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在nginx中，ngx_connection_t是对TCP连接的封装，包括已连接套接字、读事件、写事件
表示一个事件的数据结构
struct ngx_event_s {
void *data; // 通常指向ngx_connection_t
unsigned write:1; // 位域，表示事件可写
unsigned accept:1; // 只有监听套接字上的读事件的accept为1
/* used to detect the stale events in kqueue and epoll */
unsigned instance:1;
/*
* the event was passed or would be passed to a kernel;
* in aio mode - operation was posted.
*/
unsigned active:1;
unsigned disabled:1;
/* the ready event; in aio mode 0 means that no operation can be posted */
unsigned ready:1;
unsigned oneshot:1;
/* aio operation is complete */
unsigned complete:1;
unsigned eof:1;
unsigned error:1;
unsigned timedout:1;
unsigned timer_set:1;
unsigned delayed:1;
unsigned deferred_accept:1;
/* the pending eof reported by kqueue, epoll or in aio chain operation */
unsigned pending_eof:1;
unsigned posted:1;
unsigned closed:1;
/* to test on worker exit */
unsigned channel:1;
unsigned resolver:1;
unsigned cancelable:1;
#if (NGX_WIN32)
/* setsockopt(SO_UPDATE_ACCEPT_CONTEXT) was successful */
unsigned accept_context_updated:1;
#endif
#if (NGX_HAVE_KQUEUE)
unsigned kq_vnode:1;
/* the pending errno reported by kqueue */
int kq_errno;
#endif
/*
* kqueue only:
* accept: number of sockets that wait to be accepted
* read: bytes to read when event is ready
* or lowat when event is set with NGX_LOWAT_EVENT flag
* write: available space in buffer when event is ready
* or lowat when event is set with NGX_LOWAT_EVENT flag
*
* iocp: TODO
*
* otherwise:
* accept: 1 if accept many, 0 otherwise
*/
#if (NGX_HAVE_KQUEUE) || (NGX_HAVE_IOCP)
int available;
#else
unsigned available:1;
#endif
ngx_event_handler_pt handler; // 事件发生时的回调函数
#if (NGX_HAVE_IOCP)
ngx_event_ovlp_t ovlp;
#endif
ngx_uint_t index;
ngx_log_t *log;
ngx_rbtree_node_t timer;
/* the posted queue */
ngx_queue_t queue; // 加入ngx_posted_accept_events/ngx_posted_events队列
#if 0
/* the threads support */
/*
* the event thread context, we store it here
* if $(CC) does not understand __thread declaration
* and pthread_getspecific() is too costly
*/
void *thr_ctx;
#if (NGX_EVENT_T_PADDING)
/* event should not cross cache line in SMP */
uint32_t padding[NGX_EVENT_T_PADDING];
#endif
#endif
};表示一个连接的数据结构
struct ngx_connection_s {
void *data;
ngx_event_t *read; // 连接上的读事件
ngx_event_t *write; // 连接上的写事件
ngx_socket_t fd; // 已连接套接字，accept()的返回值
ngx_recv_pt recv;
ngx_send_pt send;
ngx_recv_chain_pt recv_chain;
ngx_send_chain_pt send_chain;
ngx_listening_t *listening; // 监听套接字，accept()的输入参数
off_t sent;
ngx_log_t *log;
ngx_pool_t *pool;
int type;
struct sockaddr *sockaddr; // 客户端的套接字地址结构
socklen_t socklen;
ngx_str_t addr_text;
ngx_str_t proxy_protocol_addr;
#if (NGX_SSL)
ngx_ssl_connection_t *ssl;
#endif
struct sockaddr *local_sockaddr; // 监听套接字地址结构
socklen_t local_socklen;
ngx_buf_t *buffer;
ngx_queue_t queue;
ngx_atomic_uint_t number;
ngx_uint_t requests;
unsigned buffered:8;
unsigned log_error:3; /* ngx_connection_log_error_e */
unsigned unexpected_eof:1;
unsigned timedout:1;
unsigned error:1;
unsigned destroyed:1;
unsigned idle:1;
unsigned reusable:1;
unsigned close:1;
unsigned shared:1;
unsigned sendfile:1;
unsigned sndlowat:1;
unsigned tcp_nodelay:2; /* ngx_connection_tcp_nodelay_e */
unsigned tcp_nopush:2; /* ngx_connection_tcp_nopush_e */
unsigned need_last_buf:1;
#if (NGX_HAVE_IOCP)
unsigned accept_context_updated:1;
#endif
#if (NGX_HAVE_AIO_SENDFILE)
unsigned busy_count:2;
#endif
#if (NGX_THREADS)
ngx_thread_task_t *sendfile_task;
#endif
};表示一个请求的数据结构
struct ngx_http_request_s {
uint32_t signature; /* "HTTP" */
ngx_connection_t *connection; // 请求对应的连接
void **ctx;
void **main_conf;
void **srv_conf;
void **loc_conf;
ngx_http_event_handler_pt read_event_handler;
ngx_http_event_handler_pt write_event_handler;
#if (NGX_HTTP_CACHE)
ngx_http_cache_t *cache;
#endif
ngx_http_upstream_t *upstream;
ngx_array_t *upstream_states;
/* of ngx_http_upstream_state_t */
ngx_pool_t *pool;
ngx_buf_t *header_in;
ngx_http_headers_in_t headers_in;
ngx_http_headers_out_t headers_out;
ngx_http_request_body_t *request_body;
time_t lingering_time;
time_t start_sec;
ngx_msec_t start_msec;
ngx_uint_t method;
ngx_uint_t http_version;
ngx_str_t request_line;
ngx_str_t uri;
ngx_str_t args;
ngx_str_t exten;
ngx_str_t unparsed_uri;
ngx_str_t method_name;
ngx_str_t http_protocol;
ngx_chain_t *out;
ngx_http_request_t *main;
ngx_http_request_t *parent;
ngx_http_postponed_request_t *postponed;
ngx_http_post_subrequest_t *post_subrequest;
ngx_http_posted_request_t *posted_requests;
ngx_int_t phase_handler;
ngx_http_handler_pt content_handler;
ngx_uint_t access_code;
ngx_http_variable_value_t *variables;
#if (NGX_PCRE)
ngx_uint_t ncaptures;
int *captures;
u_char *captures_data;
#endif
size_t limit_rate;
size_t limit_rate_after;
/* used to learn the Apache compatible response length without a header */
size_t header_size;
off_t request_length;
ngx_uint_t err_status;
ngx_http_connection_t *http_connection;
#if (NGX_HTTP_V2)
ngx_http_v2_stream_t *stream;
#endif
ngx_http_log_handler_pt log_handler;
ngx_http_cleanup_t *cleanup;
unsigned count:16;
unsigned subrequests:8;
unsigned blocked:8;
unsigned aio:1;
unsigned http_state:4;
/* URI with "/." and on Win32 with "//" */
unsigned complex_uri:1;
/* URI with "%" */
unsigned quoted_uri:1;
/* URI with "+" */
unsigned plus_in_uri:1;
/* URI with " " */
unsigned space_in_uri:1;
unsigned invalid_header:1;
unsigned add_uri_to_alias:1;
unsigned valid_location:1;
unsigned valid_unparsed_uri:1;
unsigned uri_changed:1;
unsigned uri_changes:4;
unsigned request_body_in_single_buf:1;
unsigned request_body_in_file_only:1;
unsigned request_body_in_persistent_file:1;
unsigned request_body_in_clean_file:1;
unsigned request_body_file_group_access:1;
unsigned request_body_file_log_level:3;
unsigned request_body_no_buffering:1;
unsigned subrequest_in_memory:1;
unsigned waited:1;
#if (NGX_HTTP_CACHE)
unsigned cached:1;
#endif
#if (NGX_HTTP_GZIP)
unsigned gzip_tested:1;
unsigned gzip_ok:1;
unsigned gzip_vary:1;
#endif
unsigned proxy:1;
unsigned bypass_cache:1;
unsigned no_cache:1;
/*
* instead of using the request context data in
* ngx_http_limit_conn_module and ngx_http_limit_req_module
* we use the single bits in the request structure
*/
unsigned limit_conn_set:1;
unsigned limit_req_set:1;
#if 0
unsigned cacheable:1;
#endif
unsigned pipeline:1;
unsigned chunked:1;
unsigned header_only:1;
unsigned keepalive:1;
unsigned lingering_close:1;
unsigned discard_body:1;
unsigned reading_body:1;
unsigned internal:1;
unsigned error_page:1;
unsigned filter_finalize:1;
unsigned post_action:1;
unsigned request_complete:1;
unsigned request_output:1;
unsigned header_sent:1;
unsigned expect_tested:1;
unsigned root_tested:1;
unsigned done:1;
unsigned logged:1;
unsigned buffered:4;
unsigned main_filter_need_in_memory:1;
unsigned filter_need_in_memory:1;
unsigned filter_need_temporary:1;
unsigned allow_ranges:1;
unsigned subrequest_ranges:1;
unsigned single_range:1;
unsigned disable_not_modified:1;
#if (NGX_STAT_STUB)
unsigned stat_reading:1;
unsigned stat_writing:1;
#endif
/* used to parse HTTP headers */
ngx_uint_t state;
ngx_uint_t header_hash;
ngx_uint_t lowcase_index;
u_char lowcase_header[NGX_HTTP_LC_HEADER_LEN];
u_char *header_name_start;
u_char *header_name_end;
u_char *header_start;
u_char *header_end;
/*
* a memory that can be reused after parsing a request line
* via ngx_http_ephemeral_t
*/
u_char *uri_start;
u_char *uri_end;
u_char *uri_ext;
u_char *args_start;
u_char *request_start;
u_char *request_end;
u_char *method_end;
u_char *schema_start;
u_char *schema_end;
u_char *host_start;
u_char *host_end;
u_char *port_start;
u_char *port_end;
unsigned http_minor:16;
unsigned http_major:16;
};