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authorErik Johnston <erik@matrix.org>2017-03-28 11:14:15 +0100
committerErik Johnston <erik@matrix.org>2017-03-30 14:14:46 +0100
commit014fee93b38ea93ee7dd9f9f9211895272e50834 (patch)
tree417fbe5dd5b45b6f69d6c8aab6fd79596887d454 /synapse/util/caches
parentDon't convert to deferreds when not necessary (diff)
downloadsynapse-014fee93b38ea93ee7dd9f9f9211895272e50834.tar.xz
Manually calculate cache key as getcallargs is expensive
This is because getcallargs recomputes the getargspec, amongst other
things, which we don't need to do as its already been done
Diffstat (limited to 'synapse/util/caches')
-rw-r--r--synapse/util/caches/descriptors.py34
1 files changed, 28 insertions, 6 deletions
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 1607978e29..eed60d567e 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -197,6 +197,7 @@ class _CacheDescriptorBase(object):
 
         arg_spec = inspect.getargspec(orig)
         all_args = arg_spec.args
+        self.arg_spec = arg_spec
 
         if "cache_context" in all_args:
             if not cache_context:
@@ -226,6 +227,14 @@ class _CacheDescriptorBase(object):
         self.num_args = num_args
         self.arg_names = all_args[1:num_args + 1]
 
+        if arg_spec.defaults:
+            self.arg_defaults = dict(zip(
+                all_args[-len(arg_spec.defaults):],
+                arg_spec.defaults
+            ))
+        else:
+            self.arg_defaults = {}
+
         if "cache_context" in self.arg_names:
             raise Exception(
                 "cache_context arg cannot be included among the cache keys"
@@ -289,18 +298,31 @@ class CacheDescriptor(_CacheDescriptorBase):
             iterable=self.iterable,
         )
 
+        def get_cache_key(args, kwargs):
+            """Given some args/kwargs return a generator that resolves into
+            the cache_key.
+
+            We loop through each arg name, looking up if its in the `kwargs`,
+            otherwise using the next argument in `args`. If there are no more
+            args then we try looking the arg name up in the defaults
+            """
+            pos = 0
+            for nm in self.arg_names:
+                if nm in kwargs:
+                    yield kwargs[nm]
+                elif pos < len(args):
+                    yield args[pos]
+                    pos += 1
+                else:
+                    yield self.arg_defaults[nm]
+
         @functools.wraps(self.orig)
         def wrapped(*args, **kwargs):
             # If we're passed a cache_context then we'll want to call its invalidate()
             # whenever we are invalidated
             invalidate_callback = kwargs.pop("on_invalidate", None)
 
-            # Add temp cache_context so inspect.getcallargs doesn't explode
-            if self.add_cache_context:
-                kwargs["cache_context"] = None
-
-            arg_dict = inspect.getcallargs(self.orig, obj, *args, **kwargs)
-            cache_key = tuple(arg_dict[arg_nm] for arg_nm in self.arg_names)
+            cache_key = tuple(get_cache_key(args, kwargs))
 
             # Add our own `cache_context` to argument list if the wrapped function
             # has asked for one