[SV 46261] Use pselect() for jobserver where supported.
* Makefile.am, configure.ac: Check for pselect() and sys/select.h.
* main.c (main): Block SIGCHLD if we have pselect() support.
* posixos.c (jobserver_acquire): If we support pselect() then use
it to query the jobserver pipe, while also listening for SIGCHLD.
Also pselect() supports a timeout so avoid alarm() calls.
diff --git a/Makefile.am b/Makefile.am
index 8c102a3..96c4ae2 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -16,8 +16,8 @@
# You should have received a copy of the GNU General Public License along with
# this program. If not, see <http://www.gnu.org/licenses/>.
-AUTOMAKE_OPTIONS = 1.8 dist-bzip2 check-news
-ACLOCAL_AMFLAGS = -I config
+AUTOMAKE_OPTIONS = dist-bzip2 silent-rules std-options
+ACLOCAL_AMFLAGS = -I config
MAKE_HOST = @MAKE_HOST@
diff --git a/configure.ac b/configure.ac
index 7062246..4e2b637 100644
--- a/configure.ac
+++ b/configure.ac
@@ -18,7 +18,7 @@
AC_INIT([GNU make],[4.1.90],[bug-make@gnu.org])
-AC_PREREQ([2.62])
+AC_PREREQ([2.69])
# Autoconf setup
AC_CONFIG_AUX_DIR([config])
@@ -29,7 +29,7 @@
# We have to enable "foreign" because ChangeLog is auto-generated
# We cannot enable -Werror because gettext 0.18.1 has invalid content
# When we update gettext to 0.18.3 or better we can add it again.
-AM_INIT_AUTOMAKE([1.11.1 silent-rules foreign -Wall])
+AM_INIT_AUTOMAKE([1.15 foreign -Werror -Wall])
# Checks for programs.
AC_USE_SYSTEM_EXTENSIONS
@@ -51,7 +51,7 @@
AC_MINIX
# Enable gettext, in "external" mode.
-AM_GNU_GETTEXT_VERSION([0.18.1])
+AM_GNU_GETTEXT_VERSION([0.19.4])
AM_GNU_GETTEXT([external])
# This test must come as early as possible after the compiler configuration
@@ -68,7 +68,8 @@
AC_HEADER_STAT
AC_HEADER_TIME
AC_CHECK_HEADERS([stdlib.h locale.h unistd.h limits.h fcntl.h string.h \
- memory.h sys/param.h sys/resource.h sys/time.h sys/timeb.h])
+ memory.h sys/param.h sys/resource.h sys/time.h sys/timeb.h \
+ sys/select.h])
AM_PROG_CC_C_O
AC_C_CONST
@@ -135,7 +136,7 @@
dup dup2 getcwd realpath sigsetmask sigaction \
getgroups seteuid setegid setlinebuf setreuid setregid \
getrlimit setrlimit setvbuf pipe strerror strsignal \
- lstat readlink atexit isatty ttyname])
+ lstat readlink atexit isatty ttyname pselect])
# We need to check declarations, not just existence, because on Tru64 this
# function is not declared without special flags, which themselves cause
diff --git a/job.c b/job.c
index 084c1b8..be539c7 100644
--- a/job.c
+++ b/job.c
@@ -527,10 +527,11 @@
/* Handle a dead child. This handler may or may not ever be installed.
- If we're using the jobserver feature, we need it. First, installing it
- ensures the read will interrupt on SIGCHLD. Second, we close the dup'd
- read FD to ensure we don't enter another blocking read without reaping all
- the dead children. In this case we don't need the dead_children count.
+ If we're using the jobserver feature without pselect(), we need it.
+ First, installing it ensures the read will interrupt on SIGCHLD. Second,
+ we close the dup'd read FD to ensure we don't enter another blocking read
+ without reaping all the dead children. In this case we don't need the
+ dead_children count.
If we don't have either waitpid or wait3, then make is unreliable, but we
use the dead_children count to reap children as best we can. */
@@ -548,10 +549,6 @@
/* The signal handler must called only once! */
signal (SIGCHLD, SIG_DFL);
#endif
-
- /* This causes problems if the SIGCHLD interrupts a printf().
- DB (DB_JOBS, (_("Got a SIGCHLD; %u unreaped children.\n"), dead_children));
- */
}
extern pid_t shell_function_pid;
diff --git a/main.c b/main.c
index 8b3dcfa..fd939a8 100644
--- a/main.c
+++ b/main.c
@@ -1870,6 +1870,18 @@
bsd_signal (SIGCLD, child_handler);
# endif
}
+
+#ifdef HAVE_PSELECT
+ /* If we have pselect() then we need to block SIGCHLD so it's deferred. */
+ {
+ sigset_t block;
+ sigemptyset (&block);
+ sigaddset (&block, SIGCHLD);
+ if (sigprocmask (SIG_SETMASK, &block, NULL) < 0)
+ pfatal_with_name ("sigprocmask(SIG_SETMASK, SIGCHLD)");
+ }
+#endif
+
#endif
#endif
diff --git a/output.c b/output.c
index 4b7bd5d..fef7ab2 100644
--- a/output.c
+++ b/output.c
@@ -46,7 +46,7 @@
#define OUTPUT_ISSET(_out) ((_out)->out >= 0 || (_out)->err >= 0)
-#ifdef HAVE_FCNTL
+#ifdef HAVE_FCNTL_H
# define STREAM_OK(_s) ((fcntl (fileno (_s), F_GETFD) != -1) || (errno != EBADF))
#else
# define STREAM_OK(_s) 1
diff --git a/posixos.c b/posixos.c
index 443c115..7ff7511 100644
--- a/posixos.c
+++ b/posixos.c
@@ -21,6 +21,9 @@
#ifdef HAVE_FCNTL_H
# include <fcntl.h>
#endif
+#if defined(HAVE_PSELECT) && defined(HAVE_SYS_SELECT_H)
+# include <sys/select.h>
+#endif
#include "debug.h"
#include "job.h"
@@ -33,7 +36,9 @@
/* These track the state of the jobserver pipe. Passed to child instances. */
static int job_fds[2] = { -1, -1 };
-/* Used to signal read() that a SIGCHLD happened. Always CLOEXEC. */
+/* Used to signal read() that a SIGCHLD happened. Always CLOEXEC.
+ If we use pselect() this will never be created and always -1.
+ */
static int job_rfd = -1;
/* Token written to the pipe (could be any character...) */
@@ -42,11 +47,16 @@
static int
make_job_rfd ()
{
+#ifdef HAVE_PSELECT
+ /* Pretend we succeeded. */
+ return 0;
+#else
EINTRLOOP (job_rfd, dup (job_fds[0]));
if (job_rfd >= 0)
CLOSE_ON_EXEC (job_rfd);
return job_rfd;
+#endif
}
void
@@ -80,19 +90,21 @@
DB (DB_JOBS,
(_("Jobserver client (fds %d,%d)\n"), job_fds[0], job_fds[1]));
-#ifdef HAVE_FCNTL
-# define FD_OK(_f) ((fcntl ((_f), F_GETFD) != -1) || (errno != EBADF))
+#ifdef HAVE_FCNTL_H
+# define FD_OK(_f) (fcntl ((_f), F_GETFD) != -1)
#else
# define FD_OK(_f) 1
#endif
- /* Create a duplicate pipe, that will be closed in the SIGCHLD handler. If
- this fails with EBADF, the parent has closed the pipe on us because it
- didn't think we were a submake. If so, warn then default to -j1. */
+ /* Make sure our pipeline is valid, and (possibly) create a duplicate pipe,
+ that will be closed in the SIGCHLD handler. If this fails with EBADF,
+ the parent has closed the pipe on us because it didn't think we were a
+ submake. If so, warn and default to -j1. */
+
if (!FD_OK (job_fds[0]) || !FD_OK (job_fds[1]) || make_job_rfd () < 0)
{
if (errno != EBADF)
- pfatal_with_name (_("dup jobserver"));
+ pfatal_with_name (_("jobserver pipeline"));
O (error, NILF,
_("warning: jobserver unavailable: using -j1. Add '+' to parent make rule."));
@@ -186,7 +198,85 @@
#endif
}
-/* The acquire algorithm goes like this (from job.c):
+void
+jobserver_signal ()
+{
+ if (job_rfd >= 0)
+ {
+ close (job_rfd);
+ job_rfd = -1;
+ }
+}
+
+void
+jobserver_pre_acquire ()
+{
+ /* Make sure we have a dup'd FD. */
+ if (job_rfd < 0 && job_fds[0] >= 0 && make_job_rfd () < 0)
+ pfatal_with_name (_("duping jobs pipe"));
+}
+
+#ifdef HAVE_PSELECT
+
+/* Use pselect() to atomically wait for both a signal and a file descriptor.
+ It also provides a timeout facility so we don't need to use SIGALRM.
+
+ This method relies on the fact that SIGCHLD will be blocked everywhere,
+ and only unblocked (atomically) within the pselect() call, so we can
+ never miss a SIGCHLD.
+ */
+int
+jobserver_acquire (int timeout)
+{
+ sigset_t empty;
+ fd_set readfds;
+ struct timespec spec;
+ struct timespec *specp = NULL;
+ int r;
+ char intake;
+
+ sigemptyset (&empty);
+
+ FD_ZERO (&readfds);
+ FD_SET (job_fds[0], &readfds);
+
+ if (timeout)
+ {
+ /* Alarm after one second (is this too granular?) */
+ spec.tv_sec = 1;
+ spec.tv_nsec = 0;
+ specp = &spec;
+ }
+
+ r = pselect (job_fds[0]+1, &readfds, NULL, NULL, specp, &empty);
+
+ if (r == -1)
+ {
+ /* Better be SIGCHLD. */
+ if (errno != EINTR)
+ pfatal_with_name (_("pselect jobs pipe"));
+ return 0;
+ }
+
+ if (r == 0)
+ /* Timeout. */
+ return 0;
+
+ /* The read FD is ready: read it! */
+ EINTRLOOP (r, read (job_fds[0], &intake, 1));
+ if (r < 0)
+ pfatal_with_name (_("read jobs pipe"));
+
+ /* What does it mean if read() returns 0? It shouldn't happen because only
+ the master make can reap all the tokens and close the write side...?? */
+ return r;
+}
+
+#else
+
+/* This method uses a "traditional" UNIX model for waiting on both a signal
+ and a file descriptor. However, it's complex and since we have a SIGCHLD
+ handler installed we need to check ALL system calls for EINTR: painful!
Read a token. As long as there's no token available we'll block. We
enable interruptible system calls before the read(2) so that if we get a
@@ -264,28 +354,6 @@
#endif
}
-void
-jobserver_signal ()
-{
- if (job_rfd >= 0)
- {
- close (job_rfd);
- job_rfd = -1;
- }
-}
-
-void
-jobserver_pre_acquire ()
-{
- /* Make sure we have a dup'd FD. */
- if (job_rfd < 0 && job_fds[0] >= 0)
- {
- DB (DB_JOBS, ("Duplicate the job FD\n"));
- if (make_job_rfd () < 0)
- pfatal_with_name (_("duping jobs pipe"));
- }
-}
-
int
jobserver_acquire (int timeout)
{
@@ -317,4 +385,6 @@
return 0;
}
+#endif
+
#endif /* MAKE_JOBSERVER */
