[java] put function meta in task spec and load functions with function meta (#2881)

This PR adds a `function_desc` field into task spec. a function descriptor is a list of strings that can uniquely describe a function.
- For a Python function, it should be: [module_name, class_name, function_name]
- For a Java function, it should be: [class_name, method_name, type_descriptor]

There're a couple of purposes to add this field:

In this PR:
- Java worker needs to know function's class name to load it. Previously, since task spec didn't have such a field to hold this info, we did a hack by appending the class name to the argument list. With this change, we fixed that hack and significantly simplified function management in Java.

Will be done in subsequent PRs:
- Support cross-language invocation (#2576): currently Python worker manages functions by saving them in GCS and pass function id in task spec. However, if we want to call a Python function from Java, we cannot save it in GCS and get the function id. But instead, we can pass the function descriptor (module name, class name, function name) in task spec and use it to load the function.
- Support deployment: one major problem of Python worker's current function management mechanism is #2327. In prod env, we should have a mechanism to deploy code and dependencies to the cluster. And when code is already deployed, we don't need to save functions to GCS any more and can use `function_desc` to manage functions.

java/cli/src/main/java/org/ray/cli/RayCli.java

@@ -1,24 +1,19 @@
 package org.ray.cli;
 
 import com.beust.jcommander.JCommander;
-import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
-import net.lingala.zip4j.core.ZipFile;
 import org.ray.api.id.UniqueId;
 import org.ray.runtime.config.PathConfig;
 import org.ray.runtime.config.RayParameters;
 import org.ray.runtime.config.RunMode;
-import org.ray.runtime.functionmanager.NativeRemoteFunctionManager;
-import org.ray.runtime.functionmanager.RemoteFunctionManager;
 import org.ray.runtime.gcs.KeyValueStoreLink;
 import org.ray.runtime.gcs.RedisClient;
 import org.ray.runtime.gcs.StateStoreProxy;
 import org.ray.runtime.gcs.StateStoreProxyImpl;
 import org.ray.runtime.runner.RunManager;
 import org.ray.runtime.runner.worker.DefaultDriver;
-import org.ray.runtime.util.FileUtil;
 import org.ray.runtime.util.config.ConfigReader;
 import org.ray.runtime.util.logger.RayLog;
 
@@ -140,64 +135,18 @@ public class RayCli {
     ConfigReader config = new ConfigReader(configPath, "ray.java.start.deploy=true");
     PathConfig paths = new PathConfig(config);
     RayParameters params = new RayParameters(config);
-
     params.redis_address = cmdSubmit.redisAddress;
     params.run_mode = RunMode.CLUSTER;
 
-
     KeyValueStoreLink kvStore = new RedisClient();
     kvStore.setAddr(cmdSubmit.redisAddress);
     StateStoreProxy stateStoreProxy = new StateStoreProxyImpl(kvStore);
     stateStoreProxy.initializeGlobalState();
 
-    RemoteFunctionManager functionManager = new NativeRemoteFunctionManager(kvStore);
-
-    // Register app to Redis. 
-    byte[] zip = FileUtil.fileToBytes(cmdSubmit.packageZip);
-
-    String packageName = cmdSubmit.packageZip.substring(
-        cmdSubmit.packageZip.lastIndexOf('/') + 1,
-        cmdSubmit.packageZip.lastIndexOf('.'));
-
-    UniqueId resourceId = functionManager.registerResource(zip);
-
     // Init RayLog before using it.
     RayLog.init(params.log_dir);
-
-    RayLog.rapp.debug(
-        "registerResource " + resourceId + " for package " + packageName + " done");
-
     UniqueId appId = params.driver_id;
-    functionManager.registerApp(appId, resourceId);
-    RayLog.rapp.debug("registerApp " + appId + " for resouorce " + resourceId + " done");
-  
-    // Unzip the package file.
     String appDir = "/tmp/" + cmdSubmit.className;
-    String extPath = appDir + "/" + packageName;
-    if (!FileUtil.createDir(extPath, false)) {
-      throw new RuntimeException("create dir " + extPath + " failed ");
-    }
-
-    ZipFile zipFile = new ZipFile(cmdSubmit.packageZip);
-    zipFile.extractAll(extPath);
-
-    // Build the args for driver process.
-    File originDirFile = new File(extPath);
-    File[] topFiles = originDirFile.listFiles();
-    String topDir = null;
-    for (File file : topFiles) {
-      if (file.isDirectory()) {
-        topDir = file.getName();
-      }
-    }
-    RayLog.rapp.debug("topDir of app classes: " + topDir);
-    if (topDir == null) {
-      RayLog.rapp.error("Can't find topDir of app classes, the app directory " + appDir);
-      return;
-    }
-
-    String additionalClassPath = appDir + "/" + packageName  + "/" + topDir + "/*";
-    RayLog.rapp.debug("Find app class path  " + additionalClassPath);
 
     // Start driver process.
     RunManager runManager = new RunManager(params, paths, config);
@@ -209,18 +158,15 @@ public class RayCli {
         params.node_ip_address,
         cmdSubmit.className,
         cmdSubmit.classArgs,
-        additionalClassPath,
+        "",
         null);
 
-    if (null == proc) { 
-      RayLog.rapp.error(
-          "Create process for app " + packageName + " in local directory " + appDir
-          + " failed");
+    if (null == proc) {
+      RayLog.rapp.error("Failed to start driver.");
       return;
     }
 
-    RayLog.rapp
-    .info("Create app " + appDir + " for package " + packageName + " succeeded");
+    RayLog.rapp.info("Driver started.");
   }
 
   private static String getConfigPath(String config) {