Merge pull request #143 from dhruvCW/use_monitor

Use Monitor to make sure we call `RedisClient` in a thread safe way.

README.md

@@ -176,14 +176,29 @@ lock_manager.get_remaining_ttl_for_resource(resource)
 
 ## Redis client configuration
 
-`Redlock::Client` expects URLs or Redis objects on initialization. Redis objects should be used for configuring the connection in more detail, i.e. setting username and password.
+`Redlock::Client` expects URLs, or configurations or Redis objects on initialization. Redis objects should be used for configuring the connection in more detail, i.e. setting username and password.
 
 ```ruby
 servers = [ 'redis://localhost:6379', RedisClient.new(:url => 'redis://someotherhost:6379') ]
 redlock = Redlock::Client.new(servers)
 ```
 
-Redlock works seamlessly with [redis sentinel](http://redis.io/topics/sentinel), which is supported in redis 3.2+.
+To utilize `Redlock::Client` with sentinels you can pass an instance of `RedisClient` or just a configuration hash as part of the servers array during initialization.
+
+```ruby
+config = {
+ name: "mymaster",
+ sentinels: [
+ { host: "127.0.0.1", port: 26380 },
+ { host: "127.0.0.1", port: 26381 },
+ ],
+ role: :master
+}
+client = RedisClient.sentinel(**config).new_client
+servers = [ config, client ]
+redlock = Redlock::Client.new(servers)
+```
+Redlock supports the same configuration hash as `RedisClient`.
 
 ## Redlock configuration
 

lib/redlock/client.rb

@@ -1,10 +1,11 @@
+require 'monitor'
 require 'redis-client'
 require 'securerandom'
 
 module Redlock
  include Scripts
 
- class LockAcquisitionError < StandardError
+ class LockAcquisitionError < LockError
  attr_reader :errors
 
  def initialize(message, errors)
@@ -163,6 +164,8 @@ def with
  end
 
  def initialize(connection)
+ @monitor = Monitor.new
+
  if connection.respond_to?(:with)
  @redis = connection
  else
@@ -198,17 +201,21 @@ def initialize_client(options)
  end
  end
 
+ def synchronize
+ @monitor.synchronize { @redis.with { |connection| yield(connection) } }
+ end
+
  def lock(resource, val, ttl, allow_new_lock)
  recover_from_script_flush do
- @redis.with { |conn|
+ synchronize { |conn|
  conn.call('EVALSHA', Scripts::LOCK_SCRIPT_SHA, 1, resource, val, ttl, allow_new_lock)
  }
  end
  end
 
  def unlock(resource, val)
  recover_from_script_flush do
- @redis.with { |conn|
+ synchronize { |conn|
  conn.call('EVALSHA', Scripts::UNLOCK_SCRIPT_SHA, 1, resource, val)
  }
  end
@@ -218,7 +225,7 @@ def unlock(resource, val)
 
  def get_remaining_ttl(resource)
  recover_from_script_flush do
- @redis.with { |conn|
+ synchronize { |conn|
  conn.call('EVALSHA', Scripts::PTTL_SCRIPT_SHA, 1, resource)
  }
  end
@@ -235,7 +242,7 @@ def load_scripts
  Scripts::PTTL_SCRIPT
  ]
 
- @redis.with do |connnection|
+ synchronize do |connnection|
  scripts.each do |script|
  connnection.call('SCRIPT', 'LOAD', script)
  end