Fix: dedup works with multistream (refs: #1506) (#1508)

lib/multistream.js

@@ -47,10 +47,18 @@ function multistream (streamsArray, opts) {
     let dest
     const level = this.lastLevel
     const { streams } = this
+    // for handling situation when several streams has the same level
+    let recordedLevel = 0
     let stream
-    for (let i = 0; i < streams.length; i++) {
+
+    // if dedupe set to true we send logs to the stream with the highest level
+    // therefore, we have to change sorting order
+    for (let i = initLoopVar(streams.length, opts.dedupe); checkLoopVar(i, streams.length, opts.dedupe); i = adjustLoopVar(i, opts.dedupe)) {
       dest = streams[i]
       if (dest.level <= level) {
+        if (recordedLevel !== 0 && recordedLevel !== dest.level) {
+          break
+        }
         stream = dest.stream
         if (stream[metadata]) {
           const { lastTime, lastMsg, lastObj, lastLogger } = this
@@ -60,10 +68,11 @@ function multistream (streamsArray, opts) {
           stream.lastObj = lastObj
           stream.lastLogger = lastLogger
         }
-        if (!opts.dedupe || dest.level === level) {
-          stream.write(data)
+        stream.write(data)
+        if (opts.dedupe) {
+          recordedLevel = dest.level
         }
-      } else {
+      } else if (!opts.dedupe) {
         break
       }
     }
@@ -153,4 +162,16 @@ function compareByLevel (a, b) {
   return a.level - b.level
 }
 
+function initLoopVar (length, dedupe) {
+  return dedupe ? length - 1 : 0
+}
+
+function adjustLoopVar (i, dedupe) {
+  return dedupe ? i - 1 : i + 1
+}
+
+function checkLoopVar (i, length, dedupe) {
+  return dedupe ? i >= 0 : i < length
+}
+
 module.exports = multistream

test/multistream.test.js

@@ -434,6 +434,41 @@ test('dedupe', function (t) {
   t.end()
 })
 
+test('dedupe when logs have different levels', function (t) {
+  let messageCount = 0
+  const stream1 = writeStream(function (data, enc, cb) {
+    messageCount += 1
+    cb()
+  })
+
+  const stream2 = writeStream(function (data, enc, cb) {
+    messageCount += 2
+    cb()
+  })
+
+  const streams = [
+    {
+      stream: stream1,
+      level: 'info'
+    },
+    {
+      stream: stream2,
+      level: 'error'
+    }
+  ]
+
+  const log = pino({
+    level: 'trace'
+  }, multistream(streams, { dedupe: true }))
+
+  log.info('info stream')
+  log.warn('warn stream')
+  log.error('error streams')
+  log.fatal('fatal streams')
+  t.equal(messageCount, 6)
+  t.end()
+})
+
 test('dedupe when some streams has the same level', function (t) {
   let messageCount = 0
   const stream1 = writeStream(function (data, enc, cb) {