Remove code which generates a deprecation warning

use monotonic time for retry timeout check

.github/workflows/CI.yml

@@ -0,0 +1,38 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby:
+          - '2.5'
+          - '2.6'
+          - '2.7'
+          - '3.0'
+          - ruby-head
+    continue-on-error: ${{ matrix.ruby == 'ruby-head' }}
+    services:
+      memcached:
+        image: memcached
+        ports:
+          - 11211:11211
+      redis:
+        image: redis
+        ports:
+          - 6379:6379
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - run: |
+          bundle exec rake

.rubocop.yml

@@ -74,7 +74,7 @@ Style/SpaceInsideBrackets:
 Style/AndOr:
   Enabled: false
 
-Style/TrailingComma:
+Style/TrailingCommaInLiteral:
   Enabled: true
 
 Style/SpaceBeforeComma:
@@ -98,7 +98,7 @@ Style/SpaceAfterColon:
 Style/SpaceAfterComma:
   Enabled: true
 
-Style/SpaceAfterControlKeyword:
+Style/SpaceAroundKeyword:
   Enabled: true
 
 Style/SpaceAfterNot:
@@ -163,7 +163,7 @@ Style/StringLiterals:
   EnforcedStyle: double_quotes
 
 Metrics/CyclomaticComplexity:
-  Max: 8
+  Max: 10
 
 Metrics/LineLength:
   Max: 128
@@ -214,3 +214,6 @@ Metrics/ParameterLists:
 
 Metrics/PerceivedComplexity:
   Enabled: false
+
+Style/Documentation:
+  Enabled: false

.travis.yml

@@ -1,6 +0,0 @@
-language: ruby
-rvm:
-  - 2.2.0
-services:
-  - memcached
-  - redis-server

CHANGELOG.md

@@ -1,3 +1,27 @@
+## 0.4.0
+
+- Monotonic clock for locks, avoiding issues with DST (thanks @doits)
+- Pooled connection support (thanks @mlarraz)
+- Switch to Github actions for tests (thanks @mlarraz)
+- Update supported Ruby versions (thanks @mlarraz & @pat)
+
+## 0.3.4
+
+- Support for connection pooling when using memcached locks, via `with` blocks using Dalli (thanks to Lev).
+
+## 0.3.3
+
+- Default TTL for keys to allow for short-lived locking keys (thanks to Ian Remillard) without leaking memory.
+- Vastly improve initial lock acquisition, especially on Redis (thanks to Jeremy Wadscak).
+
+## 0.3.2
+
+- Custom lock tokens (thanks to avokhmin).
+
+## 0.3.1
+
+- Slight memory leak fix.
+
 ## 0.3.0
 
 - Dramatically simplify the interface by forcing clients to specify the key & resources at lock initialization instead of every method call.

README.md

@@ -1,4 +1,4 @@
-# Suo [![Build Status](https://travis-ci.org/nickelser/suo.svg?branch=master)](https://travis-ci.org/nickelser/suo) [![Code Climate](https://codeclimate.com/github/nickelser/suo/badges/gpa.svg)](https://codeclimate.com/github/nickelser/suo) [![Test Coverage](https://codeclimate.com/github/nickelser/suo/badges/coverage.svg)](https://codeclimate.com/github/nickelser/suo) [![Gem Version](https://badge.fury.io/rb/suo.svg)](http://badge.fury.io/rb/suo)
+# Suo [![Build Status](https://github.com/nickelser/suo/workflows/CI/badge.svg)](https://github.com/nickelser/suo/actions?query=workflow%3ACI) [![Code Climate](https://codeclimate.com/github/nickelser/suo/badges/gpa.svg)](https://codeclimate.com/github/nickelser/suo) [![Gem Version](https://badge.fury.io/rb/suo.svg)](http://badge.fury.io/rb/suo)
 
 :lock: Distributed semaphores using Memcached or Redis in Ruby.
 
@@ -46,7 +46,7 @@ suo = Suo::Client::Memcached.new("protected_key", client: some_dalli_client, acq
 # manually locking/unlocking
 # the return value from lock without a block is a unique token valid only for the current lock
 # which must be unlocked manually
-token = suo
+token = suo.lock
 foo.baz!
 suo.unlock(token)
 
@@ -72,12 +72,21 @@ suo.lock do |token|
 end
 ```
 
+### Time To Live
+
+```ruby
+Suo::Client::Redis.new("bar_resource", ttl: 60) #ttl in seconds
+```
+
+A key representing a set of lockable resources is removed once the last resource lock is released and the `ttl` time runs out. When another lock is acquired and the key has been removed the key has to be recreated.
+
+
 ## TODO
  - more race condition tests
 
 ## History
 
-View the [changelog](https://github.com/nickelser/suo/blob/master/CHANGELOG.md)
+View the [changelog](https://github.com/nickelser/suo/blob/master/CHANGELOG.md).
 
 ## Contributing
 

lib/suo.rb

@@ -2,7 +2,6 @@ require "securerandom"
 require "monitor"
 
 require "dalli"
-require "dalli/cas/client"
 
 require "redis"
 

lib/suo/client/base.rb

@@ -5,25 +5,30 @@ module Suo
         acquisition_timeout: 0.1,
         acquisition_delay: 0.01,
         stale_lock_expiration: 3600,
-        resources: 1
+        resources: 1,
+        ttl: 60,
       }.freeze
 
+      BLANK_STR = "".freeze
+
       attr_accessor :client, :key, :resources, :options
 
       include MonitorMixin
 
       def initialize(key, options = {})
         fail "Client required" unless options[:client]
+
         @options = DEFAULT_OPTIONS.merge(options)
         @retry_count = (@options[:acquisition_timeout] / @options[:acquisition_delay].to_f).ceil
         @client = @options[:client]
         @resources = @options[:resources].to_i
         @key = key
+
         super() # initialize Monitor mixin for thread safety
       end
 
-      def lock
-        token = acquire_lock
+      def lock(custom_token = nil)
+        token = acquire_lock(custom_token)
 
         if block_given? && token
           begin
@@ -51,16 +56,13 @@ module Suo
         retry_with_timeout do
           val, cas = get
 
-          if val.nil?
-            initial_set
-            next
-          end
+          cas = initial_set if val.nil?
 
           cleared_locks = deserialize_and_clear_locks(val)
 
           refresh_lock(cleared_locks, token)
 
-          break if set(serialize_locks(cleared_locks), cas)
+          break if set(serialize_locks(cleared_locks), cas, expire: cleared_locks.empty?)
         end
       end
 
@@ -77,7 +79,7 @@ module Suo
           acquisition_lock = remove_lock(cleared_locks, token)
 
           break unless acquisition_lock
-          break if set(serialize_locks(cleared_locks), cas)
+          break if set(serialize_locks(cleared_locks), cas, expire: cleared_locks.empty?)
         end
       rescue LockClientError => _ # rubocop:disable Lint/HandleExceptions
         # ignore - assume success due to optimistic locking
@@ -91,16 +93,13 @@ module Suo
 
       attr_accessor :retry_count
 
-      def acquire_lock
-        token = SecureRandom.base64(16)
+      def acquire_lock(token = nil)
+        token ||= SecureRandom.base64(16)
 
         retry_with_timeout do
           val, cas = get
 
-          if val.nil?
-            initial_set
-            next
-          end
+          cas = initial_set if val.nil?
 
           cleared_locks = deserialize_and_clear_locks(val)
 
@@ -124,7 +123,7 @@ module Suo
         fail NotImplementedError
       end
 
-      def initial_set(val = "") # rubocop:disable Lint/UnusedMethodArgument
+      def initial_set(val = BLANK_STR) # rubocop:disable Lint/UnusedMethodArgument
         fail NotImplementedError
       end
 
@@ -133,10 +132,10 @@ module Suo
       end
 
       def retry_with_timeout
-        start = Time.now.to_f
+        start = Process.clock_gettime(Process::CLOCK_MONOTONIC)
 
         retry_count.times do
-          elapsed = Time.now.to_f - start
+          elapsed = Process.clock_gettime(Process::CLOCK_MONOTONIC) - start
           break if elapsed >= options[:acquisition_timeout]
 
           synchronize do
@@ -158,7 +157,7 @@ module Suo
       end
 
       def deserialize_locks(val)
-        unpacked = (val.nil? || val == "") ? [] : MessagePack.unpack(val)
+        unpacked = (val.nil? || val == BLANK_STR) ? [] : MessagePack.unpack(val)
 
         unpacked.map do |time, token|
           [Time.at(time), token]

lib/suo/client/memcached.rb

@@ -7,21 +7,29 @@ module Suo
       end
 
       def clear
-        @client.delete(@key)
+        @client.with { |client| client.delete(@key) }
       end
 
       private
 
       def get
-        @client.get_cas(@key)
+        @client.with { |client| client.get_cas(@key) }
       end
 
-      def set(newval, cas)
-        @client.set_cas(@key, newval, cas)
+      def set(newval, cas, expire: false)
+        if expire
+          @client.with { |client| client.set_cas(@key, newval, cas, @options[:ttl]) }
+        else
+          @client.with { |client| client.set_cas(@key, newval, cas) }
+        end
       end
 
-      def initial_set(val = "")
-        @client.set(@key, val)
+      def initial_set(val = BLANK_STR)
+        @client.with do |client|
+          client.set(@key, val)
+          _val, cas = client.get_cas(@key)
+          cas
+        end
       end
     end
   end

lib/suo/client/redis.rb

@@ -1,39 +1,54 @@
 module Suo
   module Client
     class Redis < Base
+      OK_STR = "OK".freeze
+
       def initialize(key, options = {})
         options[:client] ||= ::Redis.new(options[:connection] || {})
         super
       end
 
       def clear
-        @client.del(@key)
+        with { |r| r.del(@key) }
       end
 
       private
 
+      def with(&block)
+        if @client.respond_to?(:with)
+          @client.with(&block)
+        else
+          yield @client
+        end
+      end
+
       def get
-        [@client.get(@key), nil]
+        [with { |r| r.get(@key) }, nil]
       end
 
-      def set(newval, _)
-        ret = @client.multi do |multi|
-          multi.set(@key, newval)
+      def set(newval, _, expire: false)
+        ret = with do |r|
+          r.multi do |rr|
+            if expire
+              rr.setex(@key, @options[:ttl], newval)
+            else
+              rr.set(@key, newval)
+            end
+          end
         end
 
-        ret && ret[0] == "OK"
+        ret && ret[0] == OK_STR
       end
 
       def synchronize
-        @client.watch(@key) do
-          yield
-        end
+        with { |r| r.watch(@key) { yield } }
       ensure
-        @client.unwatch
+        with { |r| r.unwatch }
       end
 
-      def initial_set(val = "")
-        @client.set(@key, val)
+      def initial_set(val = BLANK_STR)
+        set(val, nil)
+        nil
       end
     end
   end

lib/suo/version.rb

@@ -1,3 +1,3 @@
 module Suo
-  VERSION = "0.3.0"
+  VERSION = "0.4.0".freeze
 end

suo.gemspec

@@ -16,19 +16,18 @@ Gem::Specification.new do |spec|
 
   spec.files         = `git ls-files -z`.split("\x0")
   spec.bindir        = "bin"
-  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
 
-  spec.required_ruby_version = "~> 2.0"
+  spec.required_ruby_version = ">= 2.5"
 
   spec.add_dependency "dalli"
   spec.add_dependency "redis"
   spec.add_dependency "msgpack"
 
-  spec.add_development_dependency "bundler", "~> 1.5"
-  spec.add_development_dependency "rake", "~> 10.0"
-  spec.add_development_dependency "rubocop", "~> 0.30.0"
+  spec.add_development_dependency "bundler"
+  spec.add_development_dependency "rake", "~> 13.0"
+  spec.add_development_dependency "rubocop", "~> 0.49.0"
   spec.add_development_dependency "minitest", "~> 5.5.0"
   spec.add_development_dependency "codeclimate-test-reporter", "~> 0.4.7"
 end

test/client_test.rb

@@ -31,6 +31,12 @@ module ClientTests
     assert_equal false, locked
   end
 
+  def test_lock_with_custom_token
+    token = 'foo-bar'
+    lock  = @client.lock token
+    assert_equal lock, token
+  end
+
   def test_empty_lock_on_invalid_data
     @client.send(:initial_set, "bad value")
     assert_equal false, @client.locked?