7751: Fix stack trace on shutdown caused by race between destroy() and llfuse unmount.

[arvados.git] / services / fuse / arvados_fuse / fresh.py

diff --git a/services/fuse/arvados_fuse/fresh.py b/services/fuse/arvados_fuse/fresh.py
index 85295f178b553c695aa107a11a6b7f02347b4cbc..ec2d47a269791786ad38b7cc9b1e0424869b9042 100644 (file)
--- a/services/fuse/arvados_fuse/fresh.py
+++ b/services/fuse/arvados_fuse/fresh.py
@@ -1,3 +1,8 @@
+import time
+import ciso8601
+import calendar
+import functools
+
 def convertTime(t):
     """Parse Arvados timestamp to unix time."""
     if not t:
@@ -7,14 +12,61 @@ def convertTime(t):
     except (TypeError, ValueError):
         return 0
 
+def use_counter(orig_func):
+    @functools.wraps(orig_func)
+    def use_counter_wrapper(self, *args, **kwargs):
+        try:
+            self.inc_use()
+            return orig_func(self, *args, **kwargs)
+        finally:
+            self.dec_use()
+    return use_counter_wrapper
+
+def check_update(orig_func):
+    @functools.wraps(orig_func)
+    def check_update_wrapper(self, *args, **kwargs):
+        self.checkupdate()
+        return orig_func(self, *args, **kwargs)
+    return check_update_wrapper
+
 class FreshBase(object):
-    '''Base class for maintaining fresh/stale state to determine when to update.'''
+    """Base class for maintaining object lifecycle.
+
+    Functions include:
+
+    * Indicate if an object is up to date (stale() == false) or needs to be
+      updated sets stale() == True).  Use invalidate() to mark the object as
+      stale.  An object is also automatically stale if it has not been updated
+      in `_poll_time` seconds.
+
+    * Record access time (atime) timestamp
+
+    * Manage internal use count used by the inode cache ("inc_use" and
+      "dec_use").  An object which is in use cannot be cleared by the inode
+      cache.
+
+    * Manage the kernel reference count ("inc_ref" and "dec_ref").  An object
+      which is referenced by the kernel cannot have its inode entry deleted.
+
+    * Record cache footprint, cache priority
+
+    * Record Arvados uuid at the time the object is placed in the cache
+
+    * Clear the object contents (invalidates the object)
+
+    """
     def __init__(self):
         self._stale = True
         self._poll = False
         self._last_update = time.time()
         self._atime = time.time()
         self._poll_time = 60
+        self.use_count = 0
+        self.ref_count = 0
+        self.dead = False
+        self.cache_priority = None
+        self.cache_size = 0
+        self.cache_uuid = None
 
     # Mark the value as stale
     def invalidate(self):
@@ -34,3 +86,35 @@ class FreshBase(object):
 
     def atime(self):
         return self._atime
+
+    def persisted(self):
+        return False
+
+    def clear(self, force=False):
+        pass
+
+    def in_use(self):
+        return self.use_count > 0
+
+    def inc_use(self):
+        self.use_count += 1
+
+    def dec_use(self):
+        self.use_count -= 1
+
+    def inc_ref(self):
+        self.ref_count += 1
+        return self.ref_count
+
+    def dec_ref(self, n):
+        self.ref_count -= n
+        return self.ref_count
+
+    def objsize(self):
+        return 0
+
+    def uuid(self):
+        return None
+
+    def finalize(self):
+        pass