1 #ifndef EVPQ_H

     2 #define EVPQ_H

     3 

     4 /*

     5  * Convenience functions for using libpq (the PostgreSQL client library) with libevent.

     6  */

     7 

     8 #include <event2/event.h>

     9 #include <postgresql/libpq-fe.h>

    10 

    11 /*

    12  * Our PGconn context wrapper.

    13  */

    14 struct evpq_conn;

    15 

    16 /*

    17  * Callback functions used

    18  */

    19 struct evpq_callback_info {

    20     /*

    21      * This evpq_conn has connected succesfully \o/

    22      */

    23     void (*fn_connected)(struct evpq_conn *conn, void *arg);

    24 

    25     /*

    26      * Got a result.

    27      */

    28     void (*fn_result)(struct evpq_conn *conn, PGresult *result, void *arg);

    29 

    30     /*

    31      * No more results for the query

    32      */

    33     void (*fn_done)(struct evpq_conn *conn, void *arg);

    34     

    35     /*

    36      * Something caused this evpq_conn to fail :(

    37      *

    38      * XXX: add a `what` arg?

    39      */

    40     void (*fn_failure)(struct evpq_conn *conn, void *arg);

    41 

    42     /*

    43      * Arg to pass through to all callbacks.

    44      */

    45     void *cb_arg;

    46 };

    47 

    48 /*

    49  * evpq_conn states

    50  */

    51 enum evpq_state {

    52     EVPQ_INIT,

    53 

    54     EVPQ_CONNECT,

    55     EVPQ_CONNECTED,

    56 

    57     EVPQ_QUERY,

    58 

    59     EVPQ_FAILURE,

    60 };

    61 

    62 /*

    63  * Create a new evpq connection.

    64  *

    65  * This corresponds directly to PQconnectStart, and handles all the libevent setup/polling needed.

    66  *

    67  * The connection will initially be in the EVPQ_CONNECT state, and will then either callback via fn_connected

    68  * (EVPQ_CONNECTED) or fn_failure (EVPQ_FAILURE).

    69  *

    70  * cb_info contains the callback functions (and the user argument) to use.

    71  */

    72 struct evpq_conn *evpq_connect (struct event_base *ev_base, const char *conninfo, const struct evpq_callback_info cb_info);

    73 

    74 /*

    75  * Execute a query.

    76  *

    77  * This corresponds directly to PQsendQuery. This evpq must be in the EVPQ_CONNECTED state, so you must wait after

    78  * calling evpq_connect, and you may not run two queries at the same time.

    79  *

    80  * The query will result in a series of fn_result (EVPQ_RESULT) calls (if multiple queries in the query string),

    81  * followed by a fn_done (EVPQ_CONNECTED).

    82  */

    83 int evpq_query (struct evpq_conn *conn, const char *command);

    84 

    85 /*

    86  * Get the actual PGconn.

    87  *

    88  * This can safely be used to access all of the normal PQ functions.

    89  */

    90 const PGconn *evpq_pgconn (struct evpq_conn *conn);

    91 

    92 // convenience wrappers

    93 #define evpq_error_message(conn) PQerrorMessage(evpq_pgconn(conn))

    94 

    95 

    96 #endif /* EVPQ_H */