libdb/docs/programmer_reference/transapp.cs

#include <sys/types.h>
#include <sys/stat.h>

#include <errno.h>
#include <pthread.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <db.h>

#define	ENV_DIRECTORY	"TXNAPP"

void  add_cat(DB_ENV *, DB *, char *, ...);
void  add_color(DB_ENV *, DB *, char *, int);
void  add_fruit(DB_ENV *, DB *, char *, char *);
void *checkpoint_thread(void *);
void  log_archlist(DB_ENV *);
void *logfile_thread(void *);
void  db_open(DB_ENV *, DB **, char *, int);
void  env_dir_create(void);
void  env_open(DB_ENV **);
void  usage(void);

int
main(int argc, char *argv[])
{
	extern int optind;
	DB *db_cats, *db_color, *db_fruit;
	DB_ENV *dbenv;
	pthread_t ptid;
	int ch, ret;

	while ((ch = getopt(argc, argv, "")) != EOF)
		switch (ch) {
		case '?':
		default:
			usage();
		}
	argc -= optind;
	argv += optind;

	env_dir_create();
	env_open(&dbenv);

	/* Start a checkpoint thread. */
	if ((ret = pthread_create(
	    &ptid, NULL, checkpoint_thread, (void *)dbenv)) != 0) {
		fprintf(stderr,
		    "txnapp: failed spawning checkpoint thread: %s\n",
		    strerror(ret));
		exit (1);
	}

	/* Start a logfile removal thread. */
	if ((ret = pthread_create(
	    &ptid, NULL, logfile_thread, (void *)dbenv)) != 0) {
		fprintf(stderr,
		    "txnapp: failed spawning log file removal thread: %s\n",
		    strerror(ret));
		exit (1);
	}

	/* Open database: Key is fruit class; Data is specific type. */
	db_open(dbenv, &db_fruit, "fruit", 0);

	/* Open database: Key is a color; Data is an integer. */
	db_open(dbenv, &db_color, "color", 0);

	/*
	 * Open database:
	 *	Key is a name; Data is: company name, address, cat breeds.
	 */
	db_open(dbenv, &db_cats, "cats", 1);

	add_fruit(dbenv, db_fruit, "apple", "yellow delicious");

	add_color(dbenv, db_color, "blue", 0);
	add_color(dbenv, db_color, "blue", 3);

	add_cat(dbenv, db_cats,
		"Amy Adams",
		"Oracle",
		"394 E. Riding Dr., Carlisle, MA 01741, USA",
		"abyssinian",
		"bengal",
		"chartreaux",
		NULL);

	return (0);
}

void
env_dir_create()
{
	struct stat sb;

	/*
	 * If the directory exists, we're done.  We do not further check
	 * the type of the file, DB will fail appropriately if it's the
	 * wrong type.
	 */
	if (stat(ENV_DIRECTORY, &sb) == 0)
		return;

	/* Create the directory, read/write/access owner only. */
	if (mkdir(ENV_DIRECTORY, S_IRWXU) != 0) {
		fprintf(stderr,
		    "txnapp: mkdir: %s: %s\n", ENV_DIRECTORY, strerror(errno));
		exit (1);
	}
}

void
env_open(DB_ENV **dbenvp)
{
	DB_ENV *dbenv;
	int ret;

	/* Create the environment handle. */
	if ((ret = db_env_create(&dbenv, 0)) != 0) {
		fprintf(stderr,
		    "txnapp: db_env_create: %s\n", db_strerror(ret));
		exit (1);
	}

	/* Set up error handling. */
	dbenv->set_errpfx(dbenv, "txnapp");
	dbenv->set_errfile(dbenv, stderr);

	/* Do deadlock detection internally. */
	if ((ret = dbenv->set_lk_detect(dbenv, DB_LOCK_DEFAULT)) != 0) {
		dbenv->err(dbenv, ret, "set_lk_detect: DB_LOCK_DEFAULT");
		exit (1);
	}

	/*
	 * Open a transactional environment:
	 *	create if it doesn't exist
	 *	free-threaded handle
	 *	run recovery
	 *	read/write owner only
	 */
	if ((ret = dbenv->open(dbenv, ENV_DIRECTORY,
	    DB_CREATE | DB_INIT_LOCK | DB_INIT_LOG |
	    DB_INIT_MPOOL | DB_INIT_TXN | DB_RECOVER | DB_THREAD,
	    S_IRUSR | S_IWUSR)) != 0) {
		dbenv->err(dbenv, ret, "dbenv->open: %s", ENV_DIRECTORY);
		exit (1);
	}

	*dbenvp = dbenv;
}

void *
checkpoint_thread(void *arg)
{
	DB_ENV *dbenv;
	int ret;

	dbenv = arg;
	dbenv->errx(dbenv, "Checkpoint thread: %lu", (u_long)pthread_self());

	/* Checkpoint once a minute. */
	for (;; sleep(60))
		if ((ret = dbenv->txn_checkpoint(dbenv, 0, 0, 0)) != 0) {
			dbenv->err(dbenv, ret, "checkpoint thread");
			exit (1);
		}

	/* NOTREACHED */
}

void *
logfile_thread(void *arg)
{
	DB_ENV *dbenv;
	int ret;
	char **begin, **list;

	dbenv = arg;
	dbenv->errx(dbenv,
	    "Log file removal thread: %lu", (u_long)pthread_self());

	/* Check once every 5 minutes. */
	for (;; sleep(300)) {
		/* Get the list of log files. */
		if ((ret =
		    dbenv->log_archive(dbenv, &list, DB_ARCH_ABS)) != 0) {
			dbenv->err(dbenv, ret, "DB_ENV->log_archive");
			exit (1);
		}

		/* Remove the log files. */
		if (list != NULL) {
			for (begin = list; *list != NULL; ++list)
				if ((ret = remove(*list)) != 0) {
					dbenv->err(dbenv,
					    ret, "remove %s", *list);
					exit (1);
				}
			free (begin);
		}
	}
	/* NOTREACHED */
}

void
log_archlist(DB_ENV *dbenv)
{
	int ret;
	char **begin, **list;

	/* Get the list of database files. */
	if ((ret = dbenv->log_archive(dbenv,
	    &list, DB_ARCH_ABS | DB_ARCH_DATA)) != 0) {
		dbenv->err(dbenv, ret, "DB_ENV->log_archive: DB_ARCH_DATA");
		exit (1);
	}
	if (list != NULL) {
		for (begin = list; *list != NULL; ++list)
			printf("database file: %s\n", *list);
		free (begin);
	}

	/* Get the list of log files. */
	if ((ret = dbenv->log_archive(dbenv,
	    &list, DB_ARCH_ABS | DB_ARCH_LOG)) != 0) {
		dbenv->err(dbenv, ret, "DB_ENV->log_archive: DB_ARCH_LOG");
		exit (1);
	}
	if (list != NULL) {
		for (begin = list; *list != NULL; ++list)
			printf("log file: %s\n", *list);
		free (begin);
	}
}

void
db_open(DB_ENV *dbenv, DB **dbp, char *name, int dups)
{
	DB *db;
	int ret;

	/* Create the database handle. */
	if ((ret = db_create(&db, dbenv, 0)) != 0) {
		dbenv->err(dbenv, ret, "db_create");
		exit (1);
	}

	/* Optionally, turn on duplicate data items. */
	if (dups && (ret = db->set_flags(db, DB_DUP)) != 0) {
		dbenv->err(dbenv, ret, "db->set_flags: DB_DUP");
		exit (1);
	}

	/*
	 * Open a database in the environment:
	 *	create if it doesn't exist
	 *	free-threaded handle
	 *	read/write owner only
	 */
	if ((ret = db->open(db, NULL, name, NULL, DB_BTREE,
	    DB_AUTO_COMMIT | DB_CREATE | DB_THREAD, S_IRUSR | S_IWUSR)) != 0) {
		(void)db->close(db, 0);
		dbenv->err(dbenv, ret, "db->open: %s", name);
		exit (1);
	}

	*dbp = db;
}

void
add_fruit(DB_ENV *dbenv, DB *db, char *fruit, char *name)
{
	DBT key, data;
	DB_TXN *tid;
	int ret;

	/* Initialization. */
	memset(&key, 0, sizeof(key));
	memset(&data, 0, sizeof(data));
	key.data = fruit;
	key.size = strlen(fruit);
	data.data = name;
	data.size = strlen(name);

	for (;;) {
		/* Begin the transaction. */
		if ((ret = dbenv->txn_begin(dbenv, NULL, &tid, 0)) != 0) {
			dbenv->err(dbenv, ret, "DB_ENV->txn_begin");
			exit (1);
		}

		/* Store the value. */
		switch (ret = db->put(db, tid, &key, &data, 0)) {
		case 0:
			/* Success: commit the change. */
			if ((ret = tid->commit(tid, 0)) != 0) {
				dbenv->err(dbenv, ret, "DB_TXN->commit");
				exit (1);
			}
			return;
		case DB_LOCK_DEADLOCK:
			/* Deadlock: retry the operation. */
			if ((ret = tid->abort(tid)) != 0) {
				dbenv->err(dbenv, ret, "DB_TXN->abort");
				exit (1);
			}
			break;
		default:
			/* Error: run recovery. */
			dbenv->err(dbenv, ret, "dbc->put: %s/%s", fruit, name);
			exit (1);
		}
	}
}

void
add_color(DB_ENV *dbenv, DB *dbp, char *color, int increment)
{
	DBT key, data;
	DB_TXN *tid;
	int original, ret;
	char buf[64];

	/* Initialization. */
	memset(&key, 0, sizeof(key));
	key.data = color;
	key.size = strlen(color);
	memset(&data, 0, sizeof(data));
	data.flags = DB_DBT_MALLOC;

	for (;;) {
		/* Begin the transaction. */
		if ((ret = dbenv->txn_begin(dbenv, NULL, &tid, 0)) != 0) {
			dbenv->err(dbenv, ret, "DB_ENV->txn_begin");
			exit (1);
		}

		/*
		 * Get the key.  If it exists, we increment the value.  If it
		 * doesn't exist, we create it.
		 */
		switch (ret = dbp->get(dbp, tid, &key, &data, 0)) {
		case 0:
			original = atoi(data.data);
			break;
		case DB_LOCK_DEADLOCK:
			/* Deadlock: retry the operation. */
			if ((ret = tid->abort(tid)) != 0) {
				dbenv->err(dbenv, ret, "DB_TXN->abort");
				exit (1);
			}
			continue;
		case DB_NOTFOUND:
			original = 0;
			break;
		default:
			/* Error: run recovery. */
			dbenv->err(
			    dbenv, ret, "dbc->get: %s/%d", color, increment);
			exit (1);
		}
		if (data.data != NULL)
			free(data.data);

		/* Create the new data item. */
		(void)snprintf(buf, sizeof(buf), "%d", original + increment);
		data.data = buf;
		data.size = strlen(buf) + 1;

		/* Store the new value. */
		switch (ret = dbp->put(dbp, tid, &key, &data, 0)) {
		case 0:
			/* Success: commit the change. */
			if ((ret = tid->commit(tid, 0)) != 0) {
				dbenv->err(dbenv, ret, "DB_TXN->commit");
				exit (1);
			}
			return;
		case DB_LOCK_DEADLOCK:
			/* Deadlock: retry the operation. */
			if ((ret = tid->abort(tid)) != 0) {
				dbenv->err(dbenv, ret, "DB_TXN->abort");
				exit (1);
			}
			break;
		default:
			/* Error: run recovery. */
			dbenv->err(
			    dbenv, ret, "dbc->put: %s/%d", color, increment);
			exit (1);
		}
	}
}

void
add_cat(DB_ENV *dbenv, DB *db, char *name, ...)
{
	va_list ap;
	DBC *dbc;
	DBT key, data;
	DB_TXN *tid;
	int ret;
	char *s;

	/* Initialization. */
	memset(&key, 0, sizeof(key));
	memset(&data, 0, sizeof(data));
	key.data = name;
	key.size = strlen(name);

retry:	/* Begin the transaction. */
	if ((ret = dbenv->txn_begin(dbenv, NULL, &tid, 0)) != 0) {
		dbenv->err(dbenv, ret, "DB_ENV->txn_begin");
		exit (1);
	}

	/* Delete any previously existing item. */
	switch (ret = db->del(db, tid, &key, 0)) {
	case 0:
	case DB_NOTFOUND:
		break;
	case DB_LOCK_DEADLOCK:
		/* Deadlock: retry the operation. */
		if ((ret = tid->abort(tid)) != 0) {
			dbenv->err(dbenv, ret, "DB_TXN->abort");
			exit (1);
		}
		goto retry;
	default:
		dbenv->err(dbenv, ret, "db->del: %s", name);
		exit (1);
	}

	/* Create a cursor. */
	if ((ret = db->cursor(db, tid, &dbc, 0)) != 0) {
		dbenv->err(dbenv, ret, "db->cursor");
		exit (1);
	}

	/* Append the items, in order. */
	va_start(ap, name);
	while ((s = va_arg(ap, char *)) != NULL) {
		data.data = s;
		data.size = strlen(s);
		switch (ret = dbc->c_put(dbc, &key, &data, DB_KEYLAST)) {
		case 0:
			break;
		case DB_LOCK_DEADLOCK:
			va_end(ap);

			/* Deadlock: retry the operation. */
			if ((ret = dbc->c_close(dbc)) != 0) {
				dbenv->err(
				    dbenv, ret, "dbc->c_close");
				exit (1);
			}
			if ((ret = tid->abort(tid)) != 0) {
				dbenv->err(dbenv, ret, "DB_TXN->abort");
				exit (1);
			}
			goto retry;
		default:
			/* Error: run recovery. */
			dbenv->err(dbenv, ret, "dbc->put: %s/%s", name, s);
			exit (1);
		}
	}
	va_end(ap);

	/* Success: commit the change. */
	if ((ret = dbc->c_close(dbc)) != 0) {
		dbenv->err(dbenv, ret, "dbc->c_close");
		exit (1);
	}
	if ((ret = tid->commit(tid, 0)) != 0) {
		dbenv->err(dbenv, ret, "DB_TXN->commit");
		exit (1);
	}
}

void
usage()
{
	(void)fprintf(stderr, "usage: txnapp\n");
	exit(1);
}