the .DOTLAST primitive by a boolean variable with the same name, this whole
mechanism was broken ... it doesn't save much stat calls but it was wrong.
Thanks to Jason Thorpe for the other shadow-variable fixing patches he
made.
* Replace chdir_verify_path() with Main_SetObjdir(), which can be called
externally, and can take a "const char *". (There's a lot of non-const
"char *" passing around in var.c of what should be const strings....)
* Rewrite the initial "find my .OBJDIR" code to make use of the new
function. This still functions as it had in the past, but the comment
above this block was changed to reflect reality: if MAKEOBJDIRPREFIX
or MAKEOBJDIR are set in the environment, then *only that value* is
tried; make does not fall back to obj.MACHINE, obj, and /usr/obj/`pwd`
as it would without these env vars set.
* Add a new special target, .OBJDIR:, which when parsed will cause make to
change to a new object directory and reset .OBJDIR, and PWD in the
environment. This will allow some makefiles (mainly, src/tools)
to override the default objdir semantics in order to add custom logic.
use -j; all make's in a recursive build cooperate to limit the total
number of jobs, using a token-passing scheme.
The current token passing algorithm is similar to the one implemented
by gmake; there is a single pipe which is inherited through the entire
process hierarchy; tokens are obtained by reading a byte from the
"read end" of the pipe, and are returned by writing them to the "write
end". This exact algorithm is likely to change in the future.
Implementation details:
- Use the new trace facility to allow measurement of the
effectiveness of different token-passing schemes
- Get a token in MakeStartJobs(), return it in Make_Update()
- Eliminate Job_Full() and the jobFull global since they are
redundant with token system.
- Add an "internal" -J option (to pass the token pipe fd's down to
submakes) and a -T option for tracing.
- Change how compatMake is forced so that -j means something when
inherited by submakes.
- When waiting for a token, poll the token-passing pipe as well as
the output pipes of existing jobs.
reinoud