core/ngx_cycle.c源文件分析(2)
本文我们讲述一下Nginx cycle运行上下文相关的实现。
1. 函数ngx_destroy_cycle_pools()
static void
ngx_destroy_cycle_pools(ngx_conf_t *conf)
{
ngx_destroy_pool(conf->temp_pool);
ngx_destroy_pool(conf->pool);
}这里销毁conf->temp_pool临时内存池与conf->pool.
2. 函数ngx_init_zone_pool()
static ngx_int_t
ngx_init_zone_pool(ngx_cycle_t *cycle, ngx_shm_zone_t *zn)
{
u_char *file;
ngx_slab_pool_t *sp;
sp = (ngx_slab_pool_t *) zn->shm.addr;
if (zn->shm.exists) {
if (sp == sp->addr) {
return NGX_OK;
}
#if (NGX_WIN32)
/* remap at the required address */
if (ngx_shm_remap(&zn->shm, sp->addr) != NGX_OK) {
return NGX_ERROR;
}
sp = (ngx_slab_pool_t *) zn->shm.addr;
if (sp == sp->addr) {
return NGX_OK;
}
#endif
ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
"shared zone \"%V\" has no equal addresses: %p vs %p",
&zn->shm.name, sp->addr, sp);
return NGX_ERROR;
}
sp->end = zn->shm.addr + zn->shm.size;
sp->min_shift = 3;
sp->addr = zn->shm.addr;
#if (NGX_HAVE_ATOMIC_OPS)
file = NULL;
#else
file = ngx_pnalloc(cycle->pool, cycle->lock_file.len + zn->shm.name.len);
if (file == NULL) {
return NGX_ERROR;
}
(void) ngx_sprintf(file, "%V%V%Z", &cycle->lock_file, &zn->shm.name);
#endif
if (ngx_shmtx_create(&sp->mutex, &sp->lock, file) != NGX_OK) {
return NGX_ERROR;
}
ngx_slab_init(sp);
return NGX_OK;
}注意这里cycle->shared_memory只适合于大块内存共享，因为这里会用一个相对复杂的结构来管理该共享内存，该结构本身也会占用共享内存的一部分空间。下面画出一个大体示意图：
上面首先为该共享内存块创建一个互斥锁。然后调用ngx_slab_init(sp)来建立对该共享内存块的管理机制。
3. 函数ngx_create_pidfile()
ngx_int_t
ngx_create_pidfile(ngx_str_t *name, ngx_log_t *log)
{
size_t len;
ngx_uint_t create;
ngx_file_t file;
u_char pid[NGX_INT64_LEN + 2];
if (ngx_process > NGX_PROCESS_MASTER) {
return NGX_OK;
}
ngx_memzero(&file, sizeof(ngx_file_t));
file.name = *name;
file.log = log;
create = ngx_test_config ? NGX_FILE_CREATE_OR_OPEN : NGX_FILE_TRUNCATE;
file.fd = ngx_open_file(file.name.data, NGX_FILE_RDWR,
create, NGX_FILE_DEFAULT_ACCESS);
if (file.fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
ngx_open_file_n " \"%s\" failed", file.name.data);
return NGX_ERROR;
}
if (!ngx_test_config) {
len = ngx_snprintf(pid, NGX_INT64_LEN + 2, "%P%N", ngx_pid) - pid;
if (ngx_write_file(&file, pid, len, 0) == NGX_ERROR) {
return NGX_ERROR;
}
}
if (ngx_close_file(file.fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_close_file_n " \"%s\" failed", file.name.data);
}
return NGX_OK;
}这里会根据pid指令设定的文件名称创建文件，然后向该文件中写入master进程的进程ID:
len = ngx_snprintf(pid, NGX_INT64_LEN + 2, "%P%N", ngx_pid) - pid;
这里%P的意思是打印ngx_pid_t类型；而%N是打印换行。
4. 函数ngx_delete_pidfile()
void
ngx_delete_pidfile(ngx_cycle_t *cycle)
{
u_char *name;
ngx_core_conf_t *ccf;
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
name = ngx_new_binary ? ccf->oldpid.data : ccf->pid.data;
if (ngx_delete_file(name) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
ngx_delete_file_n " \"%s\" failed", name);
}
}这里删除进程的PID文件。如果是处于升级过程，删除oldpid。
5. 函数ngx_signal_process()
ngx_int_t
ngx_signal_process(ngx_cycle_t *cycle, char *sig)
{
ssize_t n;
ngx_pid_t pid;
ngx_file_t file;
ngx_core_conf_t *ccf;
u_char buf[NGX_INT64_LEN + 2];
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "signal process started");
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
ngx_memzero(&file, sizeof(ngx_file_t));
file.name = ccf->pid;
file.log = cycle->log;
file.fd = ngx_open_file(file.name.data, NGX_FILE_RDONLY,
NGX_FILE_OPEN, NGX_FILE_DEFAULT_ACCESS);
if (file.fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_ERR, cycle->log, ngx_errno,
ngx_open_file_n " \"%s\" failed", file.name.data);
return 1;
}
n = ngx_read_file(&file, buf, NGX_INT64_LEN + 2, 0);
if (ngx_close_file(file.fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed", file.name.data);
}
if (n == NGX_ERROR) {
return 1;
}
while (n-- && (buf[n] == CR || buf[n] == LF)) { /* void */ }
pid = ngx_atoi(buf, ++n);
if (pid == (ngx_pid_t) NGX_ERROR) {
ngx_log_error(NGX_LOG_ERR, cycle->log, 0,
"invalid PID number \"%*s\" in \"%s\"",
n, buf, file.name.data);
return 1;
}
return ngx_os_signal_process(cycle, sig, pid);
}这里首先打开进程的PID文件以获得进程id，然后向该进程发送名称为sig的信号。
6. 函数ngx_test_lockfile()
static ngx_int_t
ngx_test_lockfile(u_char *file, ngx_log_t *log)
{
#if !(NGX_HAVE_ATOMIC_OPS)
ngx_fd_t fd;
fd = ngx_open_file(file, NGX_FILE_RDWR, NGX_FILE_CREATE_OR_OPEN,
NGX_FILE_DEFAULT_ACCESS);
if (fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
ngx_open_file_n " \"%s\" failed", file);
return NGX_ERROR;
}
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_close_file_n " \"%s\" failed", file);
}
if (ngx_delete_file(file) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
ngx_delete_file_n " \"%s\" failed", file);
}
#endif
return NGX_OK;
}nginx使用锁机制来实现accept mutex，并且顺序的来访问共享内存。在大多数的系统上，锁都是通过原子操作来实现的，因此会忽略配置文件中的lock_file file指令；而对于其他的一些系统，lock file机制会被使用。这里我们支持NGX_HAVE_ATOMIC_OPS。
7. 函数ngx_reopen_files()
void
ngx_reopen_files(ngx_cycle_t *cycle, ngx_uid_t user)
{
ngx_fd_t fd;
ngx_uint_t i;
ngx_list_part_t *part;
ngx_open_file_t *file;
part = &cycle->open_files.part;
file = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
file = part->elts;
i = 0;
}
if (file[i].name.len == 0) {
continue;
}
if (file[i].flush) {
file[i].flush(&file[i], cycle->log);
}
fd = ngx_open_file(file[i].name.data, NGX_FILE_APPEND,
NGX_FILE_CREATE_OR_OPEN, NGX_FILE_DEFAULT_ACCESS);
ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"reopen file \"%s\", old:%d new:%d",
file[i].name.data, file[i].fd, fd);
if (fd == NGX_INVALID_FILE) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_open_file_n " \"%s\" failed", file[i].name.data);
continue;
}
#if !(NGX_WIN32)
if (user != (ngx_uid_t) NGX_CONF_UNSET_UINT) {
ngx_file_info_t fi;
if (ngx_file_info((const char *) file[i].name.data, &fi)
== NGX_FILE_ERROR)
{
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_file_info_n " \"%s\" failed",
file[i].name.data);
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
continue;
}
if (fi.st_uid != user) {
if (chown((const char *) file[i].name.data, user, -1) == -1) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
"chown(\"%s\", %d) failed",
file[i].name.data, user);
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
continue;
}
}
if ((fi.st_mode & (S_IRUSR|S_IWUSR)) != (S_IRUSR|S_IWUSR)) {
fi.st_mode |= (S_IRUSR|S_IWUSR);
if (chmod((const char *) file[i].name.data, fi.st_mode) == -1) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
"chmod() \"%s\" failed", file[i].name.data);
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
continue;
}
}
}
if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
"fcntl(FD_CLOEXEC) \"%s\" failed",
file[i].name.data);
if (ngx_close_file(fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
continue;
}
#endif
if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
ngx_close_file_n " \"%s\" failed",
file[i].name.data);
}
file[i].fd = fd;
}
(void) ngx_log_redirect_stderr(cycle);
}这里重新打开cycle->open_files链表中指定的文件，设置打开文件的所有者为user,权限为所有者读写权限,并设置打开的文件CLOEXE属性，然后再关闭原来的fd。
值得注意的是，最后还调用了ngx_log_redirect_stderr()来重定向错误日志。这是因为我们对日志文件也做了reopen()操作，因此原来的日志句柄也发生了变化，需要进行重定向。
8. 函数ngx_shared_memory_add()
ngx_shm_zone_t *
ngx_shared_memory_add(ngx_conf_t *cf, ngx_str_t *name, size_t size, void *tag)
{
ngx_uint_t i;
ngx_shm_zone_t *shm_zone;
ngx_list_part_t *part;
part = &cf->cycle->shared_memory.part;
shm_zone = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
shm_zone = part->elts;
i = 0;
}
if (name->len != shm_zone[i].shm.name.len) {
continue;
}
if (ngx_strncmp(name->data, shm_zone[i].shm.name.data, name->len)
!= 0)
{
continue;
}
if (tag != shm_zone[i].tag) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"the shared memory zone \"%V\" is "
"already declared for a different use",
&shm_zone[i].shm.name);
return NULL;
}
if (shm_zone[i].shm.size == 0) {
shm_zone[i].shm.size = size;
}
if (size && size != shm_zone[i].shm.size) {
ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
"the size %uz of shared memory zone \"%V\" "
"conflicts with already declared size %uz",
size, &shm_zone[i].shm.name, shm_zone[i].shm.size);
return NULL;
}
return &shm_zone[i];
}
shm_zone = ngx_list_push(&cf->cycle->shared_memory);
if (shm_zone == NULL) {
return NULL;
}
shm_zone->data = NULL;
shm_zone->shm.log = cf->cycle->log;
shm_zone->shm.size = size;
shm_zone->shm.name = *name;
shm_zone->shm.exists = 0;
shm_zone->init = NULL;
shm_zone->tag = tag;
shm_zone->noreuse = 0;
return shm_zone;
}这里向cycle->shared_memory链表中添加共享内存数据结构： 首先检查是否已经有相同名字的共享内存块，有的话则返回已经存在共享内存块（tag要相同）； 否则插入到cycle->shared_memory链表中。
9. 函数ngx_clean_old_cycles()
static void
ngx_clean_old_cycles(ngx_event_t *ev)
{
ngx_uint_t i, n, found, live;
ngx_log_t *log;
ngx_cycle_t **cycle;
log = ngx_cycle->log;
ngx_temp_pool->log = log;
ngx_log_debug0(NGX_LOG_DEBUG_CORE, log, 0, "clean old cycles");
live = 0;
cycle = ngx_old_cycles.elts;
for (i = 0; i < ngx_old_cycles.nelts; i++) {
if (cycle[i] == NULL) {
continue;
}
found = 0;
for (n = 0; n < cycle[i]->connection_n; n++) {
if (cycle[i]->connections[n].fd != (ngx_socket_t) -1) {
found = 1;
ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0, "live fd:%ui", n);
break;
}
}
if (found) {
live = 1;
continue;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0, "clean old cycle: %ui", i);
ngx_destroy_pool(cycle[i]->pool);
cycle[i] = NULL;
}
ngx_log_debug1(NGX_LOG_DEBUG_CORE, log, 0, "old cycles status: %ui", live);
if (live) {
ngx_add_timer(ev, 30000);
} else {
ngx_destroy_pool(ngx_temp_pool);
ngx_temp_pool = NULL;
ngx_old_cycles.nelts = 0;
}
}这里是定时器的一个回调函数，用于清理old_cycle。这里清理时会检查cycle->connections，如果还有连接没有关闭，则暂时不对该cycle对应的pool进行清理。
