Merge 1d42ae6434 into 59338eee33

api/src/api/v2.js

@@ -50,6 +50,12 @@ const SIGNALS = [
 ];
 // ref: https://man7.org/linux/man-pages/man7/signal.7.html
 
+/**Job Fuctory Function
+ * this function is used to create a job object from the request body
+ * validates the request body and returns a promise that resolves to a job object
+ * @param {Object} body - the request body
+ * @returns {Promise<Job>} - a promise that resolves to a job object
+ */
 function get_job(body) {
     let {
         language,
@@ -106,6 +112,7 @@ function get_job(body) {
             });
         }
 
+        // check if the constraints are within the configured limits
         for (const constraint of ['memory_limit', 'timeout']) {
             for (const type of ['compile', 'run']) {
                 const constraint_name = `${type}_${constraint}`;
@@ -122,6 +129,7 @@ function get_job(body) {
                 if (configured_limit <= 0) {
                     continue;
                 }
+
                 if (constraint_value > configured_limit) {
                     return reject({
                         message: `${constraint_name} cannot exceed the configured limit of ${configured_limit}`,
@@ -172,6 +180,10 @@ router.use((req, res, next) => {
     next();
 });
 
+/** Websocket route
+ * used to create a websocket connection to the server to run code
+ * in a more interactive way by writing to stdin and reading from stdout and stderr
+ */
 router.ws('/connect', async (ws, req) => {
     let job = null;
     let event_bus = new events.EventEmitter();

api/src/job.js

@@ -21,6 +21,11 @@ let gid = 0;
 let remaining_job_spaces = config.max_concurrent_jobs;
 let job_queue = [];
 
+/** Every code execution is a job. This class is used to manage the job and its resources.
+ * @method prime Used to write the files to the job cache and transfer ownership of the files to the runner.
+ * @method safe_call Used to call the child process and limit its resources also used to compile and run the code.
+ * @method execute Used to execute the job runtime and return the result.
+ */
 class Job {
     #active_timeouts;
     #active_parent_processes;
@@ -58,6 +63,7 @@ class Job {
         uid++;
         gid++;
 
+        // generate a new uid and gid within the range of the config values (1001 , 1500)
         uid %= config.runner_uid_max - config.runner_uid_min + 1;
         gid %= config.runner_gid_max - config.runner_gid_min + 1;
 
@@ -71,7 +77,12 @@ class Job {
         );
     }
 
+    /** - Used to write the files (containing code to be executed) to the job cache folder
+     * and transfer ownership of the files to the runner.
+     */
     async prime() {
+        // wait for a job slot to open up (default concurrent jobs is 64)
+        // this is to prevent the runner from being overwhelmed with jobs
         if (remaining_job_spaces < 1) {
             this.logger.info(`Awaiting job slot`);
             await new Promise(resolve => {
@@ -84,6 +95,7 @@ class Job {
 
         this.logger.debug(`Transfering ownership`);
 
+        // create the job cache folder and transfer ownership to the runner
         await fs.mkdir(this.dir, { mode: 0o700 });
         await fs.chown(this.dir, this.uid, this.gid);
 
@@ -112,6 +124,7 @@ class Job {
         this.logger.debug('Primed job');
     }
 
+    /** Used to clear the active timeouts and processes */
     exit_cleanup() {
         for (const timeout of this.#active_timeouts) {
             clear_timeout(timeout);
@@ -123,6 +136,7 @@ class Job {
         this.logger.debug(`Finished exit cleanup`);
     }
 
+    /** Close the writables ( stdin, stdout, stderr ) of the active parent processes */
     close_cleanup() {
         for (const proc of this.#active_parent_processes) {
             proc.stderr.destroy();
@@ -136,10 +150,20 @@ class Job {
         this.logger.debug('Destroyed processes writables');
     }
 
+    /** This function is used to call the child process and limit its resources
+     * - used to compile and run the code.
+     * @param {string} file - The file to be executed
+     * @param {string[]} args - The arguments to be passed to the file
+     * @param {number} timeout - The time limit for the process
+     * @param {number} memory_limit - The memory limit for the process
+     * @param {EventEmitter} event_bus - The event bus to be used for communication
+     */
     async safe_call(file, args, timeout, memory_limit, event_bus = null) {
         return new Promise((resolve, reject) => {
             const nonetwork = config.disable_networking ? ['nosocket'] : [];
 
+            // prlimit is a linux specific command
+            // It is used to limit the resources of the child process
             const prlimit = [
                 'prlimit',
                 '--nproc=' + this.runtime.max_process_count,
@@ -147,10 +171,12 @@ class Job {
                 '--fsize=' + this.runtime.max_file_size,
             ];
 
+            // timeout is a linux specific command
+            // It is used to limit the time of the child process
             const timeout_call = [
                 'timeout',
                 '-s',
-                '9',
+                '9', // SIGKILL
                 Math.ceil(timeout / 1000),
             ];
 
@@ -159,10 +185,10 @@ class Job {
             }
 
             const proc_call = [
-                'nice',
+                'nice', // lower the priority of the process
-                ...timeout_call,
+                ...timeout_call, // kill the process if it exceeds the time limit
-                ...prlimit,
+                ...prlimit, // limit the resources of the process
-                ...nonetwork,
+                ...nonetwork, // disable networking
                 'bash',
                 file,
                 ...args,
@@ -172,6 +198,7 @@ class Job {
             var stderr = '';
             var output = '';
 
+            // spawn the child process to execute the file with the given arguments
             const proc = cp.spawn(proc_call[0], proc_call.splice(1), {
                 env: {
                     ...this.runtime.env_vars,
@@ -191,6 +218,8 @@ class Job {
                 proc.stdin.end();
                 proc.stdin.destroy();
             } else {
+                // when the event_bus receives a 'stdin' event (over websocket), write the data to the process's stdin
+                // used to handle interactive programs (like those that require input)
                 event_bus.on('stdin', data => {
                     proc.stdin.write(data);
                 });
@@ -200,14 +229,14 @@ class Job {
                 });
             }
 
+            // set a timeout to kill the process if it exceeds the time limit
             const kill_timeout =
                 (timeout >= 0 &&
                     set_timeout(async _ => {
                         this.logger.info(`Timeout exceeded timeout=${timeout}`);
                         try {
                             process.kill(proc.pid, 'SIGKILL');
-                        }
+                        } catch (e) {
-                        catch (e) {
                             // Could already be dead and just needs to be waited on
                             this.logger.debug(
                                 `Got error while SIGKILLing process ${proc}:`,
@@ -218,15 +247,18 @@ class Job {
                 null;
             this.#active_timeouts.push(kill_timeout);
 
+            // when the process writes to stderr, send the data to the event_bus (over websocket later)
             proc.stderr.on('data', async data => {
                 if (event_bus !== null) {
                     event_bus.emit('stderr', data);
-                } else if ((stderr.length + data.length) > this.runtime.output_max_size) {
+                } else if (
+                    stderr.length + data.length >
+                    this.runtime.output_max_size
+                ) {
                     this.logger.info(`stderr length exceeded`);
                     try {
                         process.kill(proc.pid, 'SIGKILL');
-                    }
+                    } catch (e) {
-                    catch (e) {
                         // Could already be dead and just needs to be waited on
                         this.logger.debug(
                             `Got error while SIGKILLing process ${proc}:`,
@@ -239,15 +271,18 @@ class Job {
                 }
             });
 
+            // when the process writes to stdout, send the data to the event_bus (over websocket later)
             proc.stdout.on('data', async data => {
                 if (event_bus !== null) {
                     event_bus.emit('stdout', data);
-                } else if ((stdout.length + data.length) > this.runtime.output_max_size) {
+                } else if (
+                    stdout.length + data.length >
+                    this.runtime.output_max_size
+                ) {
                     this.logger.info(`stdout length exceeded`);
                     try {
                         process.kill(proc.pid, 'SIGKILL');
-                    }
+                    } catch (e) {
-                    catch (e) {
                         // Could already be dead and just needs to be waited on
                         this.logger.debug(
                             `Got error while SIGKILLing process ${proc}:`,
@@ -277,6 +312,10 @@ class Job {
         });
     }
 
+    /** Used to execute the job  and return the result.
+     * @param {EventEmitter} event_bus - The event bus to be used for communication
+     * @returns {Promise} - The result of the execution
+     */
     async execute(event_bus = null) {
         if (this.state !== job_states.PRIMED) {
             throw new Error(
@@ -298,8 +337,8 @@ class Job {
         const { emit_event_bus_result, emit_event_bus_stage } =
             event_bus === null
                 ? {
-                    emit_event_bus_result: () => { },
+                      emit_event_bus_result: () => {},
-                    emit_event_bus_stage: () => { },
+                      emit_event_bus_stage: () => {},
                   }
                 : {
                       emit_event_bus_result: (stage, result, event_bus) => {
@@ -353,6 +392,9 @@ class Job {
         };
     }
 
+    /** Used to cleanup the processes and wait for any zombie processes to end
+     * - scan /proc for any processes that are owned by the runner and kill them 
+     */
     cleanup_processes(dont_wait = []) {
         let processes = [1];
         const to_wait = [];
@@ -449,6 +491,7 @@ class Job {
         this.logger.debug(`Cleaned up processes`);
     }
 
+    // used to cleanup the filesystem for any residual files
     async cleanup_filesystem() {
         for (const clean_path of globals.clean_directories) {
             const contents = await fs.readdir(clean_path);