X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/fa4c5476b4189798b2123c6948d18db43449329e..b17f04b7797eda5a5d888264f7d480d762a9966f:/services/fuse/arvados_fuse/fresh.py

diff --git a/services/fuse/arvados_fuse/fresh.py b/services/fuse/arvados_fuse/fresh.py
index 5acadfdf7a..2a3a19c54c 100644
--- a/services/fuse/arvados_fuse/fresh.py
+++ b/services/fuse/arvados_fuse/fresh.py
@@ -1,3 +1,7 @@
+# Copyright (C) The Arvados Authors. All rights reserved.
+#
+# SPDX-License-Identifier: AGPL-3.0
+
 import time
 import ciso8601
 import calendar
@@ -22,8 +26,43 @@ def use_counter(orig_func):
             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)
+
+    """
+
+    __slots__ = ("_stale", "_poll", "_last_update", "_atime", "_poll_time", "use_count",
+                 "ref_count", "dead", "cache_size", "cache_uuid", "allow_attr_cache")
+
     def __init__(self):
         self._stale = True
         self._poll = False
@@ -31,13 +70,22 @@ class FreshBase(object):
         self._atime = time.time()
         self._poll_time = 60
         self.use_count = 0
-        self.cache_priority = 0
+        self.ref_count = 0
+        self.dead = False
         self.cache_size = 0
+        self.cache_uuid = None
+
+        # Can the kernel cache attributes?
+        self.allow_attr_cache = True
 
-    # Mark the value as stale
     def invalidate(self):
+        """Indicate that object contents should be refreshed from source."""
         self._stale = True
 
+    def kernel_invalidate(self):
+        """Indicate that an invalidation for this object should be sent to the kernel."""
+        pass
+
     # Test if the entries dict is stale.
     def stale(self):
         if self._stale:
@@ -56,7 +104,7 @@ class FreshBase(object):
     def persisted(self):
         return False
 
-    def clear(self, force=False):
+    def clear(self):
         pass
 
     def in_use(self):
@@ -68,5 +116,44 @@ class FreshBase(object):
     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 has_ref(self, only_children):
+        """Determine if there are any kernel references to this
+        object or its children.
+
+        If only_children is True, ignore refcount of self and only consider
+        children.
+        """
+        if only_children:
+            return False
+        else:
+            return self.ref_count > 0
+
     def objsize(self):
         return 0
+
+    def uuid(self):
+        return None
+
+    def finalize(self):
+        pass
+
+    def child_event(self, ev):
+        pass
+
+    def time_to_next_poll(self):
+        if self._poll:
+            t = (self._last_update + self._poll_time) - self._atime
+            if t < 0:
+                return 0
+            else:
+                return t
+        else:
+            return self._poll_time