Support empty operation name, and add buffer size of dictionary for avoiding out of memory.

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/conf/Config.java

@@ -73,6 +73,15 @@ public class Config {
         public static int BUFFER_SIZE = 300;
     }
 
+    public static class Dictionary {
+        /**
+         * The buffer size of application codes and peer
+         */
+        public static int APPLICATION_CODE_BUFFER_SIZE = 10 * 10000;
+
+        public static int OPERATION_NAME_BUFFER_SIZE = 1000 * 10000;
+    }
+
     public static class Logging {
         /**
          * Log file name.

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/dictionary/ApplicationDictionary.java

@@ -9,6 +9,8 @@ import org.skywalking.apm.network.proto.ApplicationMapping;
 import org.skywalking.apm.network.proto.ApplicationRegisterServiceGrpc;
 import org.skywalking.apm.network.proto.KeyWithIntegerValue;
 
+import static org.skywalking.apm.agent.core.conf.Config.Dictionary.APPLICATION_CODE_BUFFER_SIZE;
+
 /**
  * Map of application id to application code, which is from the collector side.
  *
@@ -24,7 +26,9 @@ public enum ApplicationDictionary {
         if (applicationId != null) {
             return new Found(applicationId);
         } else {
-            unRegisterApplications.add(applicationCode);
+            if (applicationDictionary.size() + unRegisterApplications.size() < APPLICATION_CODE_BUFFER_SIZE) {
+                unRegisterApplications.add(applicationCode);
+            }
             return new NotFound();
         }
     }

apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/dictionary/OperationNameDictionary.java

@@ -10,6 +10,8 @@ import org.skywalking.apm.network.proto.ServiceNameElement;
 import org.skywalking.apm.network.proto.ServiceNameMappingCollection;
 import org.skywalking.apm.network.proto.ServiceNameMappingElement;
 
+import static org.skywalking.apm.agent.core.conf.Config.Dictionary.OPERATION_NAME_BUFFER_SIZE;
+
 /**
  * @author wusheng
  */
@@ -19,12 +21,17 @@ public enum OperationNameDictionary {
     private Set<OperationNameKey> unRegisterOperationNames = new ConcurrentSet<OperationNameKey>();
 
     public PossibleFound find(int applicationId, String operationName) {
+        if (operationName == null || operationName.length() == 0) {
+            return new NotFound();
+        }
         OperationNameKey key = new OperationNameKey(applicationId, operationName);
         Integer operationId = operationNameDictionary.get(key);
         if (operationId != null) {
             return new Found(applicationId);
         } else {
-            unRegisterOperationNames.add(key);
+            if (operationNameDictionary.size() + unRegisterOperationNames.size() < OPERATION_NAME_BUFFER_SIZE) {
+                unRegisterOperationNames.add(key);
+            }
             return new NotFound();
         }
     }