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Use transitional takeover states for migration

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Use a pair of transitional states, "takeover" and "relinquish", when
transitioning between primary and secondary coordinator states. This
provides a clsuter-wide record that the nodes are still working during
their synchronous transition states, and should allow clients to
determine when the node(s) have fully switched over. Also add an
additional 2 seconds of wait at the end of the transition jobs to ensure
everything has had a chance to start before proceeding.

References #72
This commit is contained in:
Joshua Boniface
2020-02-19 13:18:38 -05:00
parent 8678dedfea
commit d2a5fe59c0
2 changed files with 27 additions and 14 deletions
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24
node-daemon/pvcnoded/Daemon.py
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@ -575,14 +575,17 @@ def cleanup():
pass
# Force into secondary network state if needed
if zkhandler.readdata(zk_conn, '/nodes/{}/routerstate'.format(myhostname)) == 'primary':
is_primary = True
zkhandler.writedata(zk_conn, {
'/nodes/{}/routerstate'.format(myhostname): 'secondary',
'/primary_node': 'none'
})
logger.out('Waiting 5 seconds for primary migration', state='s')
time.sleep(5)
try:
if this_node.router_state == 'primary':
is_primary = True
zkhandler.writedata(zk_conn, {
'/primary_node': 'none'
})
logger.out('Waiting for primary migration', state='s')
while this_node.router_state != 'secondary':
time.sleep(1)
except:
pass
# Set stop state in Zookeeper
zkhandler.writedata(zk_conn, { '/nodes/{}/daemonstate'.format(myhostname): 'stop' })
@ -825,9 +828,10 @@ def update_primary(new_primary, stat, event=''):
logger.out('Contending for primary coordinator state', state='i')
zkhandler.writedata(zk_conn, {'/primary_node': myhostname})
elif new_primary == myhostname:
zkhandler.writedata(zk_conn, {'/nodes/{}/routerstate'.format(myhostname): 'primary'})
zkhandler.writedata(zk_conn, {'/nodes/{}/routerstate'.format(myhostname): 'takeover'})
else:
zkhandler.writedata(zk_conn, {'/nodes/{}/routerstate'.format(myhostname): 'secondary'})
if this_node.router_state != 'secondary':
zkhandler.writedata(zk_conn, {'/nodes/{}/routerstate'.format(myhostname): 'relinquish'})
else:
zkhandler.writedata(zk_conn, {'/nodes/{}/routerstate'.format(myhostname): 'client'})