}  -> ${JSON.stringify(registration.method, null, "\t")}`
       );
     }
 
diff --git a/test/side_effect.test.ts b/test/side_effect.test.ts
@@ -911,6 +911,103 @@ describe("AwaitSideEffectService", () => {
   });
 });
 
+export class UnawaitedSideEffectShouldFailSubsequentContextCallService
+  implements TestGreeter
+{
+  constructor(
+    // eslint-disable-next-line @typescript-eslint/no-empty-function
+    private readonly next = (ctx: restate.RestateContext): void => {}
+  ) {}
+
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  async greet(request: TestRequest): Promise<TestResponse> {
+    const ctx = restate.useContext(this);
+
+    ctx.sideEffect<number>(async () => {
+      // eslint-disable-next-line @typescript-eslint/no-empty-function
+      return new Promise(() => {});
+    });
+    this.next(ctx);
+
+    throw new Error("code should not reach this point");
+  }
+}
+
+describe("UnawaitedSideEffectShouldFailSubsequentContextCall", () => {
+  const defineTestCase = (
+    contextMethodCall: string,
+    next: (ctx: restate.RestateContext) => void
+  ): void => {
+    it(
+      "Not awaiting side effect should fail at next " + contextMethodCall,
+      async () => {
+        const result = await new TestDriver(
+          new UnawaitedSideEffectShouldFailSubsequentContextCallService(next),
+          [startMessage(), inputMessage(greetRequest("Till"))]
+        ).run();
+
+        checkTerminalError(
+          result[0],
+          `Invoked a RestateContext method while a side effect is still executing. 
+          Make sure you await the ctx.sideEffect call before using any other RestateContext method.`
+        );
+        expect(result.slice(1)).toStrictEqual([END_MESSAGE]);
+      }
+    );
+  };
+
+  defineTestCase("side effect", (ctx) =>
+    ctx.sideEffect<number>(async () => {
+      return 1;
+    })
+  );
+  defineTestCase("get", (ctx) => ctx.get<string>("123"));
+  defineTestCase("set", (ctx) => ctx.set("123", "abc"));
+  defineTestCase("call", (ctx) => {
+    const client = new TestGreeterClientImpl(ctx);
+    client.greet(TestRequest.create({ name: "Francesco" }));
+  });
+  defineTestCase("one way call", (ctx) => {
+    const client = new TestGreeterClientImpl(ctx);
+    ctx.oneWayCall(() =>
+      client.greet(TestRequest.create({ name: "Francesco" }))
+    );
+  });
+});
+
+export class UnawaitedSideEffectShouldFailSubsequentSetService
+  implements TestGreeter
+{
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  async greet(request: TestRequest): Promise<TestResponse> {
+    const ctx = restate.useContext(this);
+
+    ctx.sideEffect<number>(async () => {
+      // eslint-disable-next-line @typescript-eslint/no-empty-function
+      return new Promise(() => {});
+    });
+    ctx.set("123", "abc");
+
+    throw new Error("code should not reach this point");
+  }
+}
+
+describe("UnawaitedSideEffectShouldFailSubsequentSetService", () => {
+  it("Not awaiting side effects should fail", async () => {
+    const result = await new TestDriver(
+      new UnawaitedSideEffectShouldFailSubsequentSetService(),
+      [startMessage(), inputMessage(greetRequest("Till"))]
+    ).run();
+
+    checkTerminalError(
+      result[0],
+      `Invoked a RestateContext method while a side effect is still executing. 
+          Make sure you await the ctx.sideEffect call before using any other RestateContext method.`
+    );
+    expect(result.slice(1)).toStrictEqual([END_MESSAGE]);
+  });
+});
+
 export class TerminalErrorSideEffectService implements TestGreeter {
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
   async greet(request: TestRequest): Promise<TestResponse> {
