Dev: Testing with asyncronous db saving.

src/settings_default.py

@@ -152,6 +152,7 @@ DATABASE_PASSWORD = ''
 DATABASE_HOST = ''
 DATABASE_PORT = ''
 
+DATABASE_NONBLOCKING_SAVE = True 
 
 ###################################################
 # Evennia in-game parsers

src/utils/idmapper/base.py

@@ -1,10 +1,66 @@
+"""
+Idmapper base functionality. Most of this is unchanged from the idmapper distribution. 
+
+Extended for Evennia: 
+
+- made object cache a dictionary rather than a WeakValueDictionary. The latter does not work
+  well for long-time persistence in memory and caused very hard-to-track bugs in Evennia's 
+  typeclass system (which depends on cached memory adresses not changing or going out of scope).
+- Added optional asynchronous save operation for use with Twisted. 
+
+"""
+
 from weakref import WeakValueDictionary, ref
 
 from django.db.models.base import Model, ModelBase
 
 from manager import SharedMemoryManager
 
-TCACHE = {} # test cache, for debugging /Griatch
+#
+# Evennia extension: Asynchronous save functionality. This
+# is used by SharedMemoryBase.save(). 
+#
+
+from twisted.internet.defer import DeferredQueue
+from twisted.internet.task import cooperate 
+from twisted.internet.threads import deferToThread, blockingCallFromThread
+from django.conf import settings
+from src.utils import logger
+from twisted.internet import reactor 
+
+ASYNC_DB_SAVE = settings.DATABASE_NONBLOCKING_SAVE
+
+# This special form of queue has a get() function that returns deferreds. 
+# Add save function tuples to this in order to add to save queue.
+ASYNC_QUEUE = DeferredQueue(backlog=1)
+
+def async_callback(funcdef):
+    "This callback is run with the item returned from queue - a tuple (func, args, kwargs)"        
+    #d = deferToThread(funcdef[0], *funcdef[1], **funcdef[2])
+    d = reactor.callFromThread(funcdef[0], *funcdef[1], **funcdef[2])
+    #d = reactor.blockingCallFromThread(funcdef[0], *funcdef[1], **funcdef[2])
+    return d
+def async_errback(failure):
+    "errback"
+    logger.log_errmsg(str(failure))
+def async_worker(queue):
+    """
+    This will eternally yield items from queue as soon as they are
+    available (since DeferredQueue.get() only returns when there is
+    actually something in the queue). The queue automatically inserts 
+    the stored value into the callback async_exec. 
+    """
+    while True:
+        yield queue.get().addCallbacks(async_callback, async_errback)
+
+# the cooperate handler will iterate over async_worker every time its
+# returned deferred fires.
+cooperate(async_worker(ASYNC_QUEUE))
+
+# in models's save(*args, **kwargs):
+#   ASYNC_QUEUE.put((super(SharedMemoryModel, self).save, args, kwargs))
+
+# -------------------------------------------------------
 
 class SharedMemoryModelBase(ModelBase):
     #def __new__(cls, name, bases, attrs):
@@ -120,13 +176,16 @@ class SharedMemoryModel(Model):
         """
         cls._flush_cached_by_key(instance._get_pk_val())
         #key = "%s-%s" % (cls, instance.pk)            
-        #del TCACHE[key]
         #print "uncached: %s (%s: %s) (total cached: %s)" % (instance, cls.__name__, len(cls.__instance_cache__), len(TCACHE))
 
     flush_cached_instance = classmethod(flush_cached_instance)
     
     def save(self, *args, **kwargs):
-        super(SharedMemoryModel, self).save(*args, **kwargs)
+        if ASYNC_DB_SAVE:
+            logger.log_infomsg("Adding to queue %s" % self)
+            ASYNC_QUEUE.put((super(SharedMemoryModel, self).save, args, kwargs))
+        else:
+            super(SharedMemoryModel, self).save(*args, **kwargs)
         self.__class__.cache_instance(self)
 
     # TODO: This needs moved to the prepare stage (I believe?)