v watch: allow customising the auto-restart timeout for the workers with an env variable VWATCH_TIMEOUT

cmd/tools/vwatch.v

@@ -5,7 +5,7 @@ import time
 import term
 import flag
 
-const scan_timeout_s = 5 * 60
+const scan_timeout_s = get_scan_timeout_seconds()
 
 const max_v_cycles = 1000
 
@@ -15,8 +15,16 @@ const scan_period_ms = 1000 / scan_frequency_hz
 
 const max_scan_cycles = scan_timeout_s * scan_frequency_hz
 
+fn get_scan_timeout_seconds() int {
+	env_vw_timeout := os.getenv('VWATCH_TIMEOUT').int()
+	if env_vw_timeout == 0 {
+		return 5 * 60
+	}
+	return env_vw_timeout
+}
+
 //
-// Implements `v -watch file.v` , `v -watch run file.v` etc.
+// 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.
@@ -25,7 +33,7 @@ const max_scan_cycles = scan_timeout_s * scan_frequency_hz
 // 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
+// terminal, running just `v watch run file.v`, and you will see your
 // changes right after you save your .v file in your editor.
 //
 //

cmd/v/help/watch.txt

@@ -23,3 +23,6 @@ Options:
   
   --after <string>          A command to execute *after* each re-run. Example: --after 'rm -rf /tmp/v/'
 	
+You can also customise the timeout, after `v watch` will re-start a monitored
+program automatically, even if it was not changed by setting the enviroment 
+variable VWATCH_TIMEOUT (in seconds). By default, it is 5 min. (300 seconds).