added error handling for when an instance id doesn't exist

Author: bachuv

client/src/main/java/com/microsoft/durabletask/DurableTaskGrpcClient.java

@@ -374,6 +374,10 @@ public void rewindInstance(String instanceId, @Nullable String reason) {
         try {
             this.sidecarClient.rewindInstance(rewindRequestBuilder.build());
         } catch (StatusRuntimeException e) {
+            if (e.getStatus().getCode() == Status.Code.NOT_FOUND) {
+                throw new IllegalArgumentException(
+                        "No orchestration instance with ID '" + instanceId + "' was found.", e);
+            }
             if (e.getStatus().getCode() == Status.Code.FAILED_PRECONDITION) {
                 throw new IllegalStateException(
                         "Orchestration instance '" + instanceId + "' is not in a failed state and cannot be rewound.", e);

endtoendtests/src/main/java/com/functions/RewindTest.java

@@ -228,6 +228,35 @@ public String failOnceSubActivity(
         return input + "-sub-rewound-success";
     }
 
+    /**
+     * HTTP trigger that attempts to rewind a non-existent orchestration instance.
+     * This should result in an IllegalArgumentException being thrown by the client
+     * when the server returns a NOT_FOUND gRPC status.
+     */
+    @FunctionName("StartRewindNonExistentOrchestration")
+    public HttpResponseMessage startRewindNonExistentOrchestration(
+            @HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
+            @DurableClientInput(name = "durableContext") DurableClientContext durableContext,
+            final ExecutionContext context) {
+        context.getLogger().info("Attempting to rewind a non-existent orchestration instance.");
+
+        DurableTaskClient client = durableContext.getClient();
+        String nonExistentInstanceId = "non-existent-instance-" + System.currentTimeMillis();
+
+        try {
+            client.rewindInstance(nonExistentInstanceId, "Testing rewind on non-existent instance");
+            // If we get here, the rewind did not throw as expected
+            return request.createResponseBuilder(com.microsoft.azure.functions.HttpStatus.INTERNAL_SERVER_ERROR)
+                    .body("IllegalArgumentException was not thrown")
+                    .build();
+        } catch (IllegalArgumentException e) {
+            context.getLogger().info("Rewind on non-existent instance threw expected exception: " + e.getMessage());
+            return request.createResponseBuilder(com.microsoft.azure.functions.HttpStatus.OK)
+                    .body(e.getMessage())
+                    .build();
+        }
+    }
+
     /**
      * HTTP trigger to reset the sub-orchestration failure flag.
      */

endtoendtests/src/test/java/com/functions/EndToEndTests.java

@@ -253,6 +253,20 @@ public void rewindFailedOrchestration() throws InterruptedException {
         assertTrue(output.contains("rewound-success"), "Output should indicate successful rewind: " + output);
     }
 
+    @Test
+    public void rewindNonExistentOrchestration() throws InterruptedException {
+        // Attempt to rewind a non-existent orchestration instance.
+        // The trigger calls client.rewindInstance() with a fake instance ID and
+        // expects an IllegalArgumentException (from gRPC NOT_FOUND status).
+        String startOrchestrationPath = "/api/StartRewindNonExistentOrchestration";
+        Response response = post(startOrchestrationPath);
+        assertEquals(200, response.getStatusCode(),
+                "Expected 200 OK indicating the IllegalArgumentException was caught. Body: " + response.getBody().asString());
+        String body = response.getBody().asString();
+        assertTrue(body.contains("No orchestration instance with ID") && body.contains("was found"),
+                "Response should contain the not-found error message, but was: " + body);
+    }
+
     @Test
     public void rewindNonFailedOrchestration() throws InterruptedException {
         // Start a non-failing orchestration - the trigger waits for completion

samples-azure-functions/src/main/java/com/functions/RewindTest.java

@@ -94,6 +94,35 @@ public String failOnceActivity(
         return input + "-rewound-success";
     }
 
+    /**
+     * HTTP trigger that attempts to rewind a non-existent orchestration instance.
+     * This should result in an IllegalArgumentException being thrown by the client
+     * when the server returns a NOT_FOUND gRPC status.
+     */
+    @FunctionName("StartRewindNonExistentOrchestration")
+    public HttpResponseMessage startRewindNonExistentOrchestration(
+            @HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage<Optional<String>> request,
+            @DurableClientInput(name = "durableContext") DurableClientContext durableContext,
+            final ExecutionContext context) {
+        context.getLogger().info("Attempting to rewind a non-existent orchestration instance.");
+
+        DurableTaskClient client = durableContext.getClient();
+        String nonExistentInstanceId = "non-existent-instance-" + System.currentTimeMillis();
+
+        try {
+            client.rewindInstance(nonExistentInstanceId, "Testing rewind on non-existent instance");
+            // If we get here, the rewind did not throw as expected
+            return request.createResponseBuilder(HttpStatus.INTERNAL_SERVER_ERROR)
+                    .body("IllegalArgumentException was not thrown")
+                    .build();
+        } catch (IllegalArgumentException e) {
+            context.getLogger().info("Rewind on non-existent instance threw expected exception: " + e.getMessage());
+            return request.createResponseBuilder(HttpStatus.OK)
+                    .body(e.getMessage())
+                    .build();
+        }
+    }
+
     /**
      * HTTP trigger to reset the failure flag (useful for testing).
      */

samples-azure-functions/src/test/java/com/functions/EndToEndTests.java

@@ -229,6 +229,20 @@ public void orchestrationPOJO() throws InterruptedException {
         assertEquals("\"TESTNAME\"", outputName);
     }
 
+    @Test
+    public void rewindNonExistentOrchestration() throws InterruptedException {
+        // Attempt to rewind a non-existent orchestration instance.
+        // The trigger calls client.rewindInstance() with a fake instance ID and
+        // expects an IllegalArgumentException (from gRPC NOT_FOUND status).
+        String startOrchestrationPath = "/api/StartRewindNonExistentOrchestration";
+        Response response = post(startOrchestrationPath);
+        assertEquals(200, response.getStatusCode(),
+                "Expected 200 OK indicating the IllegalArgumentException was caught. Body: " + response.getBody().asString());
+        String body = response.getBody().asString();
+        assertTrue(body.contains("No orchestration instance with ID") && body.contains("was found"),
+                "Response should contain the not-found error message, but was: " + body);
+    }
+
     @Test
     public void rewindFailedOrchestration() throws InterruptedException {
         // Reset the failure flag before starting