Bug 1716322 - Enable fflate and ping payload gzipping in QML

CHANGELOG.md

@@ -5,9 +5,8 @@
 * [#411](https://github.com/mozilla/glean.js/pull/411): Tag all messages logged by Glean with the component they are coming from.
 * [#399](https://github.com/mozilla/glean.js/pull/399): Check if there are ping data before attempting to delete it.
   * This change lowers the amount of log messages related to attempting to delete inexistent data.
-* [#415](https://github.com/mozilla/glean.js/pull/415): Gzip ping paylod before upload
+* [#415](https://github.com/mozilla/glean.js/pull/415), [#430](https://github.com/mozilla/glean.js/pull/430): Gzip ping paylod before upload
   * This changes the signature of `Uploader.post` to accept `string | Uint8Array` for the `body` parameter, instead of only `string`.
-  * The gizpping functionality is disabled in Qt/QML environments. Follow [Bug 1716322](https://bugzilla.mozilla.org/show_bug.cgi?id=1716322) for updates on the status of this feature on that platform.
 * [#431](https://github.com/mozilla/glean.js/pull/431): BUGFIX: Record the timestamp for events before dispatching to the internal task queue.
 
 # v0.15.0 (2021-06-03)

glean/src/core/upload/index.ts

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-import { gzipSync } from "fflate";
+import { gzipSync, strToU8 } from "fflate";
 
 import type Platform from "../../platform/index.js";
 import type { Configuration } from "../config.js";
@@ -140,8 +140,7 @@ class PingUploader implements PingsDatabaseObserver {
 
     const stringifiedBody = JSON.stringify(ping.payload);
     try {
-      const encoder = new TextEncoder();
-      const compressedBody = gzipSync(encoder.encode(stringifiedBody));
+      const compressedBody = gzipSync(strToU8(stringifiedBody));
       headers["Content-Encoding"] = "gzip";
       headers["Content-Length"] = compressedBody.length.toString();
       return {

glean/src/platform/qt/uploader.ts

@@ -6,11 +6,12 @@ import log, { LoggingLevel } from "../../core/log.js";
 import type Uploader from "../../core/upload/uploader.js";
 import type { UploadResult } from "../../core/upload/uploader.js";
 import { DEFAULT_UPLOAD_TIMEOUT_MS, UploadResultStatus } from "../../core/upload/uploader.js";
+import { isString } from "../../core/utils.js";
 
 const LOG_TAG = "platform.qt.Uploader";
 
 class QtUploader implements Uploader {
-  async post(url: string, body: string, headers: Record<string, string> = {}): Promise<UploadResult> {
+  async post(url: string, body: string | Uint8Array, headers: Record<string, string> = {}): Promise<UploadResult> {
     return new Promise((resolve) => {
       const xhr = new XMLHttpRequest();
       xhr.timeout = DEFAULT_UPLOAD_TIMEOUT_MS;
@@ -48,7 +49,11 @@ class QtUploader implements Uploader {
         });
       };
 
-      xhr.send(body);
+      if (!isString(body)) {
+        xhr.send(body.buffer);
+      } else {
+        xhr.send(body);
+      }
     });
   }
 }

glean/webpack.config.qt.js

@@ -9,6 +9,8 @@ import { fileURLToPath } from "url";
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 
+const OUTPUT = "glean.lib.js";
+
 /**
  * Hacky plugin that removes ".js" extensions from imports before resolving.
  *
@@ -30,6 +32,22 @@ class TsResolvePlugin {
   }
 }
 
+/**
+ * Plugin to remove the "use strict" statement added by Webpack before emmiting final bundle.
+ *
+ * Context on why this is necessary: https://github.com/101arrowz/fflate/pull/75#issuecomment-865016941,
+ * tl;dr; "use strict" makes accessing a negative index throw an error in QML,
+ * and not anywhere else.
+ */
+class RemoveUseStrictPlugin {
+  apply(compiler) {
+    compiler.hooks.shouldEmit.tap("RemoveUseStrictPlugin", compilation => {
+      compilation.assets[OUTPUT]._value = compilation.assets[OUTPUT]._value.replace("\"use strict\";", "");
+      return true;
+    });
+  }
+}
+
 export default {
   entry: "./src/index/qt.ts",
   mode: "production",
@@ -58,14 +76,14 @@ export default {
     extensions: [ ".tsx", ".ts", ".js" ],
     plugins: [
       new TsResolvePlugin()
-    ],
-    alias: {
-      "fflate": path.resolve(__dirname, "src/platform/qt/fflate.stub.js")
-    }
+    ]
   },
+  plugins: [
+    new RemoveUseStrictPlugin(),
+  ],
   output: {
     path: path.resolve(__dirname, "dist/qt/org/mozilla/Glean"),
-    filename: "glean.lib.js",
+    filename: OUTPUT,
     libraryTarget: "var",
     library: "Glean",
   }