1 files changed, 150 insertions, 0 deletions
diff --git a/dom/serviceworkers/test/download_canceled/sw_download_canceled.js b/dom/serviceworkers/test/download_canceled/sw_download_canceled.js
new file mode 100644
index 0000000000..5d9d5f9bfd
--- /dev/null
+++ b/dom/serviceworkers/test/download_canceled/sw_download_canceled.js
@@ -0,0 +1,150 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// This file is derived from :bkelly's https://glitch.com/edit/#!/html-sw-stream
+
+addEventListener("install", evt => {
+  evt.waitUntil(self.skipWaiting());
+});
+
+// Create a BroadcastChannel to notify when we have closed our streams.
+const channel = new BroadcastChannel("stream-closed");
+
+const MAX_TICK_COUNT = 3000;
+const TICK_INTERVAL = 4;
+/**
+ * Generate a continuous stream of data at a sufficiently high frequency that a
+ * there"s a good chance of racing channel cancellation.
+ */
+function handleStream(evt, filename) {
+  // Create some payload to send.
+  const encoder = new TextEncoder();
+  let strChunk =
+    "Static routes are the future of ServiceWorkers! So say we all!\n";
+  while (strChunk.length < 1024) {
+    strChunk += strChunk;
+  }
+  const dataChunk = encoder.encode(strChunk);
+
+  evt.waitUntil(
+    new Promise(resolve => {
+      let body = new ReadableStream({
+        start: controller => {
+          const closeStream = why => {
+            console.log("closing stream: " + JSON.stringify(why) + "\n");
+            clearInterval(intervalId);
+            resolve();
+            // In event of error, the controller will automatically have closed.
+            if (why.why != "canceled") {
+              try {
+                controller.close();
+              } catch (ex) {
+                // If we thought we should cancel but experienced a problem,
+                // that's a different kind of failure and we need to report it.
+                // (If we didn't catch the exception here, we'd end up erroneously
+                // in the tick() method's canceled handler.)
+                channel.postMessage({
+                  what: filename,
+                  why: "close-failure",
+                  message: ex.message,
+                  ticks: why.ticks,
+                });
+                return;
+              }
+            }
+            // Post prior to performing any attempt to close...
+            channel.postMessage(why);
+          };
+
+          controller.enqueue(dataChunk);
+          let count = 0;
+          let intervalId;
+          function tick() {
+            try {
+              // bound worst-case behavior.
+              if (count++ > MAX_TICK_COUNT) {
+                closeStream({
+                  what: filename,
+                  why: "timeout",
+                  message: "timeout",
+                  ticks: count,
+                });
+                return;
+              }
+              controller.enqueue(dataChunk);
+            } catch (e) {
+              closeStream({
+                what: filename,
+                why: "canceled",
+                message: e.message,
+                ticks: count,
+              });
+            }
+          }
+          // Alternately, streams' pull mechanism could be used here, but this
+          // test doesn't so much want to saturate the stream as to make sure the
+          // data is at least flowing a little bit.  (Also, the author had some
+          // concern about slowing down the test by overwhelming the event loop
+          // and concern that we might not have sufficent back-pressure plumbed
+          // through and an infinite pipe might make bad things happen.)
+          intervalId = setInterval(tick, TICK_INTERVAL);
+          tick();
+        },
+      });
+      evt.respondWith(
+        new Response(body, {
+          headers: {
+            "Content-Disposition": `attachment; filename="${filename}"`,
+            "Content-Type": "application/octet-stream",
+          },
+        })
+      );
+    })
+  );
+}
+
+/**
+ * Use an .sjs to generate a similar stream of data to the above, passing the
+ * response through directly.  Because we're handing off the response but also
+ * want to be able to report when cancellation occurs, we create a second,
+ * overlapping long-poll style fetch that will not finish resolving until the
+ * .sjs experiences closure of its socket and terminates the payload stream.
+ */
+function handlePassThrough(evt, filename) {
+  evt.waitUntil(
+    (async () => {
+      console.log("issuing monitor fetch request");
+      const response = await fetch("server-stream-download.sjs?monitor");
+      console.log("monitor headers received, awaiting body");
+      const data = await response.json();
+      console.log("passthrough monitor fetch completed, notifying.");
+      channel.postMessage({
+        what: filename,
+        why: data.why,
+        message: data.message,
+      });
+    })()
+  );
+  evt.respondWith(
+    fetch("server-stream-download.sjs").then(response => {
+      console.log("server-stream-download.sjs Response received, propagating");
+      return response;
+    })
+  );
+}
+
+addEventListener("fetch", evt => {
+  console.log(`SW processing fetch of ${evt.request.url}`);
+  if (evt.request.url.includes("sw-stream-download")) {
+    return handleStream(evt, "sw-stream-download");
+  }
+  if (evt.request.url.includes("sw-passthrough-download")) {
+    return handlePassThrough(evt, "sw-passthrough-download");
+  }
+});
+
+addEventListener("message", evt => {
+  if (evt.data === "claim") {
+    evt.waitUntil(clients.claim());
+  }
+});