psql
create database orders;
create user orders;
alter user orders with encrypted password 'password'
grant all privileges on database orders to orders;
grant all privileges on all tables in schema public to orders;
\c orders
create table reservation (id int primary key, name varchar);
insert into reservation (id, name) values (1, 'Olivier');
insert into reservation (id, name) values (2, 'Allison');Spin up two versions of the application (that is why the port is set to 0). Grab the port number that the application is listening to.
First curl: curl http://localhost:xxxxx/reservation/1/Olivier/30000
This will Update reservation 1, and wait for 30 seconds. During that time a lock is in place.
Second curl: curl http://localhost:xxyyy/reservation/1/Matthew/5000
The second curl won't do anything, because the lock that is held.
Spin up two versions of the application (that is why the port is set to 0).
Inspect Scheduler.java. There are two scheduled tasks, running every minute.
One will run on both instances, the second one will only run for the leader. In the console output, you can figure out which of the two instances is the leader. Stop that instance, you will notice that the other instance becomes leader.
Spring integration and JdbcLockRegistry do all the work. New tables get created, including INT_LOCK to handle the locks.