github-mirror/discourse
2
0
Fork 0
mirror of https://github.com/discourse/discourse.git synced 2025-02-17 01:32:44 +08:00
Code Issues Actions 1 Packages Projects Releases Wiki Activity

DEV: Validity of distributed mutex configurable once per instance.

Browse Source 
Follow up to 4f9e5e19c8.
This commit is contained in:
Guo Xiang Tan 2019-02-20 09:28:10 +08:00
parent f2efa0da66
commit 4d31b425e3
2 changed files with 17 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
lib/distributed_mutex.rb
View File

@ -3,24 +3,29 @@ class DistributedMutex
DEFAULT_VALIDITY = 60 DEFAULT_VALIDITY = 60
def self.synchronize(key, redis: nil, validity: DEFAULT_VALIDITY, &blk) def self.synchronize(key, redis: nil, validity: DEFAULT_VALIDITY, &blk)
self.new(key, redis).synchronize(validity: DEFAULT_VALIDITY, &blk) self.new(
key,
redis: redis,
validity: validity
).synchronize(&blk)
end end
def initialize(key, redis = nil) def initialize(key, redis: nil, validity: DEFAULT_VALIDITY)
@key = key @key = key
@using_global_redis = true if !redis @using_global_redis = true if !redis
@redis = redis || $redis @redis = redis || $redis
@mutex = Mutex.new @mutex = Mutex.new
@validity = validity
end end
CHECK_READONLY_ATTEMPT ||= 10 CHECK_READONLY_ATTEMPT ||= 10
# NOTE wrapped in mutex to maintain its semantics # NOTE wrapped in mutex to maintain its semantics
def synchronize(validity: DEFAULT_VALIDITY) def synchronize
@mutex.lock @mutex.lock
attempts = 0 attempts = 0
while !try_to_get_lock(validity) while !try_to_get_lock
sleep 0.001 sleep 0.001
# in readonly we will never be able to get a lock # in readonly we will never be able to get a lock
if @using_global_redis && Discourse.recently_readonly? if @using_global_redis && Discourse.recently_readonly?
@ -41,11 +46,11 @@ class DistributedMutex
private private
def try_to_get_lock(validity) def try_to_get_lock
got_lock = false got_lock = false
if @redis.setnx @key, Time.now.to_i + validity if @redis.setnx @key, Time.now.to_i + @validity
@redis.expire @key, validity @redis.expire @key, @validity
got_lock = true got_lock = true
else else
begin begin
@ -54,7 +59,7 @@ class DistributedMutex
if time && time.to_i < Time.now.to_i if time && time.to_i < Time.now.to_i
got_lock = @redis.multi do got_lock = @redis.multi do
@redis.set @key, Time.now.to_i + validity @redis.set @key, Time.now.to_i + @validity
end end
end end
ensure ensure

6
spec/components/distributed_mutex_spec.rb
View File

@ -44,13 +44,15 @@ describe DistributedMutex do
it 'allows the validity of the lock to be configured' do it 'allows the validity of the lock to be configured' do
freeze_time freeze_time
mutex = DistributedMutex.new(key) mutex = DistributedMutex.new(key, validity: 2)
mutex.synchronize(validity: 2) do mutex.synchronize do
expect($redis.ttl(key)).to eq(2) expect($redis.ttl(key)).to eq(2)
expect($redis.get(key).to_i).to eq(Time.now.to_i + 2) expect($redis.get(key).to_i).to eq(Time.now.to_i + 2)
end end
mutex = DistributedMutex.new(key)
mutex.synchronize do mutex.synchronize do
expect($redis.ttl(key)).to eq(DistributedMutex::DEFAULT_VALIDITY) expect($redis.ttl(key)).to eq(DistributedMutex::DEFAULT_VALIDITY)