Capture SIGINT, SIGTERM, SIGQUIT signals from terminal in both iCubTelemVizServer and openmctStaticServer and close the later

.gitignore

@@ -1,7 +1,7 @@
 build*
 iCubTelemVizServer/node_modules/*
-iCubTelemVizServer/npm-debug.log
+iCubTelemVizServer/npm-debug.log*
 openmctStaticServer/node_modules/*
-openmctStaticServer/npm-debug.log
+openmctStaticServer/npm-debug.log*
 .idea
 .DS_Store

iCubTelemVizServer/iCubTelemVizServer.js

@@ -1,5 +1,13 @@
 // Server http (non secure)
 
+// Process the termination signals callbacks.
+// When the signal comes from the terminal, the generated event doesn't have a 'signal' parameter,
+// so it appears undefined in the callback body. We worked around this issue by explicitly setting
+// the 'signal' parameter case by case.
+process.once('SIGQUIT', () => {handleTermination('SIGQUIT');});
+process.once('SIGTERM', () => {handleTermination('SIGTERM');});
+process.once('SIGINT', () => {handleTermination('SIGINT');});
+
 // require and setup basic http functionalities
 var portTelemetryReqOrigin = process.env.PORT_TLM_REQ_ORIGIN || 8080
 var portTelemetryRespOrigin = process.env.PORT_TLM_RSP_ORIGIN || 8081
@@ -146,13 +154,13 @@ portRPCserver4sysCmds.onRead(function (cmdNparams) {
 });
 
 // Start history and realtime servers
-app.listen(portTelemetryRespOrigin, function () {
+const telemServer = app.listen(portTelemetryRespOrigin, function () {
     console.log('ICubTelemetry History hosted at http://localhost:' + portTelemetryRespOrigin + '/history');
     console.log('ICubTelemetry Realtime hosted at ws://localhost:' + portTelemetryRespOrigin + '/realtime');
 });
 
 // start the server!
-http.listen(3000, function(){
+const consoleServer = http.listen(3000, function(){
   console.log('listening on http://localhost:3000');
 });
 
@@ -162,3 +170,8 @@ var openMctServerHandler = new OpenMctServerHandler(console.log);
 var ret = openMctServerHandler.start();
 console.log(ret.status);
 console.log(ret.message);
+
+function handleTermination(signal) {
+    console.log('Received '+signal+' ...');
+    openMctServerHandler.stop(signal);
+}

iCubTelemVizServer/openMctServerHandler.js

@@ -6,7 +6,7 @@ const path = require('path');
 function OpenMctServerHandler(outputCallback) {
     // Create a child process spawn for later setting the NVM version and running the server
     this.childProcess = require('child_process');
-    this.processHandle = null;
+    this.processPID = undefined;
     this.outputCallback = outputCallback;
 }
 
@@ -21,8 +21,8 @@ OpenMctServerHandler.prototype.start = function () {
     const embeddedThis = this;
 
     // Start the process
-    const execPath = path.join(process.cwd(), '..', 'openmctStaticServer');
-    let npmStart = this.childProcess.spawn('npm', ['start'], {shell: 'bash', cwd: execPath});
+    const wPath = path.join(process.cwd(), '..', 'openmctStaticServer');
+    const npmStart = this.childProcess.spawn('sh', ['runModule.sh'], {shell: 'bash', cwd: wPath, stdio: ['pipe','pipe','pipe','ipc']});
 
     // Set the output callbacks
     npmStart.stdout.on('data', function (data) {
@@ -34,22 +34,30 @@ OpenMctServerHandler.prototype.start = function () {
     npmStart.on('error', function (error) {
         embeddedThis.outputCallback('[OPEN-MCT STATIC SERVER] error: ' + error.message);
     });
+    npmStart.on('message', function (m) {
+        embeddedThis.outputCallback('[OPEN-MCT STATIC SERVER] ipc: ' + JSON.stringify(m));
+        embeddedThis.processPID = m.pid;
+    });
     npmStart.on('close', function (code) {
-        embeddedThis.processHandle = null;
+        embeddedThis.processPID = undefined;
         embeddedThis.outputCallback('[OPEN-MCT STATIC SERVER] close: ' + code);
     });
 
-    this.processHandle = npmStart;
     return {status: 'OK', message: 'Opem-MCT static server process started.'};
 }
 
-OpenMctServerHandler.prototype.stop = function () {
-    this.processHandle.kill();
-    return {status: 'PROMISE', message: 'Opem-MCT static server process stopping...'};
+OpenMctServerHandler.prototype.stop = function (signal) {
+    if (this.isOn()) {
+        process.kill(this.processPID,signal);
+        console.log('Killing PID %d with signal %s',this.processPID,signal);
+        return {status: 'WRPLY', message: 'Process OpenMCT Server stopping...'};
+    } else {
+        return {status: 'WARNING', message: 'No process OpenMCT Server running...'};
+    }
 }
 
 OpenMctServerHandler.prototype.isOn = function () {
-    return (this.processHandle != null);
+    return (this.processPID !== undefined);
 }
 
 function spawnSynchInOpenMCTserverPath(childProcess, shellCommand, cmdArgs) {

iCubTelemVizServer/websocket-tracker.js

@@ -0,0 +1,22 @@
+function WebsocketTracker(server) {
+    this.server = server;
+    this.sockets = new Map();
+    server.on('connection',(socket) => {
+        console.log('NEW CONNECTION!!');
+        this.sockets.set(socket,true);
+        socket.on('close',function() {
+            console.log('CLOSE CONNECTION');
+            this.sockets.delete(socket);
+        }.bind(this));
+    })
+}
+
+WebsocketTracker.prototype.closeAll = function() {
+    this.sockets.forEach((value,key) => {
+        key.destroy();
+    });
+}
+
+module.exports = function (server) {
+    return new WebsocketTracker(server);
+}

openmctStaticServer/runModule.sh

@@ -0,0 +1,4 @@
+. ${NVM_DIR}/nvm.sh
+nvm use v14.17.0
+node server.js
+

openmctStaticServer/server.js

@@ -14,6 +14,29 @@ app.use('/', staticServer);
 
 var port = process.env.PORT || 8080
 
-app.listen(port, function () {
+// Send the process PID back to the parent through the IPC channel
+if (process.connected) {
+    process.send({"pid": process.pid});
+}
+
+// Start the server
+vizServer = app.listen(port, function () {
     console.log('iCub Telemetry Visualizer (Open MCT based) hosted at http://localhost:' + port);
 });
+
+// Track the connections
+WebsocketTracker = require('../iCubTelemVizServer/websocket-tracker');
+const vizServerTracker = new WebsocketTracker(vizServer);
+
+// Handle a clean process termination
+function handleTermination(signal) {
+    console.log('Received '+signal+' ...');
+    vizServer.close(() => {
+        console.log('Open-MCT Visualizer Server closed. No further requests accepted. Refreshing the visualizer web page will fail.');
+    })
+    vizServerTracker.closeAll();
+}
+
+process.prependOnceListener('SIGQUIT', () => {handleTermination('SIGQUIT');});
+process.prependOnceListener('SIGTERM', () => {handleTermination('SIGTERM');});
+process.prependOnceListener('SIGINT', () => {handleTermination('SIGINT');});