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diff hgext/fsmonitor/state.py @ 32835:1b25c648d5b7

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fsmonitor: don't write out state if identity has changed (issue5581) Inspired by the dirstate fix in dc7efa2826e4, this should fix any race conditions with the fsmonitor state changing from underneath. Since we now grab the wlock for any non-invalidate writes, the only situation this appears to happen in is with a concurrent invalidation. Test that.
author Siddharth Agarwal <sid0@fb.com>
date Mon, 12 Jun 2017 15:34:31 -0700
parents 15c998528c36
children 718f7acd6d5e
line wrap: on
line diff
--- a/hgext/fsmonitor/state.py	Mon Jun 12 15:34:31 2017 -0700
+++ b/hgext/fsmonitor/state.py	Mon Jun 12 15:34:31 2017 -0700
@@ -13,7 +13,10 @@
 import struct
 
 from mercurial.i18n import _
-from mercurial import pathutil
+from mercurial import (
+    pathutil,
+    util,
+)
 
 _version = 4
 _versionformat = ">I"
@@ -24,6 +27,7 @@
         self._ui = repo.ui
         self._rootdir = pathutil.normasprefix(repo.root)
         self._lastclock = None
+        self._identity = util.filestat(None)
 
         self.mode = self._ui.config('fsmonitor', 'mode', default='on')
         self.walk_on_invalidate = self._ui.configbool(
@@ -35,10 +39,13 @@
         try:
             file = self._vfs('fsmonitor.state', 'rb')
         except IOError as inst:
+            self._identity = util.filestat(None)
             if inst.errno != errno.ENOENT:
                 raise
             return None, None, None
 
+        self._identity = util.filestat.fromfp(file)
+
         versionbytes = file.read(4)
         if len(versionbytes) < 4:
             self._ui.log(
@@ -90,8 +97,16 @@
             self.invalidate()
             return
 
+        # Read the identity from the file on disk rather than from the open file
+        # pointer below, because the latter is actually a brand new file.
+        identity = util.filestat.frompath(self._vfs.join('fsmonitor.state'))
+        if identity != self._identity:
+            self._ui.debug('skip updating fsmonitor.state: identity mismatch\n')
+            return
+
         try:
-            file = self._vfs('fsmonitor.state', 'wb', atomictemp=True)
+            file = self._vfs('fsmonitor.state', 'wb', atomictemp=True,
+                checkambig=True)
         except (IOError, OSError):
             self._ui.warn(_("warning: unable to write out fsmonitor state\n"))
             return
@@ -111,6 +126,7 @@
         except OSError as inst:
             if inst.errno != errno.ENOENT:
                 raise
+        self._identity = util.filestat(None)
 
     def setlastclock(self, clock):
         self._lastclock = clock