/****************************************************************************
** (c) Copyright IBM Corp. 2007 All rights reserved.
**
** The following sample of source code ("Sample") is owned by International
** Business Machines Corporation or one of its subsidiaries ("IBM") and is
** copyrighted and licensed, not sold. You may use, copy, modify, and
** distribute the Sample in any form without payment to IBM, for the purpose of
** assisting you in the development of your applications.
**
** The Sample code is provided to you on an "AS IS" basis, without warranty of
** any kind. IBM HEREBY EXPRESSLY DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR
** IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
** MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Some jurisdictions do
** not allow for the exclusion or limitation of implied warranties, so the above
** limitations or exclusions may not apply to you. IBM shall not be liable for
** any damages you suffer as a result of using, copying, modifying or
** distributing the Sample, even if IBM has been advised of the possibility of
** such damages.
*****************************************************************************
**
** SOURCE FILE NAME: dbthrds.sqC
**
** SAMPLE: How to use multiple context APIs on UNIX
**
** This program uses the POSIX threads APIs for thread creation and
** management. On Solaris systems it is also possible to use the
** Solaris thread APIs such as thd_create.
**
** The program maintains a pool of contexts. A generate_work
** function is executed from main(), and creates dynamic SQL
** statements that are executed by worker threads. When a
** context becomes available, a thread is created and dispatched
** to do the specified work.
**
** The work generated consists of statements to delete entries
** from either the STAFF or EMPLOYEE tables of the SAMPLE database.
**
** Compile and link with C compiler options for multi-threaded
** applications supported by your platform.
**
** Note:
** On some environments, the output may appear garbled because
** one thread process outputs information at the same time as
** another process, thereby overwriting output strings. If this
** is a concern, you can add a locking mechanism for the output
** so only one process outputs at any one time.
**
** SQL STATEMENTS USED:
** CONNECT
** EXECUTE IMMEDIATE
**
**
*****************************************************************************
**
** For more information on the sample programs, see the README file.
**
** For information on developing embedded SQL applications see the Developing Embedded SQL Applications book.
**
** For information on using SQL statements, see the SQL Reference.
**
** For information on DB2 APIs, see the Administrative API Reference.
**
** For the latest information on programming, building, and running DB2
** applications, visit the DB2 Information Center:
** http://publib.boulder.ibm.com/infocenter/db2luw/v9r7/index.jsp
****************************************************************************/
#ifdef USE_UI_THREADS
// Sun has "Unix International" threads APIs
#include <thread.h>
#include <synch.h>
#else
#include <pthread.h>
#endif
#include <sql.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#if ((__cplusplus >= 199711L) && !defined DB2HP && !defined DB2AIX) || \
(DB2LINUX && (__LP64__ || (__GNUC__ >= 3)) )
#include <iostream>
using namespace std;
#else
#include <iostream.h>
#endif
#ifdef USE_UI_THREADS
// Hide the differences in the threads implementations
#define pthread_exit(x) thr_exit(x)
#define pthread_mutex_lock(x) mutex_lock(x)
#define pthread_mutex_unlock(x) mutex_unlock(x)
#define pthread_mutex_init(x,y) mutex_init(x, USYNC_THREAD, y)
#define pthread_cond_init(x,y) cond_init(x, USYNC_THREAD, y)
#define pthread_cond_wait(x,y) cond_wait(x,y)
#define pthread_cond_signal(x) cond_signal(x)
#define pthread_mutex_t mutex_t
#define pthread_cond_t cond_t
#define pthread_t thread_t
#endif
#if (defined(DB2HP))
#define DEFAULT_STACK_SIZE 0x20000
#else
#define DEFAULT_STACK_SIZE 0
#endif
#define check_expected(condition) \
{ \
if (!(condition)) \
{ \
cerr << __FILE__ << ":" << __LINE__ << " unexpected error: \"" \
<< #condition << "\" was false" << endl; \
exit(1); \
} \
}
#define CHECKERR(context, CE_STR, pStatus) \
{ \
char buf[256]; \
sprintf(buf, "Context nb.: %i\n%s", context, CE_STR); \
if (check_error(buf, &sqlca) != 0) \
{ \
*(pStatus) = sqlca.sqlcode; \
} \
}
// Generate work creates the following type of structure which is passed
// to each worker thread.
struct work
{
char database[15]; // database for thread to connect to
char userid[15];
char password[15];
char *command; // dynamic SQL statement to execute
int context; // context to use for connection
};
// The context pool consists of an array of 'struct context' types.
struct context
{
void *ctx;
int free;
};
// Global variables.
int contexts = 8; // size of context pool
struct context *ctxlist;
#ifndef USE_UI_THREADS
pthread_attr_t attr; // global thread attributes
#endif
pthread_t *thd; // array of thread ids
int loops = 15; // amount of work for the client to create
int commit = 0; // commit the work done
int verbose = 1;
char database[15];
char userid[15];
char password[15];
// for management of the context pool
int contexts_free;
pthread_cond_t cond;
pthread_mutex_t cond_m;
// mutex for serializing cout
pthread_mutex_t output;
// Prototypes.
void initialize(int argc, char *argv[]);
void usage(char *argv0);
void generate_work();
void dispatch(struct work *work_item);
void *do_work(void *args); // each thread executes this function
void clean_up(struct work *work_item, int connect_done, int *pStatus);
int check_error(char eString[], struct sqlca *caPointer);
int main(int argc, char *argv[])
{
// Initialize the mutex for serializing cout
pthread_mutex_init(&output, NULL);
pthread_mutex_lock (&output);
cout << "\nHow to use multiple context APIs" << endl << endl;
pthread_mutex_unlock (&output);
initialize(argc, argv);
generate_work();
if (verbose)
{
pthread_mutex_lock (&output);
cout << "all workers started, exiting main" << endl;
pthread_mutex_unlock (&output);
}
pthread_exit(0);
} //main
// Initialize any global program state. This includes the attributes
// used for each thread creation, the setting of the multi-manual context
// type and the creation of the context pool.
void initialize(int argc, char *argv[])
{
int c, i, rc;
struct sqlca sqlca;
strcpy(database, "sample");
strcpy(userid, "");
strcpy(password, "");
// read any command line options
while ((c = getopt(argc, argv, "d:u:p:l:c:qCh")) != EOF)
{
switch (c)
{
case 'd':
strcpy(database, optarg);
break;
case 'u':
strcpy(userid, optarg);
break;
case 'p':
strcpy(password, optarg);
break;
case 'l':
loops = atoi(optarg);
break;
case 'c':
contexts = atoi(optarg);
break;
case 'q':
verbose = 0;
break;
case 'C':
commit = 1;
break;
case 'h':
default:
usage(argv[0]);
break;
}
}
cout << "Database: " << database << endl;
cout << "Username: " << userid << endl;
cout << "Password: " << password << endl;
cout << "Loops: " << loops << endl;
cout << "Contexts: " << contexts << endl;
cout << "Verbose: " << verbose << endl;
cout << "Commit: " << commit << endl;
contexts_free = contexts;
ctxlist = new context[contexts];
check_expected(ctxlist != NULL);
thd = new pthread_t[contexts];
check_expected(thd != NULL);
#ifndef USE_UI_THREADS
rc = pthread_attr_init(&attr);
check_expected(rc == 0);
rc = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
check_expected(rc == 0);
#if (defined(DB2DYNIX)) || (defined(DB2HP))
rc = pthread_attr_setstacksize(&attr, DEFAULT_STACK_SIZE);
#endif
#ifdef _POSIX_THREAD_PRIORITY_SCHEDULING
#if (defined(DB2IRIX))
rc = pthread_attr_setscope(&attr, PTHREAD_SCOPE_PROCESS);
#else
rc = pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
#endif
check_expected(rc == 0);
#endif
#endif
sqleSetTypeCtx(SQL_CTX_MULTI_MANUAL);
if (verbose)
{
pthread_mutex_lock (&output);
cout << "creating context pool of size " << contexts << endl;
pthread_mutex_unlock (&output);
}
for (i = 0; i < contexts; i++)
{
rc = sqleBeginCtx(&ctxlist[i].ctx, SQL_CTX_CREATE_ONLY, NULL, &sqlca);
check_expected(rc == 0 && sqlca.sqlcode == 0);
ctxlist[i].free = 1;
}
rc = pthread_mutex_init(&cond_m, NULL);
check_expected(rc == 0);
rc = pthread_cond_init(&cond, NULL);
check_expected(rc == 0);
return;
} //initialize
// Print a friendly usage message.
void usage(char *argv0)
{
char *program = strrchr(argv0, '/');
if (!program)
{
program = argv0;
}
cerr << "usage: " << program << endl
<< " [-d database] [-u userid] [-p password]" << endl
<< " [-l loops] [-c contexts] [-q] [-C] [-h]" << endl
<< endl
<< " -d\t alternate sample database or database alias." << endl
<< " -u\t user id." << endl
<< " -p\t password." << endl
<< " -l\t number of loops." << endl
<< " -c\t size of context pool to use." << endl
<< " -q\t quiet mode." << endl
<< " -C\t commit changes made." << endl
<< " -h\t print this message." << endl;
exit(1);
} //usage
// Construct a "random" SQL statement to execute in a connection to an
// arbitrary database.
// Note that the exclusive use of the SAMPLE database here is not a db2
// restriction, but is a convienience to simplify this program.
void generate_work()
{
int i, empno;
unsigned int seed = getpid();
struct work *work_item;
char buf[256];
// The employee numbers are in the 10-350 range and are multiples of
// * 10.
char *delete_str1 = "DELETE FROM STAFF WHERE ID=%i";
char *delete_str2 = "DELETE FROM EMPLOYEE WHERE EMPNO='%06i'";
// Generate work to be done in each thread.
for (i = 0; i < loops; i++)
{
work_item = new work;
strcpy(work_item->database, database);
strcpy(work_item->userid, userid);
strcpy(work_item->password, password);
srand(seed);
empno = ((rand() % 1000) + 1) * 10;
sprintf(buf, i % 2 ? delete_str1 : delete_str2, empno);
work_item->command = strdup(buf);
dispatch(work_item);
}
return;
} //generate_work
// The current thread will be suspended until the required resources
// are available (ie: a context is free). At this point a thread is created
// to execute the specified SQL statement.
void dispatch(struct work *work_item)
{
int rc, ctx;
rc = pthread_mutex_lock(&cond_m);
check_expected(rc == 0);
while (!contexts_free)
{
rc = pthread_cond_wait(&cond, &cond_m);
check_expected(rc == 0);
}
// there is at least one free context at this point, find one
for (ctx = 0; ctx < contexts; ctx++)
{
if (ctxlist[ctx].free)
{
break;
}
}
ctxlist[ctx].free = 0;
contexts_free--;
rc = pthread_mutex_unlock(&cond_m);
check_expected(rc == 0);
work_item->context = ctx;
if (verbose)
{
pthread_mutex_lock (&output);
cout << "creating thread on context " << ctx << " for SQL statement:"
<< "\n\t\"" << work_item->command << "\"" << endl;
pthread_mutex_unlock (&output);
}
#ifdef USE_UI_THREADS
rc = thr_create(NULL,
DEFAULT_STACK_SIZE,
do_work,
(void *)work_item,
THR_BOUND | THR_DETACHED,
&thd[ctx]);
#else
rc = pthread_create(&thd[ctx], &attr, do_work, (void *)work_item);
#endif
check_expected(rc == 0);
return;
} //dispatch
// Execute the SQL statement. This is the "main" routine for each of the
// worker threads.
//
// A context will be attached to for the connection, a connection will be done,
// and a simple SQL statement will be prepared and executed.
//
// After this, or in the event of non-terminal error, the context will be
// detached if an attachment has occurred, and any further resource
// deallocation will occur.
//
// Before termination a condition will be signalled to wake up dispatch if
// no contexts had been available.
void *do_work(void *args)
{
EXEC SQL BEGIN DECLARE SECTION;
char dbname[15];
char user[15];
char pswd[15];
char statement[256];
EXEC SQL END DECLARE SECTION;
int rc, status = 0;
struct sqlca sqlca;
struct work *work = (struct work *)args;
strcpy(dbname, work->database);
strcpy(user, work->userid);
strcpy(pswd, work->password);
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": sqleAttachToCtx" << endl;
pthread_mutex_unlock (&output);
}
rc = sqleAttachToCtx(ctxlist[work->context].ctx, NULL, &sqlca);
check_expected(rc == 0 && sqlca.sqlcode == 0);
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": CONNECT TO " << dbname << endl;
pthread_mutex_unlock (&output);
}
if (strlen(user) == 0)
{
EXEC SQL CONNECT TO :dbname;
}
else
{
EXEC SQL CONNECT TO :dbname USER :user USING :pswd;
}
CHECKERR(work->context, "CONNECT TO DATABASE", &status);
if (sqlca.sqlcode != 0)
{
clean_up(work, 0, &status);
}
else
{
strcpy(statement, work->command);
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": EXECUTE \"" << statement << "\"" << endl;
pthread_mutex_unlock (&output);
}
EXEC SQL EXECUTE IMMEDIATE :statement;
CHECKERR(work->context, "EXECUTE IMMEDIATE", &status);
clean_up(work, 1, &status);
}
return (void *)status; // this could be obtained with a pthread_join
// if the thread was created undetached
} //do_work
void clean_up(struct work *work, int connect_done, int *pStatus)
{
int rc;
struct sqlca sqlca;
if (connect_done)
{
if (commit)
{
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": COMMIT" << endl;
pthread_mutex_unlock (&output);
}
EXEC SQL COMMIT;
CHECKERR(work->context, "COMMIT", pStatus);
}
else
{
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": ROLLBACK" << endl;
pthread_mutex_unlock (&output);
}
EXEC SQL ROLLBACK;
CHECKERR(work->context, "ROLLBACK", pStatus);
}
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": CONNECT RESET" << endl;
pthread_mutex_unlock (&output);
}
EXEC SQL CONNECT RESET;
CHECKERR(work->context, "CONNECT RESET", pStatus)}
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": sqleDetachFromCtx" << endl;
pthread_mutex_unlock (&output);
}
rc = sqleDetachFromCtx(ctxlist[work->context].ctx, NULL, &sqlca);
check_expected(rc == 0 && sqlca.sqlcode == 0);
rc = pthread_mutex_lock(&cond_m);
check_expected(rc == 0);
if (verbose)
{
pthread_mutex_lock (&output);
cout << work->context << ": marking context free" << endl;
pthread_mutex_unlock (&output);
}
ctxlist[work->context].free = 1;
contexts_free++;
rc = pthread_cond_signal(&cond);
check_expected(rc == 0);
rc = pthread_mutex_unlock(&cond_m);
check_expected(rc == 0);
delete work->command;
delete work;
return;
} //clean_up
// This procedure checks the SQLCACODE flag and prints out any
// information that is available related to the specific error.
int check_error(char eString[], struct sqlca *caPointer)
{
char eBuffer[1024];
char sBuffer[1024];
char message[1024];
char messToken[1024];
short rc, Erc;
int status = 0;
if (caPointer->sqlcode != 0 && caPointer->sqlcode != 100
&& caPointer->sqlcode != -438 && caPointer->sqlcode != -532)
{
strcpy(message, "");
sprintf(messToken, "--- error report ---\n");
strcat(message, messToken);
sprintf(messToken, "ERROR occurred : %s.\nSQLCODE : %ld\n",
eString, caPointer->sqlcode);
strcat(message, messToken);
// GET SQLSTATE MESSAGE
rc = sqlogstt(sBuffer, 1024, 80, caPointer->sqlstate);
// GET ERROR MESSAGE API called
Erc = sqlaintp(eBuffer, 1024, 80, caPointer);
// return code is the length of the eBuffer string
if (Erc > 0)
{
sprintf(messToken, "%s", eBuffer);
strcat(message, messToken);
}
if (caPointer->sqlcode < 0)
{
if (rc == 0)
{
sprintf(messToken, "\n%s", sBuffer);
strcat(message, messToken);
}
sprintf(messToken, "--- end error report ---\n");
strcat(message, messToken);
pthread_mutex_lock (&output);
cout << message;
pthread_mutex_unlock (&output);
return 1;
}
else
{
// errorCode is just a Warning message
if (rc == 0)
{
sprintf(messToken, "\n%s", sBuffer);
strcat(message, messToken);
}
sprintf(messToken, "--- end error report ---\n");
strcat(message, messToken);
sprintf(messToken, "WARNING - CONTINUING PROGRAM WITH WARNINGS!\n");
strcat(message, messToken);
pthread_mutex_lock (&output);
cout << message;
pthread_mutex_unlock (&output);
return 0;
}
}
return 0;
} //check_error