(broken) native streams

problem: jszip assumes we have a way to syncronously finish these in end() and flush(). we don't...

Author: GarboMuffin

lib/flate.js

@@ -1,26 +1,39 @@
 "use strict";
 var USE_TYPEDARRAY = (typeof Uint8Array !== "undefined") && (typeof Uint16Array !== "undefined") && (typeof Uint32Array !== "undefined");
 
-var pako = require("pako");
 var utils = require("./utils");
 var GenericWorker = require("./stream/GenericWorker");
 
 var ARRAY_TYPE = USE_TYPEDARRAY ? "uint8array" : "array";
 
 exports.magic = "\x08\x00";
 
+/* globals CompressionStream, DecompressionStream */
+
+/**
+ * @typedef {'Deflate'|'Inflate'} Action
+ */
+
 /**
  * Create a worker that uses pako to inflate/deflate.
  * @constructor
- * @param {String} action the name of the pako function to call : either "Deflate" or "Inflate".
+ * @param {Action} action the name of the pako function to call : either "Deflate" or "Inflate".
  * @param {Object} options the options to use when (de)compressing.
  */
 function FlateWorker(action, options) {
     GenericWorker.call(this, "FlateWorker/" + action);
 
+    this._initialized = false;
+    /** @type {Action} */
+    this._action = action;
+    this._options = options;
+
+    this._stream = null;
+    this._streamWriter = null;
     this._pako = null;
-    this._pakoAction = action;
-    this._pakoOptions = options;
+
+    this._handleStreamError = this._handleStreamError.bind(this);
+
     // the `meta` object from the last chunk received
     // this allow this worker to pass around metadata
     this.meta = {};
@@ -33,21 +46,45 @@ utils.inherits(FlateWorker, GenericWorker);
  */
 FlateWorker.prototype.processChunk = function (chunk) {
     this.meta = chunk.meta;
-    if (this._pako === null) {
-        this._createPako();
+
+    if (!this._initialized) {
+        this._initialize();
+    }
+
+    console.log("Writing", chunk);
+
+    if (this._streamWriter) {
+        this._streamWriter
+            .write(utils.transformTo(ARRAY_TYPE, chunk.data))
+            .catch(this._handleStreamError);
+    } else if (this._pako) {
+        this._pako.push(utils.transformTo(ARRAY_TYPE, chunk.data), false);
+    } else {
+        throw new Error("processChunk() object missing");
     }
-    this._pako.push(utils.transformTo(ARRAY_TYPE, chunk.data), false);
 };
 
 /**
  * @see GenericWorker.flush
  */
 FlateWorker.prototype.flush = function () {
     GenericWorker.prototype.flush.call(this);
-    if (this._pako === null) {
-        this._createPako();
+
+    console.log("Flushing");
+
+    if (!this._initialized) {
+        this._initialize();
+    }
+
+    if (this._streamWriter) {
+        this._streamWriter
+            .close()
+            .catch(this._handleStreamError);
+    } else if (this._pako) {
+        this._pako.push([], true);
+    } else {
+        throw new Error("flush() object missing");
     }
-    this._pako.push([], true);
 };
 /**
  * @see GenericWorker.cleanUp
@@ -58,19 +95,74 @@ FlateWorker.prototype.cleanUp = function () {
 };
 
 /**
- * Create the _pako object.
- * TODO: lazy-loading this object isn't the best solution but it's the
- * quickest. The best solution is to lazy-load the worker list. See also the
- * issue #446.
+ * Initialize worker using the best available underlying API.
  */
-FlateWorker.prototype._createPako = function () {
-    this._pako = new pako[this._pakoAction]({
+FlateWorker.prototype._initialize = function () {
+    try {
+        this._initializeStream();
+    } catch (error) {
+        // Streams not supported. Fall back to pure JS implementation.
+        this._initializePako();
+    }
+
+    this._initialized = true;
+};
+
+/**
+ * Initialize worker using native compression or decompression stream.
+ */
+FlateWorker.prototype._initializeStream = function () {
+    if (this._action === "Deflate") {
+        this._stream = new CompressionStream("deflate-raw");
+    } else if (this._action === "Inflate") {
+        this._stream = new DecompressionStream("deflate-raw");
+    } else {
+        throw new Error(`Invalid action: ${this._action}`);
+    }
+
+    const reader = this._stream.readable.getReader();
+    const writer = this._stream.writable.getWriter();
+    this._streamWriter = writer;
+
+    const handleSuccess = data => {
+        if (!data.done) {
+            console.log("Received", data.value);
+
+            this.push({
+                data: data.value,
+                meta: this.meta
+            });
+
+            reader.read().then(handleSuccess, this._handleStreamError);
+        } else {
+            console.log("Received done");
+        }
+    };
+
+    reader.read().then(handleSuccess, this._handleStreamError);
+};
+
+/**
+ * Handle errors while using the native stream.
+ */
+FlateWorker.prototype._handleStreamError = function (error) {
+    console.error('XXX', error);
+};
+
+/**
+ * Initialize worker using JavaScript pako implementation.
+ */
+FlateWorker.prototype._initializePako = function () {
+    var pako = require("pako");
+    this._pako = new pako[this._action]({
         chunkSize: 65536,
         raw: true,
-        level: this._pakoOptions.level || -1 // default compression
+        level: this._options.level || -1 // default compression
     });
     var self = this;
     this._pako.onData = function(data) {
+        console.log("Received", data);
+
         self.push({
             data : data,
             meta : self.meta