chg: do not write pidfile

Current pidfile logic will only keep the pid of the newest server, which is
not very useful if we want to kill all servers, and will become outdated if
the server auto exits after being idle for too long.

Besides, the server-side pidfile writing logic runs before chgserver gets
confighash so it's not trivial to append confighash to pidfile basename like
we did for socket file.

This patch removes --pidfile from the command starting chgserver and switches
to an alternative way (unlink socket file) to stop the server.

contrib/chg/chg.c

@@ -33,7 +33,6 b' struct cmdserveropts {'
 	char sockname[UNIX_PATH_MAX];
 	char redirectsockname[UNIX_PATH_MAX];
 	char lockfile[UNIX_PATH_MAX];
-	char pidfile[UNIX_PATH_MAX];
 	size_t argsize;
 	const char **args;
 	int lockfd;
@@ -149,16 +148,12 b' static void setcmdserveropts(struct cmds'
 	const char *basename = (envsockname) ? envsockname : sockdir;
 	const char *sockfmt = (envsockname) ? "%s" : "%s/server";
 	const char *lockfmt = (envsockname) ? "%s.lock" : "%s/lock";
-	const char *pidfmt = (envsockname) ? "%s.pid" : "%s/pid";
 	r = snprintf(opts->sockname, sizeof(opts->sockname), sockfmt, basename);
 	if (r < 0 || (size_t)r >= sizeof(opts->sockname))
 		abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r);
 	r = snprintf(opts->lockfile, sizeof(opts->lockfile), lockfmt, basename);
 	if (r < 0 || (size_t)r >= sizeof(opts->lockfile))
 		abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r);
-	r = snprintf(opts->pidfile, sizeof(opts->pidfile), pidfmt, basename);
-	if (r < 0 || (size_t)r >= sizeof(opts->pidfile))
-		abortmsg("too long TMPDIR or CHGSOCKNAME (r = %d)", r);
 }
 
 /*
@@ -214,7 +209,6 b' static void execcmdserver(const struct c'
 		"--cmdserver", "chgunix",
 		"--address", opts->sockname,
 		"--daemon-postexec", "chdir:/",
-		"--pid-file", opts->pidfile,
 		"--config", "extensions.chgserver=",
 	};
 	size_t baseargvsize = sizeof(baseargv) / sizeof(baseargv[0]);
@@ -314,21 +308,13 b' static hgclient_t *connectcmdserver(stru'
 	return hgc;
 }
 
-static void killcmdserver(const struct cmdserveropts *opts, int sig)
+static void killcmdserver(const struct cmdserveropts *opts)
 {
-	FILE *fp = fopen(opts->pidfile, "r");
-	if (!fp)
-		abortmsg("cannot open %s (errno = %d)", opts->pidfile, errno);
-	int pid = 0;
-	int n = fscanf(fp, "%d", &pid);
-	fclose(fp);
-	if (n != 1 || pid <= 0)
-		abortmsg("cannot read pid from %s", opts->pidfile);
-
-	if (kill((pid_t)pid, sig) < 0) {
-		if (errno == ESRCH)
-			return;
-		abortmsg("cannot kill %d (errno = %d)", pid, errno);
+	/* resolve config hash */
+	char *resolvedpath = realpath(opts->sockname, NULL);
+	if (resolvedpath) {
+		unlink(resolvedpath);
+		free(resolvedpath);
 	}
 }
 
@@ -536,11 +522,8 b' int main(int argc, const char *argv[], c'
 	setcmdserverargs(&opts, argc, argv);
 
 	if (argc == 2) {
-		int sig = 0;
-		if (strcmp(argv[1], "--kill-chg-daemon") == 0)
-			sig = SIGTERM;
-		if (sig > 0) {
-			killcmdserver(&opts, sig);
+		if (strcmp(argv[1], "--kill-chg-daemon") == 0) {
+			killcmdserver(&opts);
 			return 0;
 		}
 	}

tests/run-tests.py

@@ -2384,9 +2384,9 b' class TestRunner(object):'
     def _killchgdaemons(self):
         """Kill all background chg command servers spawned by tests"""
         for f in os.listdir(self._chgsockdir):
-            if not f.endswith(b'.pid'):
+            if '.' in f:
                 continue
-            killdaemons(os.path.join(self._chgsockdir, f))
+            os.unlink(os.path.join(self._chgsockdir, f))
 
     def _outputcoverage(self):
         """Produce code coverage output."""