[GitHub] [samza] rmatharu commented on a change in pull request #1029: Config logger

[GitBox <gi...@apache.org>]

rmatharu commented on a change in pull request #1029: Config logger
URL: https://github.com/apache/samza/pull/1029#discussion_r284028401
 
 

 ##########
 File path: samza-core/src/main/java/org/apache/samza/config/ConfigLogger.java
 ##########
 @@ -0,0 +1,71 @@
+package org.apache.samza.config;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.function.Consumer;
+
+/**
+ * This logger logs the config line by line, while shortening the lines which are too long (over maxLen)
+ * Logging preserves the original logger name and may be redirected to a different file
+ * by specifying a logger name that starts with ConfigLogger. in log4j configuration.
+ */
+public class ConfigLogger {
+  private final Logger log;
+  private final int maxLen;
+
+  public enum Level { INFO, DEBUG, WARN, ERROR}
+
+  public static ConfigLogger of(String loggerName, int maxLen) { return new ConfigLogger(loggerName, maxLen);}
+
+  private ConfigLogger(String loggerName, int maxLen) {
+    this.log = LoggerFactory.getLogger("ConfigLogger." + loggerName);
+    this.maxLen = maxLen;
+  }
+
+  /**
+   * log the config line by line
+   * @param header prepend the config with this header
+   * @param config config to log
+   * @param level at what level {@ConfigLogger.Leevel}
+   */
+  public void logConfig(String header, Config config, Level level) {
+    String msg = buildConfigString(header, maxLen, config);
+    log(log, msg, level);
+  }
+
+
+  // static api
+  public static void logConfig(String loggerName, String header, Config config, int maxLen, Level level) {
+    Logger logger = LoggerFactory.getLogger("ConfigLogger." + loggerName);
+    String msg = buildConfigString(header, maxLen, config);
+    log(logger, msg, level);
+  }
+
+  private static String buildConfigString(String header, int maxLen, Config config) {
+    StringBuilder bldr = new StringBuilder(header + "\n");
+    for (MapConfig.Entry e: config.entrySet()) {
+      String val;
+      if (e.getValue().toString().length() > maxLen) {
+        val = e.getValue().toString().substring(0, maxLen) + "<...>";
+      } else {
+        val = e.getValue().toString();
+      }
+      bldr.append(String.format("\t%s = %s\n", e.getKey(), val));
+    }
+    return bldr.toString();
+  }
+
+  private static void log(Logger logger, String msg, Level level) {
+    switch (level) {
+      case INFO:
+        logger.info(msg); break;
+      case DEBUG:
+        logger.debug(msg); break;
+      case WARN:
+        logger.warn(msg); break;
+      case ERROR:
+        logger.error(msg); break;
+    }
 
 Review comment:
   Probably wanna add Default here (in case someone is trying to use trace or fatal).

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