Add VideoStreamerChunked.js example

Author: uNetworkingAB

examples/VideoStreamerChunked.js

@@ -0,0 +1,80 @@
+/* This is an example of sync copying of large files.
+ * NEVER DO THIS; ONLY FOR TESTING PURPOSES. WILL CAUSE
+ * SEVERE BACKPRESSURE AND HORRIBLE PERFORMANCE.
+ * Try navigating to the adderss with Chrome and see the video
+ * in real time. */
+
+const uWS = require('uWebSockets.js');
+const fs = require('fs');
+
+const port = 9001;
+const fileName = 'spritefright.mp4';
+const videoFile = toArrayBuffer(fs.readFileSync(fileName));
+const totalSize = videoFile.byteLength;
+
+console.log('WARNING: NEVER DO LIKE THIS; WILL CAUSE HORRIBLE BACKPRESSURE!');
+console.log('Video size is: ' + totalSize + ' bytes');
+
+const CHUNK_SIZE = 1024 * 64;
+
+/* Helper function converting Node.js buffer to ArrayBuffer */
+function toArrayBuffer(buffer) {
+  return buffer.buffer.slice(buffer.byteOffset, buffer.byteOffset + buffer.byteLength);
+}
+
+/* Yes, you can easily swap to SSL streaming by uncommenting here */
+const app = uWS.App({
+  key_file_name: 'misc/key.pem',
+  cert_file_name: 'misc/cert.pem',
+  passphrase: '1234'
+
+}).get('/spritefright.mp4', (res, req) => {
+    let aborted = false;
+    let written = 0;
+
+    res.onAborted(() => {
+        aborted = true;
+    });
+
+    const stream = () => {
+        let ok = true;
+
+        // Use res.cork to pack multiple small writes into one syscall
+        res.cork(() => {
+            while (ok && written < videoFile.byteLength) {
+                let chunk = videoFile.slice(written, Math.min(written + CHUNK_SIZE, videoFile.byteLength));
+                
+                // If this is the last chunk, use end() instead of write()
+                if (written + chunk.byteLength === videoFile.byteLength) {
+                    res.end(chunk);
+                    written += chunk.byteLength;
+                    ok = false; // Stop the loop
+                } else {
+                    ok = res.write(chunk);
+                    written += chunk.byteLength;
+                }
+            }
+        });
+
+        return ok;
+    };
+
+    // Initial attempt to stream
+    let ok = stream();
+
+    // If we hit backpressure, set up the drain handler
+    if (!ok && !aborted && written < videoFile.byteLength) {
+        res.onWritable((offset) => {
+            return stream();
+        });
+    }
+}).get('/*', (res, req) => {
+  /* Make sure to always handle every route */
+  res.end('Nothing to see here!');
+}).listen(port, (token) => {
+  if (token) {
+    console.log('Listening to port ' + port);
+  } else {
+    console.log('Failed to listen to port ' + port);
+  }
+});