Updated the API for function worker readiness probe

Author: mukesh-ctds

pulsar-functions/worker/src/main/java/org/apache/pulsar/functions/worker/rest/api/FunctionsImpl.java

@@ -792,7 +792,7 @@ private Function.FunctionDetails validateUpdateRequestParams(final String tenant
         }
     }
 
-    public boolean checkReadiness() {
+    public boolean checkForIllegalStateException() {
         return this.isIllegalStateException;
     }
 }

pulsar-functions/worker/src/main/java/org/apache/pulsar/functions/worker/rest/api/v3/FunctionsApiV3Resource.java

@@ -35,6 +35,7 @@
 import javax.ws.rs.Produces;
 import javax.ws.rs.QueryParam;
 import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
 import javax.ws.rs.core.StreamingOutput;
 import lombok.extern.slf4j.Slf4j;
 import org.apache.pulsar.common.functions.FunctionConfig;
@@ -431,8 +432,16 @@ public void updateFunctionOnWorkerLeader(final @PathParam("tenant") String tenan
     }
 
     @GET
-    @Path("/readiness")
-    public boolean checkReadiness() {
-        return functions().checkReadiness();
+    @Path("/restart")
+    public Response checkForIllegalStateException() {
+        boolean isIllegalStateException = functions().checkForIllegalStateException();
+        if (isIllegalStateException) {
+            return Response.status(Response.Status.SERVICE_UNAVAILABLE)
+                    .entity("There is IllegalStateException, Service is not running. Need to restart.")
+                    .build();
+        } else {
+            return Response.ok("There is no IllegalStateException, Service is running.")
+                    .build();
+        }
     }
 }

pulsar-functions/worker/src/main/java/org/apache/pulsar/functions/worker/service/api/Functions.java

@@ -103,5 +103,5 @@ FunctionInstanceStatusData getFunctionInstanceStatus(String tenant,
 
     List<FunctionDefinition> getBuiltinFunctions(AuthenticationParameters authParams);
 
-    boolean checkReadiness();
+    boolean checkForIllegalStateException();
 }