The patch shrinks the API presented in jsxdrapi.h down to 4 functions to
encode/decode scripts and interpreted functions to/from the memory. The
newly introduced implementation header vm/Xdr.h replaces the former
JSXDRState with the template class XDRState parametrized by the enum
type with two constants, XDR_ENCODE and XDR_DECODE. This way a compiler
can fully eliminate the former runtime checks for the decoding/encoding
mode. As a drawback this required to explicitly instantiate the xdr
implementation as I do not want to put all the xdr code to header files.
The memory-only XDR allows to avoid coping filename and to-be-atomized
chars to a temporary buffer as the code can just access the buffer
directly. Another change is that new XDRScript takes as a parameter its
parent script. This allowed to avoid keeping filename in XDRState and
simplify the filename management.
Another change is the removal of JS_HAS_HDR. As CloneScript uses XDR to
copy a script, JS_HAS_XDR cannot be disabled.
Currently to serialize principals stored in JSScript we have a rather complex
schema. First there is the transcode callback that the embedding must provide
to transcode principals using XDR API. Second we use rather complex glue code
to implement that callback in terms of writing/reading nsIObjectOutputStream/
nsIObjectInputStream. This glue code is duplicated in 3 places. All this can
be avoided if we simply delegate transcoding of principals to the caller. In
addition, at least in the case of the cached startup scripts we do not even
need to transcode the principals as the the cached scripts always have the
system principal so we can skip all the transcode complexity there.
The patch implemnts this idea. In particular, the code in JS engine
responsible for transcoding of principals is replaced by the single API
function JS_XDRSetPrincipals that the embedding can use to set principals for
decoded scripts and functions. Then the startup cache uses this to set the
principals for the decoded script to the system principals. The other two
places in nsJSContext::Serialize and XBL_SerializeFunction that need to
serialize principals together with a function or script now uses common
utilities in nsXPConnect so the serialization complexity resides in the single
place.
In just 2 cases where JSPrincipals::codebase is used it can be reconstructed from the values stored in the associated nsJSPrincipal. In addition the patch makes nsJSprincipals to inherit both from nsIPrincipal and JSPrincipals allowing to use static_cast to convert between nsIPrincipal and JSPrincipals pointers and to drop many cases of manual JSPrincipal reference counting.
xpcfix -epc `find | grep -P "cpp$|h$" | perl -pe 's/\n/ /'`
This is a conservative pass, which doesn't catch absolutely all cases. But it should be good enough.
xpcfix -puc `find | grep -P "cpp$|h$" | perl -pe 's/\n/ /'`
Some of these changes aren't quite ideal, but it's the best my tooling can do and I think it's very much a step in the right direction. This is necessary to do first, because doing if(foo) -> if (foo) changes the location of parentheses, which affects how other things should be aligned. So this has to be built into the tooling, and we might as well take care of the pre-existing issues first.
