{LOOPY,CG}_NO_CACHE: allow re-enabling the cache with False value

doc/ref_other.rst

@@ -9,6 +9,17 @@ Obtaining Kernel Performance Statistics
 Controlling caching
 -------------------
 
+.. envvar:: LOOPY_NO_CACHE
+.. envvar:: CG_NO_CACHE
+
+    By default, loopy will cache (on disk) the result of various stages
+    of code generation to speed up future code generation of the same kernel.
+    By setting the environment variables :envvar:`LOOPY_NO_CACHE` or
+    :envvar:`CG_NO_CACHE` to any
+    string that :func:`pytools.strtobool` evaluates as ``True``, this caching
+    is suppressed.
+
+
 .. autofunction:: set_caching_enabled
 
 .. autoclass:: CacheMode

loopy/__init__.py

@@ -390,7 +390,7 @@ def register_preamble_generators(kernel: LoopKernel, preamble_generators):
         if pgen not in new_pgens:
             if not unpickles_equally(pgen):
                 raise LoopyError("preamble generator '%s' does not "
-                        "compare equally after being upickled "
+                        "compare equally after being unpickled "
                         "and would thus disrupt loopy's caches"
                         % pgen)
 
@@ -408,7 +408,7 @@ def register_symbol_manglers(kernel, manglers):
         if m not in new_manglers:
             if not unpickles_equally(m):
                 raise LoopyError("mangler '%s' does not "
-                        "compare equally after being upickled "
+                        "compare equally after being unpickled "
                         "and would disrupt loopy's caches"
                         % m)
 
@@ -422,10 +422,15 @@ def register_symbol_manglers(kernel, manglers):
 # {{{ cache control
 
 import os
+from pytools import strtobool
+
+# Caching is enabled by default, but can be disabled by setting
+# the environment variables LOOPY_NO_CACHE or CG_NO_CACHE to a
+# 'true' value.
 CACHING_ENABLED = (
-    "LOOPY_NO_CACHE" not in os.environ
+    not strtobool(os.environ.get("LOOPY_NO_CACHE", "false"))
     and
-    "CG_NO_CACHE" not in os.environ)
+    not strtobool(os.environ.get("CG_NO_CACHE", "false")))
 
 
 def set_caching_enabled(flag):