* guix/scripts/offload.scm (transfer-and-offload): Use 'upload' lock
instead of 'bandwidth' around 'send-files' calls, and 'download' lock
around 'retrieve-files' call.
* guix/scripts/offload.scm (remote-pipe): Remove '-z' lsh command line
argument. This makes transfers almost an order of magnitude slower.
OpenSSH's ssh(1) man page notes: "Compression is desirable on modem lines
and other slow connections, but will only slow down things on fast
networks." See also
<http://www.spikelab.org/blog/transfer-largedata-scp-tarssh-tarnc-compared.html>.
* guix/scripts/offload.scm (with-error-to-port): New macro.
(remote-pipe): Add #:error-port parameter. Use 'with-error-to-port'
around 'open-pipe*' call.
(build-log-port): New procedure.
(offload): Change #:log-port to default to (build-log-port). Call
'remote-pipe' with #:error-port LOG-PORT.
* guix/scripts/offload.scm (offload): Remove default value for
'build-timeout'. Pass '--timeout' to the remote 'guix build'
process.
(transfer-and-offload, process-request): Remove default value for
'build-timeout'.
* guix/scripts/offload.scm (transfer-and-offload): New procedure, with
core formerly in 'process-request'.
(choose-build-machine): Remove 'requirements' parameter.
(process-request): Reply 'decline' when none of MACHINES matches the
requirements, and 'postpone' when MACHINES are busy.
* guix/scripts/offload.scm (machine-choice-lock-file,
machine-slot-file, acquire-build-slot, release-build-slot): New
procedures.
(choose-build-machine): Operate with (machine-choice-lock-file)
taken. Acquire a build slot for each of MACHINES. Release those not
used.
* guix/scripts/offload.scm (lock-machine, unlock-machine): Remove.
(lock-file, unlock-file): New procedures.
(with-file-lock): New macro.
(with-machine-lock): Rewrite in terms of 'with-file-lock'.
* guix/scripts/offload.scm (machine-lock-file, lock-machine,
unlock-machine): New procedures.
(with-machine-lock): New macro.
(process-request): Wrap 'send-files' and 'retrieve-files' calls in
'with-machine-lock'.
* guix/scripts/offload.scm (machine-load, machine-less-loaded?,
machine-less-loaded-or-faster?): New procedures.
(choose-build-machine): Use 'machine-less-loaded-or-faster?' when
sorting. Return the head of MACHINES unless it's loaded is >= 2.
* guix/scripts/offload.scm (offload): Add 'log-port' keyword parameter.
Handle log display here. Return the result of (close-pipe pipe).
(process-request): Adjust 'offload' call site accordingly. Call
'retrieve-files' only when 'offload' returns zero; exit when 'offload'
returns non-zero.
* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_NO_BUILD_HOOK): New macro.
(options): Add '--no-build-hook'.
(parse_opt): Handle it.
(main)[HAVE_DAEMON_OFFLOAD_HOOK]: Set 'useBuildHook' by default.
Set $NIX_BUILD_HOOK to our offload hook unless otherwise specified.
[!HAVE_DAEMON_OFFLOAD_HOOK]: Clear 'useBuildHook'.
* pre-inst-env.in: Set and export NIX_BUILD_HOOK.
* nix/scripts/offload.in, guix/scripts/offload.scm: New files.
* guix/ui.scm (show-guix-help)[internal?]: Add "offload".
* config-daemon.ac: Call 'GUIX_CHECK_UNBUFFERED_CBIP'.
Instantiate 'nix/scripts/offload'. Set 'BUILD_DAEMON_OFFLOAD'
conditional, and optionally define 'HAVE_DEAMON_OFFLOAD_HOOK' cpp
macro.
* daemon.am (nodist_pkglibexec_SCRIPTS)[BUILD_DAEMON_OFFLOAD]: Add it.
* Makefile.am (MODULES)[BUILD_DAEMON_OFFLOAD]: Add
'guix/scripts/offload.scm'.
(EXTRA_DIST)[!BUILD_DAEMON_OFFLOAD]: Likewise.
* m4/guix.m4 (GUIX_CHECK_UNBUFFERED_CBIP): New macro.
* doc/guix.texi (Setting Up the Daemon): Move most of the body to...
(Build Environment Setup): ... this. New subsection.
(Daemon Offload Setup): New subsection.
Ludovic Courtès