From 79eab43abccec6c9c72589a2a7f13a3762323984 Mon Sep 17 00:00:00 2001
From: Alex Hultman <alexhultman@gmail.com>
Date: Tue, 15 Jan 2019 11:52:55 +0100
Subject: [PATCH] Wrap res.getWriteOffset, add VideoStreamer example

---
 examples/VideoStreamer.js | 79 +++++++++++++++++++++++++++++++++++++++
 src/HttpResponseWrapper.h |  7 ++++
 uWebSockets               |  2 +-
 3 files changed, 87 insertions(+), 1 deletion(-)
 create mode 100644 examples/VideoStreamer.js

diff --git a/examples/VideoStreamer.js b/examples/VideoStreamer.js
new file mode 100644
index 0000000..e249609
--- /dev/null
+++ b/examples/VideoStreamer.js
@@ -0,0 +1,79 @@
+/* This is an example of async streaming of large files.
+ * Try navigating to the adderss with Chrome and see the video
+ * in real time. */
+
+const uWS = require('../dist/uws.js');
+const fs = require('fs');
+const crypto = require('crypto');
+
+const port = 9001;
+const fileName = '/home/alexhultman/Downloads/Sintel.2010.720p.mkv';
+const totalSize = fs.statSync(fileName).size;
+
+console.log('Video size is: ' + totalSize + ' bytes');
+
+/* Helper function converting Node.js buffer to ArrayBuffer */
+function toArrayBuffer(buffer) {
+  return buffer.buffer.slice(buffer.byteOffset, buffer.byteOffset + buffer.byteLength);
+}
+
+/* Returns true on success, false if it's having backpressure */
+function tryStream(res, chunk, requestDataCb) {
+  /* Stream as far as we can */
+  let lastOffset = res.getWriteOffset();
+  if (!res.tryEnd(chunk, totalSize)) {
+    /* Save unsent chunk for when we can send it */
+    res.chunk = chunk;
+    res.chunkOffset = lastOffset;
+
+    res.onWritable((offset) => {
+      if (res.tryEnd(res.chunk.slice(offset - res.chunkOffset), totalSize)) {
+        requestDataCb();
+        return true;
+      }
+      return false;
+    });
+    /* Return failure */
+    return false;
+  }
+  /* Return success */
+  return true;
+}
+
+/* Yes, you can easily swap to SSL streaming by uncommenting here */
+const app = uWS./*SSL*/App({
+  key_file_name: '/home/alexhultman/key.pem',
+  cert_file_name: '/home/alexhultman/cert.pem',
+  passphrase: '1234'
+}).get('/sintel.mkv', (res, req) => {
+  /* Log */
+  console.log("Streaming Sintel video...");
+
+  /* Create read stream with Node.js and start streaming over Http */
+  const readStream = fs.createReadStream(fileName);
+  const hash = crypto.createHash('md5');
+  readStream.on('data', (chunk) => {
+
+    const ab = toArrayBuffer(chunk);
+    hash.update(chunk);
+
+    if (!tryStream(res, ab, () => {
+      /* Called once we want more data */
+      readStream.resume();
+    })) {
+      /* If we could not send this chunk, pause */
+      readStream.pause();
+    }
+  }).on('end', () => {
+    console.log("md5: " + hash.digest('hex'));
+  });
+}).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);
+  }
+});
diff --git a/src/HttpResponseWrapper.h b/src/HttpResponseWrapper.h
index 431a318..8ddcc2d 100644
--- a/src/HttpResponseWrapper.h
+++ b/src/HttpResponseWrapper.h
@@ -14,6 +14,12 @@ struct HttpResponseWrapper {
     // res.onData(JS function)
     // res.onAborted
 
+    /* Returns the current write offset */
+    template <bool SSL>
+    static void res_getWriteOffset(const FunctionCallbackInfo<Value> &args) {
+        args.GetReturnValue().Set(Integer::New(isolate, getHttpResponse<SSL>(args)->getWriteOffset()));
+    }
+
     /* Takes function of bool(int), returns this */
     template <bool SSL>
     static void res_onWritable(const FunctionCallbackInfo<Value> &args) {
@@ -100,6 +106,7 @@ struct HttpResponseWrapper {
         resTemplateLocal->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "write"), FunctionTemplate::New(isolate, res_write<SSL>));
         resTemplateLocal->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "writeHeader"), FunctionTemplate::New(isolate, res_writeHeader<SSL>));
 
+        resTemplateLocal->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "getWriteOffset"), FunctionTemplate::New(isolate, res_getWriteOffset<SSL>));
         resTemplateLocal->PrototypeTemplate()->Set(String::NewFromUtf8(isolate, "onWritable"), FunctionTemplate::New(isolate, res_onWritable<SSL>));
 
         /* Create our template */
diff --git a/uWebSockets b/uWebSockets
index 8efea34..0ca061e 160000
--- a/uWebSockets
+++ b/uWebSockets
@@ -1 +1 @@
-Subproject commit 8efea340e66bc91efbe31b618a446f821c214bbf
+Subproject commit 0ca061e7727df4fcc0c840e67188e093f966e7d3