Thread: ECPG - Remove need for "AT connection" when using threads

ECPG - Remove need for "AT connection" when using threads

From
"Lee Kindness"
Date:
Attached diff improves the handling of connections in ecpg when threading is
used. The "current connection" is now the last connection made/set for the
thread in question - not the absolute last connection made/set (over all
threads in the process). This change removes the tedious need to always use
"AT connection" for each and every EXEC SQL call (an item on the TODO).

The "test_thread_implicit" test program added in the last email will
function as intended with this patch.

Thanks, L.

----- Original Message -----
From: Lee Kindness
To: pgsql-patches@postgresql.org
Cc: Bruce Momjian ; Lee Kindness ; Shridhar Daithankar
Sent: Saturday, March 06, 2004 3:07 PM
Subject: ECPG: Update tests & memory leak fix

See attached diff which corrects a per-thread memory leak in libecpg and
changes the thread test program to create a user defined number of threads.
Also attached tar.gz adds an additional thread test, which currently does
NOT work as expected and is one of the cases Shridar and I will be looking
at (removing need for AT xxx on every EXEC SQL).

Note, the updated test shows that ECPG currently DOES support the
specification of connection names by host variables (not only static strings
as I had said previously).

Thanks, L.

Attachment

Re: ECPG - Remove need for "AT connection" when using threads

From
Bruce Momjian
Date:
Patch applied by Michael.  Thanks.

---------------------------------------------------------------------------


Lee Kindness wrote:
> Attached diff improves the handling of connections in ecpg when threading is
> used. The "current connection" is now the last connection made/set for the
> thread in question - not the absolute last connection made/set (over all
> threads in the process). This change removes the tedious need to always use
> "AT connection" for each and every EXEC SQL call (an item on the TODO).
>
> The "test_thread_implicit" test program added in the last email will
> function as intended with this patch.
>
> Thanks, L.
>
> ----- Original Message -----
> From: Lee Kindness
> To: pgsql-patches@postgresql.org
> Cc: Bruce Momjian ; Lee Kindness ; Shridhar Daithankar
> Sent: Saturday, March 06, 2004 3:07 PM
> Subject: ECPG: Update tests & memory leak fix
>
> See attached diff which corrects a per-thread memory leak in libecpg and
> changes the thread test program to create a user defined number of threads.
> Also attached tar.gz adds an additional thread test, which currently does
> NOT work as expected and is one of the cases Shridar and I will be looking
> at (removing need for AT xxx on every EXEC SQL).
>
> Note, the updated test shows that ECPG currently DOES support the
> specification of connection names by host variables (not only static strings
> as I had said previously).
>
> Thanks, L.

[ Attachment, skipping... ]

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Re: ECPG - Remove need for "AT connection" when using threads

From
Bruce Momjian
Date:
Michael Meskes wrote:
> On Sun, Mar 07, 2004 at 09:43:31PM -0000, Lee Kindness wrote:
> > Attached diff improves the handling of connections in ecpg when threading is
> > used. The "current connection" is now the last connection made/set for the
>
> I just applied this patch and the last one.

I assume you mean you applied:

    Update tests & memory leak fix

and

    ECPG - Remove need for "AT connection" when using threads

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Re: ECPG - Remove need for "AT connection" when using threads

From
Lee Kindness
Date:
The "cvs add" of test_thread_implicit.pgc seems to have been missed,
i've attached this again.

Additionally I include a small patch to remove mutex locking when a
DEFAULT/NULL connection is being retrieved. This is consistent with
libpq.

Thanks, L.

Michael Meskes writes:
 > On Sun, Mar 14, 2004 at 09:11:27AM -0500, Bruce Momjian wrote:
 > > > I just applied this patch and the last one.
 > >
 > > I assume you mean you applied:
 > >
 > >     Update tests & memory leak fix
 > >
 > > and
 > >
 > >     ECPG - Remove need for "AT connection" when using threads
 >
 > Yes. Sorry, should have said so.
 >
 > Michael

/*
 *    Thread test program
 *    by Lee Kindness.
 */

/* #define ECPGDEBUG */

#include <pthread.h>
#include <stdlib.h>

void *test_thread(void *arg);

EXEC SQL BEGIN DECLARE SECTION;
char *l_dbname;
EXEC SQL END DECLARE SECTION;
int nthreads   =  2;
int iterations = 10;

int main(int argc, char *argv[])
{
#ifdef ECPGDEBUG
  char debugfilename[] = "thread_test_implicit.log";
  FILE *debugfile;
#endif
  pthread_t *threads;
  int n;
  EXEC SQL BEGIN DECLARE SECTION;
  int l_rows;
  EXEC SQL END DECLARE SECTION;

  /* parse command line arguments */
  if( (argc < 2) || (argc > 4) )
    {
      fprintf(stderr, "Usage: %s dbname [threads] [iterations_per_thread]\n", argv[0]);
      return( 1 );
    }
  l_dbname = argv[1];
  if( argc >= 3 )
    nthreads = atoi(argv[2]);
  if( argc == 4 )
    iterations = atoi(argv[3]);

  /* open ECPG debug log? */
#ifdef ECPGDEBUG
  debugfile = fopen(debugfilename, "w");
  if( debugfile != NULL )
    ECPGdebug(1, debugfile);
  else
    fprintf(stderr, "Cannot open ECPG debug log: %s\n", debugfilename);
#endif

  /* setup test_thread table */
  EXEC SQL CONNECT TO:l_dbname;
  EXEC SQL DROP TABLE test_thread; /* DROP might fail */
  EXEC SQL COMMIT;
  EXEC SQL CREATE TABLE
    test_thread(tstamp    TIMESTAMP NOT NULL DEFAULT CAST(timeofday() AS TIMESTAMP),
        thread    TEXT      NOT NULL,
        iteration INTEGER   NOT NULL,
        PRIMARY KEY(thread, iteration));
  EXEC SQL COMMIT;
  EXEC SQL DISCONNECT;

  /* create, and start, threads */
  threads = calloc(nthreads, sizeof(pthread_t));
  if( threads == NULL )
    {
      fprintf(stderr, "Cannot alloc memory\n");
      return( 1 );
    }
  for( n = 0; n < nthreads; n++ )
    {
      pthread_create(&threads[n], NULL, test_thread, (void *)n + 1);
    }

  /* wait for thread completion */
  for( n = 0; n < nthreads; n++ )
    {
      pthread_join(threads[n], NULL);
    }
  free(threads);

  /* and check results */
  EXEC SQL CONNECT TO :l_dbname;
  EXEC SQL SELECT COUNT(*) INTO :l_rows FROM test_thread;
  EXEC SQL COMMIT;
  EXEC SQL DISCONNECT;
  if( l_rows == (nthreads * iterations) )
    printf("\nSuccess.\n");
  else
    printf("\nERROR: Failure - expecting %d rows, got %d.\n", nthreads * iterations, l_rows);

  /* close ECPG debug log? */
#ifdef ECPGDEBUG
  if( debugfile != NULL )
    {
      ECPGdebug(0, debugfile);
      fclose(debugfile);
    }
#endif

  return( 0 );
}

void *test_thread(void *arg)
{
  long threadnum = (long)arg;
  EXEC SQL BEGIN DECLARE SECTION;
  int  l_i;
  char l_connection[128];
  EXEC SQL END DECLARE SECTION;

  /* build up connection name, and connect to database */
  snprintf(l_connection, sizeof(l_connection), "thread_%03ld", threadnum);
  EXEC SQL WHENEVER sqlerror sqlprint;
  EXEC SQL CONNECT TO :l_dbname AS :l_connection;
  if( sqlca.sqlcode != 0 )
    {
      printf("%s: ERROR: cannot connect to database!\n", l_connection);
      return( NULL );
    }
  EXEC SQL BEGIN;

  /* insert into test_thread table */
  for( l_i = 1; l_i <= iterations; l_i++ )
    {
      printf("%s: inserting %d\n", l_connection, l_i);
      EXEC SQL INSERT INTO test_thread(thread, iteration) VALUES(:l_connection, :l_i);
      if( sqlca.sqlcode == 0 )
    printf("%s: insert done\n", l_connection);
      else
    printf("%s: ERROR: insert failed!\n", l_connection);
    }

  /* all done */
  EXEC SQL COMMIT;
  EXEC SQL DISCONNECT :l_connection;
  printf("%s: done!\n", l_connection);
  return( NULL );
}
Index: src/interfaces/ecpg/ecpglib/connect.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/interfaces/ecpg/ecpglib/connect.c,v
retrieving revision 1.20
diff -c -r1.20 connect.c
*** src/interfaces/ecpg/ecpglib/connect.c    14 Mar 2004 12:16:29 -0000    1.20
--- src/interfaces/ecpg/ecpglib/connect.c    15 Mar 2004 16:17:36 -0000
***************
*** 62,79 ****
  {
      struct connection *ret = NULL;

  #ifdef ENABLE_THREAD_SAFETY
!     pthread_mutex_lock(&connections_mutex);
  #endif

!     ret = ecpg_get_connection_nr(connection_name);

  #ifdef ENABLE_THREAD_SAFETY
!     pthread_mutex_unlock(&connections_mutex);
  #endif

      return (ret);
-
  }

  static void
--- 62,89 ----
  {
      struct connection *ret = NULL;

+     if ((connection_name == NULL) || (strcmp(connection_name, "CURRENT") == 0))
+     {
  #ifdef ENABLE_THREAD_SAFETY
!         ret = pthread_getspecific(actual_connection_key);
! #else
!         ret = actual_connection;
! #endif
!     }
!     else
!     {
! #ifdef ENABLE_THREAD_SAFETY
!         pthread_mutex_lock(&connections_mutex);
  #endif

!         ret = ecpg_get_connection_nr(connection_name);

  #ifdef ENABLE_THREAD_SAFETY
!         pthread_mutex_unlock(&connections_mutex);
  #endif
+     }

      return (ret);
  }

  static void

Re: ECPG - Remove need for "AT connection" when using threads

From
Bruce Momjian
Date:
Patch applied.  File added.  Thanks.

---------------------------------------------------------------------------


Lee Kindness wrote:
Content-Description: message body text

> The "cvs add" of test_thread_implicit.pgc seems to have been missed,
> i've attached this again.
>
> Additionally I include a small patch to remove mutex locking when a
> DEFAULT/NULL connection is being retrieved. This is consistent with
> libpq.
>
> Thanks, L.
>
> Michael Meskes writes:
>  > On Sun, Mar 14, 2004 at 09:11:27AM -0500, Bruce Momjian wrote:
>  > > > I just applied this patch and the last one.
>  > >
>  > > I assume you mean you applied:
>  > >
>  > >     Update tests & memory leak fix
>  > >
>  > > and
>  > >
>  > >     ECPG - Remove need for "AT connection" when using threads
>  >
>  > Yes. Sorry, should have said so.
>  >
>  > Michael
>

> /*
>  *    Thread test program
>  *    by Lee Kindness.
>  */
>
> /* #define ECPGDEBUG */
>
> #include <pthread.h>
> #include <stdlib.h>
>
> void *test_thread(void *arg);
>
> EXEC SQL BEGIN DECLARE SECTION;
> char *l_dbname;
> EXEC SQL END DECLARE SECTION;
> int nthreads   =  2;
> int iterations = 10;
>
> int main(int argc, char *argv[])
> {
> #ifdef ECPGDEBUG
>   char debugfilename[] = "thread_test_implicit.log";
>   FILE *debugfile;
> #endif
>   pthread_t *threads;
>   int n;
>   EXEC SQL BEGIN DECLARE SECTION;
>   int l_rows;
>   EXEC SQL END DECLARE SECTION;
>
>   /* parse command line arguments */
>   if( (argc < 2) || (argc > 4) )
>     {
>       fprintf(stderr, "Usage: %s dbname [threads] [iterations_per_thread]\n", argv[0]);
>       return( 1 );
>     }
>   l_dbname = argv[1];
>   if( argc >= 3 )
>     nthreads = atoi(argv[2]);
>   if( argc == 4 )
>     iterations = atoi(argv[3]);
>
>   /* open ECPG debug log? */
> #ifdef ECPGDEBUG
>   debugfile = fopen(debugfilename, "w");
>   if( debugfile != NULL )
>     ECPGdebug(1, debugfile);
>   else
>     fprintf(stderr, "Cannot open ECPG debug log: %s\n", debugfilename);
> #endif
>
>   /* setup test_thread table */
>   EXEC SQL CONNECT TO:l_dbname;
>   EXEC SQL DROP TABLE test_thread; /* DROP might fail */
>   EXEC SQL COMMIT;
>   EXEC SQL CREATE TABLE
>     test_thread(tstamp    TIMESTAMP NOT NULL DEFAULT CAST(timeofday() AS TIMESTAMP),
>         thread    TEXT      NOT NULL,
>         iteration INTEGER   NOT NULL,
>         PRIMARY KEY(thread, iteration));
>   EXEC SQL COMMIT;
>   EXEC SQL DISCONNECT;
>
>   /* create, and start, threads */
>   threads = calloc(nthreads, sizeof(pthread_t));
>   if( threads == NULL )
>     {
>       fprintf(stderr, "Cannot alloc memory\n");
>       return( 1 );
>     }
>   for( n = 0; n < nthreads; n++ )
>     {
>       pthread_create(&threads[n], NULL, test_thread, (void *)n + 1);
>     }
>
>   /* wait for thread completion */
>   for( n = 0; n < nthreads; n++ )
>     {
>       pthread_join(threads[n], NULL);
>     }
>   free(threads);
>
>   /* and check results */
>   EXEC SQL CONNECT TO :l_dbname;
>   EXEC SQL SELECT COUNT(*) INTO :l_rows FROM test_thread;
>   EXEC SQL COMMIT;
>   EXEC SQL DISCONNECT;
>   if( l_rows == (nthreads * iterations) )
>     printf("\nSuccess.\n");
>   else
>     printf("\nERROR: Failure - expecting %d rows, got %d.\n", nthreads * iterations, l_rows);
>
>   /* close ECPG debug log? */
> #ifdef ECPGDEBUG
>   if( debugfile != NULL )
>     {
>       ECPGdebug(0, debugfile);
>       fclose(debugfile);
>     }
> #endif
>
>   return( 0 );
> }
>
> void *test_thread(void *arg)
> {
>   long threadnum = (long)arg;
>   EXEC SQL BEGIN DECLARE SECTION;
>   int  l_i;
>   char l_connection[128];
>   EXEC SQL END DECLARE SECTION;
>
>   /* build up connection name, and connect to database */
>   snprintf(l_connection, sizeof(l_connection), "thread_%03ld", threadnum);
>   EXEC SQL WHENEVER sqlerror sqlprint;
>   EXEC SQL CONNECT TO :l_dbname AS :l_connection;
>   if( sqlca.sqlcode != 0 )
>     {
>       printf("%s: ERROR: cannot connect to database!\n", l_connection);
>       return( NULL );
>     }
>   EXEC SQL BEGIN;
>
>   /* insert into test_thread table */
>   for( l_i = 1; l_i <= iterations; l_i++ )
>     {
>       printf("%s: inserting %d\n", l_connection, l_i);
>       EXEC SQL INSERT INTO test_thread(thread, iteration) VALUES(:l_connection, :l_i);
>       if( sqlca.sqlcode == 0 )
>     printf("%s: insert done\n", l_connection);
>       else
>     printf("%s: ERROR: insert failed!\n", l_connection);
>     }
>
>   /* all done */
>   EXEC SQL COMMIT;
>   EXEC SQL DISCONNECT :l_connection;
>   printf("%s: done!\n", l_connection);
>   return( NULL );
> }

> Index: src/interfaces/ecpg/ecpglib/connect.c
> ===================================================================
> RCS file: /projects/cvsroot/pgsql-server/src/interfaces/ecpg/ecpglib/connect.c,v
> retrieving revision 1.20
> diff -c -r1.20 connect.c
> *** src/interfaces/ecpg/ecpglib/connect.c    14 Mar 2004 12:16:29 -0000    1.20
> --- src/interfaces/ecpg/ecpglib/connect.c    15 Mar 2004 16:17:36 -0000
> ***************
> *** 62,79 ****
>   {
>       struct connection *ret = NULL;
>
>   #ifdef ENABLE_THREAD_SAFETY
> !     pthread_mutex_lock(&connections_mutex);
>   #endif
>
> !     ret = ecpg_get_connection_nr(connection_name);
>
>   #ifdef ENABLE_THREAD_SAFETY
> !     pthread_mutex_unlock(&connections_mutex);
>   #endif
>
>       return (ret);
> -
>   }
>
>   static void
> --- 62,89 ----
>   {
>       struct connection *ret = NULL;
>
> +     if ((connection_name == NULL) || (strcmp(connection_name, "CURRENT") == 0))
> +     {
>   #ifdef ENABLE_THREAD_SAFETY
> !         ret = pthread_getspecific(actual_connection_key);
> ! #else
> !         ret = actual_connection;
> ! #endif
> !     }
> !     else
> !     {
> ! #ifdef ENABLE_THREAD_SAFETY
> !         pthread_mutex_lock(&connections_mutex);
>   #endif
>
> !         ret = ecpg_get_connection_nr(connection_name);
>
>   #ifdef ENABLE_THREAD_SAFETY
> !         pthread_mutex_unlock(&connections_mutex);
>   #endif
> +     }
>
>       return (ret);
>   }
>
>   static void

>
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--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073

Re: ECPG - Remove need for "AT connection" when using threads

From
Michael Meskes
Date:
On Sun, Mar 07, 2004 at 09:43:31PM -0000, Lee Kindness wrote:
> Attached diff improves the handling of connections in ecpg when threading is
> used. The "current connection" is now the last connection made/set for the

I just applied this patch and the last one.

Michael
--
Michael Meskes
Email: Michael at Fam-Meskes dot De
ICQ: 179140304, AIM/Yahoo: michaelmeskes, Jabber: meskes@jabber.org
Go SF 49ers! Go Rhein Fire! Use Debian GNU/Linux! Use PostgreSQL!

Re: ECPG - Remove need for "AT connection" when using threads

From
Michael Meskes
Date:
On Sun, Mar 14, 2004 at 09:11:27AM -0500, Bruce Momjian wrote:
> > I just applied this patch and the last one.
>
> I assume you mean you applied:
>
>     Update tests & memory leak fix
>
> and
>
>     ECPG - Remove need for "AT connection" when using threads

Yes. Sorry, should have said so.

Michael
--
Michael Meskes
Email: Michael at Fam-Meskes dot De
ICQ: 179140304, AIM/Yahoo: michaelmeskes, Jabber: meskes@jabber.org
Go SF 49ers! Go Rhein Fire! Use Debian GNU/Linux! Use PostgreSQL!