From: Daniele Varrazzo <daniele.varrazzo@gmail.com>
Date: Wed, 21 Dec 2022 23:00:32 +0000 (+0000)
Subject: perf: micro-optimize AdaptersMap.get_dumper
X-Git-Tag: 3.1.8~27
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=850827fa51fd75abac6cc4eef8932713983f0a76;p=thirdparty%2Fpsycopg.git

perf: micro-optimize AdaptersMap.get_dumper

Minimal amount of opcodes in case of fast-path (there is an adapter
precisely for the class queried).
---

diff --git a/psycopg/psycopg/_adapters_map.py b/psycopg/psycopg/_adapters_map.py
index a3a6ef889..70bf4cc02 100644
--- a/psycopg/psycopg/_adapters_map.py
+++ b/psycopg/psycopg/_adapters_map.py
@@ -197,9 +197,15 @@ class AdaptersMap:
             use the last one of the dumpers registered on `!cls`.
         """
         try:
-            dmap = self._dumpers[format]
+            # Fast path: the class has a known dumper.
+            return self._dumpers[format][cls]
         except KeyError:
-            raise ValueError(f"bad dumper format: {format}")
+            if format not in self._dumpers:
+                raise ValueError(f"bad dumper format: {format}")
+
+            # If the KeyError was caused by cls missing from dmap, let's
+            # look for different cases.
+            dmap = self._dumpers[format]
 
         # Look for the right class, including looking at superclasses
         for scls in cls.__mro__: