第 12 章： 事件

Redis 的文件事件处理器的四个组成部分。

digraph { label = "\n 图 12-1 文件事件处理器的四个组成部分"; rankdir = LR; node [shape = box]; subgraph cluster_sockets { style = dashed label = "套接字"; c1 [label = "s1", shape = circle]; c2 [label = "s2", shape = circle]; other_client [label = "...", width = 1.1, shape = plaintext]; c3 [label = "sN", shape = circle]; } io_multiplexing [label = "I\n/\nO\n多\n路\n复\n用\n程\n序"]; file_event_processor [label = "文\n件\n事\n件\n分\n派\n器"]; subgraph cluster_handlers { style = dashed label = "事件处理器"; write_handler [label = "命令请求处理器"]; read_handler [label = "命令回复处理器"]; connect_handler [label = "连接应答处理器"]; other_handlers [label = "...", width = 1.6]; } c1 -> io_multiplexing; c2 -> io_multiplexing; other_client -> io_multiplexing [style = invis]; c3 -> io_multiplexing; io_multiplexing -> file_event_processor; file_event_processor -> write_handler; file_event_processor -> read_handler; file_event_processor -> connect_handler; file_event_processor -> other_handlers; }

I/O 多路复用程序通过队列向文件事件分派器传送套接字的过程。

digraph { rankdir = LR; node [shape = record]; label = "\n图 12-2 I/O 多路复用程序通过队列向文件事件分派器传送套接字"; // subgraph cluster_io_multiplexing { //style = dashed label = "队列"; queue [label = " { 套接字 sN | 套接字 sN-1 | ... | 套接字 s3 | 套接字 s2 } "]; } file_event_processor [label = "文\n件\n事\n件\n分\n派\n器"]; // queue -> file_event_processor [label = "传送\n 套接字 s1", style = dashed]; }

Redis 的 I/O 多路复用程序有多个 I/O 多路复用库可选。

digraph { label = "图 12-3 Redis 的 I/O 多路复用程序有多个 I/O 多路复用库实现可选"; node [shape = box]; io_multiplexing [label = "I/O 多路复用程序"]; subgraph cluster_imp { style = dashed label = "底层实现"; labelloc = "b"; kqueue [label = "kqueue"]; evport [label = "evport"]; epoll [label = "epoll"]; select [label = "select"]; } // edge [dir = back]; io_multiplexing -> select; io_multiplexing -> epoll; io_multiplexing -> evport; io_multiplexing -> kqueue; }

客户端与服务器通过事件应答来进行通信的过程。

digraph { label = "\n图 12-7 客户端和服务器的通讯过程"; splines = polyline; rankdir = LR; node [shape = box, height = 3.0]; client [label = "客\n户\n端"]; server [label = "服\n务\n器"]; client -> server [label = "客户端向服务器发送连接请求\n服务器执行连接应答处理器"]; client -> server [label = "\n\n客户端向服务器发送命令请求\n服务器执行命令请求处理器"]; server -> client [label = "\n\n服务器向客户端发送命令回复\n服务器执行命令回复处理器"]; }

时间事件示例。

digraph { label = "\n图 12-8 用链表连接起来的三个时间事件"; rankdir = LR; node [shape = record]; time_events [shape = plaintext]; te3 [label = "time_event | id\n3 | when\n1385877600030\n（2013年12月1日\n零时之后30毫秒） | timeProc\nhandler_3"]; te2 [label = "time_event | id\n2 | when\n1385877600000\n（2013年12月1日\n零时） | timeProc\nhandler_2"]; te1 [label = "time_event | id\n1 | when\n1385877600010\n（2013年12月1日\n零时之后10毫秒） | timeProc\nhandler_1"]; time_events -> te3 -> te2 -> te1; }

事件处理角度下的 Redis 服务器运行流程。

digraph { label = "\n图 12-10 事件处理角度下的服务器运行流程"; start_server [label = "启动服务器", shape = box]; server_close_or_not [label = "是否关闭服务器？", shape = diamond]; start_server -> server_close_or_not; close_server [label = "关闭服务器", shape = box]; wait_for_file_event [label = "等待文件事件产生", shape = box]; handler_file_event [label = "处理已产生的文件事件", shape = box]; handler_time_event [label = "处理已达到的时间事件", shape = box]; wait_for_file_event -> handler_file_event -> handler_time_event; // server_close_or_not -> close_server [label = "是"]; server_close_or_not -> wait_for_file_event [label = "否"]; handler_time_event -> server_close_or_not [label = "开始新的事件循环"]; }