Revert "Revert "[Java] Automatically clean up temp files. (ray-projec…

…t#5507)""

This reverts commit dcddef6.

java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java

@@ -1,6 +1,7 @@
 package org.ray.runtime;
 
 import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import java.util.List;
 import java.util.concurrent.Callable;
@@ -32,7 +33,6 @@
 import org.ray.runtime.task.FunctionArg;
 import org.ray.runtime.task.TaskExecutor;
 import org.ray.runtime.task.TaskSubmitter;
-import org.ray.runtime.util.StringUtil;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -207,7 +207,7 @@ private RayActor createActorImpl(FunctionDescriptor functionDescriptor,
     List<FunctionArg> functionArgs = ArgumentsBuilder
         .wrap(args, functionDescriptor.getLanguage() != Language.JAVA);
     if (functionDescriptor.getLanguage() != Language.JAVA && options != null) {
-      Preconditions.checkState(StringUtil.isNullOrEmpty(options.jvmOptions));
+      Preconditions.checkState(Strings.isNullOrEmpty(options.jvmOptions));
     }
     RayActor actor = taskSubmitter
         .createActor(functionDescriptor, functionArgs,

java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java

@@ -4,11 +4,7 @@
 import com.google.common.base.Strings;
 import java.io.File;
 import java.io.IOException;
-import java.io.InputStream;
 import java.lang.reflect.Field;
-import java.nio.file.Files;
-import java.nio.file.Paths;
-import java.nio.file.StandardCopyOption;
 import java.util.HashMap;
 import java.util.Map;
 import org.apache.commons.io.FileUtils;
@@ -24,6 +20,7 @@
 import org.ray.runtime.runner.RunManager;
 import org.ray.runtime.task.NativeTaskSubmitter;
 import org.ray.runtime.task.TaskExecutor;
+import org.ray.runtime.util.FileUtil;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -42,23 +39,15 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
   private long nativeCoreWorkerPointer;
 
   static {
-    try {
-      LOGGER.debug("Loading native libraries.");
-      // Load native libraries.
-      String[] libraries = new String[]{"core_worker_library_java"};
-      for (String library : libraries) {
-        String fileName = System.mapLibraryName(library);
-        // Copy the file from resources to a temp dir, and load the native library.
-        File file = File.createTempFile(fileName, "");
-        file.deleteOnExit();
-        InputStream in = RayNativeRuntime.class.getResourceAsStream("/" + fileName);
-        Preconditions.checkNotNull(in, "{} doesn't exist.", fileName);
-        Files.copy(in, Paths.get(file.getAbsolutePath()), StandardCopyOption.REPLACE_EXISTING);
-        System.load(file.getAbsolutePath());
+    LOGGER.debug("Loading native libraries.");
+    // Load native libraries.
+    String[] libraries = new String[]{"core_worker_library_java"};
+    for (String library : libraries) {
+      String fileName = System.mapLibraryName(library);
+      try (FileUtil.TempFile libFile = FileUtil.getTempFileFromResource(fileName)) {
+        System.load(libFile.getFile().getAbsolutePath());
       }
       LOGGER.debug("Native libraries loaded.");
-    } catch (IOException e) {
-      throw new RuntimeException("Couldn't load native libraries.", e);
     }
 
     RayConfig globalRayConfig = RayConfig.create();

java/runtime/src/main/java/org/ray/runtime/config/RayConfig.java

@@ -1,6 +1,7 @@
 package org.ray.runtime.config;
 
 import com.google.common.base.Preconditions;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.typesafe.config.Config;
 import com.typesafe.config.ConfigException;
@@ -14,7 +15,6 @@
 import org.ray.runtime.generated.Common.WorkerType;
 import org.ray.runtime.util.NetworkUtil;
 import org.ray.runtime.util.ResourceUtil;
-import org.ray.runtime.util.StringUtil;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -248,7 +248,7 @@ public static RayConfig create() {
     ConfigFactory.invalidateCaches();
     Config config = ConfigFactory.systemProperties();
     String configPath = System.getProperty("ray.config");
-    if (StringUtil.isNullOrEmpty(configPath)) {
+    if (Strings.isNullOrEmpty(configPath)) {
       LOGGER.info("Loading config from \"ray.conf\" file in classpath.");
       config = config.withFallback(ConfigFactory.load(CUSTOM_CONFIG_FILE));
     } else {

java/runtime/src/main/java/org/ray/runtime/gcs/RedisClient.java

@@ -1,9 +1,8 @@
 package org.ray.runtime.gcs;
 
+import com.google.common.base.Strings;
 import java.util.List;
 import java.util.Map;
-
-import org.ray.runtime.util.StringUtil;
 import redis.clients.jedis.Jedis;
 import redis.clients.jedis.JedisPool;
 import redis.clients.jedis.JedisPoolConfig;
@@ -31,7 +30,7 @@ public RedisClient(String redisAddress, String password) {
     JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
     jedisPoolConfig.setMaxTotal(JEDIS_POOL_SIZE);
 
-    if (StringUtil.isNullOrEmpty(password)) {
+    if (Strings.isNullOrEmpty(password)) {
       jedisPool = new JedisPool(jedisPoolConfig,
           ipAndPort[0], Integer.parseInt(ipAndPort[1]), 30000);
     } else {