Merge 6a987ce into 46b7faf

CHANGELOG.md

@@ -2,6 +2,7 @@
 All notable changes to this project will be documented in this file.
 
 ## [Unreleased]
+- existence operation `AnyCache#exist?(key)` - determine if an entry exists or not;
 - support for `ActiveSupport::Cache::MemCacheStore`;
 - configuration layer `AnyCache.configure`: an ability to choose and configure a necessary cache client
   without any explicit client object instantiation (client object will be instantiated implicitly);

README.md

@@ -1,7 +1,7 @@
 # AnyCache · [![Gem Version](https://badge.fury.io/rb/any_cache.svg)](https://badge.fury.io/rb/any_cache) [![Build Status](https://travis-ci.org/0exp/any_cache.svg?branch=master)](https://travis-ci.org/0exp/any_cache) [![Coverage Status](https://coveralls.io/repos/github/0exp/any_cache/badge.svg)](https://coveralls.io/github/0exp/any_cache)
 
 AnyCache - a simplest cache wrapper that provides a minimalistic generic interface for all well-known cache storages and includes a minimal set of necessary operations:
-`read`, `write`, `delete`, `expire`, `persist`, `clear`, `increment`, `decrement`.
+`read`, `write`, `delete`, `expire`, `persist`, `exist?`, `clear`, `increment`, `decrement`.
 
 Supported clients:
 
@@ -55,6 +55,7 @@ require 'any_cache'
     - [Decrement](#decrement)
     - [Expire](#expire)
     - [Persist](#persist)
+    - [Existence](#existence)
     - [Clear](#clear)
 
 ---
@@ -234,6 +235,7 @@ If you want to use your own cache client implementation, you should provide an o
 - `#decrement(key, amount, [**options])` ([doc](#decrement))
 - `#expire(key, [**options])` ([doc](#expire))
 - `#persist(key, [**options])` ([doc](#persist))
+- `#exist?(key, [**options])` ([doc](#existence))
 - `#clear([**options])` ([doc](#clear))
 
 ```ruby
@@ -266,6 +268,7 @@ AnyCache.build(MyCacheClient.new)
 - [expire](#expire)
 - [persist](#persist)
 - [clear](#clear)
+- [exist?](#existence)
 
 ---
 
@@ -383,6 +386,20 @@ any_cache.persist("data")
 
 ---
 
+### Existence
+
+- `AnyCache#exist?(key)` - determine if an entry exists
+
+```ruby
+# --- entry exists ---
+any_cache.exist?("data") # => true
+
+# --- entry does not exist ---
+any_cache.exist?("another-data") # => false
+```
+
+---
+
 ### Clear
 
 - `AnyCache#clear()` - clear cache database

lib/any_cache.rb

@@ -73,7 +73,8 @@ def build(driver = Drivers.build(config))
                  :decrement,
                  :expire,
                  :persist,
-                 :clear
+                 :clear,
+                 :exist?
 
   # @return [AnyCache::Adapters::Basic]
   #

lib/any_cache/adapters/active_support_mem_cache_store.rb

@@ -133,5 +133,15 @@ def expire(key, expires_in: DEAD_TTL)
     def persist(key, **options)
       read(key).tap { |value| write(key, value) }
     end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      driver.exist?(key)
+    end
   end
 end

lib/any_cache/adapters/active_support_naive_store.rb

@@ -118,6 +118,16 @@ def persist(key, **options)
       lock.with_write_lock { pers_operation.call(key) }
     end
 
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      lock.with_read_lock { super }
+    end
+
     private
 
     # @return [Concurrent::ReentrantReadWriteLock]

lib/any_cache/adapters/active_support_redis_cache_store.rb

@@ -123,5 +123,15 @@ def expire(key, expires_in: DEAD_TTL)
     def persist(key, **options)
       read(key).tap { |value| write(key, value) }
     end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      driver.exist?(key)
+    end
   end
 end

lib/any_cache/adapters/basic.rb

@@ -114,5 +114,15 @@ def persist(key, **options)
     def clear(**options)
       raise NotImplementedError
     end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      raise NotImplementedError
+    end
   end
 end

lib/any_cache/adapters/dalli.rb

@@ -136,5 +136,15 @@ def persist(key, **options)
     def clear(**options)
       flush(0) # NOTE: 0 is a flush delay
     end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      !get(key).nil? # NOTE: can conflict with :cache_nils Dalli::Client option
+    end
   end
 end

lib/any_cache/adapters/delegator.rb

@@ -18,7 +18,8 @@ def supported_driver?(driver)
         driver.respond_to?(:decrement) &&
         driver.respond_to?(:expire) &&
         driver.respond_to?(:persist) &&
-        driver.respond_to?(:clear)
+        driver.respond_to?(:clear) &&
+        driver.respond_to?(:exist?)
       end
     end
 
@@ -31,6 +32,7 @@ def supported_driver?(driver)
                    :decrement,
                    :expire,
                    :persist,
-                   :clear
+                   :clear,
+                   :exist?
   end
 end

lib/any_cache/adapters/redis.rb

@@ -42,7 +42,8 @@ def supported_driver?(driver)
                    :incrby,
                    :decrby,
                    :pipelined,
-                   :flushdb
+                   :flushdb,
+                   :exists
 
     # @param key [String]
     # @param options [Hash]
@@ -147,5 +148,15 @@ def persist(key, **options)
     def clear(**options)
       flushdb
     end
+
+    # @param key [String]
+    # @param options [Hash]
+    # @return [Boolean]
+    #
+    # @api private
+    # @since 0.2.0
+    def exist?(key, **options)
+      exists(key)
+    end
   end
 end

spec/features/exist_spec.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+describe 'Operation: #exist?' do
+  after { cache_store.clear }
+
+  let(:cache_store)     { build_cache_store }
+  let(:expiration_time) { 8 } # NOTE: in seconds
+  let(:entry)           { { key: SecureRandom.hex, value: SecureRandom.hex(4) } }
+
+  context 'entry with expiration time' do
+    before { cache_store.write(entry[:key], entry[:value], expires_in: expiration_time) }
+
+    specify 'returns corresponding value (exists => true, does not exist => false)' do
+      expect(cache_store.exist?(entry[:key])).to eq(true)
+
+      sleep(expiration_time + 1)
+
+      expect(cache_store.exist?(entry[:key])).to eq(false)
+    end
+  end
+
+  context 'when entry exists' do
+    before { cache_store.write(entry[:key], entry[:value]) }
+
+    it 'returns true' do
+      expect(cache_store.exist?(entry[:key])).to eq(true)
+    end
+  end
+
+  context 'when entry does not exist' do
+    it 'returns false' do
+      expect(cache_store.exist?(entry[:key])).to eq(false)
+    end
+  end
+end