3

目标:从 RRULE 字符串(即FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH)和起始时间戳生成时间戳列表,每个时间戳代表一个事件发生。由于这些时间会随用户的心血来潮而改变,因此需要 postgresql,因为 (1) 它具有严格的业务逻辑质量和 (2) 触发器(值更改时自动更新行)

替代解决方案:

我最终使用了 plpythonu(postgresql 的 python 语言)。dateutil有一个很棒的规则解析器。

mydatabase=# CREATE FUNCTION parse_occurrences(rule text, start timestamp) RETURNS timestamp[] AS
mydatabase-# 'from dateutil.rrule import *
mydatabase'# from dateutil.parser import *
mydatabase'# import datetime
mydatabase'# dates = list(rrulestr(rule, dtstart=parse(start)))
mydatabase'# return [str(a)[0:10] for a in dates]'
mydatabase-# LANGUAGE plpythonu;
CREATE FUNCTION
mydatabase=# SELECT parse_occurrences('FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH'::text, now()::timestamp);                                                                  
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 {"2013-02-14 00:00:00","2013-02-26 00:00:00","2013-02-28 00:00:00","2013-03-12 00:00:00","2013-03-14 00:00:00","2013-03-26 00:00:00","2013-03-28 00:00:00","2013-04-09 00:00:00"}

(原始)努力:C-library libicalPostgresql C-Extensions连接起来。这需要专门的 C 程序来执行以下操作:(1) 将 postgresql 数据类型转换为 C 数据类型,(2) 执行所有必要的 C 库函数,以及 (3) 使用头文件以 postgresql 格式返回数据“ postgres.h”。

连接器文件:ical_recur.c

#include "postgres.h"
#include "icalrecur.h"
#include <time.h> /* for time() */
#include "fmgr.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

PG_FUNCTION_INFO_V1(get_occurrences);

Datum
get_occurrences(PG_FUNCTION_ARGS)
{
        //char*        rule; /* rule string */
        time_t      start; /* start time */
        int         count;
        char        *rrule;

       // *rule = PG_GETARG_CHAR(0);
        start = (time_t) PG_GETARG_INT32(1);
        count = (int) PG_GETARG_INT32(2);
        *rrule = PG_GETARG_CHAR(0);

        time_t   *result[count]; /* output array */

        icalrecur_expand_recurrence(rrule, start, count, *result);

        PG_RETURN_INT32(*result);
}

准备连接器文件:

步骤 1:编译到目标文件,创建共享对象,复制到 postgresql 查找 C-extensions 的位置

sudo gcc -I/usr/local/libical/lib -lical -I/usr/include/postgresql/9.2/server -fpic -c ical_recur.c
sudo gcc -shared -L/usr/local/libical/lib -lical -o ical_recur.so ical_recur.o
sudo cp ical_recur.so /usr/lib/postgresql/9.2/lib/

步骤 2:添加 C 找到的 libical lib 文件夹并重新加载配置

sudo echo "/usr/local/libical/lib" >> /etc/ld.so.conf.d/libc.conf
sudo ldconfig

测试连接器文件:

第 1 步:加载 psql 并创建函数

psql
mydatabase=# CREATE FUNCTION get_occurrences(text, integer, integer) RETURNS int[]
mydatabase=- AS '$libdir/ical_recur', 'get_occurrences'
mydatabase=- LANGUAGE C STRICT;
CREATE FUNCTION
mydatabase=# 

当前的障碍:

C 函数使 postgresql 服务器崩溃。

psql (9.2.3)
Type "help" for help.

mydatabase=# SELECT get_occurrences('FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH', now()::timestamp, 5);
The connection to the server was lost. Attempting reset: Failed.
!> 

日志...

2013-02-11 22:03:33 UTC LOG:  server process (PID 22733) was terminated by signal 11: Segmentation fault

2013-02-11 22:03:33 UTC DETAIL:  Failed process was running: SELECT get_occurrences('FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH', now()::timestamp, 5);
2013-02-11 22:03:33 UTC LOG:  terminating any other active server processes
2013-02-11 22:03:33 UTC WARNING:  terminating connection because of crash of another server process
2013-02-11 22:03:33 UTC DETAIL:  The postmaster has commanded this server process to roll back the current transaction and exit, because another server process exited abnormally and possibly corrupted shared memory.
2013-02-11 22:03:33 UTC HINT:  In a moment you should be able to reconnect to the database and repeat your command.
2013-02-11 22:03:33 UTC LOG:  all server processes terminated; reinitializing
2013-02-11 22:03:33 UTC FATAL:  the database system is in recovery mode
2013-02-11 22:03:33 UTC LOG:  database system was interrupted; last known up at 2013-02-11 21:47:26 UTC
2013-02-11 22:03:33 UTC LOG:  database system was not properly shut down; automatic recovery in progress
2013-02-11 22:03:33 UTC LOG:  redo starts at 0/1903A0C
2013-02-11 22:03:33 UTC LOG:  record with zero length at 0/190E1E0
2013-02-11 22:03:33 UTC LOG:  redo done at 0/190E1B8
2013-02-11 22:03:33 UTC LOG:  last completed transaction was at log time 2013-02-11 22:03:29.641161+00
2013-02-11 22:03:33 UTC LOG:  database system is ready to accept connections
2013-02-11 22:03:33 UTC LOG:  autovacuum launcher started

更新:

我已经更新了方法来解决一些建议。

#include "postgres.h"
#include "icalrecur.h"
#include <time.h> /* for time() */
#include "fmgr.h"

#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif

PG_FUNCTION_INFO_V1(get_occurrences);

Datum
get_occurrences(PG_FUNCTION_ARGS)
{
        time_t start = (time_t) PG_GETARG_INT32(1); /* convert int to time_t */
        int count = PG_GETARG_INT32(2);
        char rrule = PG_GETARG_CHAR(0);

        char *_rrule = &rrule; /* icalrecur wants a pointer to the rrule */

        time_t  result[count]; /* instantiate the output array */

        int success = icalrecur_expand_recurrence(_rrule, start, count, result);

        /* convert time_t values to int */
        int *output = malloc(sizeof(result));

        int i;
        for(i = 0; i < (int) (sizeof(result) / sizeof(result[0]) - 1); i++){
                output[i] = (int) result[i];
        }

        if(success != 1){
                PG_RETURN_INT32(0);
        } else {
                PG_RETURN_INT32(output);
        }
}

建筑与..

sudo gcc -Wall -Wextra -l/usr/local/libical/lib/ical -I/usr/local/libical/include/libical -I/usr/include/postgresql/9.2/server -fpic -c ical_recur.c
sudo gcc -Wall -shared -static -L/usr/local/libical/lib -lical -o ical_recur.so ical_recur.o
sudo cp libical.so /usr/lib/postgresql/9.2/lib/

进入数据库并执行..

mydb=# CREATE FUNCTION get_occurrences(text, integer, integer) RETURNS int[]
AS '$libdir/ical_recur', 'get_occurrences'
LANGUAGE C STRICT;
CREATE FUNCTION
mydb=# SELECT get_occurrences('FREQ=WEEKLY;INTERVAL=2;COUNT=8;WKST=SU;BYDAY=TU,TH', 1360690024, 5);
The connection to the server was lost. Attempting reset: Failed.
!> \q

相同的日志输出。文档说明了参数:

int icalrecur_expand_recurrence(char * rule, time_t start, int count, time_t * array)

问题:我们怎样才能让它在没有 postgres 崩溃的情况下工作?

4

2 回答 2

3

显示的代码中有两个明显的与指针相关的缺陷:

第一的:

    *rrule = PG_GETARG_CHAR(0);

在这个执行点,rrule是一个未初始化的指针,并且这条指令试图将一个字符写入它指向的随机位置。这通常会导致您看到的那种崩溃。

第二:

time_t   *result[count]; /* output array */

icalrecur_expand_recurrence(rrule, start, count, *result);

result应该是 的数组time_t,而不是 的数组time_t*,并且应该作为 传递result,而*result不是此时未初始化的数组。

于 2013-02-12T14:58:35.960 回答
3

现在您可以将此扩展用于 postgresql。

示例用法:

SELECT * FROM
     unnest(
         rrule_get_occurrences('FREQ=WEEKLY;INTERVAL=1;WKST=MO;UNTIL=20200101T045102Z;BYDAY=SA;BYHOUR=10;BYMINUTE=51;BYSECOND=2'::rrule,
             '2019-12-07 10:51:02+00'::timestamp with time zone)
     );

          unnest
 ------------------------
  2019-12-07 10:51:02+00
  2019-12-14 10:51:02+00
  2019-12-21 10:51:02+00
  2019-12-28 10:51:02+00
 (4 rows)
于 2014-09-15T07:18:31.037 回答