@node Jobserver
@cindex jobserver
@unnumbered Jobserver

Parallel builds are made by utilizing the jobserver protocol. Each job
have to take so called token and return it when it finishes. Jobserver
creates the pipe, consisting of read and write files, that are passed
to each @command{goredo} instance. Job takes the token by reading the
single byte from that pipe, writing it back for returning. Pipe is
pre-filled with required number of tokens.

@pindex bmake
@pindex gmake
@command{goredo} can be integrated with
@url{http://www.crufty.net/help/sjg/bmake.htm, bmake} and
@url{https://www.gnu.org/software/make/, GNU Make} (@command{gmake})
jobserver protocol. All three of them use the same principle of
jobserver, but different ways of passing pipe's file descriptors
numbers to child process.

@vindex REDO_MAKE
@env{$REDO_MAKE} environment variable controls the compatibility behaviour:

@table @command
@item bmake
Pass @code{-j 1 -J X,Y} arguments through @env{$MAKEFLAGS} variable.
@item gmake
Pass @code{--jobserver-auth=X,Y} arguments through @env{$MAKEFLAGS} variable.
@item none
Pass @code{X,Y} arguments through @env{$REDO_JS_FD} variable.
Used by default, if @env{$REDO_MAKE} is not set.
@end table