We don't need to waste the size of a long for the locks: with the plocks,
even an unsigned short would offer enough room for up to 126 threads! Let's
use an unsigned int which will be easier to place in certain structures
and will more conveniently plug some holes, and Atomic ops are at least
as fast on 32-bit as on 64-bit. This will not change anything for 32-bit
platforms.
It's a bit overkill to register an initcall to call a function to set
a lock to zero when not debugging, let's just declare the lock as
pre-initialized to zero.
We currently use only read and write lock operations with rwlocks, but
ours also support upgradable seek locks for which we do not report any
stats. Let's add them now when DEBUG_THREAD is enabled.
The thread_info struct is convenient to store various per-thread info
without having to resort to a painful thread_local storage which is
slow and painful to initialize.
The problem is, by having this one in thread.h it's very difficult to
add more entries there because everyone already includes thread.h so
conversely thread.h cannot reference certain types.
There's no point in having this there, instead let's create a new pair
of files, tinfo{,-t}.h, which declare the structure. This way it will
become possible to extend them with other includes and have certain
files store their own types there.
Since these are used as type attributes or conditional clauses, they
are used about everywhere and should not require a dependency on
thread.h. Moving them to compiler.h along with other similar statements
like ALIGN() etc looks more logical; this way they become part of the
base API. This allowed to remove thread-t.h from ~12 files, one was
found to only require thread-t and not thread and dict.c was found to
require thread.h.
That's already where MAX_PROCS is set, and we already handle the case of
the default value so there is no reason for placing it in thread.h given
that most call places don't need the rest of the threads definitions. The
include was removed from global-t.h and activity.c.
This splits the hathreads.h file into types+macros and functions. Given
that most users of this file used to include it only to get the definition
of THREAD_LOCAL and MAXTHREADS, the bare minimum was placed into thread-t.h
(i.e. types and macros).
All the thread management was left to haproxy/thread.h. It's worth noting
the drop of the trailing "s" in the name, to remove the permanent confusion
that arises between this one and the system implementation (no "s") and the
makefile's option (no "s").
For consistency, src/hathreads.c was also renamed thread.c.
A number of files were updated to only include thread-t which is the one
they really needed.
Some future improvements are possible like replacing empty inlined
functions with macros for the thread-less case, as building at -O0 disables
inlining and causes these ones to be emitted. But this really is cosmetic.
