221 lines
12 KiB
HTML
221 lines
12 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' />
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<meta name="DC.Type" content="reference" />
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<meta name="DC.Title" content="Example: Work with local SQL databases in multithreaded Pthread programs" />
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<meta name="abstract" content="This example shows how to work with local SQL databases in multithreaded Pthread programs." />
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<meta name="description" content="This example shows how to work with local SQL databases in multithreaded Pthread programs." />
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<meta name="DC.Relation" scheme="URI" content="rzahwdbcco.htm" />
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<meta name="DC.Relation" scheme="URI" content="rzahwdbcco.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzahwe22-e22rx" />
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<meta name="DC.Language" content="en-us" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<!-- US Government Users Restricted Rights -->
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<!-- Use, duplication or disclosure restricted by -->
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<!-- GSA ADP Schedule Contract with IBM Corp. -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Example: Work with local SQL databases in multithreaded
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Pthread programs</title>
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</head>
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<body id="rzahwe22-e22rx"><a name="rzahwe22-e22rx"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Example: Work with local SQL databases in multithreaded
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Pthread programs</h1>
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<div><p>This example shows how to work with local SQL databases in multithreaded
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Pthread programs.</p>
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<div class="section"><div class="note"><span class="notetitle">Note:</span> By using the code examples, you agree to the terms of the <a href="codedisclaimer.htm">Code license and disclaimer information</a>.</div>
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<div class="p"> <pre>/*********************************************************/
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/* Testcase: SQLEXAMPLE */
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/* */
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/* Function: */
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/* Demonstrate how Embedded SQL can be used within a */
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/* threaded ILE C program. This program creates and */
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/* populates an SQL Table with data. Then, threads are */
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/* created which each open a cursor and read all the */
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/* data from the table. A semaphore is used to show */
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/* how threads execution can be controlled. */
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/* */
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/* To compile program: */
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/* CRTSQLCI OBJ(QGPL/SQLEXAMPLE) SRCFILE(QGPL/QCSRC) */
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/* COMMIT(*NONE) RDB(*NONE) OBJTYPE(*MODULE) */
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/* OUTPUT(*PRINT) DBGVIEW(*SOURCE) */
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/* */
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/* To bind program: */
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/* CRTPGM PGM(QGPL/SQLEXAMPLE) */
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/* MODULE(QGPL/SQLEXAMPLE) ACTGRP(*CALLER) */
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/* */
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/* To invoke program: */
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/* SPAWN QGPL/SQLEXAMPLE */
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/* */
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/*********************************************************/
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#define _MULTI_THREADED
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#include <pthread.h>
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#include <sys/sem.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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static int semid;
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static struct sembuf op_try1[1] = {0,0,0};
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#define MAXTHREADS 2
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void *threadrtn(void *parm);
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int main(int argc, char **argv)
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{
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int rc;
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int *status;
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pthread_t thids[MAXTHREADS];
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EXEC SQL BEGIN DECLARE SECTION;
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int i, j;
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char insert[200];
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EXEC SQL END DECLARE SECTION;
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EXEC SQL INCLUDE SQLCA;
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EXEC SQL INCLUDE SQLDA;
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/* create a new semaphore */
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semid=semget(IPC_PRIVATE,1,S_IRUSR|S_IWUSR);
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printf("\nsemaphore created\n");
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rc=semctl(semid, 0, SETVAL, 1);
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printf("semaphore inited\n");
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EXEC SQL WHENEVER SQLERROR CONTINUE;
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EXEC SQL CREATE TABLE QGPL/SQLEXMP (COL1 INT,COL2 INT);
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printf("SQL table created\n");
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EXEC SQL WHENEVER SQLERROR GO TO :mainerror;
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for (i=1,j=100;i<10;i++,j++) {
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(void) sprintf(insert, "INSERT INTO QGPL/SQLEXMP \
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VALUES(%d, %d)", i, j);
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EXEC SQL EXECUTE IMMEDIATE :insert;
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}
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printf("Table primed with data\n");
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for (i=0;i<MAXTHREADS;i++) {
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pthread_create(&thids[i], NULL, threadrtn, NULL);
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}
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printf("Threads created\n");
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rc=semctl(semid, 0, SETVAL, 0);
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printf("Threads turned loose\n");
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for (i=0;i<MAXTHREADS;i++) {
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pthread_join(thids[i], &status);
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}
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printf("Threads joined\n");
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return;
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mainerror:
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printf("ERROR: sqlcode = %d sqlstate = %d\n", SQLCODE, SQLSTATE);
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}
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/**********************************************************/
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/* This thread will do the following: */
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/* - Declare a cursor for the example table */
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/* - Block on a semaphore until initial thread */
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/* is ready for us to run */
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/* - Open the cursor */
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/* - Fetch data one row at a time in a loop until */
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/* End of File is reached or an error occurs */
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/* - Close the cursor and return */
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/**********************************************************/
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void *threadrtn(void *parm)
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{
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EXEC SQL INCLUDE SQLCA;
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EXEC SQL INCLUDE SQLDA;
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EXEC SQL BEGIN DECLARE SECTION;
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long HV1, HV2;
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EXEC SQL END DECLARE SECTION;
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EXEC SQL WHENEVER SQLERROR GO TO :thderror;
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EXEC SQL WHENEVER NOT FOUND GO TO :thdeof;
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EXEC SQL DECLARE C1 CURSOR FOR SELECT * FROM QGPL/SQLEXMP;
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/* block on semaphore */
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semop(semid,&op_try1[0],1);
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EXEC SQL OPEN C1;
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printf("thid:%.8x %.8x: cursor open\n",pthread_getthreadid_np());
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/* Loop until End of File (EOF) */
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for (;;) {
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EXEC SQL FETCH C1 INTO :HV1, :HV2;
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printf("thid:%.8x %.8x: fetch done... COL1=%d COL2=%d\n",
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pthread_getthreadid_np(), HV1, HV2);
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}
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thderror:
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printf("thid:%.8x %.8x: sqlcode = %d sqlstate = %d\n",
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pthread_getthreadid_np(), SQLCODE, SQLSTATE);
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EXEC SQL CLOSE C1;
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return;
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thdeof:
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printf("thid:%.8x %.8x: Done!\n",
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pthread_getthreadid_np());
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return;
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}
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Testcase output:
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semaphore created
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semaphore inited
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SQL table created
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Table primed with data
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Threads created
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Threads turned loose
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thid:00000000 00000022: cursor open
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thid:00000000 00000023: cursor open
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thid:00000000 00000023: fetch done... COL1=1 COL2=100
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thid:00000000 00000022: fetch done... COL1=1 COL2=100
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thid:00000000 00000023: fetch done... COL1=2 COL2=101
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thid:00000000 00000022: fetch done... COL1=2 COL2=101
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thid:00000000 00000023: fetch done... COL1=3 COL2=102
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thid:00000000 00000022: fetch done... COL1=3 COL2=102
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thid:00000000 00000023: fetch done... COL1=4 COL2=103
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thid:00000000 00000022: fetch done... COL1=4 COL2=103
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thid:00000000 00000023: fetch done... COL1=5 COL2=104
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thid:00000000 00000022: fetch done... COL1=5 COL2=104
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thid:00000000 00000023: fetch done... COL1=6 COL2=105
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thid:00000000 00000022: fetch done... COL1=6 COL2=105
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thid:00000000 00000023: fetch done... COL1=7 COL2=106
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thid:00000000 00000022: fetch done... COL1=7 COL2=106
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thid:00000000 00000023: fetch done... COL1=8 COL2=107
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thid:00000000 00000022: fetch done... COL1=8 COL2=107
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thid:00000000 00000023: fetch done... COL1=9 COL2=108
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thid:00000000 00000022: fetch done... COL1=9 COL2=108
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thid:00000000 00000023: Done!
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thid:00000000 00000022: Done!
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Threads joined </pre>
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</div>
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</div>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzahwdbcco.htm" title="You should consider these items when using databases in multithreaded programs.">Database considerations for multithreaded programming</a></div>
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</div>
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<div class="relref"><strong>Related reference</strong><br />
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<div><a href="rzahwdbcco.htm" title="You should consider these items when using databases in multithreaded programs.">Database considerations for multithreaded programming</a></div>
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</div>
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</div>
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</body>
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</html>
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