nginx/src/os/unix/ngx_freebsd_rfork_thread.c
2004-02-29 21:03:02 +00:00

528 lines
12 KiB
C

/*
* Copyright (C) 2002-2004 Igor Sysoev, http://sysoev.ru/en/
*/
#include <ngx_config.h>
#include <ngx_core.h>
/*
* The threads implementation uses the rfork(RFPROC|RFTHREAD|RFMEM)
* to create threads. All threads use the stacks of the same size mmap()ed
* below the main stack. Thus the stack pointer is used to determine
* the current thread id.
*
* The mutex implementation uses the ngx_atomic_cmp_set() operation
* to acquire mutex and the SysV semaphore to wait on a mutex or to wake up
* the waiting threads.
*
* The condition variable implementation uses the SysV semaphore set of two
* semaphores. The first is used by the CV mutex, and the second is used
* by CV itself.
*
* This threads implementation currently works on i486 and amd64
* platforms only.
*/
ngx_int_t ngx_threaded;
char *ngx_freebsd_kern_usrstack;
size_t ngx_thread_stack_size;
static size_t rz_size = /* STUB: PAGE_SIZE */ 4096;
static size_t usable_stack_size;
static char *last_stack;
static ngx_uint_t nthreads;
static ngx_uint_t max_threads;
static ngx_tid_t *tids; /* the threads tids array */
/* the thread-safe libc errno */
static int errno0; /* the main thread's errno */
static int *errnos; /* the threads errno's array */
int *__error()
{
int tid;
tid = ngx_gettid();
return tid ? &errnos[tid - 1] : &errno0;
}
/*
* __isthreaded enables the spinlocks in some libc functions, i.e. in malloc()
* and some other places. Nevertheless we protect our malloc()/free() calls
* by own mutex that is more efficient than the spinlock.
*
* _spinlock() is a weak referenced stub in src/lib/libc/gen/_spinlock_stub.c
* that does nothing.
*/
extern int __isthreaded;
void _spinlock(ngx_atomic_t *lock)
{
ngx_int_t tries;
tries = 0;
for ( ;; ) {
if (*lock) {
if (ngx_freebsd_hw_ncpu > 1 && tries++ < 1000) {
continue;
}
sched_yield();
tries = 0;
} else {
if (ngx_atomic_cmp_set(lock, 0, 1)) {
return;
}
}
}
}
/*
* Before FreeBSD 5.1 _spinunlock() is a simple #define in
* src/lib/libc/include/spinlock.h that zeroes lock.
*
* Since FreeBSD 5.1 _spinunlock() is a weak referenced stub in
* src/lib/libc/gen/_spinlock_stub.c that does nothing.
*/
#ifndef _spinunlock
void _spinunlock(ngx_atomic_t *lock)
{
*lock = 0;
}
#endif
int ngx_create_thread(ngx_tid_t *tid, int (*func)(void *arg), void *arg,
ngx_log_t *log)
{
int id, err;
char *stack, *stack_top;
if (nthreads >= max_threads) {
ngx_log_error(NGX_LOG_CRIT, log, 0,
"no more than %d threads can be created", max_threads);
return NGX_ERROR;
}
last_stack -= ngx_thread_stack_size;
stack = mmap(last_stack, usable_stack_size, PROT_READ|PROT_WRITE,
MAP_STACK, -1, 0);
if (stack == MAP_FAILED) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
"mmap(" PTR_FMT ":" SIZE_T_FMT
", MAP_STACK) thread stack failed",
last_stack, usable_stack_size);
return NGX_ERROR;
}
if (stack != last_stack) {
ngx_log_error(NGX_LOG_ALERT, log, 0, "stack address was changed");
}
stack_top = stack + usable_stack_size;
ngx_log_debug2(NGX_LOG_DEBUG_CORE, log, 0,
"thread stack: " PTR_FMT "-" PTR_FMT, stack, stack_top);
#if 1
id = rfork_thread(RFPROC|RFTHREAD|RFMEM, stack_top, func, arg);
#elif 1
id = rfork_thread(RFPROC|RFMEM, stack_top, func, arg);
#elif 1
id = rfork_thread(RFFDG|RFCFDG, stack_top, func, arg);
#else
id = rfork(RFFDG|RFCFDG);
#endif
err = ngx_errno;
if (id == -1) {
ngx_log_error(NGX_LOG_ALERT, log, err, "rfork() failed");
} else {
*tid = id;
nthreads = (ngx_freebsd_kern_usrstack - stack_top)
/ ngx_thread_stack_size;
tids[nthreads] = id;
ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0, "rfork()ed thread: %d", id);
}
return err;
}
ngx_int_t ngx_init_threads(int n, size_t size, ngx_cycle_t *cycle)
{
size_t len;
char *red_zone, *zone;
max_threads = n;
len = sizeof(ngx_freebsd_kern_usrstack);
if (sysctlbyname("kern.usrstack", &ngx_freebsd_kern_usrstack, &len,
NULL, 0) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"sysctlbyname(kern.usrstack) failed");
return NGX_ERROR;
}
/* the main thread stack red zone */
red_zone = ngx_freebsd_kern_usrstack - (size + rz_size);
ngx_log_debug2(NGX_LOG_DEBUG_CORE, cycle->log, 0,
"usrstack: " PTR_FMT " red zone: " PTR_FMT,
ngx_freebsd_kern_usrstack, red_zone);
zone = mmap(red_zone, rz_size, PROT_NONE, MAP_ANON, -1, 0);
if (zone == MAP_FAILED) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"mmap(" PTR_FMT ":" SIZE_T_FMT
", PROT_NONE, MAP_ANON) red zone failed",
red_zone, rz_size);
return NGX_ERROR;
}
if (zone != red_zone) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
"red zone address was changed");
}
/* create the threads errno array */
if (!(errnos = ngx_calloc(n * sizeof(int), cycle->log))) {
return NGX_ERROR;
}
/* create the threads tid array */
if (!(tids = ngx_calloc((n + 1) * sizeof(ngx_tid_t), cycle->log))) {
return NGX_ERROR;
}
tids[0] = ngx_pid;
nthreads = 1;
last_stack = zone + rz_size;
usable_stack_size = size;
ngx_thread_stack_size = size + rz_size;
/* allow the spinlock in libc malloc() */
__isthreaded = 1;
ngx_threaded = 1;
return NGX_OK;
}
ngx_tid_t ngx_thread_self()
{
int tid;
ngx_tid_t pid;
tid = ngx_gettid();
if (tids == NULL) {
return ngx_pid;
}
#if 0
if (tids[tid] == 0) {
pid = ngx_pid;
tids[tid] = pid;
return pid;
}
#endif
return tids[tid];
}
ngx_mutex_t *ngx_mutex_init(ngx_log_t *log, uint flags)
{
int nsem, i;
ngx_mutex_t *m;
union semun op;
if (!(m = ngx_alloc(sizeof(ngx_mutex_t), log))) {
return NULL;
}
m->lock = 0;
m->log = log;
if (flags & NGX_MUTEX_LIGHT) {
m->semid = -1;
return m;
}
nsem = flags & NGX_MUTEX_CV ? 2 : 1;
m->semid = semget(IPC_PRIVATE, nsem, SEM_R|SEM_A);
if (m->semid == -1) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno, "semget() failed");
return NULL;
}
op.val = 0;
for (i = 0; i < nsem; i++) {
if (semctl(m->semid, i, SETVAL, op) == -1) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
"semctl(SETVAL) failed");
if (semctl(m->semid, 0, IPC_RMID) == -1) {
ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
"semctl(IPC_RMID) failed");
}
return NULL;
}
}
return m;
}
void ngx_mutex_done(ngx_mutex_t *m)
{
if (semctl(m->semid, 0, IPC_RMID) == -1) {
ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
"semctl(IPC_RMID) failed");
}
ngx_free((void *) m);
}
ngx_int_t ngx_mutex_dolock(ngx_mutex_t *m, ngx_int_t try)
{
uint32_t lock, new, old;
ngx_uint_t tries;
struct sembuf op;
if (!ngx_threaded) {
return NGX_OK;
}
#if (NGX_DEBUG)
if (try) {
ngx_log_debug2(NGX_LOG_DEBUG_CORE, m->log, 0,
"try lock mutex " PTR_FMT " lock:%X", m, m->lock);
} else {
ngx_log_debug2(NGX_LOG_DEBUG_CORE, m->log, 0,
"lock mutex " PTR_FMT " lock:%X", m, m->lock);
}
#endif
old = m->lock;
tries = 0;
for ( ;; ) {
if (old & NGX_MUTEX_LOCK_BUSY) {
if (try) {
return NGX_AGAIN;
}
if (ngx_freebsd_hw_ncpu > 1 && tries++ < 1000) {
/* the spinlock is used only on the SMP system */
old = m->lock;
continue;
}
if (m->semid == -1) {
sched_yield();
tries = 0;
old = m->lock;
continue;
}
ngx_log_debug2(NGX_LOG_DEBUG_CORE, m->log, 0,
"mutex " PTR_FMT " lock:%X", m, m->lock);
/*
* The mutex is locked so we increase a number
* of the threads that are waiting on the mutex
*/
lock = old + 1;
if ((lock & ~NGX_MUTEX_LOCK_BUSY) > nthreads) {
ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
"%d threads wait for mutex " PTR_FMT
", while only %d threads are available",
lock & ~NGX_MUTEX_LOCK_BUSY, m, nthreads);
return NGX_ERROR;
}
if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
ngx_log_debug2(NGX_LOG_DEBUG_CORE, m->log, 0,
"wait mutex " PTR_FMT " lock:%X", m, m->lock);
/*
* The number of the waiting threads has been increased
* and we would wait on the SysV semaphore.
* A semaphore should wake up us more efficiently than
* a simple usleep().
*/
op.sem_num = 0;
op.sem_op = -1;
op.sem_flg = SEM_UNDO;
if (semop(m->semid, &op, 1) == -1) {
ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
"semop() failed while waiting "
"on mutex " PTR_FMT, m);
return NGX_ERROR;
}
tries = 0;
old = m->lock;
continue;
}
old = m->lock;
} else {
lock = old | NGX_MUTEX_LOCK_BUSY;
if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
/* we locked the mutex */
break;
}
old = m->lock;
}
if (tries++ > 1000) {
ngx_log_debug1(NGX_LOG_DEBUG_CORE, m->log, 0,
"mutex " PTR_FMT " is contested", m);
/* the mutex is probably contested so we are giving up now */
sched_yield();
tries = 0;
old = m->lock;
}
}
ngx_log_debug2(NGX_LOG_DEBUG_CORE, m->log, 0,
"mutex " PTR_FMT " is locked, lock:%X", m, m->lock);
return NGX_OK;
}
ngx_int_t ngx_mutex_unlock(ngx_mutex_t *m)
{
uint32_t lock, new, old;
struct sembuf op;
if (!ngx_threaded) {
return NGX_OK;
}
old = m->lock;
if (!(old & NGX_MUTEX_LOCK_BUSY)) {
ngx_log_error(NGX_LOG_ALERT, m->log, 0,
"tring to unlock the free mutex " PTR_FMT, m);
return NGX_ERROR;
}
/* free the mutex */
for ( ;; ) {
lock = old & ~NGX_MUTEX_LOCK_BUSY;
if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
break;
}
old = m->lock;
}
if (m->semid == -1) {
ngx_log_debug1(NGX_LOG_DEBUG_CORE, m->log, 0,
"mutex " PTR_FMT " is unlocked", m);
return NGX_OK;
}
/* check weather we need to wake up a waiting thread */
old = m->lock;
for ( ;; ) {
if (old & NGX_MUTEX_LOCK_BUSY) {
/* the mutex is just locked by another thread */
break;
}
if (old == 0) {
break;
}
/* there are the waiting threads */
lock = old - 1;
if (ngx_atomic_cmp_set(&m->lock, old, lock)) {
/* wake up the thread that waits on semaphore */
op.sem_num = 0;
op.sem_op = 1;
op.sem_flg = SEM_UNDO;
if (semop(m->semid, &op, 1) == -1) {
ngx_log_error(NGX_LOG_ALERT, m->log, ngx_errno,
"semop() failed while waking up on mutex "
PTR_FMT, m);
return NGX_ERROR;
}
break;
}
old = m->lock;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, m->log, 0,
"mutex " PTR_FMT " is unlocked", m);
return NGX_OK;
}