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#
# Concern that helps with getting an exclusive lease for running a block
# of code.
#
# `#try_obtain_lease` takes a block which will be run if it was able to
# obtain the lease. Implement `#lease_timeout` to configure the timeout
# for the exclusive lease. Optionally override `#lease_key` to set the
# lease key, it defaults to the class name with underscores.
#
module ExclusiveLeaseGuard
extend ActiveSupport::Concern
def try_obtain_lease
lease = exclusive_lease.try_obtain
unless lease
log_error('Cannot obtain an exclusive lease. There must be another instance already in execution.')
return
end
begin
yield lease
ensure
release_lease(lease)
end
end
def exclusive_lease
@lease ||= Gitlab::ExclusiveLease.new(lease_key, timeout: lease_timeout)
end
def lease_key
@lease_key ||= self.class.name.underscore
end
def lease_timeout
raise NotImplementedError,
"#{self.class.name} does not implement #{__method__}"
end
def release_lease(uuid)
Gitlab::ExclusiveLease.cancel(lease_key, uuid)
end
def renew_lease!
exclusive_lease.renew
end
def log_error(message, extra_args = {})
logger.error(messages)
end
end