From b7cf2f1e92704d40645058148da4b066754791cc Mon Sep 17 00:00:00 2001
From: Jacob Hoffman-Andrews <github@hoffman-andrews.com>
Date: Sun, 28 Aug 2016 14:40:47 -0400
Subject: [PATCH] Add close-on-SIGHUP behavior for logrotate.

---
 lib/appenders/file.js | 75 ++++++++++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 29 deletions(-)

diff --git a/lib/appenders/file.js b/lib/appenders/file.js
index 6788d30..9c71edc 100644
--- a/lib/appenders/file.js
+++ b/lib/appenders/file.js
@@ -11,7 +11,16 @@ var layouts = require('../layouts')
 //close open files on process exit.
 process.on('exit', function() {
   openFiles.forEach(function (file) {
-    file.end();
+    file.stream.end();
+  });
+});
+
+// On SIGHUP, close and reopen all files. This allows this appender to work with
+// logrotate. Note that if you are using logrotate, you should not set
+// `logSize`.
+process.on('SIGHUP', function() {
+  openFiles.forEach(function(writer) {
+    writer.reopen();
   });
 });
 
@@ -34,38 +43,45 @@ function fileAppender (file, layout, logSize, numBackups) {
   //there has to be at least one backup if logSize has been specified
   numBackups = numBackups === 0 ? 1 : numBackups;
 
-  function openTheStream(file, fileSize, numFiles) {
-    var stream;
-    if (fileSize) {
-      stream = new streams.RollingFileStream(
-        file,
-        fileSize,
-        numFiles
-      );
-    } else {
-      stream = fs.createWriteStream(
-        file, 
-        { encoding: "utf8", 
-          mode: parseInt('0644', 8), 
-          flags: 'a' }
-      );
+  var writer = {
+    stream: openTheStream(file, logSize, numBackups),
+    reopen: function() {
+      this.stream.end();
+      this.stream = openTheStream(file, logSize, numBackups);
     }
-    stream.on("error", function (err) {
-      console.error("log4js.fileAppender - Writing to file %s, error happened ", file, err);
-    });
-    return stream;
   }
 
-  var logFile = openTheStream(file, logSize, numBackups);
-  
   // push file to the stack of open handlers
-  openFiles.push(logFile);
-  
+  openFiles.push(writer);
+
   return function(loggingEvent) {
-    logFile.write(layout(loggingEvent) + eol, "utf8");
+    writer.stream.write(layout(loggingEvent) + eol, "utf8");
   };
 }
 
+function openTheStream(file, fileSize, numFiles) {
+  var stream;
+  if (fileSize) {
+    stream = new streams.RollingFileStream(
+      file,
+      fileSize,
+      numFiles
+    );
+  } else {
+    stream = fs.createWriteStream(
+      file,
+      { encoding: "utf8",
+        mode: parseInt('0644', 8),
+        flags: 'a' }
+    );
+  }
+  stream.on("error", function (err) {
+    console.error("log4js.fileAppender - Writing to file %s, error happened ", file, err);
+  });
+  return stream;
+}
+
+
 function configure(config, options) {
   var layout;
   if (config.layout) {
@@ -81,12 +97,13 @@ function configure(config, options) {
 
 function shutdown(cb) {
   async.each(openFiles, function(file, done) {
-    if (!file.write(eol, "utf-8")) {
-      file.once('drain', function() {
-        file.end(done);
+    var stream = file.stream;
+    if (!stream.write(eol, "utf-8")) {
+      stream.once('drain', function() {
+        stream.end(done);
       });
     } else {
-      file.end(done);
+      stream.end(done);
     }
   }, cb);
 }