src/lib-sql/driver-pgsql.c

	driver-pgsql.c revision 46744f1c9837f189e1c1b13e4d83231b3c9dfff6
c25356d5978632df6203437e1953bcb29e0c736fTimo Sirainen/* Copyright (C) 2004 Timo Sirainen */
c25356d5978632df6203437e1953bcb29e0c736fTimo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "lib.h"
8e361d2906b0e44f7175a20981f8d2280645b58bTimo Sirainen#include "ioloop.h"
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "ioloop-internal.h" /* kind of dirty, but it should be fine.. */
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen#include "sql-api-private.h"
bdd7a96c363346f7c38f389791be1487ca08775bTimo Sirainen
bdd7a96c363346f7c38f389791be1487ca08775bTimo Sirainen#ifdef HAVE_PGSQL
cc833a7a4e2258afdc834ace4bfe6579820a1df3Timo Sirainen#include <stdlib.h>
cc833a7a4e2258afdc834ace4bfe6579820a1df3Timo Sirainen#include <time.h>
97cb20eb77d486ef67eac50567e3080faca025c1Timo Sirainen#include <libpq-fe.h>
97cb20eb77d486ef67eac50567e3080faca025c1Timo Sirainen
cc833a7a4e2258afdc834ace4bfe6579820a1df3Timo Sirainenstruct pgsql_db {
7e235b3a5f622813121cd18f351e036650aaf8f8Timo Sirainen    struct sql_db api;
366eb7178f2c90d97134e0c2d1958f93fcdaba12Timo Sirainen
7e235b3a5f622813121cd18f351e036650aaf8f8Timo Sirainen    pool_t pool;
7e235b3a5f622813121cd18f351e036650aaf8f8Timo Sirainen    const char *connect_string;
fadd878cd6098f5b873c21c121209a922679dae4Timo Sirainen    PGconn *pg;
fadd878cd6098f5b873c21c121209a922679dae4Timo Sirainen
863ea896fb31a16d1baec31e57650243b5547db6Timo Sirainen    struct io *io;
863ea896fb31a16d1baec31e57650243b5547db6Timo Sirainen    enum io_condition io_dir;
863ea896fb31a16d1baec31e57650243b5547db6Timo Sirainen
471e447023ab73a73f0f78da2afc0c55905330ddTimo Sirainen    struct pgsql_queue *queue, **queue_tail;
4b231ca0bbe3b536acbd350101e183441ce0247aTimo Sirainen    struct timeout *queue_to;
4b231ca0bbe3b536acbd350101e183441ce0247aTimo Sirainen
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    struct ioloop *ioloop;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    struct sql_result *sync_result;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    char *error;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    time_t last_connect;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    unsigned int connecting:1;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    unsigned int connected:1;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    unsigned int querying:1;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen};
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainenstruct pgsql_result {
bbce20cb4e5739e9a06058cf8ee1f38a7f6884f6Timo Sirainen    struct sql_result api;
bbce20cb4e5739e9a06058cf8ee1f38a7f6884f6Timo Sirainen    PGresult *pgres;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    unsigned int rownum, rows;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    unsigned int fields_count;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    const char **fields;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    const char **values;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    sql_query_callback_t *callback;
55a210942dc7da58b2fd0b11bed8da6b030af5c1Timo Sirainen    void *context;
fc7b17677ac1a5fa3f7fe13d5ef7dcfea8d9b4a1Timo Sirainen};
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainenstruct pgsql_queue {
8e361d2906b0e44f7175a20981f8d2280645b58bTimo Sirainen    struct pgsql_queue *next;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    time_t created;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    char *query;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    struct pgsql_result *result;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen};
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen
44ff75ca53188056ff5a3e50428e3f2078800b3cTimo Sirainenstruct pgsql_transaction_context {
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    struct sql_transaction_context ctx;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen
51795bfe9d05d92fe942cb451aec2b9d16d32a11Timo Sirainen    sql_commit_callback_t *callback;
51795bfe9d05d92fe942cb451aec2b9d16d32a11Timo Sirainen    void *context;
51795bfe9d05d92fe942cb451aec2b9d16d32a11Timo Sirainen
51795bfe9d05d92fe942cb451aec2b9d16d32a11Timo Sirainen    const char *error;
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen
51795bfe9d05d92fe942cb451aec2b9d16d32a11Timo Sirainen    unsigned int opened:1;
88b8aea03a24ef7a9efc30399080487b7eb03537Timo Sirainen    unsigned int failed:1;
88b8aea03a24ef7a9efc30399080487b7eb03537Timo Sirainen};
88b8aea03a24ef7a9efc30399080487b7eb03537Timo Sirainen
44ff75ca53188056ff5a3e50428e3f2078800b3cTimo Sirainenextern struct sql_result driver_pgsql_result;
8872e5c991430f96138a46e36b7f3c2c40d8e5c2Timo Sirainen
8872e5c991430f96138a46e36b7f3c2c40d8e5c2Timo Sirainenstatic void queue_send_next(struct pgsql_db *db);
8872e5c991430f96138a46e36b7f3c2c40d8e5c2Timo Sirainen
651fc0f1e43fef3e02e0e7b5f498973b05f641d7Timo Sirainenstatic void driver_pgsql_close(struct pgsql_db *db)
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen{
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    if (db->io != NULL) {
d9fdacd5fb3e07997e5c389739d2054f0c8441d8Timo Sirainen        io_remove(db->io);
d9fda7e3a0fa5551547ac3e3054b837fc77f4bfbTimo Sirainen        db->io = NULL;
d9fdacd5fb3e07997e5c389739d2054f0c8441d8Timo Sirainen    }
0dffa25d211be541ee3c953b23566a1a990789dfTimo Sirainen    db->io_dir = 0;
0dffa25d211be541ee3c953b23566a1a990789dfTimo Sirainen
0dffa25d211be541ee3c953b23566a1a990789dfTimo Sirainen    PQfinish(db->pg);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    db->pg = NULL;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    db->connecting = FALSE;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    db->connected = FALSE;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen        db->querying = FALSE;
029cfcdce65b284d5230adf1c920a5f526b03b5cTimo Sirainen}
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen
45e62043058738e294f89504c319d852e25943ccTimo Sirainenstatic const char *last_error(struct pgsql_db *db)
45e62043058738e294f89504c319d852e25943ccTimo Sirainen{
45e62043058738e294f89504c319d852e25943ccTimo Sirainen    const char *msg;
45e62043058738e294f89504c319d852e25943ccTimo Sirainen    size_t len;
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen    msg = PQerrorMessage(db->pg);
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen    if (msg == NULL)
d5960ce1c0adda5c9e259bc429123ebc29c60baeTimo Sirainen        return "(no error set)";
d5960ce1c0adda5c9e259bc429123ebc29c60baeTimo Sirainen
13c6532dc104d23061e6901783ceb1ff8872c206Timo Sirainen    /* Error message should contain trailing \n, we don't want it */
b780aa272b742a43579cdb523cc79cc8d4521306Timo Sirainen    len = strlen(msg);
0dffa25d211be541ee3c953b23566a1a990789dfTimo Sirainen    return len == 0 || msg[len-1] != '\n' ? msg :
0dffa25d211be541ee3c953b23566a1a990789dfTimo Sirainen        t_strndup(msg, len-1);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen}
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainenstatic void connect_callback(void *context)
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen{
6eb30032b4a50c383dea4c9c74342d906de6ad36Timo Sirainen    struct pgsql_db *db = context;
43d32cbe60fdaef2699d99f1ca259053e9350411Timo Sirainen    enum io_condition io_dir = 0;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    int ret;
bdd7a96c363346f7c38f389791be1487ca08775bTimo Sirainen
bdd7a96c363346f7c38f389791be1487ca08775bTimo Sirainen    while ((ret = PQconnectPoll(db->pg)) == PGRES_POLLING_ACTIVE)
bdd7a96c363346f7c38f389791be1487ca08775bTimo Sirainen        ;
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen    switch (ret) {
4bc96ba6f1d67a90a75fa131bcd2cd508ea5a05aTimo Sirainen    case PGRES_POLLING_READING:
4bc96ba6f1d67a90a75fa131bcd2cd508ea5a05aTimo Sirainen        io_dir = IO_READ;
4bc96ba6f1d67a90a75fa131bcd2cd508ea5a05aTimo Sirainen        break;
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen    case PGRES_POLLING_WRITING:
4bc96ba6f1d67a90a75fa131bcd2cd508ea5a05aTimo Sirainen        io_dir = IO_WRITE;
b222354c9553cd60b7dd418885e10c0473f73985Timo Sirainen        break;
ae8817f05005f57bba32479a610b52d083e2b6ebTimo Sirainen    case PGRES_POLLING_OK:
ae8817f05005f57bba32479a610b52d083e2b6ebTimo Sirainen        i_info("pgsql: Connected to %s", PQdb(db->pg));
4bc96ba6f1d67a90a75fa131bcd2cd508ea5a05aTimo Sirainen        db->connecting = FALSE;
4bc96ba6f1d67a90a75fa131bcd2cd508ea5a05aTimo Sirainen        db->connected = TRUE;
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen        break;
f537e7efaec891d6b3320ca94331d09ca8c4a4dbTimo Sirainen    case PGRES_POLLING_FAILED:
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen        i_error("pgsql: Connect failed to %s: %s",
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen            PQdb(db->pg), last_error(db));
2e99f3f3bb35715ce5e0a75a2f2a9bac3ab4224bTimo Sirainen        driver_pgsql_close(db);
2e99f3f3bb35715ce5e0a75a2f2a9bac3ab4224bTimo Sirainen        return;
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    }
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen
902222fb0928d1701f20a384b73f327b1d9a15ddTimo Sirainen    if (db->io_dir != io_dir) {
902222fb0928d1701f20a384b73f327b1d9a15ddTimo Sirainen        if (db->io != NULL)
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen            io_remove(db->io);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen        db->io = io_dir == 0 ? NULL :
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen            io_add(PQsocket(db->pg), io_dir, connect_callback, db);
2a6af811ea3de3cf9e2f15e446674dd21b0705f3Timo Sirainen        db->io_dir = io_dir;
ae8817f05005f57bba32479a610b52d083e2b6ebTimo Sirainen    }
6ded8819b9002150a95a7615e4f64f091c250464Timo Sirainen}
6ded8819b9002150a95a7615e4f64f091c250464Timo Sirainen
2f8da04d700cc23fcd6630226a4866e828b761bdTimo Sirainenstatic int driver_pgsql_connect(struct sql_db *_db)
2f8da04d700cc23fcd6630226a4866e828b761bdTimo Sirainen{
b87a4156eca6dcf6b29c504eb0cb9be2fdb11b63Timo Sirainen    struct pgsql_db *db = (struct pgsql_db *)_db;
ad48319996942463675b53877092ab7e13a7a75aTimo Sirainen    time_t now;
ad48319996942463675b53877092ab7e13a7a75aTimo Sirainen
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    /* don't try reconnecting more than once a second */
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    now = time(NULL);
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    if (db->connecting || db->last_connect == now)
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen        return db->connected ? 1 : (db->connecting ? 0 : -1);
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    db->last_connect = now;
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen
95a1a5195d56f3cf5d1e529aad668f87ad3b979bTimo Sirainen    db->pg = PQconnectStart(db->connect_string);
0cb2e8eb55e70f8ebe1e8349bdf49e4cbe5d8834Timo Sirainen    if (db->pg == NULL)
        i_fatal("pgsql: PQconnectStart() failed (out of memory)");

    if (PQstatus(db->pg) == CONNECTION_BAD) {
        i_error("pgsql: Connect failed to %s: %s",
            PQdb(db->pg), last_error(db));
        driver_pgsql_close(db);
        return -1;
    } else {
        /* nonblocking connecting begins. */
        db->io = io_add(PQsocket(db->pg), IO_WRITE,
                connect_callback, db);
        db->io_dir = IO_WRITE;
        db->connecting = TRUE;
        return 0;
    }
}

static struct sql_db *driver_pgsql_init(const char *connect_string)
{
    struct pgsql_db *db;

    db = i_new(struct pgsql_db, 1);
    db->connect_string = i_strdup(connect_string);
    db->api = driver_pgsql_db;
    db->queue_tail = &db->queue;
    return &db->api;
}

static void driver_pgsql_deinit(struct sql_db *_db)
{
    struct pgsql_db *db = (struct pgsql_db *)_db;

        driver_pgsql_close(db);
    i_free(db->error);
    i_free(db);
}

static enum sql_db_flags
driver_pgsql_get_flags(struct sql_db *db __attr_unused__)
{
    return 0;
}

static void consume_results(void *context)
{
    struct pgsql_db *db = context;

    do {
        if (!PQconsumeInput(db->pg)) {
            db->connected = FALSE;
            break;

        }
        if (PQisBusy(db->pg))
            return;

    } while (PQgetResult(db->pg) != NULL);

    io_remove(db->io);
    db->io = NULL;

    db->querying = FALSE;
    if (db->queue != NULL && db->connected)
        queue_send_next(db);
}

static void driver_pgsql_result_free(struct sql_result *_result)
{
    struct pgsql_db *db = (struct pgsql_db *)_result->db;
        struct pgsql_result *result = (struct pgsql_result *)_result;

    if (result->api.callback)
        return;

    if (result->pgres != NULL) {
        PQclear(result->pgres);

        /* we'll have to read the rest of the results as well */
        i_assert(db->io == NULL);
        db->io = io_add(PQsocket(db->pg), IO_READ,
                consume_results, db);
        db->io_dir = IO_READ;
        consume_results(db);
    } else {
        db->querying = FALSE;
    }

    i_free(result->fields);
    i_free(result->values);
    i_free(result);

    if (db->queue != NULL && !db->querying && db->connected)
        queue_send_next(db);
}

static void result_finish(struct pgsql_result *result)
{
    struct pgsql_db *db = (struct pgsql_db *)result->api.db;
    int free_result = TRUE;

    if (result->callback != NULL) {
        result->api.callback = TRUE;
        result->callback(&result->api, result->context);
        result->api.callback = FALSE;
        free_result = db->sync_result != &result->api;
    }
    if (free_result)
        driver_pgsql_result_free(&result->api);
}

static void get_result(void *context)
{
        struct pgsql_result *result = context;
        struct pgsql_db *db = (struct pgsql_db *)result->api.db;

    if (!PQconsumeInput(db->pg)) {
        db->connected = FALSE;
        result_finish(result);
        return;
    }

    if (PQisBusy(db->pg)) {
        if (db->io == NULL) {
            db->io = io_add(PQsocket(db->pg), IO_READ,
                    get_result, result);
            db->io_dir = IO_READ;
        }
        return;
    }

    if (db->io != NULL) {
        io_remove(db->io);
        db->io = NULL;
    }

    result->pgres = PQgetResult(db->pg);
    result_finish(result);
}

static void flush_callback(void *context)
{
    struct pgsql_result *result = context;
        struct pgsql_db *db = (struct pgsql_db *)result->api.db;
    int ret;

    ret = PQflush(db->pg);
    if (ret > 0)
        return;

    io_remove(db->io);
        db->io = NULL;

    if (ret < 0) {
        db->connected = FALSE;
        result_finish(result);
    } else {
        /* all flushed */
        get_result(result);
    }
}

static void send_query(struct pgsql_result *result, const char *query)
{
        struct pgsql_db *db = (struct pgsql_db *)result->api.db;
    int ret;

    i_assert(db->io == NULL);
    i_assert(!db->querying);
    i_assert(db->connected);

    if (!PQsendQuery(db->pg, query)) {
        db->connected = FALSE;
        result_finish(result);
        return;
    }

    ret = PQflush(db->pg);
    if (ret < 0) {
        db->connected = FALSE;
        result_finish(result);
        return;
    }

    db->querying = TRUE;
    if (ret > 0) {
        /* write blocks */
        db->io = io_add(PQsocket(db->pg), IO_WRITE,
                flush_callback, result);
        db->io_dir = IO_WRITE;
    } else {
        get_result(result);
    }
}

static void queue_send_next(struct pgsql_db *db)
{
    struct pgsql_queue *queue;

    queue = db->queue;
    db->queue = queue->next;

    send_query(queue->result, queue->query);

    i_free(queue->query);
    i_free(queue);
}

static void queue_timeout(void *context)
{
    struct pgsql_db *db = context;

    if (db->querying)
        return;

    if (!db->connected) {
        driver_pgsql_connect(&db->api);
        return;
    }

    if (db->queue != NULL)
        queue_send_next(db);

    if (db->queue == NULL) {
        timeout_remove(db->queue_to);
                db->queue_to = NULL;
    }
}

static void
driver_pgsql_queue_query(struct pgsql_result *result, const char *query)
{
        struct pgsql_db *db = (struct pgsql_db *)result->api.db;
    struct pgsql_queue *queue;

    queue = i_new(struct pgsql_queue, 1);
    queue->created = time(NULL);
    queue->query = i_strdup(query);
    queue->result = result;

    *db->queue_tail = queue;

    if (db->queue_to == NULL)
        db->queue_to = timeout_add(5000, queue_timeout, db);
}

static void do_query(struct pgsql_result *result, const char *query)
{
        struct pgsql_db *db = (struct pgsql_db *)result->api.db;

    if (db->querying) {
        /* only one query at a time */
        driver_pgsql_queue_query(result, query);
        return;
    }

    if (!db->connected) {
        /* try connecting again */
        driver_pgsql_connect(&db->api);
        driver_pgsql_queue_query(result, query);
        return;
    }

    if (db->queue == NULL)
        send_query(result, query);
    else {
        /* there's already queries queued, send them first */
        driver_pgsql_queue_query(result, query);
        queue_send_next(db);
    }
}

static void exec_callback(struct sql_result *result,
              void *context __attr_unused__)
{
        struct pgsql_db *db = (struct pgsql_db *)result->db;

    i_error("pgsql: sql_exec() failed: %s", last_error(db));
}

static void driver_pgsql_exec(struct sql_db *db, const char *query)
{
    struct pgsql_result *result;

    result = i_new(struct pgsql_result, 1);
    result->api = driver_pgsql_result;
    result->api.db = db;
    result->callback = exec_callback;

    do_query(result, query);
}

static void driver_pgsql_query(struct sql_db *db, const char *query,
                   sql_query_callback_t *callback, void *context)
{
    struct pgsql_result *result;

    result = i_new(struct pgsql_result, 1);
    result->api = driver_pgsql_result;
    result->api.db = db;
    result->callback = callback;
    result->context = context;

    do_query(result, query);
}

static void pgsql_query_s_callback(struct sql_result *result, void *context)
{
        struct pgsql_db *db = context;

    db->sync_result = result;
    io_loop_stop(db->ioloop);
}

static struct sql_result *
driver_pgsql_query_s(struct sql_db *_db, const char *query)
{
        struct pgsql_db *db = (struct pgsql_db *)_db;
    struct io old_io;

    if (db->io == NULL)
        db->ioloop = io_loop_create(default_pool);
    else {
        /* have to move our existing I/O handler to new I/O loop */
        old_io = *db->io;
        io_remove(db->io);

        db->ioloop = io_loop_create(default_pool);

        db->io = io_add(old_io.fd, old_io.condition,
                old_io.callback, old_io.context);
    }

    driver_pgsql_query(_db, query, pgsql_query_s_callback, db);

    io_loop_run(db->ioloop);
    io_loop_destroy(db->ioloop);
    db->ioloop = NULL;

    i_assert(db->io == NULL);

    return db->sync_result;
}

static int driver_pgsql_result_next_row(struct sql_result *_result)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;
    struct pgsql_db *db = (struct pgsql_db *)_result->db;

    if (result->rows != 0) {
        /* second time we're here */
        return ++result->rownum < result->rows;
    }

    if (result->pgres == NULL)
        return -1;

    switch (PQresultStatus(result->pgres)) {
    case PGRES_COMMAND_OK:
        /* no rows returned */
        return 0;
    case PGRES_TUPLES_OK:
        result->rows = PQntuples(result->pgres);
        return result->rows > 0;
    case PGRES_EMPTY_QUERY:
    case PGRES_NONFATAL_ERROR:
        /* nonfatal error */
        return -1;
    default:
        /* treat as fatal error */
        db->connected = FALSE;
        return -1;
    }
}

static void driver_pgsql_result_fetch_fields(struct pgsql_result *result)
{
    unsigned int i;

    if (result->fields != NULL)
        return;

    /* @UNSAFE */
    result->fields_count = PQnfields(result->pgres);
    result->fields = i_new(const char *, result->fields_count);
    for (i = 0; i < result->fields_count; i++)
        result->fields[i] = PQfname(result->pgres, i);
}

static unsigned int
driver_pgsql_result_get_fields_count(struct sql_result *_result)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;

        driver_pgsql_result_fetch_fields(result);
    return result->fields_count;
}

static const char *
driver_pgsql_result_get_field_name(struct sql_result *_result, unsigned int idx)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;

    driver_pgsql_result_fetch_fields(result);
    i_assert(idx < result->fields_count);
    return result->fields[idx];
}

static int driver_pgsql_result_find_field(struct sql_result *_result,
                      const char *field_name)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;
    unsigned int i;

    driver_pgsql_result_fetch_fields(result);
    for (i = 0; i < result->fields_count; i++) {
        if (strcmp(result->fields[i], field_name) == 0)
            return i;
    }
    return -1;
}

static const char *
driver_pgsql_result_get_field_value(struct sql_result *_result,
                    unsigned int idx)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;

    if (PQgetisnull(result->pgres, result->rownum, idx))
        return NULL;

    return PQgetvalue(result->pgres, result->rownum, idx);
}

static const char *
driver_pgsql_result_find_field_value(struct sql_result *result,
                     const char *field_name)
{
    int idx;

    idx = driver_pgsql_result_find_field(result, field_name);
    if (idx < 0)
        return NULL;
    return driver_pgsql_result_get_field_value(result, idx);
}

static const char *const *
driver_pgsql_result_get_values(struct sql_result *_result)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;
    unsigned int i;

    if (result->values == NULL) {
        driver_pgsql_result_fetch_fields(result);
        result->values = i_new(const char *, result->fields_count);
    }

    /* @UNSAFE */
    for (i = 0; i < result->fields_count; i++) {
        result->values[i] =
                        driver_pgsql_result_get_field_value(_result, i);
    }

    return result->values;
}

static const char *driver_pgsql_result_get_error(struct sql_result *_result)
{
    struct pgsql_result *result = (struct pgsql_result *)_result;
    struct pgsql_db *db = (struct pgsql_db *)_result->db;
    const char *msg;
    size_t len;

    msg = PQresultErrorMessage(result->pgres);
    if (msg == NULL)
        return "(no error set)";

    /* Error message should contain trailing \n, we don't want it */
    len = strlen(msg);
    i_free(db->error);
    db->error = len == 0 || msg[len-1] != '\n' ?
        i_strdup(msg) : i_strndup(msg, len-1);

    return db->error;
}

static struct sql_transaction_context *
driver_pgsql_transaction_begin(struct sql_db *db)
{
    struct pgsql_transaction_context *ctx;

    ctx = i_new(struct pgsql_transaction_context, 1);
    ctx->ctx.db = db;
    return &ctx->ctx;
}

static void
transaction_commit_callback(struct sql_result *result, void *context)
{
    struct pgsql_transaction_context *ctx =
        (struct pgsql_transaction_context *)context;

    if (sql_result_next_row(result) < 0)
        ctx->callback(sql_result_get_error(result), ctx->context);
    else
        ctx->callback(NULL, ctx->context);
}

static void
driver_pgsql_transaction_commit(struct sql_transaction_context *_ctx,
                sql_commit_callback_t *callback, void *context)
{
    struct pgsql_transaction_context *ctx =
        (struct pgsql_transaction_context *)_ctx;

    if (ctx->failed) {
        callback(ctx->error, context);
        sql_exec(_ctx->db, "ROLLBACK");
        i_free(ctx);
        return;
    }

    ctx->callback = callback;
    ctx->context = context;

    sql_query(_ctx->db, "COMMIT", transaction_commit_callback, ctx);
}

static int
driver_pgsql_transaction_commit_s(struct sql_transaction_context *_ctx,
                  const char **error_r)
{
    struct pgsql_transaction_context *ctx =
        (struct pgsql_transaction_context *)_ctx;
    struct sql_result *result;

    if (ctx->failed) {
        *error_r = ctx->error;
        sql_exec(_ctx->db, "ROLLBACK");
    } else {
        result = sql_query_s(_ctx->db, "COMMIT");
        if (sql_result_next_row(result) < 0)
            *error_r = sql_result_get_error(result);
        else
            *error_r = NULL;
        sql_result_free(result);
    }

    i_free(ctx);
    return *error_r == NULL ? 0 : -1;
}

static void
driver_pgsql_transaction_rollback(struct sql_transaction_context *_ctx)
{
    struct pgsql_transaction_context *ctx =
        (struct pgsql_transaction_context *)_ctx;

    sql_exec(_ctx->db, "ROLLBACK");
    i_free(ctx);
}

static void
transaction_update_callback(struct sql_result *result, void *context)
{
    struct pgsql_transaction_context *ctx =
        (struct pgsql_transaction_context *)context;

    if (sql_result_next_row(result) < 0) {
        ctx->failed = TRUE;
        ctx->error = sql_result_get_error(result);
    }
}

static void
driver_pgsql_update(struct sql_transaction_context *_ctx, const char *query)
{
    struct pgsql_transaction_context *ctx =
        (struct pgsql_transaction_context *)_ctx;

    if (ctx->failed)
        return;

    if (!ctx->opened) {
        ctx->opened = TRUE;
        sql_query(_ctx->db, "BEGIN", transaction_update_callback, ctx);
    }

    sql_query(_ctx->db, query, transaction_update_callback, ctx);
}

struct sql_db driver_pgsql_db = {
    "pgsql",

    driver_pgsql_init,
    driver_pgsql_deinit,
        driver_pgsql_get_flags,
    driver_pgsql_connect,
    driver_pgsql_exec,
    driver_pgsql_query,
    driver_pgsql_query_s,

    driver_pgsql_transaction_begin,
    driver_pgsql_transaction_commit,
    driver_pgsql_transaction_commit_s,
    driver_pgsql_transaction_rollback,

    driver_pgsql_update
};

struct sql_result driver_pgsql_result = {
    NULL,

    driver_pgsql_result_free,
    driver_pgsql_result_next_row,
    driver_pgsql_result_get_fields_count,
    driver_pgsql_result_get_field_name,
    driver_pgsql_result_find_field,
    driver_pgsql_result_get_field_value,
    driver_pgsql_result_find_field_value,
    driver_pgsql_result_get_values,
    driver_pgsql_result_get_error,

    FALSE
};

#endif