Nonthreadpool (#38)

* Create pulsar-functions module (#1)

* Create pulsar-functions module

* rename `sdk` package to `api`

* Added the first cut of the Java interface for Pulsar functions (#2)

* In case of Kstream style running, we dont need to spawn a executor service to run the message

* Update comment

pulsar-functions/runtime/src/main/java/org/apache/pulsar/admin/cli/CmdFunctions.java

@@ -100,7 +100,7 @@ class LocalRunner extends FunctionsCommand {
         @Override
         void run_functions_cmd() throws Exception {
             LimitsConfig limitsConfig = new LimitsConfig(
-                60000,   // 60 seconds
+                -1,   // No timelimit
                 1024,       // 1GB
                 1024   // 1024 outstanding tuples
             );

pulsar-functions/runtime/src/main/java/org/apache/pulsar/functions/runtime/instance/JavaInstance.java

@@ -109,7 +109,10 @@ public JavaInstance(JavaInstanceConfig config, ClassLoader clsLoader) {
             throw new RuntimeException("User class must be either a Request or Raw Request Handler");
         }
 
-        executorService = Executors.newFixedThreadPool(1);
+        if (config.getTimeBudgetInMs() > 0) {
+            log.info("Spinning up a executor service since time budget is infinite");
+            executorService = Executors.newFixedThreadPool(1);
+        }
     }
 
     private void computeInputAndOutputTypesAndVerifySerDe() {
@@ -145,25 +148,11 @@ private void verifySupportedType(Type type, boolean allowVoid) {
     public JavaExecutionResult handleMessage(String messageId, String topicName, byte[] data) {
         context.setCurrentMessageContext(messageId, topicName);
         JavaExecutionResult executionResult = new JavaExecutionResult();
+        if (executorService == null) {
+            return processMessage(executionResult, data);
+        }
         Future<?> future = executorService.submit(() -> {
-            if (requestHandler != null) {
-                try {
-                    Object input = inputSerDe.deserialize(data);
-                    Object output = requestHandler.handleRequest(input, context);
-                    executionResult.setResult(output);
-                } catch (Exception ex) {
-                    executionResult.setUserException(ex);
-                }
-            } else if (rawRequestHandler != null) {
-                try {
-                    ByteArrayInputStream inputStream = new ByteArrayInputStream(data);
-                    ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
-                    rawRequestHandler.handleRequest(inputStream, outputStream, context);
-                    executionResult.setResult(outputStream.toByteArray());
-                } catch (Exception ex) {
-                    executionResult.setUserException(ex);
-                }
-            }
+            return processMessage(executionResult, data);
         });
         try {
             future.get(context.getTimeBudgetInMs(), TimeUnit.MILLISECONDS);
@@ -181,4 +170,26 @@ public JavaExecutionResult handleMessage(String messageId, String topicName, byt
 
         return executionResult;
     }
+
+    private JavaExecutionResult processMessage(JavaExecutionResult executionResult, byte[] data) {
+        if (requestHandler != null) {
+            try {
+                Object input = inputSerDe.deserialize(data);
+                Object output = requestHandler.handleRequest(input, context);
+                executionResult.setResult(output);
+            } catch (Exception ex) {
+                executionResult.setUserException(ex);
+            }
+        } else if (rawRequestHandler != null) {
+            try {
+                ByteArrayInputStream inputStream = new ByteArrayInputStream(data);
+                ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+                rawRequestHandler.handleRequest(inputStream, outputStream, context);
+                executionResult.setResult(outputStream.toByteArray());
+            } catch (Exception ex) {
+                executionResult.setUserException(ex);
+            }
+        }
+        return executionResult;
+    }
 }