child_process: stop indexOf() on whole IPC buffer

lib/internal/child_process.js

@@ -446,13 +446,19 @@ function setupChannel(target, channel) {
   channel.onread = function(nread, pool, recvHandle) {
     // TODO(bnoordhuis) Check that nread > 0.
     if (pool) {
-      jsonBuffer += decoder.write(pool);
-
-      var i, start = 0;
+      // Linebreak is used as a message end sign
+      var lines = decoder.write(pool).split('\n');
+      var chunks = lines.slice(0, -1);
+      // Last line does not have trailing linebreak
+      var incompleteChunk = lines[lines.length - 1];
+      if (chunks.length === 0) {
+        jsonBuffer += incompleteChunk;
+        this.buffering = jsonBuffer.length !== 0;
+        return;
+      }
+      chunks[0] = jsonBuffer + chunks[0];
 
-      //Linebreak is used as a message end sign
-      while ((i = jsonBuffer.indexOf('\n', start)) >= 0) {
-        var json = jsonBuffer.slice(start, i);
+      chunks.forEach(function(json) {
         var message = JSON.parse(json);
 
         // There will be at most one NODE_HANDLE message in every chunk we
@@ -462,10 +468,8 @@ function setupChannel(target, channel) {
           handleMessage(target, message, recvHandle);
         else
           handleMessage(target, message, undefined);
-
-        start = i + 1;
-      }
-      jsonBuffer = jsonBuffer.slice(start);
+      });
+      jsonBuffer = incompleteChunk;
       this.buffering = jsonBuffer.length !== 0;
 
     } else {