Replaced contract I/O pipes with domain sockets. (#140)

examples/nodejs_contract/echo_contract.js

@@ -9,16 +9,16 @@ const hpc = new HotPocketContract();
 if (!hpc.readonly)
     fs.appendFileSync("exects.txt", "ts:" + hpc.timestamp + "\n");
 
-Object.keys(hpc.users).forEach(async (key) => {
-
-    const user = hpc.users[key];
-    const inputBuf = await user.readInput();
-    if (inputBuf) {
-        const userInput = inputBuf.toString("utf8");
-        if (userInput == "ts")
-            user.sendOutput(fs.readFileSync("exects.txt"));
-        else
-            user.sendOutput("Echoing: " + userInput);
+hpc.events.on("user_message", (pubKey, message) => {
+    const userInput = message.toString("utf8");
+    const user = hpc.users[pubKey];
+    if (userInput == "ts") {
+        user.sendOutput(fs.readFileSync("exects.txt"));
+        user.closeChannel();
+    }
+    else {
+        user.sendOutput("Echoing: " + userInput);
+        user.closeChannel();
     }
 });
 
@@ -30,6 +30,19 @@ if (npl) {
     npl.closeNplChannel();
 }
 
+// HP <--> SC
+const hp = hpc.control;
+hp.closeControlChannel();
+
+// let i = 0;
+// hp.events.on('message', (msg) => {
+//     console.log('control msg - ' + msg);
+//     hp.sendOutput(msg);
+//     i++;
+//     if (i == 2)
+//         hp.closeControlChannel();
+// })
+
 // Npl message sending and receiving template.
 // if (npl) {
 //     let i = 0;

examples/nodejs_contract/hp-contract-lib.js

@@ -1,7 +1,7 @@
 const fs = require('fs');
 const events = require('events');
 
-MAX_NPL_BUF_SIZE = 128*1024;
+const MAX_SEQ_PACKET_SIZE = 128 * 1024;
 
 function HotPocketContract() {
     const hpargs = JSON.parse(fs.readFileSync(0, 'utf8'));
@@ -18,53 +18,62 @@ function HotPocketContract() {
         this.npl = new HotPocketNplChannel(hpargs.nplfd);
     }
 
+    this.control = new HotPocketControlChannel(hpargs.hpfd);
+    this.events = new events.EventEmitter();
+
     this.users = {};
     Object.keys(hpargs.usrfd).forEach((userPubKey) => {
-        const userfds = hpargs.usrfd[userPubKey];
-        this.users[userPubKey] = new HotPocketChannel(userfds[0], userfds[1]);
+        this.users[userPubKey] = new HotPocketChannel(hpargs.usrfd[userPubKey], userPubKey, this.events);
     });
 }
 
-// Helper function to asynchronously read a stream to the end and fill a buffer.
-const drainStream = function (stream) {
-
-    return new Promise((resolve) => {
-
+function HotPocketChannel(fd, userPubKey, events) {
+    let socket = null;
+    if (fd > 0) {
+        socket = fs.createReadStream(null, { fd: fd });
         const dataParts = [];
-
-        const resolveBuffer = function () {
-            if (dataParts.length > 0)
-                return resolve(Buffer.concat(dataParts));
-            else
-                return resolve(null);
-        }
-
-        stream.on("data", d => {
-            dataParts.push(d);
-        });
-        stream.on('end', resolveBuffer);
-        stream.on("close", resolveBuffer);
-        stream.on("error", () => {
-            resolve(null);
-        });
-    });
-}
-
-function HotPocketChannel(infd, outfd) {
-    this.readInput = function () {
-        return new Promise((resolve) => {
-            if (infd == -1) {
-                resolve(null);
+        let msgLen = -1;
+        let bytesRead = 0;
+        socket.on("data", (buf) => {
+            if (msgLen == -1) {
+                // First two bytes indicate the message len.
+                const msgLenBuf = readBytes(buf, 0, 4);
+                if (msgLenBuf) {
+                    msgLen = msgLenBuf.readUInt32BE();
+                    const msgBuf = readBytes(buf, 4, buf.byteLength - 4);
+                    dataParts.push(msgBuf)
+                    bytesRead = msgBuf.byteLength;
+                }
+            } else {
+                dataParts.push(buf);
+                bytesRead += buf.length;
             }
-            else {
-                const s = fs.createReadStream(null, { fd: infd });
-                drainStream(s).then(buf => resolve(buf));
+            if (bytesRead == msgLen) {
+                msgLen == -1;
+                events.emit("user_message", userPubKey, Buffer.concat(dataParts));
             }
         });
+
+        socket.on("error", (e) => {
+            events.emit("user_error", userPubKey, e);
+        })
+    }
+
+    // Read bytes from the given buffer.
+    const readBytes = function (buf, pos, count) {
+        if (pos + count > buf.byteLength)
+            return null;
+        return buf.slice(pos, pos + count);
     }
 
     this.sendOutput = function (output) {
-        fs.writeFileSync(outfd, output);
+        fs.writeSync(fd, output);
+    }
+
+    this.closeChannel = function () {
+        if (fd > 0) {
+            socket.destroy();
+        }
     }
 }
 
@@ -78,7 +87,7 @@ function HotPocketNplChannel(fd) {
         // From the hotpocket when sending the npl messages first it sends the pubkey of the particular node
         // and then the message, First data buffer is taken as pubkey and the second one as message,
         // then npl message object is constructed and the event is emmited.
-        socket = fs.createReadStream(null, { fd: fd, highWaterMark: MAX_NPL_BUF_SIZE});
+        socket = fs.createReadStream(null, { fd: fd, highWaterMark: MAX_SEQ_PACKET_SIZE });
         socket.on("data", d => {
             if (!isPubKeyReceived) {
                 pubKey = d.toString('hex');
@@ -111,6 +120,34 @@ function HotPocketNplChannel(fd) {
     }
 }
 
+function HotPocketControlChannel(fd) {
+
+    this.events = new events.EventEmitter();
+    let socket = null;
+    if (fd > 0) {
+        socket = fs.createReadStream(null, { fd: fd, highWaterMark: MAX_SEQ_PACKET_SIZE });
+        socket.on("data", d => {
+            this.events.emit("message", d);
+        });
+
+        socket.on("error", (e) => {
+            this.events.emit("error", e);
+        });
+    }
+
+    this.sendOutput = (output) => {
+        if (fd > 0) {
+            fs.writeSync(fd, output);
+        }
+    }
+
+    this.closeControlChannel = () => {
+        if (fd > 0) {
+            socket.destroy();
+        }
+    }
+}
+
 module.exports = {
     HotPocketContract
 }