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Diffstat (limited to 'erts/example/pg_async2.c')
| -rw-r--r-- | erts/example/pg_async2.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/erts/example/pg_async2.c b/erts/example/pg_async2.c new file mode 100644 index 0000000000..368f9d32d0 --- /dev/null +++ b/erts/example/pg_async2.c @@ -0,0 +1,244 @@ +/* + * %CopyrightBegin% + * + * Copyright Ericsson AB 2006-2009. All Rights Reserved. + * + * The contents of this file are subject to the Erlang Public License, + * Version 1.1, (the "License"); you may not use this file except in + * compliance with the License. You should have received a copy of the + * Erlang Public License along with this software. If not, it can be + * retrieved online at http://www.erlang.org/. + * + * Software distributed under the License is distributed on an "AS IS" + * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See + * the License for the specific language governing rights and limitations + * under the License. + * + * %CopyrightEnd% + */ +/* + * Purpose: A driver using libpq to connect to Postgres + * from erlang, a sample for the driver documentation + */ + +#include <erl_driver.h> + +#include <libpq-fe.h> + +#include <ei.h> + +#include <stdlib.h> +#include <stdio.h> +#include <string.h> + +#include "pg_encode2.h" + +#define L fprintf(stderr, "%d\r\n", __LINE__) + +/* Driver interface declarations */ +static ErlDrvData start(ErlDrvPort port, char *command); +static void stop(ErlDrvData drv_data); +static int control(ErlDrvData drv_data, unsigned int command, char *buf, + int len, char **rbuf, int rlen); +static void ready_input(ErlDrvData drv_data, ErlDrvEvent event); + +static ErlDrvEntry pq_driver_entry = { + NULL, /* init */ + start, + stop, + NULL, /* output */ + ready_input, /* ready_input */ + NULL, /* ready_output */ + "pg_async2", + NULL, /* finish */ + NULL, /* handle */ + control, + NULL, /* timeout */ + NULL, /* outputv */ + NULL, + NULL, + NULL, + NULL +}; + +typedef struct our_data_t { + PGconn* conn; + ErlDrvPort port; + int socket; + char* s; +} our_data_t; + +our_data_t our_data; + +/* Keep the following definitions in alignment with the FUNC_LIST + * in erl_pq_sync.erl + */ + +#define DRV_CONNECT 1 +#define DRV_DISCONNECT 2 +#define DRV_SELECT 3 + +/* INITIALIZATION AFTER LOADING */ + +/* + * This is the init function called after this driver has been loaded. + * It must *not* be declared static. Must return the address to + * the driver entry. + */ + +#ifdef __cplusplus +extern "C" { /* this should be in the DRIVER_INIT macro! */ +#endif +DRIVER_INIT(pq_drv) +{ + return &pq_driver_entry; +} +#ifdef __cplusplus +} +#endif + +/* DRIVER INTERFACE */ +static ErlDrvData start(ErlDrvPort port, char *command) +{ + our_data_t* data = driver_alloc(sizeof(our_data_t)); + data->port = port; + data->conn = NULL; + return (ErlDrvData)data; +} + + +static char* get_s(const char* buf, int len); +static void free_s(char* s); + +static int do_connect(const char *s, our_data_t* data); +static int do_disconnect(our_data_t* data); +static int do_select(const char* s, our_data_t* data); + +static void stop(ErlDrvData drv_data) +{ + do_disconnect((our_data_t*)drv_data); +} + + +/* Since we are operating in binary mode, the return value from control + * is irrelevant, as long as it is not negative. + */ +static int control(ErlDrvData drv_data, unsigned int command, char *buf, + int len, char **rbuf, int rlen) +{ + int r; + char* s; + + s = get_s(buf, len); + switch (command) { + case DRV_CONNECT: + r = do_connect(s, (our_data_t*)drv_data); + break; + case DRV_DISCONNECT: + r = do_disconnect((our_data_t*)drv_data); + break; + case DRV_SELECT: + r = do_select(s, (our_data_t*)drv_data); + break; + default: + r = -1; + break; + } + free_s(s); + return r; +} + +static int do_connect(const char *s, our_data_t* data) +{ + ei_x_buff x; + PGconn* conn = PQconnectdb(s); + + ei_x_new_with_version(&x); + if (PQstatus(conn) != CONNECTION_OK) { + encode_error(&x, conn); + PQfinish(conn); + conn = NULL; + } else { + encode_ok(&x); + data->socket = PQsocket(conn); + driver_select(data->port, (ErlDrvEvent)data->socket, DO_READ, 1); + } + driver_output(data->port, x.buff, x.index); + ei_x_free(&x); + data->conn = conn; + return 0; +} + +static int do_disconnect(our_data_t* data) +{ + ei_x_buff x; + + if (data->socket == 0) + return 0; + driver_select(data->port, (ErlDrvEvent)data->socket, DO_READ, 0); + data->socket = 0; + PQfinish(data->conn); + data->conn = NULL; + ei_x_new_with_version(&x); + encode_ok(&x); + driver_output(data->port, x.buff, x.index); + ei_x_free(&x); + return 0; +} + +static int do_select(const char* s, our_data_t* data) +{ + PGconn* conn = data->conn; + + /* if there's an error return it now */ + if (PQsendQueryParams(conn, s, 0, NULL, NULL, NULL, NULL, 1) == 0) { + ei_x_buff x; + ei_x_new_with_version(&x); + encode_error(&x, conn); + driver_output(data->port, x.buff, x.index); + ei_x_free(&x); + } + /* else wait for ready_output to get results */ + return 0; +} + +static void ready_input(ErlDrvData drv_data, ErlDrvEvent event) +{ + our_data_t* data = (our_data_t*)drv_data; + PGconn* conn = data->conn; + ei_x_buff x; + PGresult* res; + + PQconsumeInput(conn); + if (PQisBusy(conn)) + return; + ei_x_new_with_version(&x); + res = PQgetResult(conn); + encode_result(&x, res, conn); + driver_output(data->port, x.buff, x.index); + ei_x_free(&x); + PQclear(res); + for (;;) { + res = PQgetResult(conn); + if (res == NULL) + break; + PQclear(res); + } +} + +/* utilities */ + +static char* get_s(const char* buf, int len) +{ + char* result; + if (len < 1 || len > 1000) return NULL; + result = driver_alloc(len+1); + memcpy(result, buf, len); + result[len] = '\0'; + return result; +} + +static void free_s(char* s) +{ + driver_free(s); +} |