Swoole 源码分析——Client模块之Send

前言

上一章我们说了客户端的连接 connect，对于同步客户端来说，连接已经建立成功；但是对于异步客户端来说，此时可能还在进行 DNS 的解析，onConnect 回调函数还未执行。

本节中，我们将继续说明客户端发送数据的流程，同时我们可以看到 TCP 异步客户端执行 onConnect 回调函数的过程。

send 入口

本入口函数逻辑非常简单，从 PHP 函数中获取数据 data，然后调用 connect 函数。

static PHP_METHOD(swoole_client, send)
{
    char *data;
    zend_size_t data_len;
    zend_long flags = 0;

#ifdef FAST_ZPP
    ZEND_PARSE_PARAMETERS_START(1, 2)
        Z_PARAM_STRING(data, data_len)
        Z_PARAM_OPTIONAL
        Z_PARAM_LONG(flags)
    ZEND_PARSE_PARAMETERS_END();
#else
    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &data, &data_len, &flags) == FAILURE)
    {
        return;
    }
#endif

    swClient *cli = client_get_ptr(getThis() TSRMLS_CC);

    //clear errno
    SwooleG.error = 0;
    int ret = cli->send(cli, data, data_len, flags);
    if (ret < 0)
    {
        swoole_php_sys_error(E_WARNING, "failed to send(%d) %zd bytes.", cli->socket->fd, data_len);
        zend_update_property_long(swoole_client_class_entry_ptr, getThis(), SW_STRL("errCode")-1, SwooleG.error TSRMLS_CC);
        RETVAL_FALSE;
    }
    else
    {
        RETURN_LONG(ret);
    }
}

swClient_tcp_send_sync 同步 TCP 客户端

对于同步客户端来说，发送数据是通过 swConnection_send 函数来进行阻塞式调用 send，当返回的错误是 EAGAIN 的时候调用 swSocket_wait 等待 1s。

static int swClient_tcp_send_sync(swClient *cli, char *data, int length, int flags)
{
    int written = 0;
    int n;

    assert(length > 0);
    assert(data != NULL);

    while (written < length)
    {
        n = swConnection_send(cli->socket, data, length - written, flags);
        if (n < 0)
        {
            if (errno == EINTR)
            {
                continue;
            }
            else if (errno == EAGAIN)
            {
                swSocket_wait(cli->socket->fd, 1000, SW_EVENT_WRITE);
                continue;
            }
            else
            {
                SwooleG.error = errno;
                return SW_ERR;
            }
        }
        written += n;
        data += n;
    }
    return written;
}

swClient_tcp_send_async 异步 TCP 客户端

由于异步客户端已经设置为非阻塞，并且加入了 reactor 的监控，因此发送数据只需要 reactor->write 函数即可。当此时的套接字不可写的时候，会自动放入 out_buff 缓冲区中。

当 out_buffer 大于高水线时，会自动调用 onBufferFull 回调函数。

static int swClient_tcp_send_async(swClient *cli, char *data, int length, int flags)
{
    int n = length;
    if (cli->reactor->write(cli->reactor, cli->socket->fd, data, length) < 0)
    {
        if (SwooleG.error == SW_ERROR_OUTPUT_BUFFER_OVERFLOW)
        {
            n = -1;
            cli->socket->high_watermark = 1;
        }
        else
        {
            return SW_ERR;
        }
    }
    if (cli->onBufferFull && cli->socket->out_buffer && cli->socket->high_watermark == 0
            && cli->socket->out_buffer->length >= cli->buffer_high_watermark)
    {
        cli->socket->high_watermark = 1;
        cli->onBufferFull(cli);
    }
    return n;
}

swClient_udp_send UDP 客户端

对于 UDP 客户端来说，如果 Socket 缓存区塞满，并不会像 TCP 进行等待 reactor 可写状态，而是直接返回了结果。对于异步客户端来说，仅仅是非阻塞调用 sendto 函数。

static int swClient_udp_send(swClient *cli, char *data, int len, int flags)
{
    int n;
    n = sendto(cli->socket->fd, data, len, 0, (struct sockaddr *) &cli->server_addr.addr, cli->server_addr.len);
    if (n < 0 || n < len)
    {
        return SW_ERR;
    }
    else
    {
        return n;
    }
}

sendto UDP 客户端

类似于 send 函数，sendto 函数专门针对 UDP 客户端，与 send 函数不同的是，sendto 函数在底层套接字缓冲区塞满的时候，会调用 swSocket_wait 进行阻塞等待。

static PHP_METHOD(swoole_client, sendto)
{
    char* ip;
    zend_size_t ip_len;
    long port;
    char *data;
    zend_size_t len;

    if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "sls", &ip, &ip_len, &port, &data, &len) == FAILURE)
    {
        return;
    }

    swClient *cli = (swClient *) swoole_get_object(getThis());

    int ret;
    if (cli->type == SW_SOCK_UDP)
    {
        ret = swSocket_udp_sendto(cli->socket->fd, ip, port, data, len);
    }
    else if (cli->type == SW_SOCK_UDP6)
    {
        ret = swSocket_udp_sendto6(cli->socket->fd, ip, port, data, len);
    }
    else
    {
        swoole_php_fatal_error(E_WARNING, "only supports SWOOLE_SOCK_UDP or SWOOLE_SOCK_UDP6.");
        RETURN_FALSE;
    }
    SW_CHECK_RETURN(ret);
}

int swSocket_udp_sendto(int server_sock, char *dst_ip, int dst_port, char *data, uint32_t len)
{
    struct sockaddr_in addr;
    if (inet_aton(dst_ip, &addr.sin_addr) == 0)
    {
        swWarn("ip[%s] is invalid.", dst_ip);
        return SW_ERR;
    }
    addr.sin_family = AF_INET;
    addr.sin_port = htons(dst_port);
    return swSocket_sendto_blocking(server_sock, data, len, 0, (struct sockaddr *) &addr, sizeof(addr));
}

int swSocket_udp_sendto6(int server_sock, char *dst_ip, int dst_port, char *data, uint32_t len)
{
    struct sockaddr_in6 addr;
    bzero(&addr, sizeof(addr));
    if (inet_pton(AF_INET6, dst_ip, &addr.sin6_addr) < 0)
    {
        swWarn("ip[%s] is invalid.", dst_ip);
        return SW_ERR;
    }
    addr.sin6_port = (uint16_t) htons(dst_port);
    addr.sin6_family = AF_INET6;
    return swSocket_sendto_blocking(server_sock, data, len, 0, (struct sockaddr *) &addr, sizeof(addr));
}

int swSocket_sendto_blocking(int fd, void *__buf, size_t __n, int flag, struct sockaddr *__addr, socklen_t __addr_len)
{
    int n = 0;

    while (1)
    {
        n = sendto(fd, __buf, __n, flag, __addr, __addr_len);
        if (n >= 0)
        {
            break;
        }
        else
        {
            if (errno == EINTR)
            {
                continue;
            }
            else if (swConnection_error(errno) == SW_WAIT)
            {
                swSocket_wait(fd, 1000, SW_EVENT_WRITE);
                continue;
            }
            else
            {
                break;
            }
        }
    }

    return n;
}

swClient_onWrite 写就绪状态

当 reactor 监控到套接字进入了写就绪状态时，就会调用 swClient_onWrite 函数。

从上一章我们知道，异步客户端建立连接过程中 swoole 调用了 connect 函数，该返回 0，或者返回错误码 EINPROGRESS 都会对写就绪进行监控。无论哪种情况，swClient_onWrite 被调用就说明此时连接已经建立成功，三次握手已经完成，但是 cli->socket->active 还是 0。

如果 cli->socket->active 为 0，说明此时异步客户端虽然建立了连接，但是还没有调用 onConnect 回调函数，因此这时要调用 execute_onConnect 函数。如果使用了 SSL 隧道加密，还要进行 SSL 握手，并且设置 _socket->ssl_state = SW_SSL_STATE_WAIT_STREAM。

当 active 为 1 的时候，就可以调用 swReactor_onWrite 来发送数据。

static int swClient_onWrite(swReactor *reactor, swEvent *event)
{
    swClient *cli = event->socket->object;
    swConnection *_socket = cli->socket;

    if (cli->socket->active)
    {
#ifdef SW_USE_OPENSSL
        if (cli->open_ssl && _socket->ssl_state == SW_SSL_STATE_WAIT_STREAM)
        {
            if (swClient_ssl_handshake(cli) < 0)
            {
                goto connect_fail;
            }
            else if (_socket->ssl_state == SW_SSL_STATE_READY)
            {
                goto connect_success;
            }
            else
            {
                if (_socket->ssl_want_read)
                {
                    cli->reactor->set(cli->reactor, event->fd, SW_FD_STREAM_CLIENT | SW_EVENT_READ);
                }
                return SW_OK;
            }
        }
#endif
        if (swReactor_onWrite(cli->reactor, event) < 0)
        {
            return SW_ERR;
        }
        if (cli->onBufferEmpty && _socket->high_watermark && _socket->out_buffer->length <= cli->buffer_low_watermark)
        {
            _socket->high_watermark = 0;
            cli->onBufferEmpty(cli);
        }
        return SW_OK;
    }

    socklen_t len = sizeof(SwooleG.error);
    if (getsockopt(event->fd, SOL_SOCKET, SO_ERROR, &SwooleG.error, &len) < 0)
    {
        swWarn("getsockopt(%d) failed. Error: %s[%d]", event->fd, strerror(errno), errno);
        return SW_ERR;
    }

    //success
    if (SwooleG.error == 0)
    {
        //listen read event
        cli->reactor->set(cli->reactor, event->fd, SW_FD_STREAM_CLIENT | SW_EVENT_READ);
        //connected
        _socket->active = 1;
        
#ifdef SW_USE_OPENSSL
        if (cli->open_ssl)
        {
            if (swClient_enable_ssl_encrypt(cli) < 0)
            {
                goto connect_fail;
            }
            if (swClient_ssl_handshake(cli) < 0)
            {
                goto connect_fail;
            }
            else
            {
                _socket->ssl_state = SW_SSL_STATE_WAIT_STREAM;
            }
            return SW_OK;
        }
        connect_success:
#endif
        if (cli->onConnect)
        {
            execute_onConnect(cli);
        }
    }
    else
    {
#ifdef SW_USE_OPENSSL
        connect_fail:
#endif
        _socket->active = 0;
        cli->close(cli);
        if (cli->onError)
        {
            cli->onError(cli);
        }
    }

    return SW_OK;
}

static sw_inline void execute_onConnect(swClient *cli)
{
    if (cli->timer)
    {
        swTimer_del(&SwooleG.timer, cli->timer);
        cli->timer = NULL;
    }
    cli->onConnect(cli);
}

client_onConnect

static void client_onConnect(swClient *cli)
{
    zval *zobject = (zval *) cli->object;
#ifdef SW_USE_OPENSSL
    if (cli->ssl_wait_handshake)
    {
        client_execute_callback(zobject, SW_CLIENT_CB_onSSLReady);
    }
    else
#endif
    if (!cli->redirect)
    {
        client_execute_callback(zobject, SW_CLIENT_CB_onConnect);
    }
    else
    {
        client_callback *cb = (client_callback *) swoole_get_property(zobject, 0);
        if (!cb || !cb->onReceive)
        {
            swoole_php_fatal_error(E_ERROR, "has no 'onReceive' callback function.");
        }
    }
}