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#ifndef EVSQL_H

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#define EVSQL_H

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/*

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 * An event-based (Postgre)SQL client API using libevent

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 */

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// XXX: libpq

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#include <postgresql/libpq-fe.h>

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#include <event2/event.h>

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/*

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 * The generic context handle

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 */

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struct evsql;

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/*

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 * A query handle

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 */

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struct evsql_query;

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/*

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 * Parameter type

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 */

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enum evsql_param_format {

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    EVSQL_FMT_TEXT,

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    EVSQL_FMT_BINARY,

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};

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enum evsql_param_type {

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    EVSQL_PARAM_INVALID,

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    EVSQL_PARAM_NULL,

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    EVSQL_PARAM_STRING,

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    EVSQL_PARAM_UINT16,

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    EVSQL_PARAM_UINT32,

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    EVSQL_PARAM_UINT64,

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};

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/*

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 * Query parameter info.

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 *

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 * Use the EVSQL_PARAM_* macros to define the value of list

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 */

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struct evsql_query_params {

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    // nonzero to get results in binary format

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    enum evsql_param_format result_fmt;

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    // the list of parameters, terminated by { 0, 0 }

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    struct evsql_query_param {

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        // the param type

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        enum evsql_param_type type;

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        // pointer to the raw data

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        const char *data_raw;

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        // the value

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        union {

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            uint16_t uint16;

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            uint32_t uint32;

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            uint64_t uint64;

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        } data;

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        // the explicit length of the parameter if it's binary, zero for text.

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        // set to -1 to indicate that the value is still missing

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        ssize_t length;

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    } list[];

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};

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// macros for defining evsql_query_params

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#define EVSQL_PARAMS(result_fmt)            { result_fmt, 

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#define EVSQL_PARAM(typenam)                    { EVSQL_PARAM_ ## typenam, NULL }

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#define EVSQL_PARAMS_END                        { EVSQL_PARAM_INVALID, NULL } \

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                                              } // <<<

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/*

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 * Result type

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 */

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struct evsql_result_info {

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    struct evsql *evsql;

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    int error;

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};

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/*

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 *

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 */

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typedef void (*evsql_query_cb)(const struct evsql_result_info *res, void *arg);

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/*

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 *

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 */

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typedef void (*evsql_error_cb)(struct evsql *evsql, void *arg);

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/*

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 * Create a new PostgreSQL/libpq(evpq) -based evsql using the given conninfo.

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 */

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struct evsql *evsql_new_pq (struct event_base *ev_base, const char *pq_conninfo, evsql_error_cb error_fn, void *cb_arg);

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/*

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 */

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/*

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 */

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/*

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 * Param-building functions

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 */

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int evsql_param_string (struct evsql_query_params *params, size_t param, const char *ptr);

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int evsql_param_uint32 (struct evsql_query_params *params, size_t param, uint32_t uval);

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/*

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 * Result-handling functions

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 */

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// get error message associated with function

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const char *evsql_result_error (const struct evsql_result_info *res);

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// number of rows in the result

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size_t evsql_result_rows (const struct evsql_result_info *res);

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// number of columns in the result

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size_t evsql_result_cols (const struct evsql_result_info *res);

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// fetch the raw binary value from a result set, and return it via ptr

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// if size is nonzero, check that the size of the field data matches

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int evsql_result_binary (const struct evsql_result_info *res, size_t row, size_t col, const char **ptr, size_t size, int nullok);

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int evsql_result_string (const struct evsql_result_info *res, size_t row, size_t col, const char **ptr, int nullok);

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// fetch certain kinds of values from a binary result set

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int evsql_result_uint16 (const struct evsql_result_info *res, size_t row, size_t col, uint16_t *uval, int nullok);

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int evsql_result_uint32 (const struct evsql_result_info *res, size_t row, size_t col, uint32_t *uval, int nullok);

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int evsql_result_uint64 (const struct evsql_result_info *res, size_t row, size_t col, uint64_t *uval, int nullok);

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// release the result set, freeing its memory

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void evsql_result_free (const struct evsql_result_info *res);

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// platform-dependant aliases

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#define evsql_result_ushort evsql_result_uint16

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#if _LP64

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#define evsql_result_ulong evsql_result_uint64

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#else

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#define evsql_result_ulong evsql_result_uint32

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#endif /* _LP64 */

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/*

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 * Close a connection. Callbacks for waiting queries will not be run.

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 *

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 * XXX: not implemented yet.

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 */

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void evsql_close (struct evsql *evsql);

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#endif /* EVSQL_H */