fix race in config reloader

nothing dangerous, just confusing log messages if an
admin hammers the reload button 100+ times per second,
or another linux process rapidly sends SIGUSR1

copyparty/svchub.py

@@ -94,7 +94,7 @@ class SvcHub(object):
         self.stopping = False
         self.stopped = False
         self.reload_req = False
-        self.reloading = False
+        self.reloading = 0
         self.stop_cond = threading.Condition()
         self.nsigs = 3
         self.retcode = 0
@@ -662,21 +662,24 @@ class SvcHub(object):
                 self.log("root", "ssdp startup failed;\n" + min_ex(), 3)
 
     def reload(self) -> str:
+        with self.up2k.mutex:
             if self.reloading:
                 return "cannot reload; already in progress"
+            self.reloading = 1
 
-        self.reloading = True
         Daemon(self._reload, "reloading")
         return "reload initiated"
 
     def _reload(self) -> None:
-        self.log("root", "reload scheduled")
         with self.up2k.mutex:
+            if self.reloading != 1:
+                return
+            self.reloading = 2
+            self.log("root", "reloading config")
             self.asrv.reload()
             self.up2k.reload()
             self.broker.reload()
-
-        self.reloading = False
+            self.reloading = 0
 
     def stop_thr(self) -> None:
         while not self.stop_req:

copyparty/up2k.py

@@ -200,10 +200,10 @@ class Up2k(object):
         Daemon(self.deferred_init, "up2k-deferred-init")
 
     def reload(self) -> None:
-        self.gid += 1
-        self.log("reload #{} initiated".format(self.gid))
+        """mutex me"""
+        self.log("reload #{} scheduled".format(self.gid + 1))
         all_vols = self.asrv.vfs.all_vols
-        self.rescan(all_vols, list(all_vols.keys()), True, False)
+        self._rescan(all_vols, list(all_vols.keys()), True, False)
 
     def deferred_init(self) -> None:
         all_vols = self.asrv.vfs.all_vols
@@ -232,7 +232,7 @@ class Up2k(object):
                 for n in range(max(1, self.args.mtag_mt)):
                     Daemon(self._tagger, "tagger-{}".format(n))
 
-                Daemon(self._run_all_mtp, "up2k-mtp-init")
+                Daemon(self._run_all_mtp, "up2k-mtp-init", (self.gid,))
 
     def log(self, msg: str, c: Union[int, str] = 0) -> None:
         if self.pp:
@@ -337,14 +337,21 @@ class Up2k(object):
     def rescan(
         self, all_vols: dict[str, VFS], scan_vols: list[str], wait: bool, fscan: bool
     ) -> str:
+        with self.mutex:
+            return self._rescan(all_vols, scan_vols, wait, fscan)
+
+    def _rescan(
+        self, all_vols: dict[str, VFS], scan_vols: list[str], wait: bool, fscan: bool
+    ) -> str:
+        """mutex me"""
         if not wait and self.pp:
             return "cannot initiate; scan is already in progress"
 
-        args = (all_vols, scan_vols, fscan)
+        self.gid += 1
         Daemon(
             self.init_indexes,
             "up2k-rescan-{}".format(scan_vols[0] if scan_vols else "all"),
-            args,
+            (all_vols, scan_vols, fscan, self.gid),
         )
         return ""
 
@@ -575,19 +582,32 @@ class Up2k(object):
         return True, ret
 
     def init_indexes(
-        self, all_vols: dict[str, VFS], scan_vols: list[str], fscan: bool
+        self, all_vols: dict[str, VFS], scan_vols: list[str], fscan: bool, gid: int = 0
     ) -> bool:
+        if not gid:
+            with self.mutex:
                 gid = self.gid
-        while self.pp and gid == self.gid:
+
+        nspin = 0
+        while True:
+            nspin += 1
+            if nspin > 1:
                 time.sleep(0.1)
 
+            with self.mutex:
                 if gid != self.gid:
                     return False
 
-        if gid:
-            self.log("reload #{} running".format(self.gid))
+                if self.pp:
+                    continue
 
                 self.pp = ProgressPrinter(self.log, self.args)
+
+            break
+
+        if gid:
+            self.log("reload #%d running" % (gid,))
+
         vols = list(all_vols.values())
         t0 = time.time()
         have_e2d = False
@@ -775,7 +795,7 @@ class Up2k(object):
         if self.mtag:
             t = "online (running mtp)"
             if scan_vols:
-                thr = Daemon(self._run_all_mtp, "up2k-mtp-scan", r=False)
+                thr = Daemon(self._run_all_mtp, "up2k-mtp-scan", (gid,), r=False)
         else:
             self.pp = None
             t = "online, idle"
@@ -1809,8 +1829,7 @@ class Up2k(object):
         self.pending_tags = []
         return ret
 
-    def _run_all_mtp(self) -> None:
-        gid = self.gid
+    def _run_all_mtp(self, gid: int) -> None:
         t0 = time.time()
         for ptop, flags in self.flags.items():
             if "mtp" in flags: