void dispatch_conn_new_to_thread(int tid, int sfd, enum conn_states init_state,
int event_flags, int read_buffer_size,
enum protocol prot,
enum network_transport transport,
conn_funcs *funcs, void *extra) {
assert(tid > 0);
assert(tid < settings.num_threads);
LIBEVENT_THREAD *thread = threads + tid;
CQ_ITEM *cq_item = cqi_new();
cq_item->sfd = sfd;
cq_item->init_state = init_state;
cq_item->event_flags = event_flags;
cq_item->read_buffer_size = read_buffer_size;
cq_item->protocol = prot;
cq_item->transport = transport;
cq_item->funcs = funcs;
cq_item->extra = extra;
cq_push(thread->new_conn_queue, cq_item);
MEMCACHED_CONN_DISPATCH(sfd, thread->thread_id);
if (write(thread->notify_send_fd, "", 1) != 1) {
perror("Writing to thread notify pipe");
}
}
/*
* Dispatches a new connection to another thread. This is only ever called
* from the main thread, either during initialization (for UDP) or because
* of an incoming connection.
*/
void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
CQ_ITEM *item = cqi_new();
char buf[1];
if (item == NULL) {
close(sfd);
/* given that malloc failed this may also fail, but let's try */
fprintf(stderr, "Failed to allocate memory for connection object\n");
return ;
}
int tid = (last_thread + 1) % settings.num_threads;
LIBEVENT_THREAD *thread = threads + tid;
last_thread = tid;
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
item->mode = queue_new_conn;
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, thread->thread_id);
buf[0] = 'c';
if (write(thread->notify_send_fd, buf, 1) != 1) {
perror("Writing to thread notify pipe");
}
}
/*
* Dispatches a new connection to another thread. This is only ever called
* from the main thread, either during initialization (for UDP) or because
* of an incoming connection.
*
* 分发新的连接到线程池中的一个线程中, 其实就是在一个线程的工作队列中加入一个
* 工作任务, 并通过管道给相应的线程发送信号
*
*/
void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
// CQ_ITEM connection queue item
CQ_ITEM *item = cqi_new();
char buf[1];
// 线程池中有多个线程, 每个线程都有一个工作队列, 线程所需要做的就是从工作队列中取出工作任务并执行, 只要队列为空线程就可以进入等待状态
// 计算线程信息下标
int tid = (last_thread + 1) % settings.num_threads;
// LIBEVENT_THREAD threads 是一个全局数组变量
LIBEVENT_THREAD *thread = threads + tid; // 定位到下一个线程信息,通过简单地轮放方式
last_thread = tid;
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
// 将工作任务放入对应线程的工作队列中
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, thread->thread_id);
// 有意思, 这里向一个熟睡的线程写了一个字符: char buf[1]
// 当管道中被写入数据后, libevent 中的注册事件会被触发, thread_libevent_process() 函数会被调用. 因为在 setup_thread() 中线程中管道描述符被设置到 event 中, 并注册到 libevent 中
buf[0] = 'c';
if (write(thread->notify_send_fd, buf, 1) != 1) {
perror("Writing to thread notify pipe");
}
}
/*
* Dispatches a new connection to another thread. This is only ever called
* from the main thread, either during initialization (for UDP) or because
* of an incoming connection.
*/
void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
CQ_ITEM *item = cqi_new();
char buf[1];
if (item == NULL) {
close(sfd);
/* given that malloc failed this may also fail, but let's try */
fprintf(stderr, "Failed to allocate memory for connection object\n");
return ;
}
int tid = (last_thread + 1) % settings.num_threads;
LIBEVENT_THREAD *thread = threads + tid;
last_thread = tid;
#ifdef DUP_AWARE
fprintf(stderr, "last_thread = %d, tid = %d\n", last_thread, tid);
#endif
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
item->priority = -1; // ignored unless DUP_AWARE
#ifdef DUP_AWARE
if (!IS_UDP(transport)) {
if (settings.num_threads != NUM_THREADS) {
fprintf(stderr, "settings.num_threads must be %d for duplicate awareness"
"to work in its current implementation. You specified %d "
"threads.", NUM_THREADS, settings.num_threads);
exit(1);
}
static int is_priority = NUM_THREADS;
// The first set of `num_thread` connections will all be primary, while any
// subsequent will be duplicate.
item->priority = (is_priority-- > 0) ? PRIMARY : DUPLICATE;
fprintf(stderr, "<%d item->priority is %s\n", sfd, (item->priority == PRIMARY) ? "PRIMARY" : "DUPLICATE");
}
#endif
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, thread->thread_id);
buf[0] = 'c';
if (write(thread->notify_send_fd, buf, 1) != 1) {
perror("Writing to thread notify pipe");
}
}
/*
* Dispatches a new connection to another thread. This is only ever called
* from the main thread, either during initialization (for UDP) or because
* of an incoming connection.
*/
void dispatch_conn_new(SOCKET sfd, STATE_FUNC init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
CQ_ITEM *item = cqi_new();
int tid = (last_thread + 1) % settings.num_threads;
LIBEVENT_THREAD *thread = threads + tid;
last_thread = tid;
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, (uintptr_t)thread->thread_id);
notify_thread(thread);
}
/*
* Dispatches a new connection to another thread. This is only ever called
* from the main thread, either during initialization (for UDP) or because
* of an incoming connection.
*/
void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
CQ_ITEM *item = cqi_new();
int tid = (last_thread + 1) % settings.num_threads;
LIBEVENT_THREAD *thread = threads + tid;
last_thread = tid;
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, thread->thread_id);
if (write(thread->notify_send_fd, "", 1) != 1) {
perror("Writing to thread notify pipe");
}
}
//将主线程的连接分发给worker线程
void dispatch_conn_new(int sfd, enum conn_states init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
//创建CQ_ITEM对象，封装了client_fd以及一些client连接信息
CQ_ITEM *item = cqi_new();
char buf[1];
if (item == NULL) {
close(sfd);
/* given that malloc failed this may also fail, but let's try */
fprintf(stderr, "Failed to allocate memory for connection object\n");
return ;
}
//通过轮询的方式选择worker线程
int tid = (last_thread + 1) % settings.num_threads;
LIBEVENT_THREAD *thread = threads + tid;
last_thread = tid;
//初始化CQ_ITEM对象
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
//将CQ_ITEM放入所选择的worker线程的CQ_ITEM队列中
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, thread->thread_id);
buf[0] = 'c';
//主线程向所选择的worker线程的管道中写入一个'c'字符，
//由于worker线程会监听管道的receive_fd, 于是会收到事件通知
//触发worker线程的事件处理函数thread_libevent_process
if (write(thread->notify_send_fd, buf, 1) != 1) {
perror("Writing to thread notify pipe");
}
}
/*
* Dispatches a new connection to another thread. This is only ever called
* from the main thread, either during initialization (for UDP) or because
* of an incoming connection.
*/
void dispatch_conn_new(int sfd, STATE_FUNC init_state, int event_flags,
int read_buffer_size, enum network_transport transport) {
CQ_ITEM *item = cqi_new();
int tid = (last_thread + 1) % settings.num_threads;
LIBEVENT_THREAD *thread = threads + tid;
last_thread = tid;
item->sfd = sfd;
item->init_state = init_state;
item->event_flags = event_flags;
item->read_buffer_size = read_buffer_size;
item->transport = transport;
cq_push(thread->new_conn_queue, item);
MEMCACHED_CONN_DISPATCH(sfd, (uintptr_t)thread->thread_id);
if (write(thread->notify_send_fd, "", 1) != 1) {
mc_logger->log(EXTENSION_LOG_WARNING, NULL,
"Writing to thread notify pipe: %s", strerror(errno));
}
}