Add rotation of log files by size. Configuration requires user to pr…

lib/bunyan.js

@@ -1092,16 +1092,18 @@ if (mv) {
 
 function RotatingFileStream(options) {
     this.path = options.path;
-    this.stream = fs.createWriteStream(this.path,
-        {flags: 'a', encoding: 'utf8'});
     this.count = (options.count == null ? 10 : options.count);
+
     assert.equal(typeof (this.count), 'number',
         format('rotating-file stream "count" is not a number: %j (%s) in %j',
             this.count, typeof (this.count), this));
     assert.ok(this.count >= 0,
         format('rotating-file stream "count" is not >= 0: %j in %j',
             this.count, this));
 
+    assert.ok((options.period && !options.size) || (!options.period && options.size),
+        format('period and size setting on rotating-file are mutually exclusive'));
+
     // Parse `options.period`.
     if (options.period) {
         // <number><scope> where scope is:
@@ -1125,6 +1127,12 @@ function RotatingFileStream(options) {
         }
         this.periodNum = Number(m[1]);
         this.periodScope = m[2];
+    } else if (options.size) {
+        this.rotateFileSize = options.size;
+        this.alreadyWritten = 0;
+        assert.equal(typeof (this.rotateFileSize), 'number',
+            format('rotating-file stream "size" is not a number: %j (%s) in %j',
+                this.rotateFileSize, typeof (this.rotateFileSize), this));
     } else {
         this.periodNum = 1;
         this.periodScope = 'd';
@@ -1149,25 +1157,52 @@ function RotatingFileStream(options) {
     this.rotQueue = [];
     this.rotating = false;
     this._setupNextRot();
+
+    var self = this;
+    var createStream = true;
+
+
+    if (this.rotateFileSize) {
+        // Check current log file size.  If already too large, go ahead and rotate.
+        if (fs.existsSync(this.path)) {
+            var stats = fs.statSync(this.path);
+            if (stats.size > this.rotateFileSize) {
+                // End of the rotate call will create a new write stream, let's not do that twice.  Use flag to track
+                // whether we need to init here or if rotate will do it for us.
+                createStream = false;
+                self.rotate();
+            } else {
+                self.alreadyWritten = stats.size;
+            }
+        }
+    }
+
+    if (createStream) {
+        this.stream = fs.createWriteStream(this.path,
+            {flags: 'a', encoding: 'utf8'});
+    }
+
 }
 
 util.inherits(RotatingFileStream, EventEmitter);
 
 RotatingFileStream.prototype._setupNextRot = function () {
-    var self = this;
-    this.rotAt = this._nextRotTime();
-    var delay = this.rotAt - Date.now();
-    // Cap timeout to Node's max setTimeout, see
-    // <https://github.com/joyent/node/issues/8656>.
-    var TIMEOUT_MAX = 2147483647; // 2^31-1
-    if (delay > TIMEOUT_MAX) {
-        delay = TIMEOUT_MAX;
-    }
-    this.timeout = setTimeout(
-        function () { self.rotate(); },
-        delay);
-    if (typeof (this.timeout.unref) === 'function') {
-        this.timeout.unref();
+    if (this.periodNum && this.periodScope) {
+        var self = this;
+        this.rotAt = this._nextRotTime();
+        var delay = this.rotAt - Date.now();
+        // Cap timeout to Node's max setTimeout, see
+        // <https://github.com/joyent/node/issues/8656>.
+        var TIMEOUT_MAX = 2147483647; // 2^31-1
+        if (delay > TIMEOUT_MAX) {
+            delay = TIMEOUT_MAX;
+        }
+        this.timeout = setTimeout(
+            function () { self.rotate(); },
+            delay);
+        if (typeof (this.timeout.unref) === 'function') {
+            this.timeout.unref();
+        }
     }
 }
 
@@ -1258,8 +1293,10 @@ RotatingFileStream.prototype.rotate = function rotate() {
 
     // If rotation period is > ~25 days, we have to break into multiple
     // setTimeout's. See <https://github.com/joyent/node/issues/8656>.
-    if (self.rotAt && self.rotAt > Date.now()) {
-        return self._setupNextRot();
+    if (this.periodNum && this.periodScope) {
+        if (self.rotAt && self.rotAt > Date.now()) {
+            return self._setupNextRot();
+        }
     }
 
     if (_DEBUG) {
@@ -1271,7 +1308,11 @@ RotatingFileStream.prototype.rotate = function rotate() {
     }
     self.rotating = true;
 
-    self.stream.end();  // XXX can do moves sync after this? test at high rate
+    // Rotate file by size may rotate before the stream is created.  Let's make sure we have a stream before trying to
+    // end it.
+    if (self.stream) {
+        self.stream.end();  // XXX can do moves sync after this? test at high rate
+    }
 
     function del() {
         var toDel = self.path + '.' + String(n - 1);
@@ -1339,7 +1380,13 @@ RotatingFileStream.prototype.write = function write(s) {
         this.rotQueue.push(s);
         return false;
     } else {
-        return this.stream.write(s);
+        if ((this.alreadyWritten + this.stream.bytesWritten) > this.rotateFileSize) {
+            this.rotate();
+            this.alreadyWritten = 0;
+            return false;
+        } else {
+            return this.stream.write(s);
+        }
     }
 };