[sanlock] 01/06: sanlock: skip short delay in delta lease reacquire

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teigland pushed a commit to branch master
in repository sanlock.

commit a239c898c12a92cb5fb74f0eb74bc5919db45b94
Author: David Teigland 
AuthorDate: Fri Dec 8 17:48:02 2023 -0600

sanlock: skip short delay in delta lease reacquire

When a host with the same host name reacquires the
    same host_id, the "fast" delta lease reacquire was
    still applying the short delay (default 20s) which
    should not be necessary.  Reduce this further to
    just 1 second when the lease is also free.
---
 src/delta_lease.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/src/delta_lease.c b/src/delta_lease.c
index 9d5aafd..d36d4e0 100644
--- a/src/delta_lease.c
+++ b/src/delta_lease.c
@@ -340,6 +340,7 @@ int delta_lease_acquire(struct task *task,
    uint32_t checksum;
    int other_io_timeout, other_host_dead_seconds, other_id_renewal_seconds;
    int i, error, rv, delay, delta_large_delay;
+	int fast_free_delay = 0;

log_space(sp, "delta_acquire begin %.48s:%llu",
    	  sp->space_name, (unsigned long long)host_id);
@@ -361,6 +362,19 @@ int delta_lease_acquire(struct task *task,
    		  leader.io_timeout, sp->io_timeout);
    }

+	/*
+	 * This delay-free reacquire could probably be used whenever
+	 * our_host_name matches the current leader.resource_name,
+	 * regardless of wheter the lease is free (i.e. we cleanly
+	 * released the lease last time we held it.)
+	 */
+	if (!strncmp(leader.resource_name, our_host_name, NAME_ID_SIZE) &&
+	    (leader.timestamp == LEASE_FREE)) {
+		log_space(sp, "delta_acquire free fast reacquire");
+		fast_free_delay = 1;
+		goto write_new;
+	}
+
    if (leader.timestamp == LEASE_FREE)
    	goto write_new;

@@ -475,7 +489,10 @@ int delta_lease_acquire(struct task *task,

memcpy(&leader1, &leader, sizeof(struct leader_record));

-	delay = 2 * other_io_timeout;
+	if (fast_free_delay)
+		delay = 1;
+	else
+		delay = 2 * other_io_timeout;
    log_space(sp, "delta_acquire delta_short_delay %d", delay);

for (i = 0; i < delay; i++) {