Update body parsing and file streaming examples

Author: RatchetS2

examples/FileStreaming.js

@@ -0,0 +1,105 @@
+/* This is an example of streaming files */
+
+const uWS = require('../dist/uws.js');
+const fs = require('fs');
+const port = 9001;
+
+/* Small file is cached in memory */
+const smallFileType = 'application/json';
+const smallFileName = 'absolutPathTo/smallFile.json';
+const smallFileCachedBuffer = fs.readFileSync(smallFileName);
+console.log('Small file size is: '+ smallFileCachedBuffer.length +' bytes');
+
+/* Big file is streamed from storage */
+const bigFileType = 'video/mpeg';
+const bigFileName = 'absolutPathTo/bigFile.mp3';
+const bigFileSize = fs.statSync(bigFileName).size;
+console.log('Big file size is: '+ bigFileSize +' bytes');
+
+let lastStreamIndex = 0;
+let openStreams = 0;
+
+/* Helper function to stream data */
+/** @param {import('node:Stream').Readable} readStream */
+const streamData = (res, readStream, totalSize, onSucceed) => {
+    let chunkBuffer; /* Actual chunk being streamed */
+    let totalOffset = 0; /* Actual chunk offset */
+
+    /* Function to send actual chunk */
+    const sendChunkBuffer = () => {
+        const [ok, done] = res.tryEnd(chunkBuffer, totalSize);
+        if (done) {
+            /* Streaming finished */
+            readStream.destroy();
+            onSucceed();
+        } else if (ok) {
+            /* Chunk send succeed */
+            totalOffset += chunkBuffer.length;
+        } else {
+            /* Chunk send failed (client backpressure)
+             * onWritable will be called once client ready to receive new chunk
+             * Pause stream to wait client */
+            readStream.pause();
+        }
+        return ok;
+    };
+
+    /* Register onWritable callback
+     * Will be called to drain client backpressure */
+    res.onWritable((offset) => {
+        if (offset !== totalOffset) {
+            /* If start of the chunk was successfully sent
+             * We only send the missing part */
+            chunkBuffer = chunkBuffer.subarray(offset - totalOffset);
+            totalOffset = offset;
+        }
+        if (sendChunkBuffer()) {
+            /* Resume stream if resend succeed */
+            readStream.resume();
+            return true;
+        }
+        return false;
+    });
+
+    /* Register callback for stream events */
+    readStream.on('error', (err) => {
+        console.log('Error reading file: '+ err);
+        /* res.close() calls onAborted callback */
+        res.close();
+    }).on('data', (newChunkBuffer) => {
+        chunkBuffer = newChunkBuffer;
+        /* Cork before sending new chunk */
+        res.cork(sendChunkBuffer);
+    });
+};
+
+const app = uWS./*SSL*/App({
+    key_file_name: 'misc/key.pem',
+    cert_file_name: 'misc/cert.pem',
+    passphrase: '1234'
+}).get('/smallFile', (res, req) => {
+    res.writeHeader('Content-Type', smallFileType);
+    /* !! Use this only for small-sized bodies !!
+     * May cause server backpressure and bad performance
+     * For large bodies you must use the streaming method */
+    res.end(smallFileCachedBuffer);
+}).get('/bigFile', (res, req) => {
+    const streamIndex = ++ lastStreamIndex;
+    console.log('Stream ('+ streamIndex +') was opened, openStreams: '+ (++ openStreams));
+    const readStream = fs.createReadStream(bigFileName);
+    /* Attach onAborted handler because streaming is async */
+    res.onAborted(() => {
+        readStream.destroy();
+        console.log('Stream ('+ streamIndex +') failed, openStreams: '+ (-- openStreams));
+    });
+    res.writeHeader('Content-Type', bigFileType);
+    streamData(res, readStream, bigFileSize, () => {
+        console.log('Stream ('+ streamIndex +') succeed, openStreams: '+ (-- openStreams));
+    });
+}).listen(port, (token) => {
+    if (token) {
+        console.log('Listening to port ' + port);
+    } else {
+        console.log('Failed to listen to port ' + port);
+    }
+});

examples/JsonPost.js

@@ -0,0 +1,56 @@
+/* This is an example of parsing request body */
+
+const uWS = require('../dist/uws.js');
+const port = 9001;
+
+/* Helper function to parse JSON body */
+const parseJSONBody = (res, callback) => {
+    let buffer;
+    /* Register data callback */
+    res.onData((ab, isLast) => {
+        const chunk = Buffer.from(ab);
+        if (isLast) {
+            let json;
+            try {
+                json = JSON.parse(buffer ? Buffer.concat([buffer, chunk]) : chunk);
+            } catch (e) {
+                json = undefined;
+            }
+            callback(json);
+        } else if (buffer) {
+            buffer = Buffer.concat([buffer, chunk]);
+        } else {
+            buffer = Buffer.concat([chunk]);
+        }
+    });
+};
+
+const app = uWS./*SSL*/App({
+    key_file_name: 'misc/key.pem',
+    cert_file_name: 'misc/cert.pem',
+    passphrase: '1234'
+}).get('/jsonAPI', (res, req) => {
+    /* Attach onAborted handler because body parsing is async */
+    res.onAborted(() => {
+        console.log('Request aborted!');
+    });
+    parseJSONBody(res, (parsedJson) => {
+        if (parsedJson !== undefined) {
+            console.log('Valid JSON:', parsedJson);
+            res.cork(() => {
+                res.end('Thanks for your data!');
+            });
+        } else {
+            console.log('Invalid JSON or no data at all!');
+            res.cork(() => {
+                res.writeStatus('400 Bad Request').end();
+            });
+        }
+    });
+}).listen(port, (token) => {
+    if (token) {
+        console.log('Listening to port ' + port);
+    } else {
+        console.log('Failed to listen to port ' + port);
+    }
+});