Proces Controller Object

src/main/java/JobServ/ProcessController.java

@@ -0,0 +1,101 @@
+/*
+ * ProcessController
+ *
+ * v1.0
+ *
+ * May 22, 2019
+ */
+
+package JobServ;
+
+/*
+ * ProcessController
+ * This class wraps a java Process object with metadata
+ * such as translated PID that exist for this specific API
+ * as well as general metadata like IO streams.
+ */
+class ProcessController {
+    // incremented in constructor
+    private static int nextPid = 0;
+    private int pid;
+
+    // TODO: add an api endpoint for streaming client input into
+    // interactive processes (out of scope for initial API)
+    private OutputStream output;
+    private InputStream input;
+    private Scanner outputScanner;
+
+    private Process process;
+
+    /*
+     * Constructor
+     * Takes a command and spawns it in a new process
+     * Redirects IO streams and assigns a fake PID
+     */
+    public ProcessController(String command) throws IOException {
+        this.pid = ProcessController.nextPid;
+        ProcessController.nextPid += 1;
+
+        this.process = Runtime.exec(command);
+        this.output = this.process.getOutputStream();
+        this.input = this.process.getInputStream();
+        this.outputScanner = new Scanner(this.input);
+        this.outputScanner.useDelimieter("\\A");
+    }
+
+    /*
+     * getStatus()
+     * returns whether or not the process is running
+     * this isnt a very direct way of getting the information
+     * The alternative is to use reflection to get into the private UNIXProcess class
+     * for the PID and to check that against 'ps' or a similar command
+     *
+     * TODO: (for future release) return thread state
+     */
+    public Boolean getStatus() {
+        try {
+            process.exitValue();
+            return true;
+        } catch (IllegalThreadStateException e) {
+            return false;
+        }
+    }
+
+    /*
+     * getReturn()
+     * returns the exit code of the process
+     * or 256 if process is still running
+     * (unix/posix defines an exit code as a uint8, so 256 is fair game)
+     */
+    public int getReturn() {
+        try {
+            return process.exitValue();
+        } catch (IllegalThreadStateException e) {
+            return 256;
+        }
+    }
+
+    /*
+     * getOutput()
+     * gets new output from stream
+     * (TODO: investigate whether this would better be done by )
+     */
+    public String getOutput() {
+        String out = "";
+        while(scanner.hasNext()) {
+            out += scanner.next();
+        }
+
+        return out;
+    }
+
+    /*
+     * kill()
+     * Cleans up resources and destroys process
+     */
+    public void kill() {
+        this.input.close();
+        this.output.close();
+        process.destroy();
+    }
+}