Merge pull request #68 from zopefoundation/load-calls-loadBefore

Load calls load before

src/ZODB/DemoStorage.py

@@ -31,7 +31,9 @@
 import ZODB.POSException
 import ZODB.utils
 import zope.interface
+
 from .ConflictResolution import ConflictResolvingStorage, ResolvedSerial
+from .utils import load_current, maxtid
 
 @zope.interface.implementer(
         ZODB.interfaces.IStorage,
@@ -167,11 +169,8 @@ def lastTransaction(self):
     def __len__(self):
         return len(self.changes)
 
-    def load(self, oid, version=''):
-        try:
-            return self.changes.load(oid, version)
-        except ZODB.POSException.POSKeyError:
-            return self.base.load(oid, version)
+    # still want load for old clients (e.g. zeo servers)
+    load = load_current
 
     def loadBefore(self, oid, tid):
         try:
@@ -190,12 +189,27 @@ def loadBefore(self, oid, tid):
                 pass
             else:
                 if result and not result[-1]:
-                    end_tid = None
-                    t = self.changes.load(oid)
+                    # The oid is current in the base.  We need to find
+                    # the end tid in the base by fining the first tid
+                    # in the changes. Unfortunately, there isn't an
+                    # api for this, so we have to walk back using
+                    # loadBefore.
+
+                    if tid == maxtid:
+                        # Special case: we were looking for the
+                        # current value. We won't find anything in
+                        # changes, so we're done.
+                        return result
+
+                    end_tid = maxtid
+                    t = self.changes.loadBefore(oid, end_tid)
                     while t:
                         end_tid = t[1]
                         t = self.changes.loadBefore(oid, end_tid)
-                    result = result[:2] + (end_tid,)
+                    result = result[:2] + (
+                        end_tid if end_tid != maxtid else None,
+                        )
+
         return result
 
     def loadBlob(self, oid, serial):
@@ -240,10 +254,10 @@ def new_oid(self):
             oid = ZODB.utils.p64(self._next_oid )
             if oid not in self._issued_oids:
                 try:
-                    self.changes.load(oid, '')
+                    load_current(self.changes, oid)
                 except ZODB.POSException.POSKeyError:
                     try:
-                        self.base.load(oid, '')
+                        load_current(self.base, oid)
                     except ZODB.POSException.POSKeyError:
                         self._next_oid += 1
                         self._issued_oids.add(oid)
@@ -288,12 +302,9 @@ def store(self, oid, serial, data, version, transaction):
 
         # See if we already have changes for this oid
         try:
-            old = self.changes.load(oid, '')[1]
+            old = load_current(self, oid)[1]
         except ZODB.POSException.POSKeyError:
-            try:
-                old = self.base.load(oid, '')[1]
-            except ZODB.POSException.POSKeyError:
-                old = serial
+            old = serial
 
         if old != serial:
             rdata = self.tryToResolveConflict(oid, old, serial, data)

src/ZODB/FileStorage/FileStorage.py

@@ -70,6 +70,7 @@
 from ZODB.utils import as_bytes
 from ZODB.utils import as_text
 from ZODB.utils import cp
+from ZODB.utils import load_current
 from ZODB.utils import mktemp
 from ZODB.utils import p64
 from ZODB.utils import u64
@@ -443,6 +444,8 @@ def _lookup_pos(self, oid):
         except TypeError:
             raise TypeError("invalid oid %r" % (oid,))
 
+    load = load_current # Keep load for now for old clients
+
     def load(self, oid, version=''):
         """Return pickle data and serial number."""
         assert not version
@@ -1314,7 +1317,7 @@ def record_iternext(self, next=None):
         except ValueError: # "empty tree" error
             next_oid = None
 
-        data, tid = self.load(oid, "")
+        data, tid = load_current(self, oid)
 
         return oid, tid, data, next_oid
 

src/ZODB/MappingStorage.py

@@ -134,15 +134,7 @@ def lastTransaction(self):
     def __len__(self):
         return len(self._data)
 
-    # ZODB.interfaces.IStorage
-    @ZODB.utils.locked(opened)
-    def load(self, oid, version=''):
-        assert not version, "Versions are not supported"
-        tid_data = self._data.get(oid)
-        if tid_data:
-            tid = tid_data.maxKey()
-            return tid_data[tid], tid
-        raise ZODB.POSException.POSKeyError(oid)
+    load = ZODB.utils.load_current
 
     # ZODB.interfaces.IStorage
     @ZODB.utils.locked(opened)

src/ZODB/tests/hexstorage.py

@@ -13,6 +13,7 @@
 ##############################################################################
 import ZODB.blob
 import ZODB.interfaces
+import ZODB.utils
 import zope.interface
 from binascii import hexlify, unhexlify
 
@@ -45,9 +46,7 @@ def __getattr__(self, name):
     def __len__(self):
         return len(self.base)
 
-    def load(self, oid, version=''):
-        data, serial = self.base.load(oid, version)
-        return unhexlify(data[2:]), serial
+    load = ZODB.utils.load_current
 
     def loadBefore(self, oid, tid):
         r = self.base.loadBefore(oid, tid)

src/ZODB/utils.py

@@ -28,7 +28,6 @@
 from ZODB._compat import BytesIO
 from ZODB._compat import ascii_bytes
 
-
 __all__ = ['z64',
            'p64',
            'u64',
@@ -375,3 +374,26 @@ def notify_all(self):
 else:
 
     from threading import Condition, Lock, RLock
+
+
+import ZODB.POSException
+
+def load_current(storage, oid, version=''):
+    """Load the most recent revision of an object by calling loadBefore
+
+    Starting in ZODB 5, it's no longer necessary for storages to
+    provide a load method.
+
+    This function is mainly intended to facilitate transitioning from
+    load to loadBefore.  It's mainly useful for tests that are meant
+    to test storages, but do so by calling load on the storages.
+
+    This function will likely become unnecessary and be deprecated
+    some time in the future.
+    """
+    assert not version
+    r = storage.loadBefore(oid, maxtid)
+    if r is None:
+        raise ZODB.POSException.POSKeyError(oid)
+    assert r[2] is None
+    return r[:2]