BugFix #636 Pause and resume (In a quick succession) gets you lot of exceptions and an infinite loop (#637)

papaparse.js

@@ -473,6 +473,7 @@ License: MIT
 		this._handle = null;
 		this._finished = false;
 		this._completed = false;
+		this._halted = false;
 		this._input = null;
 		this._baseIndex = 0;
 		this._partialLine = '';
@@ -497,6 +498,7 @@ License: MIT
 					chunk = modifiedChunk;
 			}
 			this.isFirstChunk = false;
+			this._halted = false;
 
 			// Rejoin the line we likely just split in two by chunking the file
 			var aggregate = this._partialLine + chunk;
@@ -504,8 +506,10 @@ License: MIT
 
 			var results = this._handle.parse(aggregate, this._baseIndex, !this._finished);
 
-			if (this._handle.paused() || this._handle.aborted())
+			if (this._handle.paused() || this._handle.aborted()) {
+				this._halted = true;
 				return;
+			}
 
 			var lastIndex = results.meta.cursor;
 
@@ -531,8 +535,10 @@ License: MIT
 			else if (isFunction(this._config.chunk) && !isFakeChunk)
 			{
 				this._config.chunk(results, this._handle);
-				if (this._handle.paused() || this._handle.aborted())
+				if (this._handle.paused() || this._handle.aborted()) {
+					this._halted = true;
 					return;
+				}
 				results = undefined;
 				this._completeResults = undefined;
 			}
@@ -992,7 +998,6 @@ License: MIT
 		// One goal is to minimize the use of regular expressions...
 		var FLOAT = /^\s*-?(\d*\.?\d+|\d+\.?\d*)(e[-+]?\d+)?\s*$/i;
 		var ISO_DATE = /(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d\.\d+([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))|(\d{4}-[01]\d-[0-3]\dT[0-2]\d:[0-5]\d([+-][0-2]\d:[0-5]\d|Z))/;
-
 		var self = this;
 		var _stepCounter = 0;	// Number of times step was called (number of rows parsed)
 		var _rowCounter = 0;	// Number of rows that have been parsed so far
@@ -1089,8 +1094,14 @@ License: MIT
 
 		this.resume = function()
 		{
+			if(self.streamer._halted) {
 				_paused = false;
 				self.streamer.parseChunk(_input, true);
+			} else {
+				// Bugfix: #636 In case the processing hasn't halted yet
+				// wait for it to halt in order to resume
+				setTimeout(this.resume, 3);
+			}
 		};
 
 		this.aborted = function()

tests/node-tests.js

@@ -41,6 +41,42 @@ describe('PapaParse', function() {
 		assertLongSampleParsedCorrectly(Papa.parse(longSampleRawCsv));
 	});
 
+	it('Pause and resume works (Regression Test for Bug #636)', function(done) {
+		this.timeout(30000);
+		var mod200Rows = [
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Lorem ipsum dolor sit","42","ABC"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Etiam a dolor vitae est vestibulum","84"],
+			["Lorem ipsum dolor sit","42","ABC"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Lorem ipsum dolor sit","42","ABC"],
+			["Lorem ipsum dolor sit","42"]
+		];
+		var stepped = 0;
+		var dataRows = [];
+		Papa.parse(fs.createReadStream(__dirname + '/verylong-sample.csv'), {
+			step: function(results, parser) {
+				stepped++;
+				if (results)
+				{
+					parser.pause();
+					parser.resume();
+					if (results.data && stepped % 200 === 0) {
+						dataRows.push(results.data);
+					}
+				}
+			},
+			complete: function() {
+				assert.strictEqual(2001, stepped);
+				assert.deepEqual(mod200Rows, dataRows);
+				done();
+			}
+		});
+	});
+
 	it('asynchronously parsed CSV should be correctly parsed', function(done) {
 		Papa.parse(longSampleRawCsv, {
 			complete: function(parsedCsv) {

tests/test-cases.js

@@ -1780,6 +1780,49 @@ describe('Unparse Tests', function() {
 
 
 var CUSTOM_TESTS = [
+	{
+		description: "Pause and resume works (Regression Test for Bug #636)",
+		disabled: !XHR_ENABLED,
+		timeout: 30000,
+		expected: [2001, [
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Lorem ipsum dolor sit","42","ABC"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Etiam a dolor vitae est vestibulum","84"],
+			["Lorem ipsum dolor sit","42","ABC"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Etiam a dolor vitae est vestibulum","84","DEF"],
+			["Lorem ipsum dolor sit","42","ABC"],
+			["Lorem ipsum dolor sit","42"]
+		], 0],
+		run: function(callback) {
+			var stepped = 0;
+			var dataRows = [];
+			var errorCount = 0;
+			var output = [];
+			Papa.parse(BASE_PATH + "verylong-sample.csv", {
+				download: true,
+				step: function(results, parser) {
+					stepped++;
+					if (results)
+					{
+						parser.pause();
+						parser.resume();
+						if (results.data && stepped % 200 === 0) {
+							dataRows.push(results.data);
+						}
+					}
+				},
+				complete: function() {
+					output.push(stepped);
+					output.push(dataRows);
+					output.push(errorCount);
+					callback(output);
+				}
+			});
+		}
+	},
 	{
 		description: "Complete is called with all results if neither step nor chunk is defined",
 		expected: [['A', 'b', 'c'], ['d', 'E', 'f'], ['G', 'h', 'i']],
@@ -2263,6 +2306,9 @@ var CUSTOM_TESTS = [
 describe('Custom Tests', function() {
 	function generateTest(test) {
 		(test.disabled ? it.skip : it)(test.description, function(done) {
+			if(test.timeout) {
+				this.timeout(test.timeout);
+			}
 			test.run(function(actual) {
 				assert.deepEqual(JSON.stringify(actual), JSON.stringify(test.expected));
 				done();