v/cmd/tools/vwatch.v

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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}
}
}
// always add the v compiler itself, so that if it is recompiled with `v self`
// the watcher will rerun the compilation too
newstats << VFileStat{context.vexe, os.file_last_mod_unix(context.vexe)}
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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(' ')}'
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_ := <-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() {
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mut context := unsafe { &Context(voidptr(&ccontext)) }
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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 () {
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mut context := unsafe { &Context(voidptr(&ccontext)) }
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context.is_exiting = true
context.kill_pgroup()
})
go context.compilation_runner_loop()
change_detection_loop(context)
}