-# Copyright (C) 2016-2018 all contributors <meta@public-inbox.org>
+# Copyright (C) 2016-2021 all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
#
# This allows vfork to be used for spawning subprocesses if
-# PERL_INLINE_DIRECTORY is explicitly defined in the environment.
+# ~/.cache/public-inbox/inline-c is writable or if PERL_INLINE_DIRECTORY
+# is explicitly defined in the environment (and writable).
# Under Linux, vfork can make a big difference in spawning performance
# as process size increases (fork still needs to mark pages for CoW use).
# Currently, we only use this for code intended for long running
# daemons (inside the PSGI code (-httpd) and -nntpd). The short-lived
# scripts (-mda, -index, -learn, -init) either use IPC::run or standard
# Perl routines.
+#
+# There'll probably be more OS-level C stuff here, down the line.
+# We don't want too many DSOs: https://udrepper.livejournal.com/8790.html
package PublicInbox::Spawn;
use strict;
-use warnings;
-use base qw(Exporter);
+use parent qw(Exporter);
use Symbol qw(gensym);
-use IO::Handle;
use PublicInbox::ProcessPipe;
-our @EXPORT_OK = qw/which spawn popen_rd/;
-sub RLIMITS () { qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA) }
+our @EXPORT_OK = qw(which spawn popen_rd run_die nodatacow_dir);
+our @RLIMITS = qw(RLIMIT_CPU RLIMIT_CORE RLIMIT_DATA);
my $vfork_spawn = <<'VFORK_SPAWN';
#include <sys/types.h>
-#include <sys/uio.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#include <stdlib.h>
+#include <errno.h>
/* some platforms need alloca.h, but some don't */
#if defined(__GNUC__) && !defined(alloca)
dst[real_len] = 0; \
} while (0)
-static void *deconst(const char *s)
-{
- union { const char *in; void *out; } u;
- u.in = s;
- return u.out;
-}
-
/* needs to be safe inside a vfork'ed process */
-static void xerr(const char *msg)
+static void exit_err(int *cerrnum)
{
- struct iovec iov[3];
- const char *err = strerror(errno); /* should be safe in practice */
-
- iov[0].iov_base = deconst(msg);
- iov[0].iov_len = strlen(msg);
- iov[1].iov_base = deconst(err);
- iov[1].iov_len = strlen(err);
- iov[2].iov_base = deconst("\n");
- iov[2].iov_len = 1;
- writev(2, iov, 3);
+ *cerrnum = errno;
_exit(1);
}
-#define REDIR(var,fd) do { \
- if (var != fd && dup2(var, fd) < 0) \
- xerr("error redirecting std"#var ": "); \
-} while (0)
-
/*
- * unstable internal API. This was easy to implement but does not
- * support arbitrary redirects. It'll be updated depending on
+ * unstable internal API. It'll be updated depending on
* whatever we'll need in the future.
* Be sure to update PublicInbox::SpawnPP if this changes
*/
-int pi_fork_exec(int in, int out, int err,
- SV *file, SV *cmdref, SV *envref, SV *rlimref)
+int pi_fork_exec(SV *redirref, SV *file, SV *cmdref, SV *envref, SV *rlimref,
+ const char *cd)
{
+ AV *redir = (AV *)SvRV(redirref);
AV *cmd = (AV *)SvRV(cmdref);
AV *env = (AV *)SvRV(envref);
AV *rlim = (AV *)SvRV(rlimref);
const char *filename = SvPV_nolen(file);
pid_t pid;
char **argv, **envp;
- sigset_t set, old;
- int ret, errnum;
+ sigset_t set, old, cset;
+ int ret, perrnum, cerrnum = 0;
AV2C_COPY(argv, cmd);
AV2C_COPY(envp, env);
assert(ret == 0 && "BUG calling sigfillset");
ret = sigprocmask(SIG_SETMASK, &set, &old);
assert(ret == 0 && "BUG calling sigprocmask to block");
+ ret = sigemptyset(&cset);
+ assert(ret == 0 && "BUG calling sigemptyset");
+ ret = sigaddset(&cset, SIGCHLD);
+ assert(ret == 0 && "BUG calling sigaddset for SIGCHLD");
pid = vfork();
if (pid == 0) {
int sig;
- I32 i, max;
+ I32 i, child_fd, max = av_len(redir);
- REDIR(in, 0);
- REDIR(out, 1);
- REDIR(err, 2);
+ for (child_fd = 0; child_fd <= max; child_fd++) {
+ SV **parent = av_fetch(redir, child_fd, 0);
+ int parent_fd = SvIV(*parent);
+ if (parent_fd == child_fd)
+ continue;
+ if (dup2(parent_fd, child_fd) < 0)
+ exit_err(&cerrnum);
+ }
for (sig = 1; sig < NSIG; sig++)
signal(sig, SIG_DFL); /* ignore errors on signals */
+ if (*cd && chdir(cd) < 0)
+ exit_err(&cerrnum);
max = av_len(rlim);
for (i = 0; i < max; i += 3) {
rl.rlim_cur = SvIV(*soft);
rl.rlim_max = SvIV(*hard);
if (setrlimit(SvIV(*res), &rl) < 0)
- xerr("sertlimit");
+ exit_err(&cerrnum);
}
/*
- * don't bother unblocking, we don't want signals
- * to the group taking out a subprocess
+ * don't bother unblocking other signals for now, just SIGCHLD.
+ * we don't want signals to the group taking out a subprocess
*/
+ (void)sigprocmask(SIG_UNBLOCK, &cset, NULL);
execve(filename, argv, envp);
- xerr("execve failed");
+ exit_err(&cerrnum);
}
- errnum = errno;
+ perrnum = errno;
ret = sigprocmask(SIG_SETMASK, &old, NULL);
assert(ret == 0 && "BUG calling sigprocmask to restore");
- errno = errnum;
-
+ if (cerrnum) {
+ if (pid > 0)
+ waitpid(pid, NULL, 0);
+ pid = -1;
+ errno = cerrnum;
+ } else if (perrnum) {
+ errno = perrnum;
+ }
return (int)pid;
}
VFORK_SPAWN
-my $inline_dir = $ENV{PERL_INLINE_DIRECTORY};
-$vfork_spawn = undef unless defined $inline_dir && -d $inline_dir && -w _;
+# btrfs on Linux is copy-on-write (COW) by default. As of Linux 5.7,
+# this still leads to fragmentation for SQLite and Xapian files where
+# random I/O happens, so we disable COW just for SQLite files and Xapian
+# directories. Disabling COW disables checksumming, so we only do this
+# for regeneratable files, and not canonical git storage (git doesn't
+# checksum refs, only data under $GIT_DIR/objects).
+my $set_nodatacow = $^O eq 'linux' ? <<'SET_NODATACOW' : '';
+#include <sys/ioctl.h>
+#include <sys/vfs.h>
+#include <linux/magic.h>
+#include <linux/fs.h>
+#include <dirent.h>
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+
+void nodatacow_fd(int fd)
+{
+ struct statfs buf;
+ int val = 0;
+
+ if (fstatfs(fd, &buf) < 0) {
+ fprintf(stderr, "fstatfs: %s\\n", strerror(errno));
+ return;
+ }
+
+ /* only btrfs is known to have this problem, so skip for non-btrfs */
+ if (buf.f_type != BTRFS_SUPER_MAGIC)
+ return;
+
+ if (ioctl(fd, FS_IOC_GETFLAGS, &val) < 0) {
+ fprintf(stderr, "FS_IOC_GET_FLAGS: %s\\n", strerror(errno));
+ return;
+ }
+ val |= FS_NOCOW_FL;
+ if (ioctl(fd, FS_IOC_SETFLAGS, &val) < 0)
+ fprintf(stderr, "FS_IOC_SET_FLAGS: %s\\n", strerror(errno));
+}
+
+void nodatacow_dir(const char *dir)
+{
+ DIR *dh = opendir(dir);
+ int fd;
+
+ if (!dh) croak("opendir(%s): %s", dir, strerror(errno));
+ fd = dirfd(dh);
+ if (fd >= 0)
+ nodatacow_fd(fd);
+ /* ENOTSUP probably won't happen under Linux... */
+ closedir(dh);
+}
+SET_NODATACOW
+
+my $inline_dir = $ENV{PERL_INLINE_DIRECTORY} //= (
+ $ENV{XDG_CACHE_HOME} //
+ ( ($ENV{HOME} // '/nonexistent').'/.cache' )
+ ).'/public-inbox/inline-c';
+
+$set_nodatacow = $vfork_spawn = undef unless -d $inline_dir && -w _;
if (defined $vfork_spawn) {
# Inline 0.64 or later has locking in multi-process env,
# but we support 0.5 on Debian wheezy
my $f = "$inline_dir/.public-inbox.lock";
open my $fh, '>', $f or die "failed to open $f: $!\n";
flock($fh, LOCK_EX) or die "LOCK_EX failed on $f: $!\n";
- eval 'use Inline C => $vfork_spawn'; #, BUILD_NOISY => 1';
+ eval 'use Inline C => $vfork_spawn . $set_nodatacow';
my $err = $@;
+ my $ndc_err;
+ if ($err && $set_nodatacow) { # missing Linux kernel headers
+ $ndc_err = $err;
+ undef $set_nodatacow;
+ eval 'use Inline C => $vfork_spawn';
+ }
flock($fh, LOCK_UN) or die "LOCK_UN failed on $f: $!\n";
die $err if $err;
+ warn $ndc_err if $ndc_err;
};
if ($@) {
warn "Inline::C failed for vfork: $@\n";
- $vfork_spawn = undef;
+ $set_nodatacow = $vfork_spawn = undef;
}
}
unless (defined $vfork_spawn) {
require PublicInbox::SpawnPP;
+ *pi_fork_exec = \&PublicInbox::SpawnPP::pi_fork_exec
+}
+unless ($set_nodatacow) {
+ require PublicInbox::NDC_PP;
no warnings 'once';
- *pi_fork_exec = *PublicInbox::SpawnPP::pi_fork_exec
+ *nodatacow_fd = \&PublicInbox::NDC_PP::nodatacow_fd;
+ *nodatacow_dir = \&PublicInbox::NDC_PP::nodatacow_dir;
}
+undef $set_nodatacow;
+undef $vfork_spawn;
sub which ($) {
my ($file) = @_;
- return $file if index($file, '/') == 0;
+ return $file if index($file, '/') >= 0;
foreach my $p (split(':', $ENV{PATH})) {
$p .= "/$file";
return $p if -x $p;
my @env;
$opts ||= {};
- my %env = $opts->{-env} ? () : %ENV;
- if ($env) {
- foreach my $k (keys %$env) {
- my $v = $env->{$k};
- if (defined $v) {
- $env{$k} = $v;
- } else {
- delete $env{$k};
- }
- }
- }
+ my %env = $env ? (%ENV, %$env) : %ENV;
while (my ($k, $v) = each %env) {
push @env, "$k=$v";
}
- my $in = $opts->{0} || 0;
- my $out = $opts->{1} || 1;
- my $err = $opts->{2} || 2;
+ my $redir = [];
+ for my $child_fd (0..2) {
+ my $parent_fd = $opts->{$child_fd};
+ if (defined($parent_fd) && $parent_fd !~ /\A[0-9]+\z/) {
+ defined(my $fd = fileno($parent_fd)) or
+ die "$parent_fd not an IO GLOB? $!";
+ $parent_fd = $fd;
+ }
+ $redir->[$child_fd] = $parent_fd // $child_fd;
+ }
my $rlim = [];
- foreach my $l (RLIMITS()) {
+ foreach my $l (@RLIMITS) {
defined(my $v = $opts->{$l}) or next;
my $r = eval "require BSD::Resource; BSD::Resource::$l();";
unless (defined $r) {
}
push @$rlim, $r, @$v;
}
- my $pid = pi_fork_exec($in, $out, $err, $f, $cmd, \@env, $rlim);
- $pid < 0 ? undef : $pid;
+ my $cd = $opts->{'-C'} // ''; # undef => NULL mapping doesn't work?
+ my $pid = pi_fork_exec($redir, $f, $cmd, \@env, $rlim, $cd);
+ die "fork_exec @$cmd failed: $!\n" unless $pid > 0;
+ $pid;
}
sub popen_rd {
$opts ||= {};
$opts->{1} = fileno($w);
my $pid = spawn($cmd, $env, $opts);
- return unless defined $pid;
return ($r, $pid) if wantarray;
my $ret = gensym;
tie *$ret, 'PublicInbox::ProcessPipe', $pid, $r;
$ret;
}
+sub run_die ($;$$) {
+ my ($cmd, $env, $rdr) = @_;
+ my $pid = spawn($cmd, $env, $rdr);
+ waitpid($pid, 0) == $pid or die "@$cmd did not finish";
+ $? == 0 or die "@$cmd failed: \$?=$?\n";
+}
+
1;