New STDIN mode

node/venv.js

@@ -10,29 +10,77 @@ module.exports = function(RED) {
         const json = fs.readFileSync(jsonPath)
         const pythonPath = JSON.parse(json).NODE_PYENV_PYTHON
 
+        let stdoutData = ''
+        let stderrData = ''
         const child_process = require('child_process')
+        let pythonProcess = null
 
-        node.on('input', function(msg) {
-            let code = ''
-            if(config.code !== null && config.code !== '') {
-                code = config.code
-            } else {
-                code = msg.code
+        // config.continuous = true // TODO
+
+        /**
+         * In this mode, a single Python process runs continuously.
+         * The messages are passed to the Python script via STDIN and read from STDOUT line by line.
+         */
+        function processContinous() {
+            if (typeof config.code === 'string' && config.code !== '') {
+                fs.writeFileSync(filePath, config.code)
             }
-            fs.writeFileSync(filePath, code)
+            pythonProcess = child_process.spawn(pythonPath, [filePath])
+
+            pythonProcess.on('message', console.log)
+
+            stdoutData = ''
+            pythonProcess.stdout.on('data', (chunk) => {
+                stdoutData += chunk.toString()
+                let lines = stdoutData.split('\n')
+                stdoutData = lines.pop()
+                for (let line of lines) {
+                    if (line === '') {
+                        continue
+                    }
+                    try {
+                        let msg = JSON.parse(line)
+                        node.send(msg)
+                    } catch (e) {
+                        node.error(e)
+                    }
+                }
+            })
+
+            stderrData = ''
+            pythonProcess.stderr.on('data', (chunk) => {
+                stderrData += chunk.toString()
+            })
+
+            pythonProcess.on('close', (exitCode) => {
+                if (exitCode !== 0) {
+                    node.error(`Error ${exitCode}: ` + stderrData)
+                }
+                pythonProcess = null
+            })
+        }
 
+        /**
+         * In this mode, a new Python process is started for each message.
+         * The message is passed to the Python script via a command line parameter and automatically decoded into the `msg` variable.
+         * The result is read from STDOUT until the Python process is closed.
+         */
+        function processUntilClose(msg) {
+            if (typeof msg.code === 'string' && msg.code !== '') {
+                fs.writeFileSync(filePath, msg.code)
+            }
             const message = Buffer.from(JSON.stringify(msg)).toString('base64')
             const args = ['-c', `import base64;import json;msg=json.loads(base64.b64decode(r'${message}'));exec(open(r'${filePath}').read())`]
-            const pythonProcess = child_process.spawn(pythonPath, args)
-            let stdoutData = ''
-            let stderrData = ''
+            pythonProcess = child_process.spawn(pythonPath, args)
 
             pythonProcess.on('message', console.log)
 
+            stdoutData = ''
             pythonProcess.stdout.on('data', (chunk) => {
                 stdoutData += chunk.toString()
             })
 
+            stderrData = ''
             pythonProcess.stderr.on('data', (chunk) => {
                 stderrData += chunk.toString()
             })
@@ -44,9 +92,19 @@ module.exports = function(RED) {
                     msg.payload = stdoutData
                     node.send(msg)
                 }
-                stdoutData = ''
-                stderrData = ''
+                pythonProcess = null
             })
+        }
+
+        node.on('input', function(msg) {
+            if (config.continuous) {
+                if (pythonProcess === null) {
+                    processContinous()
+                }
+                pythonProcess.stdin.write(JSON.stringify(msg) + '\n')
+            } else {
+                processUntilClose(msg)
+            }
         })
     }
     RED.nodes.registerType("venv", Venv)