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#ifndef EVPQ_H

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#define EVPQ_H

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/*

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

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 */

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#include <event2/event.h>

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#include <postgresql/libpq-fe.h>

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/*

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 * Our PGconn context wrapper.

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 */

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struct evpq_conn;

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/*

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 * Callback functions used

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 */

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struct evpq_callback_info {

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    /*

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     * This evpq_conn has connected succesfully \o/

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     */

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

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    /*

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     * Got a result.

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     */

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

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    /*

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     * No more results for the query

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     */

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

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    /*

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     * The evpq_conn has suffered a complete failure.

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     *

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     * Most likely, this means that the connection to the server was lost, or not established at all.

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     *

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     * XXX: add a `what` arg?

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     */

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

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};

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/*

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 * evpq_conn states

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 */

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enum evpq_state {

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    EVPQ_INIT,

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    EVPQ_CONNECT,

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    EVPQ_CONNECTED,

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    EVPQ_QUERY,

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    EVPQ_FAILURE,

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};

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/*

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 * Create a new evpq connection.

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 *

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

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 *

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

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 * (EVPQ_CONNECTED) or fn_failure (EVPQ_FAILURE).

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 *

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

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 */

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

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/*

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 * Execute a query.

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 *

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

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

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 *

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

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 * followed by a fn_done (EVPQ_CONNECTED).

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 */

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

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/*

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 * Execute a query with params.

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 *

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 * See evpq_query and PQsendQueryParams/PQexecParams

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 */

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int evpq_query_params (struct evpq_conn *conn, const char *command, int nParams, const Oid *paramTypes, const char * const *paramValues, const int *paramLengths, const int *paramFormats, int resultFormat);

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/*

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 * Connection state à la evpq.

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 */

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enum evpq_state evpq_state (struct evpq_conn *conn);

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/*

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 * Get the actual PGconn.

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 *

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

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 */

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const PGconn *evpq_pgconn (struct evpq_conn *conn);

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// convenience wrappers

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

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/*

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 * Release the evpq_conn, closing all connections and freeing all resources.

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 *

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 * You must call this yourself in all cases after evpq_connect returns an evpq_conn.

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 */

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void evpq_release (struct evpq_conn *conn);

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#endif /* EVPQ_H */