include/sbuf.h

   1 /*
   2  * PgBouncer - Lightweight connection pooler for PostgreSQL.
   3  *
   4  * Copyright (c) 2007-2009  Marko Kreen, Skype Technologies OÜ
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 /*
  20  * event types for protocol handler
  21  */
  22 typedef enum {
  23         SBUF_EV_READ,           /* got new packet */
  24         SBUF_EV_RECV_FAILED,    /* error */
  25         SBUF_EV_SEND_FAILED,    /* error */
  26         SBUF_EV_CONNECT_FAILED, /* error */
  27         SBUF_EV_CONNECT_OK,     /* got connection */
  28         SBUF_EV_FLUSH,          /* data is sent, buffer empty */
  29         SBUF_EV_PKT_CALLBACK,   /* next part of pkt data */
  30 } SBufEvent;
  31
  32 /*
  33  * If less that this amount of data is pending, then
  34  * prefer to merge it with next recv().
  35  *
  36  * It needs to be larger than data handler wants
  37  * to see completely.  Generally just header,
  38  * but currently also ServerParam pkt.
  39  */
  40 #define SBUF_SMALL_PKT  64
  41
  42 /* fwd def */
  43 typedef struct SBuf SBuf;
  44
  45 /* callback should return true if it used one of sbuf_prepare_* on sbuf,
  46    false if it used sbuf_pause(), sbuf_close() or simply wants to wait for
  47    next event loop (eg. too few data available). */
  48 typedef bool (*sbuf_cb_t)(SBuf *sbuf,
  49                         SBufEvent evtype,
  50                         MBuf *mbuf);
  51
  52 /* for some reason, libevent has no typedef for callback */
  53 typedef void (*sbuf_libevent_cb)(int, short, void *);
  54
  55 /*
  56  * Stream Buffer.
  57  *
  58  * Stream is divided to packets.  On each packet start
  59  * protocol handler is called that decides what to do.
  60  */
  61 struct SBuf {
  62         struct event ev;        /* libevent handle */
  63
  64         bool is_unix;           /* is it unix socket */
  65         uint8_t wait_type;      /* track wait state */
  66         uint8_t pkt_action;     /* method for handling current pkt */
  67
  68         int sock;               /* fd for this socket */
  69
  70         unsigned pkt_remain;    /* total packet length remaining */
  71
  72         sbuf_cb_t proto_cb;     /* protocol callback */
  73
  74         SBuf *dst;              /* target SBuf for current packet */
  75
  76         IOBuf *io;              /* data buffer, lazily allocated */
  77 };
  78
  79 #define sbuf_socket(sbuf) ((sbuf)->sock)
  80
  81 void sbuf_init(SBuf *sbuf, sbuf_cb_t proto_fn);
  82 bool sbuf_accept(SBuf *sbuf, int read_sock, bool is_unix)  _MUSTCHECK;
  83 bool sbuf_connect(SBuf *sbuf, const PgAddr *addr, const char *unix_dir, int timeout_sec)  _MUSTCHECK;
  84
  85 bool sbuf_pause(SBuf *sbuf) _MUSTCHECK;
  86 void sbuf_continue(SBuf *sbuf);
  87 bool sbuf_close(SBuf *sbuf) _MUSTCHECK;
  88
  89 /* proto_fn can use those functions to order behaviour */
  90 void sbuf_prepare_send(SBuf *sbuf, SBuf *dst, unsigned amount);
  91 void sbuf_prepare_skip(SBuf *sbuf, unsigned amount);
  92 void sbuf_prepare_fetch(SBuf *sbuf, unsigned amount);
  93
  94 bool sbuf_answer(SBuf *sbuf, const void *buf, unsigned len)  _MUSTCHECK;
  95
  96 bool sbuf_continue_with_callback(SBuf *sbuf, sbuf_libevent_cb cb)  _MUSTCHECK;
  97
  98 /*
  99  * Returns true if SBuf is has no data buffered
 100  * and is not in a middle of a packet.
 101  */
 102 static inline bool sbuf_is_empty(SBuf *sbuf)
 103 {
 104         return iobuf_empty(sbuf->io) && sbuf->pkt_remain == 0;
 105 }
 106
 107 static inline bool sbuf_is_closed(SBuf *sbuf)
 108 {
 109         return sbuf->sock == 0;
 110 }
 111
 112