issue #48: fix a couple issues with dtrace support

- before this, if there were no non-raw streams on the logger the
  `str` for the dtrace probe.fire would not be created
- ensure that with no non-raw streams we only render a record's
  JSON string if the dtrace probe is enabled

lib/bunyan.js

@@ -308,7 +308,7 @@ function Logger(options, _childOptions, _childSimple) {
     for (var level in levelFromName) {
       var probe;
 
-      probes[levelFromName[level]] = probe = 
+      probes[levelFromName[level]] = probe =
         dtp.addProbe('log-' + level, 'char *');
 
       // Explicitly add a reference to dtp to prevent it from being GC'd
@@ -660,33 +660,12 @@ Logger.prototype._mkRecord = function (fields, level, msgArgs) {
  * Emit a log record.
  *
  * @param rec {log record}
- * @param noemit {Boolean} Optional. Set to true to only return the string.
+ * @param noemit {Boolean} Optional. Set to true to skip emission
+ *      and just return the JSON string.
  */
 Logger.prototype._emit = function (rec, noemit) {
   var i;
 
-  var obj = objCopy(rec[0]);
-  var level = obj.level = rec[2];
-  var recFields = rec[1];
-  if (recFields) {
-    if (this.serializers) {
-      this._applySerializers(recFields);
-    }
-    Object.keys(recFields).forEach(function (k) {
-      obj[k] = recFields[k];
-    });
-  }
-  xxx('Record:', rec)
-  obj.msg = format.apply(this, rec[3]);
-  if (!obj.time) {
-    obj.time = (new Date());
-  }
-  // Get call source info
-  if (this.src && !obj.src) {
-    obj.src = getCaller3Info()
-  }
-  obj.v = LOG_VERSION;
-
   // Lazily determine if this Logger has non-"raw" streams. If there are
   // any, then we need to stringify the log record.
   if (this.haveNonRawStreams === undefined) {
@@ -701,19 +680,20 @@ Logger.prototype._emit = function (rec, noemit) {
 
   // Stringify the object. Attempt to warn/recover on error.
   var str;
-  if (this.haveNonRawStreams) {
-    str = JSON.stringify(obj, safeCycles()) + '\n';
+  if (noemit || this.haveNonRawStreams) {
+    str = JSON.stringify(rec, safeCycles()) + '\n';
   }
 
   if (noemit)
     return str;
 
+  var level = rec.level;
   for (i = 0; i < this.streams.length; i++) {
     var s = this.streams[i];
     if (s.level <= level) {
       xxx('writing log rec "%s" to "%s" stream (%d <= %d): %j',
-        obj.msg, s.type, s.level, level, obj);
-      s.stream.write(s.raw ? obj : str);
+        rec.msg, s.type, s.level, level, rec);
+      s.stream.write(s.raw ? rec : str);
     }
   };
 
@@ -729,7 +709,7 @@ function mkLogEmitter(minLevel) {
   return function () {
     var log = this;
 
-    var mkRecord = function (args) {
+    function mkRecord(args) {
       if (args[0] instanceof Error) {
         // `log.<level>(err, ...)`
         fields = {err: errSerializer(args[0])};
@@ -750,27 +730,49 @@ function mkLogEmitter(minLevel) {
         fields = args[0];
         msgArgs = Array.prototype.slice.call(args, 1);
       }
-      return log._mkRecord(fields, minLevel, msgArgs);
+
+      // Build up the record object.
+      var rec = objCopy(log.fields);
+      var level = rec.level = minLevel;
+      var recFields = (fields ? objCopy(fields) : null);
+      if (recFields) {
+        if (log.serializers) {
+          log._applySerializers(recFields);
+        }
+        Object.keys(recFields).forEach(function (k) {
+          rec[k] = recFields[k];
+        });
+      }
+      rec.msg = format.apply(log, msgArgs);
+      if (!rec.time) {
+        rec.time = (new Date());
+      }
+      // Get call source info
+      if (log.src && !rec.src) {
+        rec.src = getCaller3Info()
+      }
+      rec.v = LOG_VERSION;
+
+      return rec;
     };
 
-    var fields = null, msgArgs = null;
+    var fields = null;
+    var msgArgs = arguments;
+    var str = null;
+    var rec = null;
     if (arguments.length === 0) {   // `log.<level>()`
       return (this._level <= minLevel);
     } else if (this._level > minLevel) {
-      /*
-       * Even if our level is such that we will not emit the record, we want
-       * to fire the DTrace probe associated with the level -- but we only
-       * assemble the string representation if the probe is in fact enabled.
-       */
-      msgArgs = arguments;
-
-      probes[minLevel].fire(function () {
-         return [ log._emit(mkRecord(msgArgs), true) ];
-      });
+      /* pass through */
     } else {
-      var str = this._emit(mkRecord(arguments));
-      probes[minLevel].fire(function () { return [ str ]; });
+      rec = mkRecord(msgArgs);
+      str = this._emit(rec);
     }
+    probes[minLevel].fire(function () {
+        return [ str ||
+          (rec && log._emit(rec, true)) ||
+          log._emit(mkRecord(msgArgs), true) ];
+    });
   }
 }
 

package.json

@@ -16,7 +16,7 @@
   "keywords": ["log", "logging", "log4j", "json"],
 
   "dependencies": {
-    "dtrace-provider": "0.2.2"
+    "dtrace-provider": "0.2.3"
   },
   "devDependencies": {
     "tap": "0.2.0",