There is an issue with .pause/.resume

I heavily rely on pause-resume methods. I use chunk-streaming processing and here is what I’ve found: https://github.com/mholt/PapaParse/blob/master/papaparse.js#L403

else if (isFunction(this._config.chunk))
{
    this._config.chunk(results, this._handle);
    if (this._paused)
        return;
    results = undefined;
}

this._paused is always false in this context. It has to be checked by this._handle.paused()

Another part of the issue is in the resume implementation, but let’s look at pause method at first:

this.pause = function()
{
    _paused = true;
    _parser.abort();
    _input = _input.substr(_parser.getCharIndex());
};

_input will be always an empty string (!) if we use chunk-streaming. On resume, PapaParse will parse the empty string again and will fire callbacks with empty results.

My JavaScript code is not that good, which is why I’m creating this issue instead of a pull request, but here is my attempt to patch the issue:

@@ -367,6 +367,12 @@

                 this.parseChunk = function(chunk)
                 {
+                        if (chunk.length === 0) {
+                                // It is possible due to the pause/resume implementation.
+                                this._nextChunk();
+                                return;
+                        }
+
                         // Rejoin the line we likely just split in two by chunking the file
                         var aggregate = this._partialLine + chunk;
                         this._partialLine = "";
@@ -400,7 +406,7 @@
                         else if (isFunction(this._config.chunk))
                         {
                                 this._config.chunk(results, this._handle);
-                                if (this._paused)
+                                if (this._handle.paused())
                                         return;
                                 results = undefined;
                         }

[gabegorelick]

After more testing, it appears the issues with step are not exactly the same as with chunk. Changing my above code to use chunk makes it work after the fix from #479 is applied. But step still doesn’t work.

[thiagonuic]

@mrksbnch I have the same problem, busy with projects… I’ll see if I find some time and I’ll keep this topic updated if I find something