Twemproxy source analysis of the five: zero copy

The data structure of MSG is given first:

Truct MSG {tailq_entry (msg) C_TQE; tailq_entry (msg) S_TQE; tailq_entry (msg) M_TQE;      uint64_t              Id                  int                  route_ Idx          struct msg            *peer;              struct Conn           *owner;               struct Rbnode         tmo_rbe;             struct MHDR           mhdr;                 uint32_t             mlen;                 int                   state;              uint8_t               *pos;                uint8_t               *token;               msg_parse_t           parser;              msg_parse_result_t    Result               mbuf_copy_t          pre_splitcopy;      msg_post_splitcopy_t post_splitcopy;      msg_coalesce_t       pre_coalesce;        msg_coalesce_t       post_coalesce;       msg_type_t           type ;                 uint8_t               *key_start;          uint8_t               *key_end;             uint32_t              vlen;                 uint8_t               *end;                 uint8_t               *narg_start;        uint8_t               *narg_end;          uint32_t              narg;                uint32_t              rnarg;              uint32_t              rlen;                 uint32_t              integer;             struct msg            *frag_owner;        uint32_t              nfrag;              uint64_t              frag_id;             err_t                 err;                unsigned              error:1;            unsigned              ferror:1;            unsigned              request:1;          unsigned              quit:1;              unsigned              noreply:1;          unsigned              done:1;              unsigned              fdone:1;            unsigned             first_fragment:1;    unsigned              last_fragment:1;     unsigned             swallow:1;          unsigned              redis:1;

See these three members of Tailq_entry (msg) C_TQE;tailq_entry (msg) S_TQE; tailq_entry (msg) M_TQE; C_TQE is an input or output queue that is used to insert input into the conn of the client type or output queue s_tqe is used to insert into the conn of the type of server (that is, Conn that connects to the back-end Redis server) m_ TQE is used to insert into a send-to column (a send queue corresponding to a remote or client or redisinstance) in the input or output queue of the specific insertion and deletion process see the previous article.

Twemproxy source analysis of the five: zero copy