more C code fixes. Activated caching.

Also removed some code that I accidentially left in.
Also added a traceback printing decorator around get_chunk() because the
C code can potentially swallow those exceptions.

overviewer_core/world.py

@@ -55,6 +55,24 @@ def base36encode(number, alphabet='0123456789abcdefghijklmnopqrstuvwxyz'):
         return "-" + base36
     return base36
 
+def log_other_exceptions(func):
+    """A decorator that prints out any errors that are not ChunkDoesntExist
+    errors. This decorates get_chunk because the C code is likely to swallow
+    exceptions, so this will at least make them visible.
+
+    """
+    functools.wraps(func)
+    def newfunc(*args):
+        try:
+            return func(*args)
+        except ChunkDoesntExist:
+            raise
+        except Exception, e:
+            logging.exception("%s raised this exception", func.func_name)
+            raise
+    return newfunc
+
+
 class World(object):
     """Encapsulates the concept of a Minecraft "world". A Minecraft world is a
     level.dat file, a players directory with info about each player, a data
@@ -237,7 +255,7 @@ class RegionSet(object):
 
         # Caching implementaiton: a simple LRU cache
         # Decorate the get_chunk method with the cache decorator
-        #self.get_chunk = cache.lru_cache(cachesize)(self.get_chunk)
+        self.get_chunk = cache.lru_cache(cachesize)(self.get_chunk)
 
     # Re-initialize upon unpickling
     def __getstate__(self):
@@ -247,6 +265,7 @@ class RegionSet(object):
     def __repr__(self):
         return "<RegionSet regiondir=%r>" % self.regiondir
 
+    @log_other_exceptions
     def get_chunk(self, x, z):
         """Returns a dictionary object representing the "Level" NBT Compound
         structure for a chunk given its x, z coordinates. The coordinates are
@@ -434,83 +453,3 @@ def get_worlds():
             ret[info['Data']['LevelName']] = info['Data']
 
     return ret
-
-
-def lru_cache(maxsize=100):
-    '''Generalized Least-recently-used cache decorator.
-
-    Arguments to the cached function must be hashable.
-    Cache performance statistics stored in f.hits and f.misses.
-    Clear the cache with f.clear().
-    http://en.wikipedia.org/wiki/Cache_algorithms#Least_Recently_Used
-
-    This snippet is from
-    http://code.activestate.com/recipes/498245-lru-and-lfu-cache-decorators/
-
-    '''
-    maxqueue = maxsize * 10
-    def decorating_function(user_function,
-            len=len, iter=iter, tuple=tuple, sorted=sorted, KeyError=KeyError):
-        cache = {}                  # mapping of args to results
-        queue = collections.deque() # order that keys have been used
-        refcount = collections.defaultdict(int)# times each key is in the queue
-        sentinel = object()         # marker for looping around the queue
-        kwd_mark = object()         # separate positional and keyword args
-
-        # lookup optimizations (ugly but fast)
-        queue_append, queue_popleft = queue.append, queue.popleft
-        queue_appendleft, queue_pop = queue.appendleft, queue.pop
-
-        @functools.wraps(user_function)
-        def wrapper(*args, **kwds):
-            # cache key records both positional and keyword args
-            key = args
-            if kwds:
-                key += (kwd_mark,) + tuple(sorted(kwds.items()))
-
-            # record recent use of this key
-            queue_append(key)
-            refcount[key] += 1
-
-            # get cache entry or compute if not found
-            try:
-                result = cache[key]
-                wrapper.hits += 1
-            except KeyError:
-                result = user_function(*args, **kwds)
-                cache[key] = result
-                wrapper.misses += 1
-
-                # purge least recently used cache entry
-                if len(cache) > maxsize:
-                    key = queue_popleft()
-                    refcount[key] -= 1
-                    while refcount[key]:
-                        key = queue_popleft()
-                        refcount[key] -= 1
-                    del cache[key], refcount[key]
-
-            # periodically compact the queue by eliminating duplicate keys
-            # while preserving order of most recent access
-            if len(queue) > maxqueue:
-                refcount.clear()
-                queue_appendleft(sentinel)
-                for key in ifilterfalse(refcount.__contains__,
-                                        iter(queue_pop, sentinel)):
-                    queue_appendleft(key)
-                    refcount[key] = 1
-
-
-            return result
-
-        def clear():
-            cache.clear()
-            queue.clear()
-            refcount.clear()
-            wrapper.hits = wrapper.misses = 0
-
-        wrapper.hits = wrapper.misses = 0
-        wrapper.clear = clear
-        return wrapper
-    return decorating_function
-