tdb2: test lock timeout plugin code.

ccan/tdb2/test/external-agent.c

@@ -124,6 +124,10 @@ static enum agent_return do_operation(enum operation op, const char *name)
 		ret = tdb_close(tdb) == 0 ? SUCCESS : OTHER_FAILURE;
 		tdb = NULL;
 		break;
+	case SEND_SIGNAL:
+		/* We do this async */
+		ret = SUCCESS;
+		break;
 	default:
 		ret = OTHER_FAILURE;
 	}
@@ -175,6 +179,13 @@ struct agent *prepare_external_agent(void)
 		if (write(response[1], &result, sizeof(result))
 		    != sizeof(result))
 			err(1, "Writing response");
+		if (name[0] == SEND_SIGNAL) {
+			struct timeval ten_ms;
+			ten_ms.tv_sec = 0;
+			ten_ms.tv_usec = 10000;
+			select(0, NULL, NULL, NULL, &ten_ms);
+			kill(getppid(), SIGUSR1);
+		}
 	}
 	exit(0);
 }
@@ -225,6 +236,7 @@ const char *operation_name(enum operation op)
 	case TRANSACTION_START: return "TRANSACTION_START";
 	case TRANSACTION_COMMIT: return "TRANSACTION_COMMIT";
 	case NEEDS_RECOVERY: return "NEEDS_RECOVERY";
+	case SEND_SIGNAL: return "SEND_SIGNAL";
 	case CLOSE: return "CLOSE";
 	}
 	return "**INVALID**";

ccan/tdb2/test/external-agent.h

@@ -12,6 +12,7 @@ enum operation {
 	TRANSACTION_COMMIT,
 	NEEDS_RECOVERY,
 	CHECK,
+	SEND_SIGNAL,
 	CLOSE,
 };
 

ccan/tdb2/test/run-locktimeout.c

+#include <ccan/tdb2/tdb.c>
+#include <ccan/tdb2/open.c>
+#include <ccan/tdb2/free.c>
+#include <ccan/tdb2/lock.c>
+#include <ccan/tdb2/io.c>
+#include <ccan/tdb2/hash.c>
+#include <ccan/tdb2/transaction.c>
+#include <ccan/tdb2/check.c>
+#include <ccan/tap/tap.h>
+#include "logging.h"
+#include "external-agent.h"
+
+#undef alarm
+#define alarm fast_alarm
+
+/* Speed things up by doing things in milliseconds. */
+static unsigned int fast_alarm(unsigned int milli_seconds)
+{
+	struct itimerval it;
+
+	it.it_interval.tv_sec = it.it_interval.tv_usec = 0;
+	it.it_value.tv_sec = milli_seconds / 1000;
+	it.it_value.tv_usec = milli_seconds * 1000;
+	setitimer(ITIMER_REAL, &it, NULL);
+	return 0;
+}
+
+#define CatchSignal(sig, handler) signal((sig), (handler))
+
+static void do_nothing(int signum)
+{
+}
+
+/* This example code is taken from SAMBA, so try not to change it. */
+static struct flock flock_struct;
+
+/* Return a value which is none of v1, v2 or v3. */
+static inline short int invalid_value(short int v1, short int v2, short int v3)
+{
+	short int try = (v1+v2+v3)^((v1+v2+v3) << 16);
+	while (try == v1 || try == v2 || try == v3)
+		try++;
+	return try;
+}
+
+/* We invalidate in as many ways as we can, so the OS rejects it */
+static void invalidate_flock_struct(int signum)
+{
+	flock_struct.l_type = invalid_value(F_RDLCK, F_WRLCK, F_UNLCK);
+	flock_struct.l_whence = invalid_value(SEEK_SET, SEEK_CUR, SEEK_END);
+	flock_struct.l_start = -1;
+	/* A large negative. */
+	flock_struct.l_len = (((off_t)1 << (sizeof(off_t)*CHAR_BIT - 1)) + 1);
+}
+
+static int timeout_lock(int fd, int rw, off_t off, off_t len, bool waitflag,
+			void *_timeout)
+{
+	int ret, saved_errno = errno;
+	unsigned int timeout = *(unsigned int *)_timeout;
+
+	flock_struct.l_type = rw;
+	flock_struct.l_whence = SEEK_SET;
+	flock_struct.l_start = off;
+	flock_struct.l_len = len;
+
+	CatchSignal(SIGALRM, invalidate_flock_struct);
+	alarm(timeout);
+
+	for (;;) {
+		if (waitflag)
+			ret = fcntl(fd, F_SETLKW, &flock_struct);
+		else
+			ret = fcntl(fd, F_SETLK, &flock_struct);
+
+		if (ret == 0)
+			break;
+
+		/* Not signalled?  Something else went wrong. */
+		if (flock_struct.l_len == len) {
+			if (errno == EAGAIN || errno == EINTR)
+				continue;
+			saved_errno = errno;
+			break;
+		} else {
+			saved_errno = EINTR;
+			break;
+		}
+	}
+
+	alarm(0);
+	errno = saved_errno;
+	return ret;
+}
+
+static int tdb_chainlock_with_timeout_internal(struct tdb_context *tdb,
+					       TDB_DATA key,
+					       unsigned int timeout,
+					       int rw_type)
+{
+	union tdb_attribute locking;
+	enum TDB_ERROR ecode;
+
+	if (timeout) {
+		locking.base.attr = TDB_ATTRIBUTE_FLOCK;
+		ecode = tdb_get_attribute(tdb, &locking);
+		if (ecode != TDB_SUCCESS)
+			return ecode;
+
+		/* Replace locking function with our own. */
+		locking.flock.data = &timeout;
+		locking.flock.lock = timeout_lock;
+
+		ecode = tdb_set_attribute(tdb, &locking);
+		if (ecode != TDB_SUCCESS)
+			return ecode;
+	}
+	if (rw_type == F_RDLCK)
+		ecode = tdb_chainlock_read(tdb, key);
+	else
+		ecode = tdb_chainlock(tdb, key);
+
+	if (timeout) {
+		tdb_unset_attribute(tdb, TDB_ATTRIBUTE_FLOCK);
+	}
+	return ecode;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	struct tdb_context *tdb;
+	TDB_DATA key = tdb_mkdata("hello", 5);
+	int flags[] = { TDB_DEFAULT, TDB_NOMMAP,
+			TDB_CONVERT, TDB_NOMMAP|TDB_CONVERT };
+	struct agent *agent;
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 15);
+
+	agent = prepare_external_agent();
+
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		enum TDB_ERROR ecode;
+		tdb = tdb_open("run-locktimeout.tdb", flags[i],
+			       O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		if (!ok1(tdb))
+			break;
+
+		/* Simple cases: should succeed. */ 
+		ecode = tdb_chainlock_with_timeout_internal(tdb, key, 20,
+							    F_RDLCK);
+		ok1(ecode == TDB_SUCCESS);
+		ok1(tap_log_messages == 0);
+
+		tdb_chainunlock_read(tdb, key);
+		ok1(tap_log_messages == 0);
+
+		ecode = tdb_chainlock_with_timeout_internal(tdb, key, 20,
+							    F_WRLCK);
+		ok1(ecode == TDB_SUCCESS);
+		ok1(tap_log_messages == 0);
+
+		tdb_chainunlock(tdb, key);
+		ok1(tap_log_messages == 0);
+
+		/* OK, get agent to start transaction, then we should time out. */
+		ok1(external_agent_operation(agent, OPEN, "run-locktimeout.tdb")
+		    == SUCCESS);
+		ok1(external_agent_operation(agent, TRANSACTION_START, "") 
+		    == SUCCESS);
+		ecode = tdb_chainlock_with_timeout_internal(tdb, key, 20,
+							    F_WRLCK);
+		ok1(ecode == TDB_ERR_LOCK);
+		ok1(tap_log_messages == 0);
+
+		/* Even if we get a different signal, should be fine. */
+		CatchSignal(SIGUSR1, do_nothing);
+		external_agent_operation(agent, SEND_SIGNAL, "");
+		ecode = tdb_chainlock_with_timeout_internal(tdb, key, 20,
+							    F_WRLCK);
+		ok1(ecode == TDB_ERR_LOCK);
+		ok1(tap_log_messages == 0);
+
+		ok1(external_agent_operation(agent, TRANSACTION_COMMIT, "")
+		    == SUCCESS);
+		ok1(external_agent_operation(agent, CLOSE, "")
+		    == SUCCESS);
+		tdb_close(tdb);
+	}
+	free_external_agent(agent);
+	return exit_status();
+}