- //memcached.h
- //返回在item中data字段key的地址，即把指针指向key
- #define ITEM_key(item) (((char*)&((item)->data)) \
- + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))
- //返回在item中data字段suffix的地址，即把指针指向suffix
- #define ITEM_suffix(item) ((char*) &((item)->data) + (item)->nkey + 1 \
- + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))
- //返回在item中data字段value的地址，即把指针指向value
- #define ITEM_data(item) ((char*) &((item)->data) + (item)->nkey + 1 \
- + (item)->nsuffix \
- + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))
- //item总字节数
- #define ITEM_ntotal(item) (sizeof(struct _stritem) + (item)->nkey + 1 \
- + (item)->nsuffix + (item)->nbytes \
- + (((item)->it_flags & ITEM_CAS) ? sizeof(uint64_t) : 0))
- //conn结构体中state字段的枚举，代表连接状态
- enum conn_states {
- conn_listening, /**< the socket which listens for connections */
- conn_new_cmd, /**< Prepare connection for next command */
- conn_waiting, /**< waiting for a readable socket */
- conn_read, /**< reading in a command line */
- conn_parse_cmd, /**< try to parse a command from the input buffer */
- conn_write, /**< writing out a simple response */
- conn_nread, /**< reading in a fixed number of bytes */
- conn_swallow, /**< swallowing unnecessary bytes w/o storing */
- conn_closing, /**< closing this connection */
- conn_mwrite, /**< writing out many items sequentially */
- conn_closed, /**< connection is closed */
- conn_max_state /**< Max state value (used for assertion) */
- };
- //item保存结果枚举
- enum store_item_type {
- NOT_STORED=0, STORED, EXISTS, NOT_FOUND
- };
- //item结构体
- typedef struct _stritem {
- struct _stritem *next; //链表中下一个，这个链表有可能是slots链表，也有可能是LRU链表，但一个item不可能同时这两个链表中，所以复用一个指针。
- struct _stritem *prev; //链表中上一个。
- struct _stritem *h_next; //相同hash值中链表的下一个。
- rel_time_t time; //最近访问时间
- rel_time_t exptime; //过期时间
- int nbytes; //value的字节数
- unsigned short refcount; //引用计数
- uint8_t nsuffix; //后缀长度
- uint8_t it_flags; //标记
- uint8_t slabs_clsid; //item所在的slabclass的id值
- uint8_t nkey; //键长
- /* this odd type prevents type-punning issues when we do
- * the little shuffle to save space when not using CAS. */
- union {
- uint64_t cas;
- char end;
- } data[]; //数据，这个数据不仅仅包括key对应的value，还有key、CAS、后缀等等数据也存在此，所以它有4部分“拼”成：CAS(可选)，KEY，后缀，VALUE。
- /* if it_flags & ITEM_CAS we have 8 bytes CAS */
- /* then null-terminated key */
- /* then " flags length\r\n" (no terminating null) */
- /* then data with terminating \r\n (no terminating null; it‘s binary!) */
- } item;
- /**
- worker线程结构体
- */
- typedef struct {
- pthread_t thread_id; //线程id
- struct event_base *base; //每个线程自己独立的event_base，监听的就是下面的notify_event事件对象
- struct event notify_event; //事件对象，fd即为下面的notify_receive_fd
- int notify_receive_fd; //管道接收fd
- int notify_send_fd; //管道写入fd
- struct thread_stats stats; //线程的一些统计
- struct conn_queue *new_conn_queue; //连接参数对象CQ_ITEM队列
- cache_t *suffix_cache;
- uint8_t item_lock_type; //控制线程锁的粒度
- } LIBEVENT_THREAD;
- /**
- 主线程结构体
- */
- typedef struct {
- pthread_t thread_id; //线程id
- struct event_base *base; //event_base
- } LIBEVENT_DISPATCHER_THREAD;
- typedef struct conn conn;
- struct conn {
- int sfd; //连接的socket fd
- sasl_conn_t *sasl_conn;
- bool authenticated;
- enum conn_states state; //当前的连接状态
- enum bin_substates substate;
- rel_time_t last_cmd_time;
- struct event event; // 监听的事件
- short ev_flags; //监听的事件 类型
- short which; /** which events were just triggered */ //刚触发的事件
- /**
- 读buffer会涉及两个方向上的“读”：
- 一个是从socket读进来到rbuf里面
- 一个是从rbuf里面把数据读出去解析，读buffer相当于一个中介，从socket读进来最终还是得被别人读出去解析，而
- rcurr工作指针与rbytes就是在rbuf数据被读出去解析的时候用到，用来控制可以读出去被解析的数据还剩余多少。
- */
- char *rbuf; /** buffer to read commands into */ //读buffer
- char *rcurr; /** but if we parsed some already, this is where we stopped */ //读buffer的当前指针
- int rsize; /** total allocated size of rbuf */ //读buffer大小
- int rbytes; /** how much data, starting from rcur, do we have unparsed */ //剩余buffer字节数
- //下面4个属性和上面4个类似
- char *wbuf;
- char *wcurr;
- int wsize;
- int wbytes;
- /** which state to go into after finishing current write */
- enum conn_states write_and_go; //完成当前写操作后，连接状态将会置为此状态
- void *write_and_free; /** free this memory after finishing writing */
- char *ritem; /** when we read in an item‘s value, it goes here */ //这个指针指向item结构体中data中的value地址
- int rlbytes; //尚未读完item的data的value的字节数
- void *item; /* for commands set/add/replace */ //当执行set/add/replace 命令时，此指针用于指向分配的item空间
- /* data for the swallow state */
- int sbytes; /* how many bytes to swallow */
- //下面是往socket写出数据时用的字段
- struct iovec *iov; //iovec结构体数组
- int iovsize; //*iov数组大小
- int iovused; //*iov数组已被使用的元素个数
- struct msghdr *msglist; //msghdr结构体数组，表示sendmsg要发送的消息列表
- int msgsize; //*msglist数组大小
- int msgused; //*msglist数组已使用的元素个数
- int msgcurr; //当前要发送的msghdr
- int msgbytes; //当前msghdr的字节数
- item **ilist; //get key1 key2命令时，要发送给客户端的item列表
- int isize; //列表大小
- item **icurr; //当前要发送的item
- int ileft; //剩余数目
- char **suffixlist;
- int suffixsize;
- char **suffixcurr;
- int suffixleft;
- enum protocol protocol; /* which protocol this connection speaks */
- enum network_transport transport; /* what transport is used by this connection */
- //UDP相关的字段
- int request_id; /* Incoming UDP request ID, if this is a UDP "connection" */
- struct sockaddr_in6 request_addr; /* udp: Who sent the most recent request */
- socklen_t request_addr_size;
- unsigned char *hdrbuf; /* udp packet headers */
- int hdrsize; /* number of headers‘ worth of space is allocated */
- bool noreply; /* True if the reply should not be sent. */
- /* current stats command */
- struct {
- char *buffer;
- size_t size;
- size_t offset;
- } stats;
- // 二进制相关的字段
- protocol_binary_request_header binary_header;
- uint64_t cas; /* the cas to return */
- short cmd; /* current command being processed */
- int opaque;
- int keylen;
- conn *next; /* Used for generating a list of conn structures */
- LIBEVENT_THREAD *thread; /* Pointer to the thread object serving this connection */
- };
- //非阻塞方式获取互斥锁
- static inline int mutex_lock(pthread_mutex_t *mutex)
- {
- while (pthread_mutex_trylock(mutex));
- return 0;
- }
- //释放锁
- #define mutex_unlock(x) pthread_mutex_unlock(x)
- #include "stats.h"
- #include "slabs.h"
- #include "assoc.h"
- #include "items.h"
- #include "trace.h"
- #include "hash.h"
- #include "util.h"
时间： 2024-08-24 04:07:35