all: support v -watch run (#9577)

cmd/tools/vwatch.v

@@ -0,0 +1,288 @@
+module main
+
+import os
+import time
+
+const scan_timeout_s = 5 * 60
+
+const max_v_cycles = 1000
+
+const scan_frequency_hz = 4
+
+const scan_period_ms = 1000 / scan_frequency_hz
+
+const max_scan_cycles = scan_timeout_s * scan_frequency_hz
+
+//
+// Implements `v -watch file.v` , `v -watch run file.v` etc.
+// With this command, V will collect all .v files that are needed for the
+// compilation, then it will enter an infinite loop, monitoring them for
+// changes.
+//
+// When a change is detected, it will stop the current process, if it is
+// still running, then rerun/recompile/etc.
+//
+// In effect, this makes it easy to have an editor session and a separate
+// terminal, running just `v -watch run file.v`, and you will see your
+// changes right after you save your .v file in your editor.
+//
+//
+//    Since -gc boehm is not available on all platforms yet,
+// and this program leaks ~8MB/minute without it, the implementation here
+// is done similarly to vfmt in 2 modes, in the same executable:
+//
+//   a) A parent/manager process that only manages a single worker
+//   process. The parent process does mostly nothing except restarting
+//   workers, thus it does not leak much.
+//
+//   b) A worker process, doing the actual monitoring/polling.
+//    NB: *workers are started with the -vwatchworker option*
+//
+//    Worker processes will run for a limited number of iterations, then
+// they will do exit(255), and then the parent will start a new worker.
+// Exiting by any other code will cause the parent to also exit with the
+// same error code. This limits the potential leak that a worker process
+// can do, even without using the garbage collection mode.
+//
+
+struct VFileStat {
+	path  string
+	mtime int
+}
+
+[unsafe]
+fn (mut vfs VFileStat) free() {
+	unsafe { vfs.path.free() }
+}
+
+enum RerunCommand {
+	restart
+	quit
+}
+
+struct Context {
+mut:
+	pid             int  // the pid of the current process; useful while debugging manager/worker interactions
+	is_worker       bool // true in the workers, false in the manager process
+	check_period_ms int = scan_period_ms
+	vexe            string
+	affected_paths  []string
+	vfiles          []VFileStat
+	opts            []string
+	rerun_channel   chan RerunCommand
+	child_process   &os.Process
+	is_exiting      bool // set by SIGINT/Ctrl-C
+	v_cycles        int  // how many times the worker has restarted the V compiler
+	scan_cycles     int  // how many times the worker has scanned for source file changes
+}
+
+[if debug_vwatch]
+fn (mut context Context) elog(msg string) {
+	eprintln('> vredo $context.pid, $msg')
+}
+
+fn (context &Context) str() string {
+	return 'Context{ pid: $context.pid, is_worker: $context.is_worker, check_period_ms: $context.check_period_ms, vexe: $context.vexe, opts: $context.opts, is_exiting: $context.is_exiting, vfiles: $context.vfiles'
+}
+
+fn (mut context Context) get_stats_for_affected_vfiles() []VFileStat {
+	if context.affected_paths.len == 0 {
+		mut apaths := map[string]bool{}
+		// The next command will make V parse the program, and print all .v files,
+		// needed for its compilation, without actually compiling it.
+		copts := context.opts.join(' ')
+		cmd := '"$context.vexe" -silent -print-v-files $copts'
+		// context.elog('> cmd: $cmd')
+		mut vfiles := os.execute(cmd)
+		if vfiles.exit_code == 0 {
+			paths_trimmed := vfiles.output.trim_space()
+			mut paths := paths_trimmed.split('\n')
+			for vf in paths {
+				apaths[os.real_path(os.dir(vf))] = true
+			}
+		}
+		context.affected_paths = apaths.keys()
+		// context.elog('vfiles paths to be scanned: $context.affected_paths')
+	}
+	// scan all files in the found folders
+	mut newstats := []VFileStat{}
+	for path in context.affected_paths {
+		mut files := os.ls(path) or { []string{} }
+		for pf in files {
+			pf_ext := os.file_ext(pf).to_lower()
+			if pf_ext in ['', '.bak', '.exe', '.dll', '.so', '.def'] {
+				continue
+			}
+			if pf.starts_with('.#') {
+				continue
+			}
+			if pf.ends_with('~') {
+				continue
+			}
+			f := os.join_path(path, pf)
+			fullpath := os.real_path(f)
+			mtime := os.file_last_mod_unix(fullpath)
+			newstats << VFileStat{fullpath, mtime}
+		}
+	}
+	return newstats
+}
+
+fn (mut context Context) get_changed_vfiles() int {
+	mut changed := 0
+	newfiles := context.get_stats_for_affected_vfiles()
+	for vfs in newfiles {
+		mut found := false
+		for existing_vfs in context.vfiles {
+			if existing_vfs.path == vfs.path {
+				found = true
+				if existing_vfs.mtime != vfs.mtime {
+					context.elog('> new updates for file: $vfs')
+					changed++
+				}
+				break
+			}
+		}
+		if !found {
+			changed++
+			continue
+		}
+	}
+	context.vfiles = newfiles
+	if changed > 0 {
+		context.elog('> get_changed_vfiles: $changed')
+	}
+	return changed
+}
+
+fn change_detection_loop(ocontext &Context) {
+	mut context := ocontext
+	for {
+		if context.v_cycles >= max_v_cycles || context.scan_cycles >= max_scan_cycles {
+			context.is_exiting = true
+			context.kill_pgroup()
+			time.sleep(50 * time.millisecond)
+			exit(255)
+		}
+		if context.is_exiting {
+			return
+		}
+		changes := context.get_changed_vfiles()
+		if changes > 0 {
+			context.rerun_channel <- RerunCommand.restart
+		}
+		time.sleep(context.check_period_ms * time.millisecond)
+		context.scan_cycles++
+	}
+}
+
+fn (mut context Context) kill_pgroup() {
+	if context.child_process == 0 {
+		return
+	}
+	if context.child_process.is_alive() {
+		context.child_process.signal_pgkill()
+	}
+	context.child_process.wait()
+}
+
+fn (mut context Context) compilation_runner_loop() {
+	cmd := '"$context.vexe" ${context.opts.join(' ')}'
+	_ := <-context.rerun_channel
+	for {
+		context.elog('>> loop: v_cycles: $context.v_cycles')
+		timestamp := time.now().format_ss_milli()
+		context.child_process = os.new_process(context.vexe)
+		context.child_process.use_pgroup = true
+		context.child_process.set_args(context.opts)
+		context.child_process.run()
+		eprintln('$timestamp: $cmd | pid: ${context.child_process.pid:7d} | reload cycle: ${context.v_cycles:5d}')
+		for {
+			mut cmds := []RerunCommand{}
+			for {
+				if context.is_exiting {
+					return
+				}
+				if !context.child_process.is_alive() {
+					context.child_process.wait()
+				}
+				select {
+					action := <-context.rerun_channel {
+						cmds << action
+						if action == .quit {
+							context.kill_pgroup()
+							return
+						}
+					}
+					> 100 * time.millisecond {
+						should_restart := RerunCommand.restart in cmds
+						cmds = []
+						if should_restart {
+							// context.elog('>>>>>>>> KILLING $context.child_process.pid')
+							context.kill_pgroup()
+							break
+						}
+					}
+				}
+			}
+			if !context.child_process.is_alive() {
+				context.child_process.wait()
+				break
+			}
+		}
+		context.v_cycles++
+	}
+}
+
+const ccontext = Context{
+	child_process: 0
+}
+
+fn main() {
+	mut context := &ccontext
+	context.pid = os.getpid()
+	context.vexe = os.getenv('VEXE')
+	context.is_worker = os.args.contains('-vwatchworker')
+	context.opts = os.args[1..].filter(it != '-vwatchworker')
+	context.elog('>>> context.pid: $context.pid')
+	context.elog('>>> context.vexe: $context.vexe')
+	context.elog('>>> context.opts: $context.opts')
+	context.elog('>>> context.is_worker: $context.is_worker')
+	if context.is_worker {
+		context.worker_main()
+	} else {
+		context.manager_main()
+	}
+}
+
+fn (mut context Context) manager_main() {
+	myexecutable := os.executable()
+	mut worker_opts := ['-vwatchworker']
+	worker_opts << context.opts
+	for {
+		mut worker_process := os.new_process(myexecutable)
+		worker_process.set_args(worker_opts)
+		worker_process.run()
+		for {
+			if !worker_process.is_alive() {
+				worker_process.wait()
+				break
+			}
+			time.sleep(200 * time.millisecond)
+		}
+		if !(worker_process.code == 255 && worker_process.status == .exited) {
+			break
+		}
+	}
+}
+
+fn (mut context Context) worker_main() {
+	context.rerun_channel = chan RerunCommand{cap: 10}
+	os.signal(C.SIGINT, fn () {
+		mut context := &ccontext
+		context.is_exiting = true
+		context.kill_pgroup()
+	})
+	go context.compilation_runner_loop()
+	change_detection_loop(context)
+}