User Pluggable Connection Time Trace Logger (nats-io#1077)

src/main/java/io/nats/client/Options.java

@@ -32,13 +32,14 @@
 import java.security.GeneralSecurityException;
 import java.security.NoSuchAlgorithmException;
 import java.time.Duration;
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
 import java.util.*;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicInteger;
 
 import static io.nats.client.support.Encoding.uriDecode;
 import static io.nats.client.support.NatsConstants.*;
-import static io.nats.client.support.NatsUri.DEFAULT_NATS_URI;
 import static io.nats.client.support.SSLUtils.DEFAULT_TLS_ALGORITHM;
 import static io.nats.client.support.Validator.*;
 
@@ -235,6 +236,11 @@ public class Options {
      * {@link Builder#errorListener(ErrorListener) errorListener}.
      */
     public static final String PROP_ERROR_LISTENER = PFX + "callback.error";
+    /**
+     * Property used to configure a builder from a Properties object. {@value}, see
+     * {@link Builder#timeTraceLogger(TimeTraceLogger) timeTraceLogger}.
+     */
+    public static final String PROP_TIME_TRACE_LOGGER = PFX + "time.trace";
     /**
      * Property used to configure a builder from a Properties object. {@value}, see
      * {@link Builder#statisticsCollector(StatisticsCollector) statisticsCollector}.
@@ -597,6 +603,7 @@ public class Options {
     private final ReconnectDelayHandler reconnectDelayHandler;
 
     private final ErrorListener errorListener;
+    private final TimeTraceLogger timeTraceLogger;
     private final ConnectionListener connectionListener;
     private final StatisticsCollector statisticsCollector;
     private final String dataPortType;
@@ -710,6 +717,7 @@ public static class Builder {
         private ReconnectDelayHandler reconnectDelayHandler;
 
         private ErrorListener errorListener = null;
+        private TimeTraceLogger timeTraceLogger = null;
         private ConnectionListener connectionListener = null;
         private StatisticsCollector statisticsCollector = null;
         private String dataPortType = DEFAULT_DATA_PORT_TYPE;
@@ -819,6 +827,7 @@ public Builder properties(Properties props) {
             booleanProperty(props, PROP_USE_OLD_REQUEST_STYLE, b -> this.useOldRequestStyle = b);
 
             classnameProperty(props, PROP_ERROR_LISTENER, o -> this.errorListener = (ErrorListener) o);
+            classnameProperty(props, PROP_TIME_TRACE_LOGGER, o -> this.timeTraceLogger = (TimeTraceLogger) o);
             classnameProperty(props, PROP_CONNECTION_CB, o -> this.connectionListener = (ConnectionListener) o);
             classnameProperty(props, PROP_STATISTICS_COLLECTOR, o -> this.statisticsCollector = (StatisticsCollector) o);
 
@@ -1400,6 +1409,16 @@ public Builder errorListener(ErrorListener listener) {
             return this;
         }
 
+        /**
+         * Set the {@link TimeTraceLogger TimeTraceLogger} to receive trace events related to this connection.
+         * @param logger The new TimeTraceLogger for this connection.
+         * @return the Builder for chaining
+         */
+        public Builder timeTraceLogger(TimeTraceLogger logger) {
+            this.timeTraceLogger = logger;
+            return this;
+        }
+
         /**
          * Set the {@link ConnectionListener ConnectionListener} to receive asynchronous notifications of disconnect
          * events.
@@ -1674,6 +1693,26 @@ else if (useDefaultTls) {
                 socketWriteTimeout = null;
             }
 
+            if (errorListener == null) {
+                errorListener = new ErrorListenerLoggerImpl();
+            }
+
+            if (timeTraceLogger == null) {
+                if (traceConnection) {
+                    timeTraceLogger = (format, args) -> {
+                        String timeStr = DateTimeFormatter.ISO_TIME.format(LocalDateTime.now());
+                        System.out.println("[" + timeStr + "] connect trace: " + String.format(format, args));
+                    };
+                }
+                else {
+                    timeTraceLogger = (f, a) -> {};
+                }
+            }
+            else {
+                // if the dev provided an impl, we assume they meant to time trace the connection
+                traceConnection = true;
+            }
+
             return new Options(this);
         }
 
@@ -1723,6 +1762,7 @@ public Builder(Options o) {
             this.reconnectDelayHandler = o.reconnectDelayHandler;
 
             this.errorListener = o.errorListener;
+            this.timeTraceLogger = o.timeTraceLogger;
             this.connectionListener = o.connectionListener;
             this.statisticsCollector = o.statisticsCollector;
             this.dataPortType = o.dataPortType;
@@ -1745,13 +1785,8 @@ public Builder(Options o) {
     // CONSTRUCTOR
     // ----------------------------------------------------------------------------------------------------
     private Options(Builder b) {
-        if (b.natsServerUris.isEmpty()) {
-            this.natsServerUris = Collections.singletonList(DEFAULT_NATS_URI);
-        }
-        else {
-            this.natsServerUris = Collections.unmodifiableList(b.natsServerUris);
-        }
-        this.unprocessedServers = b.unprocessedServers;  // exactly how the user gave them
+        this.natsServerUris = Collections.unmodifiableList(b.natsServerUris);
+        this.unprocessedServers = Collections.unmodifiableList(b.unprocessedServers);  // exactly how the user gave them
         this.noRandomize = b.noRandomize;
         this.noResolveHostnames = b.noResolveHostnames;
         this.reportNoResponders = b.reportNoResponders;
@@ -1787,7 +1822,8 @@ private Options(Builder b) {
         this.authHandler = b.authHandler;
         this.reconnectDelayHandler = b.reconnectDelayHandler;
 
-        this.errorListener = b.errorListener == null ? new ErrorListenerLoggerImpl() : b.errorListener;
+        this.errorListener = b.errorListener;
+        this.timeTraceLogger = b.timeTraceLogger;
         this.connectionListener = b.connectionListener;
         this.statisticsCollector = b.statisticsCollector;
         this.dataPortType = b.dataPortType;
@@ -1838,6 +1874,16 @@ public ErrorListener getErrorListener() {
         return this.errorListener;
     }
 
+    /**
+     * If the user provided a TimeTraceLogger, it's returned here.
+     * If the user set traceConnection but did not supply their own, the original time trace logging will occur
+     * If the user did not provide a TimeTraceLogger and did not set traceConnection, this will be a no-op implementation.
+     * @return the time trace logger
+     */
+    public TimeTraceLogger getTimeTraceLogger() {
+        return this.timeTraceLogger;
+    }
+
     /**
      * @return the connection listener, or null, see {@link Builder#connectionListener(ConnectionListener) connectionListener()} in the builder doc
      */
@@ -2005,7 +2051,8 @@ public boolean isTrackAdvancedStats() {
     }
 
     /**
-     * @return should we trace the connection process to system.out
+     * If isTraceConnection is true, the user provided a TimeTraceLogger or manually called traceConnection in the builder
+     * @return should we trace the connection?
      */
     public boolean isTraceConnection() {
         return traceConnection;

src/main/java/io/nats/client/TimeTraceLogger.java

@@ -0,0 +1,18 @@
+// Copyright 2024 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package io.nats.client;
+
+public interface TimeTraceLogger {
+    void trace(String format, Object... args);
+}