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s3-prefork: implement prefork framework

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Primarily built for forked off rpc service daemons, but not tied to rpc
services and generic enough to be used elsewhere easily.

Signed-off-by: Andreas Schneider <asn@samba.org>
This commit is contained in:
Simo Sorce 2011-04-20 16:28:57 -04:00 committed by Andreas Schneider
parent 88b901b6ee
commit 4fef4fe498
4 changed files with 580 additions and 0 deletions
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1
source3/Makefile.in
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@ -465,6 +465,7 @@ LIB_OBJ = $(LIBSAMBAUTIL_OBJ) $(UTIL_OBJ) $(CRYPTO_OBJ) $(LIBTSOCKET_OBJ) \
lib/module.o lib/events.o @LIBTEVENT_OBJ0@ \
@CCAN_OBJ@ \
lib/server_contexts.o \
lib/server_prefork.o \
lib/ldap_escape.o @CHARSET_STATIC@ \
../libcli/security/secdesc.o ../libcli/security/access_check.o \
../libcli/security/secace.o ../libcli/security/object_tree.o \

502
source3/lib/server_prefork.c Normal file
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@ -0,0 +1,502 @@
/*
Unix SMB/CIFS implementation.
Common server globals
Copyright (C) Simo Sorce <idra@samba.org> 2011
This program 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.
This program 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 "includes.h"
#include "system/time.h"
#include "system/shmem.h"
#include "system/filesys.h"
#include "server_prefork.h"
#include "../lib/util/util.h"
struct prefork_pool {
int listen_fd;
int lock_fd;
prefork_main_fn_t *main_fn;
void *private_data;
int pool_size;
struct pf_worker_data *pool;
};
int prefork_pool_destructor(struct prefork_pool *pfp)
{
munmap(pfp->pool, pfp->pool_size * sizeof(struct pf_worker_data));
return 0;
}
bool prefork_create_pool(struct tevent_context *ev_ctx,
TALLOC_CTX *mem_ctx, int listen_fd,
int min_children, int max_children,
prefork_main_fn_t *main_fn, void *private_data,
struct prefork_pool **pf_pool)
{
struct prefork_pool *pfp;
pid_t pid;
time_t now = time(NULL);
size_t data_size;
int ret;
int i;
pfp = talloc(mem_ctx, struct prefork_pool);
if (!pfp) {
DEBUG(1, ("Out of memory!\n"));
return false;
}
pfp->listen_fd = listen_fd;
pfp->main_fn = main_fn;
pfp->private_data = private_data;
pfp->lock_fd = create_unlink_tmp(NULL);
if (pfp->lock_fd == -1) {
DEBUG(1, ("Failed to create prefork lock fd!\n"));
talloc_free(pfp);
return false;
}
pfp->pool_size = max_children;
data_size = sizeof(struct pf_worker_data) * max_children;
pfp->pool = mmap(NULL, data_size, PROT_READ|PROT_WRITE,
MAP_SHARED|MAP_ANONYMOUS, -1, 0);
if (pfp->pool == MAP_FAILED) {
DEBUG(1, ("Failed to mmap memory for prefork pool!\n"));
talloc_free(pfp);
return false;
}
talloc_set_destructor(pfp, prefork_pool_destructor);
for (i = 0; i < min_children; i++) {
pid = sys_fork();
switch (pid) {
case -1:
DEBUG(1, ("Failed to prefork child n. %d !\n", i));
break;
case 0: /* THE CHILD */
pfp->pool[i].status = PF_WORKER_IDLE;
ret = pfp->main_fn(ev_ctx, &pfp->pool[i],
pfp->listen_fd, pfp->lock_fd,
pfp->private_data);
exit(ret);
default: /* THE PARENT */
pfp->pool[i].pid = pid;
pfp->pool[i].started = now;
break;
}
}
*pf_pool = pfp;
return true;
}
int prefork_add_children(struct tevent_context *ev_ctx,
struct prefork_pool *pfp,
int num_children)
{
pid_t pid;
time_t now = time(NULL);
int ret;
int i, j;
for (i = 0, j = 0; i < pfp->pool_size && j < num_children; i++) {
if (pfp->pool[i].status != PF_WORKER_NONE) {
continue;
}
pid = sys_fork();
switch (pid) {
case -1:
DEBUG(1, ("Failed to prefork child n. %d !\n", j));
break;
case 0: /* THE CHILD */
pfp->pool[i].status = PF_WORKER_IDLE;
ret = pfp->main_fn(ev_ctx, &pfp->pool[i],
pfp->listen_fd, pfp->lock_fd,
pfp->private_data);
pfp->pool[i].status = PF_WORKER_EXITING;
exit(ret);
default: /* THE PARENT */
pfp->pool[i].pid = pid;
pfp->pool[i].started = now;
j++;
break;
}
}
DEBUG(5, ("Added %d children!\n", j));
return j;
}
struct prefork_oldest {
int num;
time_t started;
};
/* sort in inverse order */
static int prefork_sort_oldest(const void *ap, const void *bp)
{
struct prefork_oldest *a = (struct prefork_oldest *)ap;
struct prefork_oldest *b = (struct prefork_oldest *)bp;
if (a->started == b->started) {
return 0;
}
if (a->started < b->started) {
return 1;
}
return -1;
}
int prefork_retire_children(struct prefork_pool *pfp,
int num_children, time_t age_limit)
{
time_t now = time(NULL);
struct prefork_oldest *oldest;
int i, j;
oldest = talloc_array(pfp, struct prefork_oldest, pfp->pool_size);
if (!oldest) {
return -1;
}
for (i = 0; i < pfp->pool_size; i++) {
oldest[i].num = i;
if (pfp->pool[i].status == PF_WORKER_IDLE) {
oldest[i].started = pfp->pool[i].started;
} else {
oldest[i].started = now;
}
}
qsort(oldest, pfp->pool_size,
sizeof(struct prefork_oldest),
prefork_sort_oldest);
for (i = 0, j = 0; i < pfp->pool_size && j < num_children; i++) {
if (pfp->pool[i].status == PF_WORKER_IDLE &&
pfp->pool[i].started <= age_limit) {
/* tell the child it's time to give up */
DEBUG(5, ("Retiring pid %d!\n", pfp->pool[i].pid));
pfp->pool[i].cmds = PF_SRV_MSG_EXIT;
kill(pfp->pool[i].pid, SIGHUP);
j++;
}
}
return j;
}
int prefork_count_active_children(struct prefork_pool *pfp, int *total)
{
int i, a, t;
a = 0;
t = 0;
for (i = 0; i < pfp->pool_size; i++) {
if (pfp->pool[i].status == PF_WORKER_NONE) {
continue;
}
t++;
if (pfp->pool[i].num_clients == 0) {
continue;
}
a++;
}
*total = t;
return a;
}
/* to be used to finally mark a children as dead, so that it's slot can
* be reused */
bool prefork_mark_pid_dead(struct prefork_pool *pfp, pid_t pid)
{
int i;
for (i = 0; i < pfp->pool_size; i++) {
if (pfp->pool[i].pid == pid) {
if (pfp->pool[i].status != PF_WORKER_EXITING) {
DEBUG(2, ("pid %d terminated abnormally!\n",
(int)pid));
}
/* reset all fields,
* this makes status = PF_WORK_NONE */
memset(&pfp->pool[i], 0,
sizeof(struct pf_worker_data));
return true;
}
}
return false;
}
/* ==== Functions used by children ==== */
static SIG_ATOMIC_T pf_alarm;
static void pf_alarm_cb(int signum)
{
pf_alarm = 1;
}
/*
* Parameters:
* pf - the worker shared data structure
* lock_fd - the file descriptor used for locking
* timeout - expressed in seconds:
* -1 never timeouts,
* 0 timeouts immediately
* N seconds before timing out
*
* Returns values:
* negative errno on fatal error
* 0 on success to acquire lock
* -1 on timeout/lock held by other
* -2 on server msg to terminate
* ERRNO on other errors
*/
static int prefork_grab_lock(struct pf_worker_data *pf,
int lock_fd, int timeout)
{
struct flock lock;
int op;
int ret;
if (pf->cmds == PF_SRV_MSG_EXIT) {
return -2;
}
pf_alarm = 0;
if (timeout > 0) {
CatchSignal(SIGALRM, pf_alarm_cb);
alarm(timeout);
}
if (timeout == 0) {
op = F_SETLK;
} else {
op = F_SETLKW;
}
ret = 0;
do {
ZERO_STRUCT(lock);
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
ret = fcntl(lock_fd, op, &lock);
if (ret == 0) break;
ret = errno;
if (pf->cmds == PF_SRV_MSG_EXIT) {
ret = -2;
goto done;
}
switch (ret) {
case EINTR:
break;
case EACCES:
case EAGAIN:
/* lock held by other proc */
ret = -1;
goto done;
default:
goto done;
}
if (pf_alarm == 1) {
/* timed out */
ret = -1;
goto done;
}
} while (timeout != 0);
if (ret != 0) {
/* We have the Lock */
pf->status = PF_WORKER_ACCEPTING;
}
done:
if (timeout > 0) {
alarm(0);
CatchSignal(SIGALRM, SIG_IGN);
}
if (ret > 0) {
DEBUG(1, ("Failed to get lock (%d, %s)!\n",
ret, strerror(ret)));
}
return ret;
}
/*
* Parameters:
* pf - the worker shared data structure
* lock_fd - the file descriptor used for locking
* timeout - expressed in seconds:
* -1 never timeouts,
* 0 timeouts immediately
* N seconds before timing out
*
* Returns values:
* negative errno on fatal error
* 0 on success to release lock
* -1 on timeout
* ERRNO on error
*/
static int prefork_release_lock(struct pf_worker_data *pf,
int lock_fd, int timeout)
{
struct flock lock;
int op;
int ret;
pf_alarm = 0;
if (timeout > 0) {
CatchSignal(SIGALRM, pf_alarm_cb);
alarm(timeout);
}
if (timeout == 0) {
op = F_SETLK;
} else {
op = F_SETLKW;
}
do {
ZERO_STRUCT(lock);
lock.l_type = F_UNLCK;
lock.l_whence = SEEK_SET;
ret = fcntl(lock_fd, op, &lock);
if (ret == 0) break;
ret = errno;
if (ret != EINTR) {
goto done;
}
if (pf_alarm == 1) {
/* timed out */
ret = -1;
goto done;
}
} while (timeout != 0);
done:
if (timeout > 0) {
alarm(0);
CatchSignal(SIGALRM, SIG_IGN);
}
if (ret > 0) {
DEBUG(1, ("Failed to release lock (%d, %s)!\n",
ret, strerror(ret)));
}
return ret;
}
/* returns:
* negative errno on error
* -2 if server commands to terminate
* 0 if all ok
* ERRNO on other errors
*/
int prefork_wait_for_client(struct pf_worker_data *pf,
int lock_fd, int listen_fd,
struct sockaddr *addr,
socklen_t *addrlen, int *fd)
{
int ret;
int sd = -1;
int err;
ret = prefork_grab_lock(pf, lock_fd, -1);
if (ret != 0) {
return ret;
}
err = 0;
do {
sd = accept(listen_fd, addr, addrlen);
if (sd != -1) break;
if (errno == EINTR) {
if (pf->cmds == PF_SRV_MSG_EXIT) {
err = -2;
}
} else {
err = errno;
}
} while ((sd == -1) && (err == 0));
/* return lock now, even if the accept failed.
* if it takes more than 10 seconds we are in deep trouble */
ret = prefork_release_lock(pf, lock_fd, 2);
if (ret != 0) {
/* we were unable to release the lock!! */
DEBUG(0, ("Terminating due to fatal failure!\n"));
/* Just exit we cannot hold the whole server, better to error
* on this one client and hope it was a transiet problem */
err = -2;
}
if (err != 0) {
if (sd != -1) {
close(sd);
sd = -1;
}
return err;
}
pf->status = PF_WORKER_BUSY;
pf->num_clients++;
*fd = sd;
return 0;
}

76
source3/lib/server_prefork.h Normal file
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@ -0,0 +1,76 @@
/*
Unix SMB/CIFS implementation.
Common server globals
Copyright (C) Simo Sorce <idra@samba.org> 2011
This program 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.
This program 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 "system/network.h"
#include <tevent.h>
enum pf_worker_status {
PF_WORKER_NONE = 0,
PF_WORKER_IDLE,
PF_WORKER_ACCEPTING,
PF_WORKER_BUSY,
PF_WORKER_EXITING
};
enum pf_server_cmds {
PF_SRV_MSG_NONE = 0,
PF_SRV_MSG_EXIT
};
struct pf_worker_data {
pid_t pid;
enum pf_worker_status status;
enum pf_server_cmds cmds;
time_t started;
time_t last_used;
int num_clients;
};
typedef int (prefork_main_fn_t)(struct tevent_context *ev,
struct pf_worker_data *pf,
int listen_fd,
int lock_fd,
void *private_data);
struct prefork_pool;
/* ==== Functions used by controlling process ==== */
bool prefork_create_pool(struct tevent_context *ev_ctx,
TALLOC_CTX *mem_ctx, int listen_fd,
int min_children, int max_children,
prefork_main_fn_t *main_fn, void *private_data,
struct prefork_pool **pf_pool);
int prefork_add_children(struct tevent_context *ev_ctx,
struct prefork_pool *pfp,
int num_children);
int prefork_retire_children(struct prefork_pool *pfp,
int num_children, time_t age_limit);
int prefork_count_active_children(struct prefork_pool *pfp, int *total);
bool prefork_mark_pid_dead(struct prefork_pool *pfp, pid_t pid);
/* ==== Functions used by children ==== */
int prefork_wait_for_client(struct pf_worker_data *pf,
int lock_fd, int listen_fd,
struct sockaddr *addr,
socklen_t *addrlen, int *fd);

1
source3/wscript_build
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@ -81,6 +81,7 @@ LIB_SRC = '''
lib/sessionid_tdb.c
lib/module.c lib/events.c
lib/server_contexts.c
lib/server_prefork.c
lib/ldap_escape.c
lib/fncall.c
libads/krb5_errs.c lib/system_smbd.c lib/audit.c