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[SV 62100] Add '--shuffle' option support

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Introduce non-deterministic ordering into goal and prerequisite
traversal to help tease out inconsistent failures that may happen
when running in parallel build mode.

Introduce second order into each dependency chain:
1. Existing order is syntactic order reachable via 'dep->next'
2. New order is shuffled order stored as 'dep->shuf' in each 'dep'

When updating goals and prerequisites and '--shuffle' is provided,
use the shuffled order to walk the graph.  When automatic variable
are set always use the syntactic order of parameters.

* Makefile.am: Add new src/shuffle.c and src/shuffle.h file.
* build_w32.bat: Ditto.
* builddos.bat: Ditto.
* makefile.com: Ditto.
* po/POTFILES.in: Ditto.
* doc/make.texi: Add documentation for --shuffle.
* doc/make.1: Ditto.
* src/dep.h (DEP): Add the shuf pointer.
* src/filedef.h (struct file): Add was_shuffled flag.
* src/main.c: (shuffle_mode): Global flag for the shuffle mode.
(usage): Add the --shuffle option.
(switches): Ditto.
(main): Set shuffle_mode based on the command line parameter.
Reshuffle prerequisites if requested.
* src/remake.c (update_goal_chain): Walk the shuffled list if enabled.
(update_file_1): Ditto.
* src/shuffle.h: Provide an interface for shuffling prerequisites.
* src/shuffle.c: Implement option parsing and prerequisite shuffling.
* tests/scripts/options/shuffle: Test shuffle option and modes.
This commit is contained in:
Sergei Trofimovich 2022-06-04 15:48:01 -04:00 committed by Paul Smith
parent e4b7ac21dc
commit 621d3196fa
18 changed files with 593 additions and 76 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
AUTHORS
View file

@ -90,6 +90,7 @@ Other contributors:
Carl Staelin (Princeton University)
Ian Stewartson (Data Logic Limited)
Tobias Stoeckmann <tobias@stoeckmann.org>
Sergei Trofimovich <siarheit@google.com>
Marc Ullman <marc@mathworks.com>
Christof Warlich <cwarlich@gmx.de>
Florian Weimer <fweimer@redhat.com>

5
Makefile.am
View file

@ -35,8 +35,9 @@ make_SRCS = src/ar.c src/arscan.c src/commands.c src/commands.h \
src/hash.c src/hash.h src/implicit.c src/job.c src/job.h \
src/load.c src/loadapi.c src/main.c src/makeint.h src/misc.c \
src/os.h src/output.c src/output.h src/read.c src/remake.c \
src/rule.c src/rule.h src/signame.c src/strcache.c \
src/variable.c src/variable.h src/version.c src/vpath.c
src/rule.c src/rule.h src/shuffle.h src/shuffle.c \
src/signame.c src/strcache.c src/variable.c src/variable.h \
src/version.c src/vpath.c
w32_SRCS = src/w32/pathstuff.c src/w32/w32os.c src/w32/compat/dirent.c \
src/w32/compat/posixfcn.c src/w32/include/dirent.h \

7
NEWS
View file

@ -61,6 +61,13 @@ https://sv.gnu.org/bugs/index.php?group=make&report_id=111&fix_release_id=109&se
avoiding the need for heuristics.
Implementation provided by Sven C. Dack <sdack@gmx.com>
* New feature: The --shuffle command line option
This option reorders goals and prerequisites to simulate non-determinism
that may be seen using parallel build. Shuffle mode allows a form of "fuzz
testing" of parallel builds to verify that all prerequisites are correctly
described in the makefile.
Implementation provided by Sergei Trofimovich <siarheit@google.com>
* GNU make has sometimes chosen unexpected, and sub-optimal, chains of
implicit rules due to the definition of "ought to exist" in the implicit
rule search algorithm, which considered any prerequisite mentioned in the

1
build_w32.bat
View file

@ -257,6 +257,7 @@ call :Compile src/read
call :Compile src/remake
call :Compile src/remote-stub
call :Compile src/rule
call :Compile src/shuffle
call :Compile src/signame
call :Compile src/strcache
call :Compile src/variable

3
builddos.bat
View file

@ -68,12 +68,13 @@ gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/s
gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/src/remote-stub.c -o remote-stub.o
gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/src/getopt.c -o getopt.o
gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/src/getopt1.c -o getopt1.o
gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/src/shuffle.c -o shuffle.o
gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/lib/glob.c -o lib/glob.o
gcc -c -I./src -I%XSRC%/src -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/lib/fnmatch.c -o lib/fnmatch.o
@echo off
echo commands.o > respf.$$$
for %%f in (job output dir file misc main read remake rule implicit default variable) do echo %%f.o >> respf.$$$
for %%f in (expand function vpath hash strcache version ar arscan signame remote-stub getopt getopt1) do echo %%f.o >> respf.$$$
for %%f in (expand function vpath hash strcache version ar arscan signame remote-stub getopt getopt1 shuffle) do echo %%f.o >> respf.$$$
for %%f in (lib\glob lib\fnmatch) do echo %%f.o >> respf.$$$
rem gcc -c -I./src -I%XSRC% -I./lib -I%XSRC%/lib -DHAVE_CONFIG_H -O2 -g %XSRC%/guile.c -o guile.o
rem echo guile.o >> respf.$$$

22
doc/make.1
View file

@ -1,4 +1,4 @@
.TH MAKE 1 "28 February 2016" "GNU" "User Commands"
.TH MAKE 1 "31 May 2022" "GNU" "User Commands"
.SH NAME
make \- GNU make utility to maintain groups of programs
.SH SYNOPSIS
@ -319,6 +319,26 @@ Turn off
.BR \-w ,
even if it was turned on implicitly.
.TP 0.5i
.BI \-\-shuffle "[=MODE]"
Enable shuffling of goal and prerequisite ordering.
.I MODE
is one of
.I none
to disable shuffle mode,
.I random
to shuffle prerequisites in random order,
.I reverse
to consider prerequisites in reverse order, or an integer
.I <seed>
which enables
.I random
mode with a specific
.I seed
value. If
.I MODE
is omitted the default is
.IR random .
.TP 0.5i
\fB\-W\fR \fIfile\fR, \fB\-\-what\-if\fR=\fIfile\fR, \fB\-\-new\-file\fR=\fIfile\fR, \fB\-\-assume\-new\fR=\fIfile\fR
Pretend that the target
.I file

39
doc/make.texi
View file

@ -9422,6 +9422,45 @@ from the top-level @code{make} via @code{MAKEFLAGS}
(@pxref{Recursion, ,Recursive Use of @code{make}})
or if you set @samp{-k} in @code{MAKEFLAGS} in your environment.@refill
@item --shuffle[=@var{mode}]
@cindex @code{--shuffle}
@c Extra blank line here makes the table look better.
This option enables a form of fuzz-testing of prerequisite relationships.
When parallelism is enabled (@samp{-j}) the order in which targets are
built becomes less deterministic. If prerequisites are not fully declared
in the makefile this can lead to intermittent and hard-to-track-down build
failures.
The @samp{--shuffle} option forces @code{make} to purposefully reorder goals
and prerequisites so target/prerequisite relationships still hold, but
ordering of prerequisites of a given target are reordered as described below.
The order in which prerequisites are listed in automatic variables is not
changed by this option.
The @code{.NOTPARALLEL} pseudo-target disables shuffling for that makefile.
The @samp{--shuffle=} option accepts these values:
@table @code
@item random
Choose a random seed for the shuffle. This is the default if no mode is
specified. The chosen seed is also provided to sub-@code{make} commands. The
seed is included in error messages so that it can be re-used in future runs to
reproduce the problem or verify that it has been resolved.
@item reverse
Reverse the order of goals and prerequisites, rather than a random shuffle.
@item @var{seed}
Use @samp{random} shuffle initialized with the specified seed value. The
@var{seed} is an integer.
@item none
Disable shuffling. This negates any previous @samp{--shuffle} options.
@end table
@item -t
@cindex @code{-t}
@itemx --touch

2
makefile.com
View file

@ -76,7 +76,7 @@ $ filelist = "[.src]ar [.src]arscan [.src]commands [.src]default [.src]dir " + -
"[.src]hash [.src]implicit [.src]job [.src]load [.src]main " + -
"[.src]misc [.src]read [.src]remake [.src]remote-stub " + -
"[.src]rule [.src]output [.src]signame [.src]variable " + -
"[.src]version [.src]strcache [.src]vpath " + -
"[.src]version [.src]shuffle [.src]strcache [.src]vpath " + -
"[.src]vmsfunctions [.src]vmsify [.src]vms_progname " + -
"[.src]vms_exit [.src]vms_export_symbol " + -
"[.lib]alloca [.lib]fnmatch [.lib]glob [.src]getopt1 [.src]getopt"

1
po/POTFILES.in
View file

@ -37,6 +37,7 @@ src/read.c
src/remake.c
src/remote-cstms.c
src/rule.c
src/shuffle.c
src/signame.c
src/strcache.c
src/variable.c

1
src/dep.h
View file

@ -46,6 +46,7 @@ struct nameseq
#define DEP(_t) \
NAMESEQ (_t); \
struct file *file; \
_t *shuf; \
const char *stem; \
unsigned int flags : 8; \
unsigned int changed : 1; \

2
src/filedef.h
View file

@ -108,6 +108,8 @@ struct file
pattern-specific variables. */
unsigned int no_diag:1; /* True if the file failed to update and no
diagnostics has been issued (dontcare). */
unsigned int was_shuffled:1; /* Did we already shuffle 'deps'? used when
--shuffle passes through the graph. */
};

7
src/implicit.c
View file

@ -22,6 +22,7 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
#include "variable.h"
#include "job.h" /* struct child, used inside commands.h */
#include "commands.h" /* set_file_variables */
#include "shuffle.h"
#include <assert.h>
static int pattern_search (struct file *file, int archive,
@ -1053,8 +1054,14 @@ pattern_search (struct file *file, int archive,
dep->next = file->deps;
file->deps = dep;
/* The file changed its dependencies; schedule the shuffle. */
file->was_shuffled = 0;
}
if (!file->was_shuffled)
shuffle_deps_recursive (file->deps);
if (!tryrules[foundrule].checked_lastslash)
{
/* Always allocate new storage, since STEM might be on the stack for an

22
src/job.c
View file

@ -25,6 +25,8 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
#include "commands.h"
#include "variable.h"
#include "os.h"
#include "dep.h"
#include "shuffle.h"
/* Default shell to use. */
#ifdef WINDOWS32
@ -539,6 +541,7 @@ child_error (struct child *child,
const struct file *f = child->file;
const floc *flocp = &f->cmds->fileinfo;
const char *nm;
const char *smode;
size_t l;
if (ignored && run_silent)
@ -564,18 +567,29 @@ child_error (struct child *child,
l = strlen (pre) + strlen (nm) + strlen (f->name) + strlen (post);
smode = shuffle_get_mode ();
if (smode)
{
#define SHUFFLE_PREFIX " shuffle="
char *a = alloca (CSTRLEN(SHUFFLE_PREFIX) + strlen (smode) + 1);
sprintf (a, SHUFFLE_PREFIX "%s", smode);
smode = a;
l += strlen (smode);
#undef SHUFFLE_PREFIX
}
OUTPUT_SET (&child->output);
show_goal_error ();
if (exit_sig == 0)
error (NILF, l + INTSTR_LENGTH,
_("%s[%s: %s] Error %d%s"), pre, nm, f->name, exit_code, post);
error (NILF, l + INTSTR_LENGTH, _("%s[%s: %s] Error %d%s%s"),
pre, nm, f->name, exit_code, post, smode ? smode : "");
else
{
const char *s = strsignal (exit_sig);
error (NILF, l + strlen (s) + strlen (dump),
"%s[%s: %s] %s%s%s", pre, nm, f->name, s, dump, post);
error (NILF, l + strlen (s) + strlen (dump), "%s[%s: %s] %s%s%s%s",
pre, nm, f->name, s, dump, post, smode ? smode : "");
}
OUTPUT_UNSET ();

29
src/main.c
View file

@ -24,6 +24,7 @@ this program. If not, see <http://www.gnu.org/licenses/>. */
#include "rule.h"
#include "debug.h"
#include "getopt.h"
#include "shuffle.h"
#include <assert.h>
#ifdef _AMIGA
@ -233,6 +234,10 @@ static const int inf_jobs = 0;
static char *jobserver_auth = NULL;
/* Shuffle mode for goals and prerequisites. */
static char *shuffle_mode = NULL;
/* Handle for the mutex used on Windows to synchronize output of our
children under -O. */
@ -361,6 +366,9 @@ static const char *const usage[] =
N_("\
-R, --no-builtin-variables Disable the built-in variable settings.\n"),
N_("\
--shuffle[={SEED|random|reverse|none}]\n\
Perform shuffle of prerequisites and goals.\n"),
N_("\
-s, --silent, --quiet Don't echo recipes.\n"),
N_("\
--no-silent Echo recipes (disable --silent mode).\n"),
@ -479,6 +487,7 @@ static const struct command_switch switches[] =
{ CHAR_MAX+9, string, &jobserver_auth, 1, 0, 0, 0, 0, "jobserver-fds" },
/* There is special-case handling for this in decode_switches() as well. */
{ TEMP_STDIN_OPT, filename, &makefiles, 0, 0, 0, 0, 0, "temp-stdin" },
{ CHAR_MAX+11, string, &shuffle_mode, 1, 1, 0, "random", 0, "shuffle" },
{ 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};
@ -1504,6 +1513,22 @@ main (int argc, char **argv, char **envp)
arg_job_slots = env_slots;
}
/* Handle shuffle mode argument. */
if (shuffle_mode)
{
const char *effective_mode;
shuffle_set_mode (shuffle_mode);
/* Write fixed seed back to argument list to propagate mode and
fixed seed to child $(MAKE) runs. */
free (shuffle_mode);
effective_mode = shuffle_get_mode ();
if (effective_mode)
shuffle_mode = xstrdup (effective_mode);
else
shuffle_mode = NULL;
}
/* Set a variable specifying whether stdout/stdin is hooked to a TTY. */
#ifdef HAVE_ISATTY
if (isatty (fileno (stdout)))
@ -2759,6 +2784,10 @@ main (int argc, char **argv, char **envp)
O (fatal, NILF, _("No targets specified and no makefile found"));
}
/* Shuffle prerequisites to catch makefiles with incomplete depends. */
shuffle_goaldeps_recursive (goals);
/* Update the goals. */
DB (DB_BASIC, (_("Updating goal targets....\n")));

142
src/remake.c
View file

@ -93,8 +93,8 @@ update_goal_chain (struct goaldep *goaldeps)
enum update_status status = us_none;
/* Duplicate the chain so we can remove things from it. */
struct dep *goals = copy_dep_chain ((struct dep *)goaldeps);
struct dep *goals_orig = copy_dep_chain ((struct dep *)goaldeps);
struct dep *goals = goals_orig;
goal_list = rebuilding_makefiles ? goaldeps : NULL;
@ -108,7 +108,7 @@ update_goal_chain (struct goaldep *goaldeps)
while (goals != 0)
{
struct dep *g, *lastgoal;
struct dep *gu, *g, *lastgoal;
/* Start jobs that are waiting for the load to go down. */
@ -119,13 +119,15 @@ update_goal_chain (struct goaldep *goaldeps)
reap_children (1, 0);
lastgoal = 0;
g = goals;
while (g != 0)
gu = goals;
while (gu != 0)
{
/* Iterate over all double-colon entries for this file. */
struct file *file;
int stop = 0, any_not_updated = 0;
g = gu->shuf ? gu->shuf : gu;
goal_dep = g;
for (file = g->file->double_colon ? g->file->double_colon : g->file;
@ -235,31 +237,30 @@ update_goal_chain (struct goaldep *goaldeps)
/* This goal is finished. Remove it from the chain. */
if (lastgoal == 0)
goals = g->next;
goals = gu->next;
else
lastgoal->next = g->next;
lastgoal->next = gu->next;
/* Free the storage. */
free (g);
g = lastgoal == 0 ? goals : lastgoal->next;
gu = lastgoal == 0 ? goals : lastgoal->next;
if (stop)
break;
}
else
{
lastgoal = g;
g = g->next;
lastgoal = gu;
gu = gu->next;
}
}
/* If we reached the end of the dependency graph update CONSIDERED
for the next pass. */
if (g == 0)
if (gu == 0)
++considered;
}
free_dep_chain (goals_orig);
if (rebuilding_makefiles)
{
touch_flag = t;
@ -424,7 +425,7 @@ update_file_1 (struct file *file, unsigned int depth)
FILE_TIMESTAMP this_mtime;
int noexist, must_make, deps_changed;
struct file *ofile;
struct dep *d, *ad;
struct dep *du, *d, *ad;
struct dep amake;
int running = 0;
@ -532,16 +533,18 @@ update_file_1 (struct file *file, unsigned int depth)
struct dep *lastd = 0;
/* Find the deps we're scanning */
d = ad->file->deps;
du = ad->file->deps;
ad = ad->next;
while (d)
while (du)
{
enum update_status new;
FILE_TIMESTAMP mtime;
int maybe_make;
int dontcare = 0;
d = du->shuf ? du->shuf : du;
check_renamed (d->file);
mtime = file_mtime (d->file);
@ -551,14 +554,16 @@ update_file_1 (struct file *file, unsigned int depth)
{
OSS (error, NILF, _("Circular %s <- %s dependency dropped."),
file->name, d->file->name);
/* We cannot free D here because our the caller will still have
a reference to it when we were called recursively via
check_dep below. */
if (lastd == 0)
file->deps = d->next;
file->deps = du->next;
else
lastd->next = d->next;
d = d->next;
lastd->next = du->next;
du = du->next;
continue;
}
@ -607,8 +612,8 @@ update_file_1 (struct file *file, unsigned int depth)
d->changed = ((file_mtime (d->file) != mtime)
|| (mtime == NONEXISTENT_MTIME));
lastd = d;
d = d->next;
lastd = du;
du = du->next;
}
}
@ -617,58 +622,61 @@ update_file_1 (struct file *file, unsigned int depth)
if (must_make || always_make_flag)
{
for (d = file->deps; d != 0; d = d->next)
if (d->file->intermediate)
{
enum update_status new;
int dontcare = 0;
for (du = file->deps; du != 0; du = du->next)
{
d = du->shuf ? du->shuf : du;
if (d->file->intermediate)
{
enum update_status new;
int dontcare = 0;
FILE_TIMESTAMP mtime = file_mtime (d->file);
check_renamed (d->file);
d->file->parent = file;
FILE_TIMESTAMP mtime = file_mtime (d->file);
check_renamed (d->file);
d->file->parent = file;
/* Inherit dontcare flag from our parent. */
if (rebuilding_makefiles)
{
dontcare = d->file->dontcare;
d->file->dontcare = file->dontcare;
}
/* We may have already considered this file, when we didn't know
we'd need to update it. Force update_file() to consider it and
not prune it. */
d->file->considered = 0;
new = update_file (d->file, depth);
if (new > dep_status)
dep_status = new;
/* Restore original dontcare flag. */
if (rebuilding_makefiles)
d->file->dontcare = dontcare;
check_renamed (d->file);
/* Inherit dontcare flag from our parent. */
if (rebuilding_makefiles)
{
dontcare = d->file->dontcare;
d->file->dontcare = file->dontcare;
struct file *f = d->file;
if (f->double_colon)
f = f->double_colon;
do
{
running |= (f->command_state == cs_running
|| f->command_state == cs_deps_running);
f = f->prev;
}
while (f != 0);
}
/* We may have already considered this file, when we didn't know
we'd need to update it. Force update_file() to consider it and
not prune it. */
d->file->considered = 0;
if (dep_status && !keep_going_flag)
break;
new = update_file (d->file, depth);
if (new > dep_status)
dep_status = new;
/* Restore original dontcare flag. */
if (rebuilding_makefiles)
d->file->dontcare = dontcare;
check_renamed (d->file);
{
struct file *f = d->file;
if (f->double_colon)
f = f->double_colon;
do
{
running |= (f->command_state == cs_running
|| f->command_state == cs_deps_running);
f = f->prev;
}
while (f != 0);
if (!running)
d->changed = ((file->phony && file->cmds != 0)
|| file_mtime (d->file) != mtime);
}
if (dep_status && !keep_going_flag)
break;
if (!running)
d->changed = ((file->phony && file->cmds != 0)
|| file_mtime (d->file) != mtime);
}
}
}
finish_updating (file);

240
src/shuffle.c Normal file
View file

@ -0,0 +1,240 @@
/* Provide prerequisite shuffle support.
Copyright (C) 2022 Free Software Foundation, Inc.
This file is part of GNU Make.
GNU Make is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3 of the License, or (at your option) any later
version.
GNU Make is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>. */
#include "makeint.h"
#include "shuffle.h"
#include "filedef.h"
#include "dep.h"
/* Supported shuffle modes. */
static void random_shuffle_array (void ** a, size_t len);
static void reverse_shuffle_array (void ** a, size_t len);
static void identity_shuffle_array (void ** a, size_t len);
/* The way goals and rules are shuffled during update. */
enum shuffle_mode
{
/* No shuffle data is populated or used. */
sm_none,
/* Random within dependency list. */
sm_random,
/* Inverse order. */
sm_reverse,
/* identity order. Differs from SM_NONE by explicitly populating
the traversal order. */
sm_identity,
};
/* Shuffle configuration. */
static struct
{
enum shuffle_mode mode;
unsigned int seed;
void (*shuffler) (void **a, size_t len);
char strval[INTSTR_LENGTH];
} config = { sm_none, 0, NULL, "" };
/* Return string value of --shuffle= option passed.
If none was passed or --shuffle=none was used function
returns NULL. */
const char *
shuffle_get_mode ()
{
return config.strval[0] ? config.strval : NULL;
}
void
shuffle_set_mode (const char *cmdarg)
{
/* Parse supported '--shuffle' mode. */
if (strcasecmp (cmdarg, "random") == 0)
{
config.mode = sm_random;
config.seed = (unsigned int) (time (NULL) ^ make_pid ());
}
else if (strcasecmp (cmdarg, "reverse") == 0)
config.mode = sm_reverse;
else if (strcasecmp (cmdarg, "identity") == 0)
config.mode = sm_identity;
else if (strcasecmp (cmdarg, "none") == 0)
config.mode = sm_none;
/* Assume explicit seed if starts from a digit. */
else
{
const char *err;
config.mode = sm_random;
config.seed = make_toui (cmdarg, &err);
if (err)
{
OS (error, NILF, _("invalid shuffle mode: '%s'"), cmdarg);
die (MAKE_FAILURE);
}
}
switch (config.mode)
{
case sm_random:
config.shuffler = random_shuffle_array;
sprintf (config.strval, "%u", config.seed);
break;
case sm_reverse:
config.shuffler = reverse_shuffle_array;
strcpy (config.strval, "reverse");
break;
case sm_identity:
config.shuffler = identity_shuffle_array;
strcpy (config.strval, "identity");
break;
case sm_none:
config.strval[0] = '\0';
break;
}
}
/* Shuffle array elements using RAND(). */
static void
random_shuffle_array (void **a, size_t len)
{
size_t i;
for (i = 0; i < len; i++)
{
void *t;
/* Pick random element and swap. */
unsigned int j = rand () % len;
if (i == j)
continue;
/* Swap. */
t = a[i];
a[i] = a[j];
a[j] = t;
}
}
/* Shuffle array elements using reverse order. */
static void
reverse_shuffle_array (void **a, size_t len)
{
size_t i;
for (i = 0; i < len / 2; i++)
{
void *t;
/* Pick mirror and swap. */
unsigned int j = len - 1 - i;
/* Swap. */
t = a[i];
a[i] = a[j];
a[j] = t;
}
}
/* Shuffle array elements using identity order. */
static void
identity_shuffle_array (void **a UNUSED, size_t len UNUSED)
{
/* No-op! */
}
/* Shuffle list of dependencies by populating '->next'
field in each 'struct dep'. */
static void
shuffle_deps (struct dep *deps)
{
size_t ndeps = 0;
struct dep *dep;
void **da;
void **dp;
for (dep = deps; dep; dep = dep->next)
ndeps++;
if (ndeps == 0)
return;
/* Allocate array of all deps, store, shuffle, write back. */
da = xmalloc (sizeof (struct dep *) * ndeps);
/* Store locally. */
for (dep = deps, dp = da; dep; dep = dep->next, dp++)
*dp = dep;
/* Shuffle. */
config.shuffler (da, ndeps);
/* Write back. */
for (dep = deps, dp = da; dep; dep = dep->next, dp++)
dep->shuf = *dp;
free (da);
}
/* Shuffle 'deps' of each 'file' recursively. */
static void
shuffle_file_deps_recursive (struct file *f)
{
struct dep *dep;
/* Implicit rules do not always provide any depends. */
if (!f)
return;
/* Avoid repeated shuffles and loops. */
if (f->was_shuffled)
return;
f->was_shuffled = 1;
shuffle_deps (f->deps);
/* Shuffle dependencies. */
for (dep = f->deps; dep; dep = dep->next)
shuffle_file_deps_recursive (dep->file);
}
/* Shuffle goal dependencies first, then shuffle dependency list
of each file reachable from goaldep recursively. Used by
--shuffle flag to introduce artificial non-determinism in build
order. .*/
void
shuffle_deps_recursive (struct dep *deps)
{
struct dep *dep;
/* Exit early if shuffling was not requested. */
if (config.mode == sm_none)
return;
/* Do not reshuffle targets if Makefile is explicitly marked as
problematic for parallelism. */
if (not_parallel)
return;
/* Set specific seed at the top level of recursion. */
if (config.mode == sm_random)
srand (config.seed);
shuffle_deps (deps);
/* Shuffle dependencies. */
for (dep = deps; dep; dep = dep->next)
shuffle_file_deps_recursive (dep->file);
}

26
src/shuffle.h Normal file
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@ -0,0 +1,26 @@
/* Declarations for target shuffling support.
Copyright (C) 2022-2022 Free Software Foundation, Inc.
This file is part of GNU Make.
GNU Make is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3 of the License, or (at your option) any later
version.
GNU Make is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>. */
struct dep;
struct goaldep;
void shuffle_set_mode (const char *cmdarg);
const char * shuffle_get_mode ();
void shuffle_deps_recursive (struct dep* g);
#define shuffle_goaldeps_recursive(_g) do{ \
shuffle_deps_recursive ((struct dep *)_g); \
} while(0)

119
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# -*-perl-*-
$description = "Test the --shuffle option.";
$details = "Verify that --shuffle has expected effect on target order and argument order.";
#
# Test --shuffle=random
#
# TEST 1: Fixed seed should yield the same order from run to run.
$makefile = &get_tmpfile;
open(MAKEFILE, "> $makefile");
print MAKEFILE <<'EOF';
# More target prerequisites lower collision chance in TEST 2
all: a_ b_ c_ d_ e_ f_ g_ i_ j_ k_ l_
%: ; echo $@
EOF
close(MAKEFILE);
$log1 = &get_logfile;
$log2 = &get_logfile;
&run_make_with_options($makefile, "--shuffle=12345", $log1);
&run_make_with_options($makefile, "--shuffle=12345", $log2);
&compare_output(&read_file_into_string($log1), $log2);
# TEST 2: Sequential runs should produce different orders.
$log3 = &get_logfile;
$log4 = &get_logfile;
&run_make_with_options($makefile, "--shuffle", $log3);
&run_make_with_options($makefile, "--shuffle", $log4);
++$tests_run;
if (&read_file_into_string($log3) ne &read_file_into_string($log4)) {
print "ok\n" if $debug;
++$tests_passed;
}
#
# Test --shuffle=reverse
#
run_make_test('
%: ; @echo $@
all: a b c
',
'--shuffle=reverse', "c\nb\na\nall");
run_make_test('
%: ; @echo $@
all: a b c
',
'--shuffle=none', "a\nb\nc\nall");
run_make_test('
%: ; @echo $@
all: a b c
',
'--shuffle=identity', "a\nb\nc\nall");
# Make sure prerequisites get reverse order and commands don't get affected.
run_make_test('
all: foo.o ; @echo $@
%.o : %.c ; @echo cc -c -o $@ $<
foo.o : foo.c foo.h bar.h baz.h
%.h: ; @echo $@
%.c: ; @echo $@
',
'--shuffle=reverse',
"baz.h\nbar.h\nfoo.h\nfoo.c\ncc -c -o foo.o foo.c\nall");
# Make sure pattern prerequisites get reverse order and commands don't get
# affected.
run_make_test('
all: foo_ ; @echo $@
foo%: arg%1 arg%2 arg%3 arg%4 ; @echo bld $@ $< $(word 3,$^) $(word 2,$^) $(word 4,$^)
arg%: ; @echo $@
',
'--shuffle=reverse',
"arg_4\narg_3\narg_2\narg_1\nbld foo_ arg_1 arg_3 arg_2 arg_4\nall");
# Check if make can survive circular dependency.
run_make_test('
all: a_ b_ ; @echo $@
%_: ; @echo $@
a_: b_
b_: a_
',
'--shuffle=reverse', "#MAKE#: Circular a_ <- b_ dependency dropped.\na_\nb_\nall");
# Check if order-only dependencies get reordered.
run_make_test('
all: a_ ; @echo $@
%_: ; @echo $@
a_: b_ c_ | d_ e_
',
'--shuffle=reverse', "e_\nd_\nc_\nb_\na_\nall");
# Check if goals are reordered.
run_make_test('
%_: ; @echo $@
',
'--shuffle=reverse a_ b_ c_', "c_\nb_\na_");
# .NOTPARALLEL should prevent reordering from happening.
run_make_test('
%_: ; @echo $@
# disable shuffling
.NOTPARALLEL:
',
'--shuffle=reverse a_ b_ c_', "a_\nb_\nc_");
1;