Polish OpenSergoClientManager and rename OpenSergoClientConfig

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Author: sczyh30

src/main/java/io/opensergo/OpenSergoClient.java

@@ -38,6 +38,8 @@
  */
 public class OpenSergoClient implements AutoCloseable {
 
+    private final OpenSergoClientConfig clientConfig;
+
     private final ManagedChannel channel;
     private final OpenSergoUniversalTransportServiceGrpc.OpenSergoUniversalTransportServiceStub transportGrpcStub;
 
@@ -52,41 +54,51 @@ public static class Builder {
 
         private String host;
         private int port;
-        private OpenSergoConfig openSergoConfig;
+        private OpenSergoClientConfig openSergoConfig;
 
         public OpenSergoClient.Builder endpoint(String host, int port) {
             this.host = host;
             this.port = port;
             return this;
         }
 
-        public OpenSergoClient.Builder openSergoConfig(OpenSergoConfig openSergoConfig) {
+        public OpenSergoClient.Builder openSergoConfig(OpenSergoClientConfig openSergoConfig) {
             this.openSergoConfig = openSergoConfig;
             return this;
         }
 
         public OpenSergoClient build() {
             if (this.openSergoConfig == null) {
-                this.openSergoConfig = new OpenSergoConfig();
+                this.openSergoConfig = new OpenSergoClientConfig();
             }
 
             return new OpenSergoClient(this.host, this.port, this.openSergoConfig);
         }
 
     }
 
-    private OpenSergoClient(String host, int port, OpenSergoConfig config) {
-        // TODO: add customized config business for the OpenSergoClient.
+    public OpenSergoClient(String host, int port) {
+        // TODO: improve default config logic here.
+        this(host, port, new OpenSergoClientConfig());
+    }
+
+    public OpenSergoClient(String host, int port, OpenSergoClientConfig clientConfig) {
+        checkClientConfig(clientConfig);
         // TODO: support TLS
+        this.clientConfig = clientConfig;
         this.channel = ManagedChannelBuilder.forAddress(host, port)
-                .usePlaintext()
-                .build();
+            .usePlaintext()
+            .build();
         this.transportGrpcStub = OpenSergoUniversalTransportServiceGrpc.newStub(channel);
         this.configCache = new SubscribedConfigCache();
         this.subscribeRegistry = new SubscribeRegistry();
         this.reqId = new AtomicInteger(0);
     }
 
+    private void checkClientConfig(OpenSergoClientConfig clientConfig) {
+        AssertUtils.assertNotNull(clientConfig, "clientConfig cannot be null");
+    }
+
     public void start() throws Exception {
         this.requestAndResponseWriter = transportGrpcStub
             .withWaitForReady()

src/main/java/io/opensergo/OpenSergoConfig.java renamed to src/main/java/io/opensergo/OpenSergoClientConfig.java

@@ -16,10 +16,9 @@
 package io.opensergo;
 
 /**
- * .
- *
  * @author Jiangnan Jia
- **/
-public class OpenSergoConfig {
-
+ * @author Eric Zhao
+ */
+public class OpenSergoClientConfig {
+    // TODO: add config attribute
 }

src/main/java/io/opensergo/OpenSergoClientManager.java

@@ -16,29 +16,26 @@
 package io.opensergo;
 
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 /**
- * .
- *
  * @author Jiangnan Jia
- **/
+ */
 public class OpenSergoClientManager {
 
     private static volatile OpenSergoClientManager instance;
 
     /**
      * Cached all the shared OpenSergoClients.
      */
-    private ConcurrentHashMap<String, OpenSergoClient> sharedOpenSergoClientCache = new ConcurrentHashMap<>();
-
+    private final ConcurrentMap<String, OpenSergoClient> sharedClientCache = new ConcurrentHashMap<>();
 
-    private OpenSergoClientManager() {
-
-    }
+    private OpenSergoClientManager() {}
 
     /**
-     * get OpenSergoClientManager by DCL (Double Check Lock)
-     * @return
+     * Get OpenSergoClientManager by DCL (Double Check Lock).
+     *
+     * @return the OpenSergoClientManager singleton
      */
     public static OpenSergoClientManager get() {
         if (instance == null) {
@@ -56,38 +53,42 @@ private String buildSharedCacheKey(String host, int port) {
     }
 
     /**
-     * get the instance from sharedOpenSergoClientCache，
-     * if there is no one， will create a new instance and return it.
+     * Get the instance from sharedOpenSergoClientCache.
+     * If there is no one, the manager will create a new client instance and return it.
      *
      * @param host endpoint of the OpenSergo Control Plane
      * @param port port of the OpenSergo Control Plane
      * @return OpenSergoClient
      */
     public OpenSergoClient getOrCreateClient(String host, int port) {
-        return this.getOrCreateClient(host, port, new OpenSergoConfig());
+        return this.getOrCreateClient(host, port, new OpenSergoClientConfig());
     }
 
     /**
-     * get the instance from sharedOpenSergoClientCache with config.
+     * Get the instance from sharedOpenSergoClientCache with config.
      * If instance can be found by host and port, the one will be returned, whether the config is matched or not.
      *
-     * @param host endpoint of the OpenSergo Control Plane
-     * @param port port of the OpenSergo Control Plane
-     * @param config OpenSergoConfig
+     * @param host   endpoint of the OpenSergo Control Plane
+     * @param port   port of the OpenSergo Control Plane
+     * @param config client config
      * @return OpenSergoClient
      */
-    public OpenSergoClient getOrCreateClient(String host, int port, OpenSergoConfig config) {
+    public OpenSergoClient getOrCreateClient(String host, int port, OpenSergoClientConfig config) {
         String sharedOpenSergoClientKey = buildSharedCacheKey(host, port);
-        OpenSergoClient openSergoClient = sharedOpenSergoClientCache.get(sharedOpenSergoClientKey);
+        synchronized (this) {
+            OpenSergoClient openSergoClient = sharedClientCache.get(sharedOpenSergoClientKey);
+            if (openSergoClient != null) {
+                return openSergoClient;
+            }
 
-        if (openSergoClient != null) {
-            return openSergoClient;
+            if (config == null) {
+                config = new OpenSergoClientConfig();
+            }
+            openSergoClient = new OpenSergoClient.Builder().endpoint(host, port)
+                .openSergoConfig(config).build();
+            sharedClientCache.putIfAbsent(sharedOpenSergoClientKey, openSergoClient);
+            return sharedClientCache.get(sharedOpenSergoClientKey);
         }
-
-        config = config == null ? new OpenSergoConfig() : config;
-        openSergoClient = new OpenSergoClient.Builder().endpoint(host, port).openSergoConfig(config).build();
-        sharedOpenSergoClientCache.putIfAbsent(sharedOpenSergoClientKey, openSergoClient);
-        return sharedOpenSergoClientCache.get(sharedOpenSergoClientKey);
     }
 
 }