Commit cda0b7e1 authored by Jacob Vosmaer's avatar Jacob Vosmaer

Rename ExpiringLock to ExclusiveLease

parent acd9bc02
......@@ -246,7 +246,7 @@ class ApplicationController < ActionController::Base
def ldap_security_check
if current_user && current_user.requires_ldap_check?
return unless Gitlab::LDAP::Access.try_lock_user(user)
return unless Gitlab::LDAP::Access.try_lock_user(current_user)
unless Gitlab::LDAP::Access.allowed?(current_user)
sign_out current_user
......
require 'securerandom'
module Gitlab
# This class implements an 'exclusive lease'. We call it a 'lease'
# because it has a set expiry time. We call it 'exclusive' because only
# one caller may obtain a lease for a given key at a time. The
# implementation is intended to work across GitLab processes and across
# servers. It is a 'cheap' alternative to using SQL queries and updates:
# you do not need to change the SQL schema to start using
# ExclusiveLease.
class ExclusiveLease
def initialize(key, timeout)
@key, @timeout = key, timeout
end
# Try to obtain the lease. Return true on succes,
# false if the lease is already taken.
def try_obtain
!!redis.set(redis_key, redis_value, nx: true, ex: @timeout)
end
private
def redis
# Maybe someday we want to use a connection pool...
@redis ||= Redis.new(url: Gitlab::RedisConfig.url)
end
def redis_key
"gitlab:exclusive_lease:#{@key}"
end
def redis_value
@redis_value ||= SecureRandom.hex(10)
end
end
end
module Gitlab
# This class implements a distributed self-expiring lock.
#
# [2] pry(main)> l = Gitlab::ExpiringLock.new('foobar', 5)
# => #<Gitlab::ExpiringLock:0x007ffb9d7cb7f8 @key="foobar", @timeout=5>
# [3] pry(main)> l.try_lock
# => true
# [4] pry(main)> l.try_lock # Only the first try_lock succeeds
# => false
# [5] pry(main)> l.locked?
# => true
# [6] pry(main)> sleep 5
# => 5
# [7] pry(main)> l.locked? # After the timeout the lock is released
# => false
#
class ExpiringLock
def initialize(key, timeout)
@key, @timeout = key, timeout
end
# Try to obtain the lock. Return true on succes,
# false if the lock is already taken.
def try_lock
# INCR does not change the key TTL
if redis.incr(redis_key) == 1
# We won the race to insert the key into Redis
redis.expire(redis_key, @timeout)
true
else
# Somebody else won the race
false
end
end
# Check if somebody somewhere locked this key
def locked?
!!redis.get(redis_key)
end
private
def redis
# Maybe someday we want to use a connection pool...
@redis ||= Redis.new(url: Gitlab::RedisConfig.url)
end
def redis_key
"gitlab:expiring_lock:#{@key}"
end
end
end
......@@ -10,7 +10,7 @@ module Gitlab
LOCK_TIMEOUT = 600
def self.try_lock_user(user)
Gitlab::ExpiringLock.new("user_ldap_check:#{user.id}", LOCK_TIMEOUT).try_lock
Gitlab::ExclusiveLease.new("user_ldap_check:#{user.id}", LOCK_TIMEOUT).try_obtain
end
def self.open(user, &block)
......
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