static void rwl_lock_mutex(ngx_rwlock_t *lock) {
#if (NGX_HAVE_ATOMIC_OPS)
ngx_atomic_t *mutex = &lock->mutex;
ngx_uint_t i, n;
for(;;) {
if(*mutex == 0 && ngx_atomic_cmp_set(mutex, 0, ngx_pid)) {
return;
}
if(ngx_ncpu > 1) {
for(n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) {
for(i = 0; i < n; i++) {
ngx_cpu_pause();
}
#if (DEBUG_NGX_RWLOCK)
ngx_log_error(NGX_LOG_WARN, ngx_cycle->log, 0, "rwlock %p mutex wait", lock);
#endif
if(*mutex == 0 && ngx_atomic_cmp_set(mutex, 0, ngx_pid)) {
return;
}
}
}
ngx_sched_yield();
}
#else
#if (NGX_THREADS)
#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !
#endif
#endif
}
void
ngx_rwlock_wlock(ngx_atomic_t *lock)
{
ngx_uint_t i, n;
for ( ;; ) {
if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK)) {
return;
}
if (ngx_ncpu > 1) {
for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) {
for (i = 0; i < n; i++) {
ngx_cpu_pause();
}
if (*lock == 0
&& ngx_atomic_cmp_set(lock, 0, NGX_RWLOCK_WLOCK))
{
return;
}
}
}
ngx_sched_yield();
}
}
void ngx_spinlock(ngx_atomic_t *lock, ngx_uint_t spin)
{
#if (NGX_HAVE_ATOMIC_OPS)
ngx_uint_t tries;
tries = 0;
for ( ;; ) {
if (*lock) {
if (ngx_ncpu > 1 && tries++ < spin) {
continue;
}
ngx_sched_yield();
tries = 0;
} else {
if (ngx_atomic_cmp_set(lock, 0, 1)) {
return;
}
}
}
#else
#endif
}
static void
ngx_shmtx_wakeup(ngx_shmtx_t *mtx)
{
#if (NGX_HAVE_POSIX_SEM)
ngx_atomic_uint_t wait;
if (!mtx->semaphore) {
return;
}
for ( ;; ) {
wait = *mtx->wait;
if ((ngx_atomic_int_t) wait <= 0) {
return;
}
if (ngx_atomic_cmp_set(mtx->wait, wait, wait - 1)) {
break;
}
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx wake %uA", wait);
if (sem_post(&mtx->sem) == -1) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, ngx_errno,
"sem_post() failed while wake shmtx");
}
#endif
}
static void rwl_unlock_mutex(ngx_rwlock_t *lock) {
#if (NGX_HAVE_ATOMIC_OPS)
ngx_atomic_cmp_set(&lock->mutex, ngx_pid, 0);
#else
#if (NGX_THREADS)
#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !
#endif
#endif
}
void
ngx_spinlock(ngx_atomic_t *lock, ngx_atomic_int_t value, ngx_uint_t spin)
{
#if (NGX_HAVE_ATOMIC_OPS)
ngx_uint_t i, n;
for ( ;; ) {
if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
return;
}
if (ngx_ncpu > 1) {
for (n = 1; n < spin; n <<= 1) {
for (i = 0; i < n; i++) {
ngx_cpu_pause();
}
if (*lock == 0 && ngx_atomic_cmp_set(lock, 0, value)) {
return;
}
}
}
ngx_sched_yield();
}
#else
#if (NGX_THREADS)
#error ngx_spinlock() or ngx_atomic_cmp_set() are not defined !
#endif
#endif
}
void
ngx_shmtx_unlock(ngx_shmtx_t *mtx)
{
if (mtx->spin != (ngx_uint_t) -1) {
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx unlock");
}
if (ngx_atomic_cmp_set(mtx->lock, ngx_pid, 0)) {
ngx_shmtx_wakeup(mtx);
}
}
ngx_uint_t
ngx_shmtx_force_unlock(ngx_shmtx_t *mtx, ngx_pid_t pid)
{
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx forced unlock");
if (ngx_atomic_cmp_set(mtx->lock, pid, 0)) {
ngx_shmtx_wakeup(mtx);
return 1;
}
return 0;
}
void
ngx_rwlock_rlock(ngx_atomic_t *lock)
{
ngx_uint_t i, n;
ngx_atomic_uint_t readers;
for ( ;; ) {
readers = *lock;
if (readers != NGX_RWLOCK_WLOCK
&& ngx_atomic_cmp_set(lock, readers, readers + 1))
{
return;
}
if (ngx_ncpu > 1) {
for (n = 1; n < NGX_RWLOCK_SPIN; n <<= 1) {
for (i = 0; i < n; i++) {
ngx_cpu_pause();
}
readers = *lock;
if (readers != NGX_RWLOCK_WLOCK
&& ngx_atomic_cmp_set(lock, readers, readers + 1))
{
return;
}
}
}
ngx_sched_yield();
}
}
static void
ngx_http_file_cache_loader(void *data)
{
ngx_http_file_cache_t *cache = data;
ngx_tree_ctx_t tree;
// ???
if (!cache->sh->cold || cache->sh->loading) {
return;
}
if (!ngx_atomic_cmp_set(&cache->sh->loading, 0, ngx_pid)) {
return;
}
ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ngx_cycle->log, 0,
"http file cache loader");
tree.init_handler = NULL;
tree.file_handler = ngx_http_file_cache_manage_file;
tree.pre_tree_handler = ngx_http_file_cache_noop;
tree.post_tree_handler = ngx_http_file_cache_noop;
tree.spec_handler = ngx_http_file_cache_delete_file;
tree.data = cache;
tree.alloc = 0;
tree.log = ngx_cycle->log;
cache->last = ngx_current_msec; // 更新缓存最后被访问的时间
cache->files = 0;
if (ngx_walk_tree(&tree, &cache->path->name) == NGX_ABORT) {
cache->sh->loading = 0;
return;
}
cache->sh->cold = 0;
cache->sh->loading = 0;
ngx_log_error(NGX_LOG_NOTICE, ngx_cycle->log, 0,
"http file cache: %V %.3fM, bsize: %uz",
&cache->path->name,
((double) cache->sh->size * cache->bsize) / (1024 * 1024),
cache->bsize);
}
void
ngx_rwlock_unlock(ngx_atomic_t *lock)
{
ngx_atomic_uint_t readers;
readers = *lock;
if (readers == NGX_RWLOCK_WLOCK) {
*lock = 0;
return;
}
for ( ;; ) {
if (ngx_atomic_cmp_set(lock, readers, readers - 1)) {
return;
}
readers = *lock;
}
}
static void ngx_http_healthcheck_try_for_ownership(ngx_event_t *event) {
ngx_http_healthcheck_status_t * stat;
ngx_int_t i_own_it;
stat = event->data;
if (ngx_terminate || ngx_exiting || ngx_quit) {
ngx_http_healthcheck_clear_events(stat->health_ev.log);
return;
}
i_own_it = 0;
// nxg_time_update(0, 0);
// Spinlock. So don't own for a long time!
// Use spinlock so two worker processes don't try to healthcheck the same
// peer
ngx_spinlock(&stat->shm->lock, ngx_pid, 1024);
if (stat->shm->owner == ngx_pid) {
i_own_it = 1;
} else if (ngx_current_msec - stat->shm->action_time >=
(stat->conf->health_delay + stat->conf->health_timeout) * 3) {
stat->shm->owner = ngx_pid;
stat->shm->action_time = ngx_current_msec;
stat->state = NGX_HEALTH_WAITING;
ngx_http_healthcheck_begin_healthcheck(&stat->health_ev);
i_own_it = 1;
}
if (!ngx_atomic_cmp_set(&stat->shm->lock, ngx_pid, 0)) {
ngx_log_error(NGX_LOG_CRIT, event->log, 0,
"healthcheck: spinlock didn't work. Should be %P, but isn't",
ngx_pid);
stat->shm->lock = 0;
}
if (!i_own_it) {
// Try again for ownership later in case the guy that DOES own it dies or
// something
ngx_add_timer(&stat->ownership_ev, 5000);
}
}
void _spinlock(ngx_atomic_t *lock)
{
ngx_int_t tries;
tries = 0;
for ( ;; ) {
if (*lock) {
if (ngx_ncpu > 1 && tries++ < 1000) {
continue;
}
sched_yield();
tries = 0;
} else {
if (ngx_atomic_cmp_set(lock, 0, 1)) {
return;
}
}
}
}
static void
ngx_process_get_status(void)
{
int status;
char *process;
ngx_pid_t pid;
ngx_err_t err;
ngx_int_t i;
ngx_uint_t one;
one = 0;
for ( ;; ) {
pid = waitpid(-1, &status, WNOHANG);
if (pid == 0) {
return;
}
if (pid == -1) {
err = ngx_errno;
if (err == NGX_EINTR) {
continue;
}
if (err == NGX_ECHILD && one) {
return;
}
#if (NGX_SOLARIS || NGX_FREEBSD)
/*
* Solaris always calls the signal handler for each exited process
* despite waitpid() may be already called for this process.
*
* When several processes exit at the same time FreeBSD may
* erroneously call the signal handler for exited process
* despite waitpid() may be already called for this process.
*/
if (err == NGX_ECHILD) {
ngx_log_error(NGX_LOG_INFO, ngx_cycle->log, 0,
"waitpid() failed (%d: %s)",
err, ngx_sigsafe_strerror(err));
return;
}
#endif
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"waitpid() failed (%d: %s)",
err, ngx_sigsafe_strerror(err));
return;
}
if (ngx_accept_mutex_ptr) {
/*
* unlock the accept mutex if the abnormally exited process
* held it
*/
ngx_atomic_cmp_set(ngx_accept_mutex_ptr, pid, 0);
}
one = 1;
process = "unknown process";
for (i = 0; i < ngx_last_process; i++) {
if (ngx_processes[i].pid == pid) {
ngx_processes[i].status = status;
ngx_processes[i].exited = 1;
process = ngx_processes[i].name;
break;
}
}
if (WTERMSIG(status)) {
#ifdef WCOREDUMP
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s %P exited on signal %d%s",
process, pid, WTERMSIG(status),
WCOREDUMP(status) ? " (core dumped)" : "");
#else
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s %P exited on signal %d",
process, pid, WTERMSIG(status));
#endif
} else {
ngx_log_error(NGX_LOG_NOTICE, ngx_cycle->log, 0,
"%s %P exited with code %d",
process, pid, WEXITSTATUS(status));
}
if (WEXITSTATUS(status) == 2 && ngx_processes[i].respawn) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s %P exited with fatal code %d "
"and can not be respawn",
process, pid, WEXITSTATUS(status));
ngx_processes[i].respawn = 0;
}
}
}
static ngx_int_t
ngx_event_module_init(ngx_cycle_t *cycle)
{
void ***cf;
u_char *shared;
size_t size, cl;
ngx_shm_t shm;
ngx_time_t *tp;
ngx_core_conf_t *ccf;
ngx_event_conf_t *ecf;
cf = ngx_get_conf(cycle->conf_ctx, ngx_events_module);
ecf = (*cf)[ngx_event_core_module.ctx_index];
if (!ngx_test_config && ngx_process <= NGX_PROCESS_MASTER) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
"using the \"%s\" event method", ecf->name);
}
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
ngx_timer_resolution = ccf->timer_resolution;
#if !(NGX_WIN32)
{
ngx_int_t limit;
struct rlimit rlmt;
if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"getrlimit(RLIMIT_NOFILE) failed, ignored");
} else {
if (ecf->connections > (ngx_uint_t) rlmt.rlim_cur
&& (ccf->rlimit_nofile == NGX_CONF_UNSET
|| ecf->connections > (ngx_uint_t) ccf->rlimit_nofile))
{
limit = (ccf->rlimit_nofile == NGX_CONF_UNSET) ?
(ngx_int_t) rlmt.rlim_cur : ccf->rlimit_nofile;
ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
"%ui worker_connections exceed "
"open file resource limit: %i",
ecf->connections, limit);
}
}
}
#endif /* !(NGX_WIN32) */
if (ccf->master == 0) {
return NGX_OK;
}
if (ngx_accept_mutex_ptr) {
return NGX_OK;
}
/* cl should be equal to or greater than cache line size */
cl = 128;
size = cl /* ngx_accept_mutex */
+ cl /* ngx_connection_counter */
+ cl; /* ngx_temp_number */
#if (NGX_STAT_STUB)
size += cl /* ngx_stat_accepted */
+ cl /* ngx_stat_handled */
+ cl /* ngx_stat_requests */
+ cl /* ngx_stat_active */
+ cl /* ngx_stat_reading */
+ cl /* ngx_stat_writing */
+ cl; /* ngx_stat_waiting */
#endif
shm.size = size;
shm.name.len = sizeof("nginx_shared_zone");
shm.name.data = (u_char *) "nginx_shared_zone";
shm.log = cycle->log;
if (ngx_shm_alloc(&shm) != NGX_OK) {
return NGX_ERROR;
}
shared = shm.addr;
ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
ngx_accept_mutex.spin = (ngx_uint_t) -1;
if (ngx_shmtx_create(&ngx_accept_mutex, (ngx_shmtx_sh_t *) shared,
cycle->lock_file.data)
!= NGX_OK)
{
return NGX_ERROR;
}
ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl);
(void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1);
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"counter: %p, %d",
ngx_connection_counter, *ngx_connection_counter);
ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl);
tp = ngx_timeofday();
ngx_random_number = (tp->msec << 16) + ngx_pid;
#if (NGX_STAT_STUB)
ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl);
ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl);
ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl);
ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl);
ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl);
ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl);
ngx_stat_waiting = (ngx_atomic_t *) (shared + 9 * cl);
#endif
return NGX_OK;
}
static ngx_int_t
ngx_event_module_init(ngx_cycle_t *cycle)
{
void ***cf;
u_char *shared;
size_t size, cl;
ngx_shm_t shm;
ngx_time_t *tp;
ngx_core_conf_t *ccf;
ngx_event_conf_t *ecf;
cf = ngx_get_conf(cycle->conf_ctx, ngx_events_module);
if (cf == NULL) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
"no \"events\" section in configuration");
return NGX_ERROR;
}
ecf = (*cf)[ngx_event_core_module.ctx_index];
if (!ngx_test_config && ngx_process <= NGX_PROCESS_MASTER) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
"using the \"%s\" event method", ecf->name);
}
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
ngx_timer_resolution = ccf->timer_resolution;
#if !(NGX_WIN32)
{
ngx_int_t limit;
struct rlimit rlmt;
if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) { /* [analy] 获取进程能打开的最大文件数，内核默认是1024 */
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"getrlimit(RLIMIT_NOFILE) failed, ignored");
} else {
/* [analy] 1. 当worker_connections指定的连接数量 > 进程可以打开的文件个数 并且 指令worker_rlimit_nofile没有显示指定
2. 当worker_connections指定的连接数量 > 指令worker_rlimit_nofile指定的打开文件数
*/
if (ecf->connections > (ngx_uint_t) rlmt.rlim_cur
&& (ccf->rlimit_nofile == NGX_CONF_UNSET
|| ecf->connections > (ngx_uint_t) ccf->rlimit_nofile))
{
limit = (ccf->rlimit_nofile == NGX_CONF_UNSET) ?
(ngx_int_t) rlmt.rlim_cur : ccf->rlimit_nofile;
ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
"%ui worker_connections are more than "
"open file resource limit: %i",
ecf->connections, limit);
}
}
}
#endif /* !(NGX_WIN32) */
if (ccf->master == 0) { /* [analy] 单进程工作模式，开发和调试时使用；master_process = off */
return NGX_OK;
}
if (ngx_accept_mutex_ptr) {
return NGX_OK;
}
/* cl should be equal or bigger than cache line size */
cl = 128;
size = cl /* ngx_accept_mutex */
+ cl /* ngx_connection_counter */
+ cl; /* ngx_temp_number */
#if (NGX_STAT_STUB)
size += cl /* ngx_stat_accepted */
+ cl /* ngx_stat_handled */
+ cl /* ngx_stat_requests */
+ cl /* ngx_stat_active */
+ cl /* ngx_stat_reading */
+ cl; /* ngx_stat_writing */
#endif
shm.size = size;
shm.name.len = sizeof("nginx_shared_zone");
shm.name.data = (u_char *) "nginx_shared_zone";
shm.log = cycle->log;
if (ngx_shm_alloc(&shm) != NGX_OK) {
return NGX_ERROR;
}
shared = shm.addr;
ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
ngx_accept_mutex.spin = (ngx_uint_t) -1;
/* 设置ngx_accept_mutex="nginx.lock.accept", cycle->lock_file被unlink后在目录下已经被移除，
但还存在磁盘中当调用close()时才会被真正删掉
*/
if (ngx_shmtx_create(&ngx_accept_mutex, (ngx_shmtx_sh_t *) shared,
cycle->lock_file.data)
!= NGX_OK)
{
return NGX_ERROR;
}
ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl);
(void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1);
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"counter: %p, %d",
ngx_connection_counter, *ngx_connection_counter);
ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl);
tp = ngx_timeofday();
ngx_random_number = (tp->msec << 16) + ngx_pid;
#if (NGX_STAT_STUB)
ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl);
ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl);
ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl);
ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl);
ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl);
ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl);
#endif
return NGX_OK;
}
// 在ngx_init_cycle里调用，fork子进程之前
// 创建共享内存，存放负载均衡锁和统计用的原子变量
static ngx_int_t
ngx_event_module_init(ngx_cycle_t *cycle)
{
void ***cf;
u_char *shared;
size_t size, cl;
ngx_shm_t shm;
ngx_time_t *tp;
ngx_core_conf_t *ccf;
ngx_event_conf_t *ecf;
// events模块的配置结构体
cf = ngx_get_conf(cycle->conf_ctx, ngx_events_module);
// event_core模块的配置结构体
ecf = (*cf)[ngx_event_core_module.ctx_index];
if (!ngx_test_config && ngx_process <= NGX_PROCESS_MASTER) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
"using the \"%s\" event method", ecf->name);
}
// core模块的配置结构体
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
// 获取核心配置的时间精度，用在epoll里更新缓存时间
ngx_timer_resolution = ccf->timer_resolution;
// unix专用代码, 可打开的最多文件描述符
#if !(NGX_WIN32)
{
ngx_int_t limit;
struct rlimit rlmt;
// 系统调用getrlimit，Linux内核对进程的限制
// RLIMIT_NOFILE,进程可打开的最大文件描述符数量，超出将产生EMFILE错误
if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) {
// 系统调用失败则记录alert级别日志
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"getrlimit(RLIMIT_NOFILE) failed, ignored");
} else {
// 成功获取内核参数
//
// rlmt.rlim_cur是系统的软限制
// event里配置的连接数不能超过系统内核限制
// 或者是配置的rlimit_nofile限制
if (ecf->connections > (ngx_uint_t) rlmt.rlim_cur
&& (ccf->rlimit_nofile == NGX_CONF_UNSET
|| ecf->connections > (ngx_uint_t) ccf->rlimit_nofile))
{
// 如果超过了报警告级别日志
// limit就是上限
limit = (ccf->rlimit_nofile == NGX_CONF_UNSET) ?
(ngx_int_t) rlmt.rlim_cur : ccf->rlimit_nofile;
ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
"%ui worker_connections exceed "
"open file resource limit: %i",
ecf->connections, limit);
}
}
}
#endif /* !(NGX_WIN32) */
// 如果非master/worker进程，即只启动一个进程，那么就没必要使用负载均衡锁
if (ccf->master == 0) {
return NGX_OK;
}
// 已经有了负载均衡锁，已经初始化过了，就没必要再做操作
if (ngx_accept_mutex_ptr) {
return NGX_OK;
}
/* cl should be equal to or greater than cache line size */
// cl是一个基本长度，可以容纳原子变量
cl = 128;
// 最基本的三个：负载均衡锁，连接计数器,
size = cl /* ngx_accept_mutex */
+ cl /* ngx_connection_counter */
+ cl; /* ngx_temp_number */
// 其他统计用的原子变量
#if (NGX_STAT_STUB)
size += cl /* ngx_stat_accepted */
+ cl /* ngx_stat_handled */
+ cl /* ngx_stat_requests */
+ cl /* ngx_stat_active */
+ cl /* ngx_stat_reading */
+ cl /* ngx_stat_writing */
+ cl; /* ngx_stat_waiting */
#endif
// 创建共享内存，存放负载均衡锁和统计用的原子变量
shm.size = size;
shm.name.len = sizeof("nginx_shared_zone") - 1;
shm.name.data = (u_char *) "nginx_shared_zone";
shm.log = cycle->log;
if (ngx_shm_alloc(&shm) != NGX_OK) {
return NGX_ERROR;
}
// shared是共享内存的地址指针
shared = shm.addr;
// 第一个就是负载均衡锁
ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
ngx_accept_mutex.spin = (ngx_uint_t) -1;
if (ngx_shmtx_create(&ngx_accept_mutex, (ngx_shmtx_sh_t *) shared,
cycle->lock_file.data)
!= NGX_OK)
{
return NGX_ERROR;
}
// 连接计数器
ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl);
(void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1);
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"counter: %p, %uA",
ngx_connection_counter, *ngx_connection_counter);
// 临时文件用
ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl);
tp = ngx_timeofday();
// 随机数
ngx_random_number = (tp->msec << 16) + ngx_pid;
#if (NGX_STAT_STUB)
ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl);
ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl);
ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl);
ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl);
ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl);
ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl);
ngx_stat_waiting = (ngx_atomic_t *) (shared + 9 * cl);
#endif
return NGX_OK;
}
static ngx_int_t
ngx_event_module_init(ngx_cycle_t *cycle)
{
void ***cf;
u_char *shared;
size_t size, cl;
ngx_shm_t shm; //nginx多进程间的共享内存
ngx_time_t *tp;
ngx_core_conf_t *ccf;
ngx_event_conf_t *ecf;
// 获取使用的事件模块，如IOCP，epool
cf = ngx_get_conf(cycle->conf_ctx, ngx_events_module);
if (cf == NULL) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
"no \"events\" section in configuration");
return NGX_ERROR;
}
// 获取使用的事件模块ngx_event_core_module的配置
ecf = (*cf)[ngx_event_core_module.ctx_index];
if (!ngx_test_config && ngx_process <= NGX_PROCESS_MASTER) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
"using the \"%s\" event method", ecf->name);
}
// 获取ngx_core_module模块的配置
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
// 设置时间精度
ngx_timer_resolution = ccf->timer_resolution;
#if !(NGX_WIN32)
{
ngx_int_t limit;
struct rlimit rlmt;
if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"getrlimit(RLIMIT_NOFILE) failed, ignored");
} else {
if (ecf->connections > (ngx_uint_t) rlmt.rlim_cur // 检查连接上否已经超过上限
&& (ccf->rlimit_nofile == NGX_CONF_UNSET
|| ecf->connections > (ngx_uint_t) ccf->rlimit_nofile))
{
limit = (ccf->rlimit_nofile == NGX_CONF_UNSET) ?
(ngx_int_t) rlmt.rlim_cur : ccf->rlimit_nofile;
ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
"%ui worker_connections are more than "
"open file resource limit: %i",
ecf->connections, limit);
}
}
}
#endif /* !(NGX_WIN32) */
// 检查master进程是否关闭。如果master进程关闭了，就是单进程方式了。下面步骤是实现内存实现锁等，单进程不需要。
if (ccf->master == 0) {
return NGX_OK;
}
if (ngx_accept_mutex_ptr) { // 已经存在accept互斥体了，不需要再重复创建
return NGX_OK;
}
/* cl should be equal or bigger than cache line size */
cl = 128;
// 创建共享内存，用于accept mutex，connection counter和ngx_temp_number
size = cl /* ngx_accept_mutex */
+ cl /* ngx_connection_counter */
+ cl; /* ngx_temp_number */
#if (NGX_STAT_STUB)
size += cl /* ngx_stat_accepted */
+ cl /* ngx_stat_handled */
+ cl /* ngx_stat_requests */
+ cl /* ngx_stat_active */
+ cl /* ngx_stat_reading */
+ cl; /* ngx_stat_writing */
#endif
shm.size = size;
shm.name.len = sizeof("nginx_shared_zone");
shm.name.data = (u_char *) "nginx_shared_zone";
shm.log = cycle->log;
// 创建共享内存，共享内存的起始地址保存在shm.addr
if (ngx_shm_alloc(&shm) != NGX_OK) {
return NGX_ERROR;
}
// 获得共享内存的起始地址
shared = shm.addr;
// accept互斥体取得共享内存的第一段cl大小内存
ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
ngx_accept_mutex.spin = (ngx_uint_t) -1;
// 系统支持原子数据则使用原子数据实现accept mutex，否则使用文件上锁实现
if (ngx_shmtx_create(&ngx_accept_mutex, shared, cycle->lock_file.data)
!= NGX_OK)
{
return NGX_ERROR;
}
// ngx_connection_counter指到共享内存那
ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl);
(void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1);
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"counter: %p, %d",
ngx_connection_counter, *ngx_connection_counter);
ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl);
tp = ngx_timeofday();
//根据当前时间和进程ID，获取一个随机数
ngx_random_number = (tp->msec << 16) + ngx_pid;
#if (NGX_STAT_STUB)
ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl);
ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl);
ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl);
ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl);
ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl);
ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl);
#endif
return NGX_OK;
}
int msg_refcount_invalidate_if_zero(nchan_msg_t *msg) {
return ngx_atomic_cmp_set((ngx_atomic_uint_t *)&msg->refcount, 0, MSG_REFCOUNT_INVALID);
}
/**
* @param [in] mtx 锁对象
* @return 0|1
* 非阻塞尝试获取mtx锁
*/
ngx_uint_t
ngx_shmtx_trylock(ngx_shmtx_t *mtx)
{
return (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid));
}
void
ngx_shmtx_lock(ngx_shmtx_t *mtx)
{
ngx_uint_t i, n;
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0, "shmtx lock");
for ( ;; ) {
if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) {
return;
}
if (ngx_ncpu > 1) {
for (n = 1; n < mtx->spin; n <<= 1) {
for (i = 0; i < n; i++) {
ngx_cpu_pause();
}
if (*mtx->lock == 0
&& ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid))
{
return;
}
}
}
#if (NGX_HAVE_POSIX_SEM)
if (mtx->semaphore) {
(void) ngx_atomic_fetch_add(mtx->wait, 1);
if (*mtx->lock == 0 && ngx_atomic_cmp_set(mtx->lock, 0, ngx_pid)) {
(void) ngx_atomic_fetch_add(mtx->wait, -1);
return;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx wait %uA", *mtx->wait);
while (sem_wait(&mtx->sem) == -1) {
ngx_err_t err;
err = ngx_errno;
if (err != NGX_EINTR) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, err,
"sem_wait() failed while waiting on shmtx");
break;
}
}
ngx_log_debug0(NGX_LOG_DEBUG_CORE, ngx_cycle->log, 0,
"shmtx awoke");
continue;
}
#endif
ngx_sched_yield();
}
}
/*
ngx_event_module_init方法其实很简单，它主要初始化了一些变量，尤其是ngx_http_stub_status_module统计模块使用的一些原子性的统计变量
*/
static ngx_int_t
ngx_event_module_init(ngx_cycle_t *cycle)
{
void ***cf;
u_char *shared;
size_t size, cl;
ngx_shm_t shm;
ngx_time_t *tp;
ngx_core_conf_t *ccf;
ngx_event_conf_t *ecf;
cf = ngx_get_conf(cycle->conf_ctx, ngx_events_module);
ecf = (*cf)[ngx_event_core_module.ctx_index];
if (!ngx_test_config && ngx_process <= NGX_PROCESS_MASTER) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
"using the \"%s\" event method", ecf->name);
}
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
ngx_timer_resolution = ccf->timer_resolution;
#if !(NGX_WIN32)
{
ngx_int_t limit;
struct rlimit rlmt;
if (getrlimit(RLIMIT_NOFILE, &rlmt) == -1) { // 每个进程能打开的最多文件数。
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"getrlimit(RLIMIT_NOFILE) failed, ignored");
} else {
if (ecf->connections > (ngx_uint_t) rlmt.rlim_cur
&& (ccf->rlimit_nofile == NGX_CONF_UNSET
|| ecf->connections > (ngx_uint_t) ccf->rlimit_nofile))
{
limit = (ccf->rlimit_nofile == NGX_CONF_UNSET) ?
(ngx_int_t) rlmt.rlim_cur : ccf->rlimit_nofile;
ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
"%ui worker_connections exceed "
"open file resource limit: %i",
ecf->connections, limit);
}
}
}
#endif /* !(NGX_WIN32) */
if (ccf->master == 0) {
return NGX_OK;
}
if (ngx_accept_mutex_ptr) {
return NGX_OK;
}
/* cl should be equal to or greater than cache line size */
/*
计算出需要使用的共享内存的大小。为什么每个统计成员需要使用128字节呢？这似乎太大了，看上去，每个ngx_atomic_t原子变量最多需要8字
节而已。其实是因为Nginx充分考虑了CPU的二级缓存。在目前许多CPU架构下缓存行的大小都是128字节，而下面需要统计的变量都是访问非常频
繁的成员，同时它们占用的内存又非常少，所以采用了每个成员都使用128字节存放的形式，这样速度更快
*/
cl = 128;
size = cl /* ngx_accept_mutex */
+ cl /* ngx_connection_counter */
+ cl; /* ngx_temp_number */
#if (NGX_STAT_STUB)
size += cl /* ngx_stat_accepted */
+ cl /* ngx_stat_handled */
+ cl /* ngx_stat_requests */
+ cl /* ngx_stat_active */
+ cl /* ngx_stat_reading */
+ cl /* ngx_stat_writing */
+ cl; /* ngx_stat_waiting */
#endif
shm.size = size;
shm.name.len = sizeof("nginx_shared_zone") - 1;
shm.name.data = (u_char *) "nginx_shared_zone";
shm.log = cycle->log;
//开辟一块共享内存，共享内存的大小为shm.size
if (ngx_shm_alloc(&shm) != NGX_OK) {
return NGX_ERROR;
}
//共享内存的首地址就在shm.addr成员中
shared = shm.addr;
//原子变量类型的accept锁使用了128字节的共享内存
ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
/*
ngx_accept_mutex就是负载均衡锁，spin值为-1则是告诉Nginx这把锁不可以使进程进入睡眠状态，详见14.8节
*/
ngx_accept_mutex.spin = (ngx_uint_t) -1;
if (ngx_shmtx_create(&ngx_accept_mutex, (ngx_shmtx_sh_t *) shared,
cycle->lock_file.data)
!= NGX_OK)
{
return NGX_ERROR;
}
//原予变量类型的ngx_connection counter将统计所有建立过的连接数（包括主动发起的连接）
ngx_connection_counter = (ngx_atomic_t *) (shared + 1 * cl);
(void) ngx_atomic_cmp_set(ngx_connection_counter, 0, 1);
ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"counter: %p, %d",
ngx_connection_counter, *ngx_connection_counter);
ngx_temp_number = (ngx_atomic_t *) (shared + 2 * cl);
tp = ngx_timeofday();
ngx_random_number = (tp->msec << 16) + ngx_pid;
#if (NGX_STAT_STUB)
//依次初始化需要统计的6个原子变量，也就是使用共享内存作为原子变量
ngx_stat_accepted = (ngx_atomic_t *) (shared + 3 * cl);
ngx_stat_handled = (ngx_atomic_t *) (shared + 4 * cl);
ngx_stat_requests = (ngx_atomic_t *) (shared + 5 * cl);
ngx_stat_active = (ngx_atomic_t *) (shared + 6 * cl);
ngx_stat_reading = (ngx_atomic_t *) (shared + 7 * cl);
ngx_stat_writing = (ngx_atomic_t *) (shared + 8 * cl);
ngx_stat_waiting = (ngx_atomic_t *) (shared + 9 * cl);
#endif
return NGX_OK;
}
void ngx_process_get_status()
{
int status;
char *process;
ngx_pid_t pid;
ngx_err_t err;
ngx_int_t i;
ngx_uint_t one;
struct timeval tv;
one = 0;
for ( ;; ) {
pid = waitpid(-1, &status, WNOHANG);
if (pid == 0) {
return;
}
if (pid == -1) {
err = ngx_errno;
if (err == NGX_EINTR) {
continue;
}
if (err == NGX_ECHILD && one) {
return;
}
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, errno,
"waitpid() failed");
return;
}
if (ngx_accept_mutex_ptr) {
/*
* unlock the accept mutex if the abnormally exited process
* held it
*/
ngx_atomic_cmp_set(ngx_accept_mutex_ptr, pid, 0);
}
one = 1;
process = "unknown process";
for (i = 0; i < ngx_last_process; i++) {
if (ngx_processes[i].pid == pid) {
ngx_processes[i].status = status;
ngx_processes[i].exited = 1;
process = ngx_processes[i].name;
break;
}
}
if (WTERMSIG(status)) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s " PID_T_FMT " exited on signal %d%s",
process, pid, WTERMSIG(status),
WCOREDUMP(status) ? " (core dumped)" : "");
} else {
ngx_log_error(NGX_LOG_INFO, ngx_cycle->log, 0,
"%s " PID_T_FMT " exited with code %d",
process, pid, WEXITSTATUS(status));
}
if (WEXITSTATUS(status) == 2 && ngx_processes[i].respawn) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s " PID_T_FMT
" exited with fatal code %d and could not respawn",
process, pid, WEXITSTATUS(status));
ngx_processes[i].respawn = 0;
}
}
}
