Implement a transactional uid buffer.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@4161 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ZSQLCatalog/SQLCatalog.py

@@ -18,12 +18,13 @@ import ExtensionClass
 import Globals
 from Globals import DTMLFile, PersistentMapping
 from string import lower, split, join
-from thread import allocate_lock
+from thread import allocate_lock, get_ident
 from OFS.Folder import Folder
 from AccessControl import ClassSecurityInfo, getSecurityManager
 from BTrees.OIBTree import OIBTree
 from App.config import getConfiguration
 from BTrees.Length import Length
+from Shared.DC.ZRDB.TM import TM
 
 from DateTime import DateTime
 from Products.PluginIndexes.common.randid import randid
@@ -57,13 +58,7 @@ try:
 except ImportError:
   psyco = None
 
-UID_BUFFER_SIZE = 900
-MAX_UID_BUFFER_SIZE = 20000
-MAX_QUEUE_SIZE = 100
-
-# Put the queue of catalogged objects in RAM for distributed computation.
-catalogged_path_dict = {}
-catalogged_path_dict_lock = threading.Lock()
+UID_BUFFER_SIZE = 300
 
 valid_method_meta_type_list = ('Z SQL Method', 'Script (Python)')
 
@@ -86,6 +81,72 @@ def manage_addSQLCatalog(self, id, title,
     return self.manage_main(self, REQUEST,update_menu=1)
 
     
+class UidBuffer(TM):
+  """Uid Buffer class caches a list of reserved uids in a transaction-safe way."""
+  
+  def __init__(self):
+    """Initialize some variables.
+    
+      temporary_buffer is used to hold reserved uids created by non-committed transactions.
+      
+      finished_buffer is used to hold reserved uids created by committed-transactions.
+      
+      This distinction is important, because uids by non-committed transactions might become
+      invalid afterwards, so they may not be used by other transactions."""
+    self.temporary_buffer = {}
+    self.finished_buffer = []
+    
+  def _finish(self):
+    """Move the uids in the temporary buffer to the finished buffer."""
+    tid = get_ident()
+    try:
+      self.finished_buffer.extend(self.temporary_buffer[tid])
+      del self.temporary_buffer[tid]
+    except KeyError:
+      pass
+    
+  def _abort(self):
+    """Erase the uids in the temporary buffer."""
+    tid = get_ident()
+    try:
+      del self.temporary_buffer[tid]
+    except KeyError:
+      pass
+      
+  def __len__(self):
+    tid = get_ident()
+    l = len(self.finished_buffer)
+    try:
+      l += len(self.temporary_buffer[tid])
+    except KeyError:
+      pass
+    return l
+    
+  def remove(self, value):
+    self._register()
+    for uid_list in self.temporary_buffer.values():
+      try:
+        uid_list.remove(value)
+      except ValueError:
+        pass
+    try:
+      self.finished_buffer.remove(value)
+    except ValueError:
+      pass
+      
+  def pop(self):
+    self._register()
+    tid = get_ident()
+    try:
+      return self.temporary_buffer[tid].pop()
+    except (KeyError, IndexError):
+      return self.finished_buffer.pop()
+      
+  def extend(self, iterable):
+    self._register()
+    tid = get_ident()
+    self.temporary_buffer.setdefault(tid, []).extend(iterable)
+
 class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
   """ An Object Catalog
 
@@ -712,13 +773,14 @@ class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
     """
     klass = self.__class__
     assert klass._reserved_uid_lock.locked()
-    uid_list = getattr(self, '_v_uid_buffer', [])
     # This checks if the list of local reserved uids was cleared after clearReserved
     # had been called.
     if klass._local_clear_reserved_time != self._last_clear_reserved_time:
-      uid_list = []
+      self._v_uid_buffer = UidBuffer()
       klass._local_clear_reserved_time = self._last_clear_reserved_time
-    if len(uid_list) == 0:
+    elif not hasattr(self, '_v_uid_buffer'):
+      self._v_uid_buffer = UidBuffer()
+    if len(self._v_uid_buffer) == 0:
       method_id = self.sql_catalog_produce_reserved
       method = getattr(self, method_id)
       instance_id = klass._instance_id
@@ -732,9 +794,8 @@ class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
           pass
         instance_id = md5.new(str(random_factor_list)).hexdigest()[:30]
         klass._instance_id = instance_id
-      new_uid_list = method(count = UID_BUFFER_SIZE, instance_id=instance_id)
-      uid_list.extend( filter(lambda x: x != 0, map(lambda x: x.uid, new_uid_list )))
-    self._v_uid_buffer = uid_list
+      uid_list = [x.uid for x in method(count = UID_BUFFER_SIZE, instance_id = instance_id) if x.uid != 0]
+      self._v_uid_buffer.extend(uid_list)
 
   def newUid(self):
     """
@@ -759,9 +820,8 @@ class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
     try:
       klass._reserved_uid_lock.acquire()
       self.produceUid()
-      uid_list = getattr(self, '_v_uid_buffer', [])
-      if len(uid_list) > 0:
-        uid = uid_list.pop()
+      if len(self._v_uid_buffer) > 0:
+        uid = self._v_uid_buffer.pop()
         if self._max_uid is None:
           self._max_uid = Length()
         if uid > self._max_uid():
@@ -935,8 +995,7 @@ class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
             klass = self.__class__
             try:
               klass._reserved_uid_lock.acquire()
-              uid_list = getattr(aq_base(self), '_v_uid_buffer', [])
-              if uid in uid_list:
+              if hasattr(self, '_v_uid_buffer'):
                 # This is the case where:
                 #   1. The object got an uid.
                 #   2. The catalog was cleared.
@@ -945,8 +1004,10 @@ class Catalog(Folder, Persistent, Acquisition.Implicit, ExtensionClass.Base):
                 # In this case, the uid is not reserved any longer, but
                 # SQLCatalog believes that it is still reserved. So it is
                 # necessary to remove the uid from the list explicitly.
-                uid_list.remove(uid)
-                self._v_uid_buffer = uid_list
+                try:
+                  self._v_uid_buffer.remove(uid)
+                except ValueError:
+                  pass
             finally:
               klass._reserved_uid_lock.release()
           elif catalog_path is not None: