pgbouncer学习

struct List {
	/** Pointer to next node or head. */
	struct List *next;
	/** Pointer to previous node or head. */
	struct List *prev;
};
/**
 * Header structure for StatList.
 */
struct StatList {
	/** Actual list head */
	struct List head;
	/** Count of objects currently in list */
	int cur_count;
};
/*
 * Store for pre-initialized objects of one type.
 */
struct Slab {
	struct List head;
	struct StatList freelist;
	struct StatList fraglist;
	char name[32];
	unsigned final_size;
	unsigned total_count;
	slab_init_fn  init_func;
	CxMem *cx;
};
/*
 * Stream Buffer.
 *
 * Stream is divided to packets.  On each packet start
 * protocol handler is called that decides what to do.
 */
struct SBuf {
	struct event ev;	/* libevent handle */

	uint8_t wait_type;	/* track wait state */
	uint8_t pkt_action;	/* method for handling current pkt */
	uint8_t tls_state;	/* progress of tls */

	int sock;		/* fd for this socket */

	unsigned pkt_remain;	/* total packet length remaining */

	sbuf_cb_t proto_cb;	/* protocol callback */

	SBuf *dst;		/* target SBuf for current packet */

	IOBuf *io;		/* data buffer, lazily allocated */

	const SBufIO *ops;	/* normal vs. TLS */
	struct tls *tls;	/* TLS context */
	const char *tls_host;	/* target hostname */
};

struct ListenSocket {
	struct List node;
	int fd;
	bool active;
	struct event ev;
	PgAddr addr;
};

/*
 * parsed packet header, plus whatever data is
 * available in SBuf for this packet.
 *
 * if (pkt->len == mbuf_avail(&pkt->data))
 *     packet is fully in buffer
 *
 * get_header() points pkt->data.pos after header.
 * to packet body.
 */
struct PktHdr {
	unsigned type;
	unsigned len;
	struct MBuf data;
};

const struct CfLookup pool_mode_map[] = {
	{ "session", POOL_SESSION },
	{ "transaction", POOL_TX },
	{ "statement", POOL_STMT },
	{ NULL }
};

struct StatList active_server_list;
struct StatList idle_server_list;
struct StatList used_server_list; 
struct StatList tested_server_list;
struct StatList new_server_list;