Refactor ConfigWatcherRegister to only read interested configs. fixes #2834 (#2835)

oap-server/server-configuration/configuration-api/src/main/java/org/apache/skywalking/oap/server/configuration/api/ConfigWatcherRegister.java

@@ -64,12 +64,12 @@ public abstract class ConfigWatcherRegister implements DynamicConfigurationServi
         logger.info("Current configurations after the bootstrap sync." + LINE_SEPARATOR + register.toString());
 
         Executors.newSingleThreadScheduledExecutor().scheduleAtFixedRate(
-            new RunnableWithExceptionProtection(() -> configSync(),
+            new RunnableWithExceptionProtection(this::configSync,
                 t -> logger.error("Sync config center error.", t)), syncPeriod, syncPeriod, TimeUnit.SECONDS);
     }
 
     void configSync() {
-        ConfigTable configTable = readConfig();
+        ConfigTable configTable = readConfig(register.keys());
 
         configTable.getItems().forEach(item -> {
             String itemName = item.getName();
@@ -99,7 +99,7 @@ public abstract class ConfigWatcherRegister implements DynamicConfigurationServi
         logger.trace("Current configurations after the sync." + LINE_SEPARATOR + register.toString());
     }
 
-    public abstract ConfigTable readConfig();
+    public abstract ConfigTable readConfig(Set<String> keys);
 
     public class Register {
         private Map<String, WatcherHolder> register = new HashMap<>();
@@ -116,6 +116,10 @@ public abstract class ConfigWatcherRegister implements DynamicConfigurationServi
             return register.get(name);
         }
 
+        public Set<String> keys() {
+            return register.keySet();
+        }
+
         @Override public String toString() {
             StringBuilder registerTableDescription = new StringBuilder();
             registerTableDescription.append("Following dynamic config items are available.").append(LINE_SEPARATOR);

oap-server/server-configuration/configuration-api/src/test/java/org/apache/skywalking/oap/server/configuration/api/ConfigWatcherRegisterTest.java

@@ -22,6 +22,8 @@ import org.apache.skywalking.oap.server.library.module.*;
 import org.junit.*;
 import org.powermock.reflect.Whitebox;
 
+import java.util.Set;
+
 /**
  * @author wusheng
  */
@@ -80,7 +82,7 @@ public class ConfigWatcherRegisterTest {
 
     public static class MockConfigWatcherRegister extends ConfigWatcherRegister {
 
-        @Override public ConfigTable readConfig() {
+        @Override public ConfigTable readConfig(Set<String> keys) {
             ConfigTable.ConfigItem item1 = new ConfigTable.ConfigItem("module.provider.prop1", "abc");
             ConfigTable.ConfigItem item2 = new ConfigTable.ConfigItem("MockModule.provider.prop2", "abc2");
 

oap-server/server-configuration/grpc-configuration-sync/src/main/java/org/apache/skywalking/oap/server/configuration/grpc/GRPCConfigWatcherRegister.java

@@ -23,6 +23,8 @@ import org.apache.skywalking.oap.server.configuration.api.*;
 import org.apache.skywalking.oap.server.configuration.service.*;
 import org.slf4j.*;
 
+import java.util.Set;
+
 /**
  * @author wusheng
  */
@@ -38,12 +40,15 @@ public class GRPCConfigWatcherRegister extends ConfigWatcherRegister {
         stub = ConfigurationServiceGrpc.newBlockingStub(NettyChannelBuilder.forAddress(settings.getHost(), settings.getPort()).usePlaintext().build());
     }
 
-    @Override public ConfigTable readConfig() {
+    @Override public ConfigTable readConfig(Set<String> keys) {
         ConfigTable table = new ConfigTable();
         try {
             ConfigurationResponse response = stub.call(ConfigurationRequest.newBuilder().setClusterName(settings.getClusterName()).build());
             response.getConfigTableList().forEach(config -> {
-                table.add(new ConfigTable.ConfigItem(config.getName(), config.getValue()));
+                final String name = config.getName();
+                if (keys.contains(name)) {
+                    table.add(new ConfigTable.ConfigItem(name, config.getValue()));
+                }
             });
         } catch (Exception e) {
             logger.error("Remote config center [" + settings + "] is not available.", e);