X-Git-Url: https://git.arvados.org/arvados.git/blobdiff_plain/650265966e83fca4ce8e9a416e9b5e358e82be98..10801e63c5029a2fffc3599235dddab62a2f3480:/sdk/python/arvados/diskcache.py

diff --git a/sdk/python/arvados/diskcache.py b/sdk/python/arvados/diskcache.py
index 74b2a77b28..f8fca57803 100644
--- a/sdk/python/arvados/diskcache.py
+++ b/sdk/python/arvados/diskcache.py
@@ -12,13 +12,14 @@ import fcntl
 import time
 import errno
 import logging
+import weakref
 
 _logger = logging.getLogger('arvados.keep')
 
 cacheblock_suffix = ".keepcacheblock"
 
 class DiskCacheSlot(object):
-    __slots__ = ("locator", "ready", "content", "cachedir", "filehandle")
+    __slots__ = ("locator", "ready", "content", "cachedir", "filehandle", "linger")
 
     def __init__(self, locator, cachedir):
         self.locator = locator
@@ -26,6 +27,7 @@ class DiskCacheSlot(object):
         self.content = None
         self.cachedir = cachedir
         self.filehandle = None
+        self.linger = None
 
     def get(self):
         self.ready.wait()
@@ -36,15 +38,18 @@ class DiskCacheSlot(object):
         try:
             if value is None:
                 self.content = None
+                self.ready.set()
                 return
 
             if len(value) == 0:
                 # Can't mmap a 0 length file
                 self.content = b''
+                self.ready.set()
                 return
 
             if self.content is not None:
                 # Has been set already
+                self.ready.set()
                 return
 
             blockdir = os.path.join(self.cachedir, self.locator[0:3])
@@ -66,6 +71,8 @@ class DiskCacheSlot(object):
             tmpfile = None
 
             self.content = mmap.mmap(self.filehandle.fileno(), 0, access=mmap.ACCESS_READ)
+            # only set the event when mmap is successful
+            self.ready.set()
         finally:
             if tmpfile is not None:
                 # If the tempfile hasn't been renamed on disk yet, try to delete it.
@@ -76,6 +83,13 @@ class DiskCacheSlot(object):
 
     def size(self):
         if self.content is None:
+            if self.linger is not None:
+                # If it is still lingering (object is still accessible
+                # through the weak reference) it is still taking up
+                # space.
+                content = self.linger()
+                if content is not None:
+                    return len(content)
             return 0
         else:
             return len(self.content)
@@ -133,8 +147,13 @@ class DiskCacheSlot(object):
                 pass
             finally:
                 self.filehandle = None
+                self.linger = weakref.ref(self.content)
                 self.content = None
-            return False
+        return False
+
+    def gone(self):
+        # Test if an evicted object is lingering
+        return self.content is None and (self.linger is None or self.linger() is None)
 
     @staticmethod
     def get_from_disk(locator, cachedir):