bitbake: event/utils/methodpool: Add a cache of compiled code objects

With the addition of function line number handling, the overhead of
the compile functions is no longer negligible. We tend to compile
the same pieces of code over and over again so wrapping a cache around
this is beneficial and removes the overhead of line numbered functions.

Life cycle of a cache using a global like this is in theory problematic
although in reality unlikely to be an issue. It can be dealt with
if/as/when we deal with the other global caches.

(Bitbake rev: 98d7002d1dca4b62042e1589fd5b9b3805d57f7a)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/utils.py

@@ -298,10 +298,15 @@ def better_compile(text, file, realfile, mode = "exec", lineno = None):
     will print the offending lines.
     """
     try:
+        cache = bb.methodpool.compile_cache(text)
+        if cache:
+            return cache
         code = compile(text, realfile, mode, ast.PyCF_ONLY_AST)
         if lineno is not None:
             ast.increment_lineno(code, lineno)
-        return compile(code, realfile, mode)
+        code = compile(code, realfile, mode)
+        bb.methodpool.compile_cache_add(text, code)
+        return code
     except Exception as e:
         error = []
         # split the text into lines again