src/cmd.c src/paxos_lease.c src/paxos_lease.h src/resource.c src/sanlock_resource.h src/sanlock_rv.h

[David Teigland]

 src/cmd.c              |    6 ++++--
 src/paxos_lease.c      |    9 +++++++++
 src/paxos_lease.h      |    1 +
 src/resource.c         |   10 ++++++++--
 src/sanlock_resource.h |    6 ++++++
 src/sanlock_rv.h       |    1 +
 6 files changed, 29 insertions(+), 4 deletions(-)

New commits:
commit badc556ff4f0c60b7e82af25fe5d0f362cc41ccb
Author: David Teigland <teigland(a)redhat.com&gt;
Date:   Wed Oct 14 12:02:33 2015 -0500

    sanlock: add acquire flag to avoid waiting
    
    When a paxos lease is requested that was held by
    a failed, but not yet expired host, the acquire
    routine waits for the lease to expire before
    returning.  Add a flag to avoid waiting for the
    expiration for programs that want to just retry
    instead of block in sanlock_acquire().

diff --git a/src/cmd.c b/src/cmd.c
index 93387c0..64f7f00 100644
--- a/src/cmd.c
+++ b/src/cmd.c
@@ -126,6 +126,7 @@ static const char *acquire_error_str(int error)
 	case SANLK_ACQUIRE_IDLIVE:
 	case SANLK_ACQUIRE_OWNED:
 	case SANLK_ACQUIRE_OTHER:
+	case SANLK_ACQUIRE_OWNED_RETRY:
 		return "lease owned by other host";
 
 	case SANLK_ACQUIRE_SHRETRY:
@@ -181,8 +182,8 @@ static void cmd_acquire(struct task *task, struct cmd_args *ca)
 
 	new_tokens_count = ca->header.data;
 
-	log_debug("cmd_acquire %d,%d,%d ci_in %d fd %d count %d",
-		  cl_ci, cl_fd, cl_pid, ca->ci_in, fd, new_tokens_count);
+	log_debug("cmd_acquire %d,%d,%d ci_in %d fd %d count %d flags %x",
+		  cl_ci, cl_fd, cl_pid, ca->ci_in, fd, new_tokens_count, ca->header.cmd_flags);
 
 	if (new_tokens_count > SANLK_MAX_RESOURCES) {
 		log_error("cmd_acquire %d,%d,%d new %d max %d",
@@ -396,6 +397,7 @@ static void cmd_acquire(struct task *task, struct cmd_args *ca)
 			case SANLK_ACQUIRE_IDLIVE:
 			case SANLK_ACQUIRE_OWNED:
 			case SANLK_ACQUIRE_OTHER:
+			case SANLK_ACQUIRE_OWNED_RETRY:
 				lvl = com.quiet_fail ? LOG_DEBUG : LOG_ERR;
 				break;
 			default:
diff --git a/src/paxos_lease.c b/src/paxos_lease.c
index df60ee6..eae2fd9 100644
--- a/src/paxos_lease.c
+++ b/src/paxos_lease.c
@@ -1661,6 +1661,15 @@ int paxos_lease_acquire(struct task *task,
 			goto run;
 		}
 
+		if (flags & PAXOS_ACQUIRE_OWNER_NOWAIT) {
+			log_token(token, "paxos_acquire owner %llu %llu %llu no wait",
+				  (unsigned long long)cur_leader.owner_id,
+				  (unsigned long long)cur_leader.owner_generation,
+				  (unsigned long long)cur_leader.timestamp);
+			error = SANLK_ACQUIRE_OWNED_RETRY;
+			goto out;
+		}
+
  skip_live_check:
 		/* TODO: test with sleep(2) here */
 		sleep(1);
diff --git a/src/paxos_lease.h b/src/paxos_lease.h
index de5e095..d66a210 100644
--- a/src/paxos_lease.h
+++ b/src/paxos_lease.h
@@ -12,6 +12,7 @@
 #define PAXOS_ACQUIRE_FORCE		0x00000001
 #define PAXOS_ACQUIRE_QUIET_FAIL	0x00000002
 #define PAXOS_ACQUIRE_SHARED		0x00000004
+#define PAXOS_ACQUIRE_OWNER_NOWAIT	0x00000008
 
 uint32_t leader_checksum(struct leader_record *lr);
 
diff --git a/src/resource.c b/src/resource.c
index 15d88a9..b378f62 100644
--- a/src/resource.c
+++ b/src/resource.c
@@ -569,7 +569,7 @@ int res_get_lvb(struct sanlk_resource *res, char **lvb_out, int
*lvblen)
 
 static int acquire_disk(struct task *task, struct token *token,
 			uint64_t acquire_lver, int new_num_hosts,
-			struct leader_record *leader)
+			int owner_nowait, struct leader_record *leader)
 {
 	struct leader_record leader_tmp;
 	int rv;
@@ -581,6 +581,9 @@ static int acquire_disk(struct task *task, struct token *token,
 	if (token->acquire_flags & SANLK_RES_SHARED)
 		flags |= PAXOS_ACQUIRE_SHARED;
 
+	if (owner_nowait)
+		flags |= PAXOS_ACQUIRE_OWNER_NOWAIT;
+
 	memset(&leader_tmp, 0, sizeof(leader_tmp));
 
 	rv = paxos_lease_acquire(task, token, flags, &leader_tmp, acquire_lver,
@@ -1320,6 +1323,7 @@ int acquire_token(struct task *task, struct token *token, uint32_t
cmd_flags,
 	int live_count = 0;
 	int allow_orphan = 0;
 	int only_orphan = 0;
+	int owner_nowait = 0;
 	int rv;
 
 	if (token->acquire_flags & SANLK_RES_LVER)
@@ -1331,6 +1335,8 @@ int acquire_token(struct task *task, struct token *token, uint32_t
cmd_flags,
 		allow_orphan = 1;
 	if (cmd_flags & SANLK_ACQUIRE_ORPHAN_ONLY)
 		only_orphan = 1;
+	if (cmd_flags & SANLK_ACQUIRE_OWNER_NOWAIT)
+		owner_nowait = 1;
 
 	pthread_mutex_lock(&resource_mutex);
 
@@ -1493,7 +1499,7 @@ int acquire_token(struct task *task, struct token *token, uint32_t
cmd_flags,
  retry:
 	memset(&leader, 0, sizeof(struct leader_record));
 
-	rv = acquire_disk(task, token, acquire_lver, new_num_hosts, &leader);
+	rv = acquire_disk(task, token, acquire_lver, new_num_hosts, owner_nowait, &leader);
 
 	if (rv == SANLK_ACQUIRE_IDLIVE || rv == SANLK_ACQUIRE_OWNED || rv ==
SANLK_ACQUIRE_OTHER) {
 		/*
diff --git a/src/sanlock_resource.h b/src/sanlock_resource.h
index 624a7d0..d412482 100644
--- a/src/sanlock_resource.h
+++ b/src/sanlock_resource.h
@@ -43,11 +43,17 @@
  * If the lock already exists as an orphan,
  * then acquire it.  Otherwise, do not acquire
  * a lock at all and return -ENOENT.
+ *
+ * SANLK_ACQUIRE_OWNER_NOWAIT
+ * If the lock cannot be granted immediately
+ * because the owner's lease needs to time out, do
+ * not wait, but return -SANLK_ACQUIRE_OWNED_RETRY.
  */
 
 #define SANLK_ACQUIRE_LVB		0x00000001
 #define SANLK_ACQUIRE_ORPHAN		0x00000002
 #define SANLK_ACQUIRE_ORPHAN_ONLY	0x00000004
+#define SANLK_ACQUIRE_OWNER_NOWAIT	0x00000008
 
 /*
  * release flags
diff --git a/src/sanlock_rv.h b/src/sanlock_rv.h
index 686603a..bafef2b 100644
--- a/src/sanlock_rv.h
+++ b/src/sanlock_rv.h
@@ -47,6 +47,7 @@
 #define SANLK_ACQUIRE_OWNED	-244
 #define SANLK_ACQUIRE_OTHER	-245
 #define SANLK_ACQUIRE_SHRETRY	-246
+#define SANLK_ACQUIRE_OWNED_RETRY -247
 
 #define SANLK_RELEASE_LVER	-250
 #define SANLK_RELEASE_OWNER	-251