tree c7e6b1c1bb19779d0841e17982d8b7a0f8f593de
parent 0a0daecbb26755a662a74069e36d72f6cb671427
author Willy Tarreau <w@1wt.eu> 1364913272 +0200
committer Willy Tarreau <w@1wt.eu> 1364947982 +0200
encoding latin1

MAJOR: sample: maintain a per-proxy list of the fetch args to resolve

While ACL args were resolved after all the config was parsed, it was not the
case with sample fetch args because they're almost everywhere now.

The issue is that ACLs now solely rely on sample fetches, so their args
resolving doesn't work anymore. And many fetches involving a server, a
proxy or a userlist don't work at all.

The real issue is that at the bottom layers we have no information about
proxies, line numbers, even ACLs in order to report understandable errors,
and that at the top layers we have no visibility over the locations where
fetches are referenced (think log node).

After failing multiple unsatisfying solutions attempts, we now have a new
concept of args list. The principle is that every proxy has a list head
which contains a number of indications such as the config keyword, the
context where it's used, the file and line number, etc... and a list of
arguments. This list head is of the same type as the elements, so it
serves as a template for adding new elements. This way, it is filled from
top to bottom by the callers with the information they have (eg: line
numbers, ACL name, ...) and the lower layers just have to duplicate it and
add an element when they face an argument they cannot resolve yet.

Then at the end of the configuration parsing, a loop passes over each
proxy's list and resolves all the args in sequence. And this way there is
all necessary information to report verbose errors.

The first immediate benefit is that for the first time we got very precise
location of issues (arg number in a keyword in its context, ...). Second,
in order to do this we had to parse log-format and unique-id-format a bit
earlier, so that was a great opportunity for doing so when the directives
are encountered (unless it's a default section). This way, the recorded
line numbers for these args are the ones of the place where the log format
is declared, not the end of the file.

Userlists report slightly more information now. They're the only remaining
ones in the ACL resolving function.