From 9d464476970176fa4bdcd448910c52f5d387d188 Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Fri, 27 May 2016 00:42:21 +0200
Subject: [PATCH 01/10] Create hybrid hash/redis storage

---
 .travis.yml                        |  19 ++--
 lib/lit.rb                         |   3 +
 lib/lit/adapters/hybrid_storage.rb | 153 +++++++++++++++++++++++++++++
 lib/lit/i18n_backend.rb            |   8 +-
 lit.gemspec                        |   1 +
 test/dummy/config/database.yml     |   4 +-
 test/support/clear_snapshots.rb    |   7 ++
 test/test_helper.rb                |   1 +
 8 files changed, 184 insertions(+), 12 deletions(-)
 create mode 100644 lib/lit/adapters/hybrid_storage.rb
 create mode 100644 test/support/clear_snapshots.rb

diff --git a/.travis.yml b/.travis.yml
index 97f26977..f8bceee0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,21 +1,22 @@
 language: ruby
 sudo: false
 rvm:
-  - 2.0.0
-  - 2.1.2
-  - 2.2.5
-  - 2.3.1
+#  - 2.0.0
+#  - 2.1.2
+#  - 2.2.5
+   - 2.3.0
 gemfile:
-  - gemfiles/rails_4.gemfile
-  - gemfiles/rails_4.1.gemfile
+#  - gemfiles/rails_4.gemfile
+#  - gemfiles/rails_4.1.gemfile
   - gemfiles/rails_4.2.gemfile
 services:
   - redis-server
 env:
-  - LIT_STORAGE=hash
-  - LIT_STORAGE=redis
+  # - LIT_STORAGE=hash
+  # - LIT_STORAGE=redis
+  - LIT_STORAGE=hybrid
 before_script:
   - cp test/dummy/config/database.yml.travis test/dummy/config/database.yml
   - psql -c 'create database lit_test;' -U postgres
   - RAILS_ENV=test bundle exec rake db:migrate
-script: "bundle exec rake test"
+script: "bundle exec rake test" # TEST=test/unit/lit_behaviour_test.rb"
diff --git a/lib/lit.rb b/lib/lit.rb
index e10d6448..b79feea7 100644
--- a/lib/lit.rb
+++ b/lib/lit.rb
@@ -46,6 +46,9 @@ def self.get_key_value_engine
         when 'redis'
           require 'lit/adapters/redis_storage'
           return RedisStorage.new
+        when 'hybrid'
+          require 'lit/adapters/hybrid_storage'
+          return HybridStorage.new
         else
           require 'lit/adapters/hash_storage'
           return HashStorage.new
diff --git a/lib/lit/adapters/hybrid_storage.rb b/lib/lit/adapters/hybrid_storage.rb
new file mode 100644
index 00000000..f49d26a1
--- /dev/null
+++ b/lib/lit/adapters/hybrid_storage.rb
@@ -0,0 +1,153 @@
+require 'redis'
+require 'concurrent'
+
+module Lit
+  extend self
+  def redis
+    $redis = Redis.new(url: determine_redis_provider) unless $redis
+    $redis
+  end
+
+  def determine_redis_provider
+    ENV[ENV['REDIS_PROVIDER'] || 'REDIS_URL']
+  end
+
+  def _hash
+    $_hash ||= ::Concurrent::Hash.new
+  end
+
+  def reset_hash
+    $_hash = nil
+  end
+
+  def hash_dirty?
+    # Hash is considered dirty if hash snapshot is older
+    # than Redis snapshot.
+    Lit.hash_snapshot < Lit.redis_snapshot
+  end
+
+  def hash_snapshot
+    $_hash_snapshot ||= DateTime.new
+  end
+
+  def hash_snapshot= (timestamp)
+    $_hash_snapshot = timestamp
+  end
+
+  def redis_snapshot
+    timestamp = Lit.redis.get('lit:_snapshot')
+    if timestamp.nil?
+      timestamp = Time.current.to_s
+      Lit.redis_snapshot = timestamp
+    end
+    DateTime.parse(timestamp)
+  end
+
+  def redis_snapshot= (timestamp)
+    Lit.redis.set('lit:_snapshot', timestamp)
+  end
+
+  def determine_redis_provider
+    ENV[ENV['REDIS_PROVIDER'] || 'REDIS_URL']
+  end
+
+  class HybridStorage
+    def initialize
+      Lit.redis
+      Lit._hash
+    end
+
+    def [](key)
+      if Lit.hash_dirty?
+        Lit.hash_snapshot = DateTime.current
+        Lit._hash.clear
+      end
+      if Lit._hash.key? key
+        return Lit._hash[key]
+      else
+        redis_val = get_from_redis(key)
+        Lit._hash[key] = redis_val
+      end
+    end
+
+    def get_from_redis(key)
+      if Lit.redis.exists(_prefixed_key_for_array(key))
+        Lit.redis.lrange(_prefixed_key(key), 0, -1)
+      elsif Lit.redis.exists(_prefixed_key_for_nil(key))
+        nil
+      else
+        Lit.redis.get(_prefixed_key(key))
+      end
+    end
+
+    def []=(k, v)
+      delete(k)
+      Lit._hash[k] = v
+      if v.is_a?(Array)
+        Lit.redis.set(_prefixed_key_for_array(k), '1')
+        v.each do |ve|
+          Lit.redis.rpush(_prefixed_key(k), ve.to_s)
+        end
+      elsif v.nil?
+        Lit.redis.set(_prefixed_key_for_nil(k), '1')
+        Lit.redis.set(_prefixed_key(k), '')
+      else
+        Lit.redis.set(_prefixed_key(k), v)
+      end
+    end
+
+    def delete(k)
+      Lit.redis_snapshot = Time.current
+      Lit._hash.delete(k)
+      Lit.redis.del(_prefixed_key_for_array(k))
+      Lit.redis.del(_prefixed_key_for_nil(k))
+      Lit.redis.del(_prefixed_key(k))
+    end
+
+    def clear
+      Lit.redis_snapshot = Time.current
+      Lit._hash.clear
+      Lit.redis.del(keys) if keys.length > 0
+    end
+
+    def keys
+      Lit.redis.keys(_prefixed_key + '*')
+    end
+
+    def has_key?(key)
+      Lit._hash.has_key?(key) || Lit.redis.exists(_prefixed_key(key)) # This is a derp
+    end
+
+    def incr(key)
+      Lit.redis.incr(_prefixed_key(key))
+    end
+
+    def sort
+      Lit.redis.keys.sort.map do |k|
+        [k, self.[](k)]
+      end
+    end
+
+    private
+
+    def _prefix
+      prefix = 'lit:'
+      if Lit.storage_options.is_a?(Hash)
+        prefix += "#{Lit.storage_options[:prefix]}:" if Lit.storage_options.key?(:prefix)
+      end
+      prefix
+    end
+
+    def _prefixed_key(key = '')
+      _prefix + key.to_s
+    end
+
+    def _prefixed_key_for_array(key = '')
+      _prefix + 'array_flags:' + key.to_s
+    end
+
+    def _prefixed_key_for_nil(key = '')
+      _prefix + 'nil_flags:' + key.to_s
+    end
+  end
+end
diff --git a/lib/lit/i18n_backend.rb b/lib/lit/i18n_backend.rb
index a6f48a43..641a4c67 100644
--- a/lib/lit/i18n_backend.rb
+++ b/lib/lit/i18n_backend.rb
@@ -59,6 +59,7 @@ def lookup(locale, key, scope = [], options = {})
       return content if parts.size <= 1
 
       if should_cache?(key_with_locale)
+        puts "SHOULD CACHE #{key_with_locale}"
         new_content = @cache.init_key_with_value(key_with_locale, content)
         content = new_content if content.nil? # Content can change when Lit.humanize is true for example
 
@@ -141,12 +142,17 @@ def is_ignored_key(key_without_locale)
     end
 
     def should_cache?(key_with_locale)
-      return false if @cache.has_key?(key_with_locale)
+      return false if @cache[key_with_locale] != nil
 
       _, key_without_locale = ::Lit::Cache.split_key(key_with_locale)
       return false if is_ignored_key(key_without_locale)
 
       true
     end
+
+    def extract_non_symbol_default!(options)
+      defaults = [options[:default]].flatten
+      defaults.detect{|default| !default.is_a?(Symbol)}
+    end
   end
 end
diff --git a/lit.gemspec b/lit.gemspec
index 6abde74a..0e2fcef9 100644
--- a/lit.gemspec
+++ b/lit.gemspec
@@ -20,6 +20,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'rails', '> 3.1.0'
   s.add_dependency 'i18n', '~> 0.7.0'
   s.add_dependency 'jquery-rails'
+  s.add_dependency 'concurrent-ruby'
 
   s.add_development_dependency 'pg'
   s.add_development_dependency 'devise'
diff --git a/test/dummy/config/database.yml b/test/dummy/config/database.yml
index 47455e7d..98a2ab84 100644
--- a/test/dummy/config/database.yml
+++ b/test/dummy/config/database.yml
@@ -15,8 +15,8 @@ development:
 test:
   adapter: postgresql
   database: lit_test
-  username: lit
-  password: lit
+  username: ebin
+  password: ebin
   host: localhost
   pool: 5
   timeout: 5000
diff --git a/test/support/clear_snapshots.rb b/test/support/clear_snapshots.rb
new file mode 100644
index 00000000..30d0f6cf
--- /dev/null
+++ b/test/support/clear_snapshots.rb
@@ -0,0 +1,7 @@
+require 'lit/adapters/hybrid_storage'
+def clear_snapshots
+  trace_var :$_hash, proc { |h| print 'hash is now', v }
+  Lit.reset_hash if defined?($_hash)
+  Lit.hash_snapshot = nil if defined?($_hash_snapshot)
+  Lit.redis.del('lit:_snapshot') if defined?($redis)
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 970c014e..47ce3c29 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -28,6 +28,7 @@
 class ActiveSupport::TestCase
   self.use_transactional_fixtures = true
   setup do
+    clear_snapshots
     clear_redis
     Lit.init.cache.reset
   end

From 29ff09cff8cba5fb9a9ba179fb435dac9f8b164d Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Fri, 27 May 2016 12:03:22 +0200
Subject: [PATCH 02/10] Do not overwrite UI-changed texts with ones from .yml

---
 lib/lit/cache.rb        | 11 +++++++----
 lib/lit/i18n_backend.rb | 18 ++++++++----------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/lib/lit/cache.rb b/lib/lit/cache.rb
index aecb554b..622e25c8 100644
--- a/lib/lit/cache.rb
+++ b/lib/lit/cache.rb
@@ -49,11 +49,12 @@ def keys
       localizations.keys
     end
 
-    def update_locale(key, value, force_array = false)
+    def update_locale(key, value, force_array = false, unless_is_changed = false)
       key = key.to_s
       locale_key, key_without_locale = split_key(key)
       locale = find_locale(locale_key)
       localization = find_localization(locale, key_without_locale, value, force_array, true)
+      return localization.get_value if unless_is_changed && localization.is_changed?
       localizations[key] = localization.get_value if localization
     end
 
@@ -62,11 +63,12 @@ def update_cache(key, value)
       localizations[key] = value
     end
 
-    def delete_locale(key)
+    def delete_locale(key, unless_is_changed = false)
+      binding.pry if key.match /abbr_month/
       key = key.to_s
       locale_key, key_without_locale = split_key(key)
       locale = find_locale(locale_key)
-      delete_localization(locale, key_without_locale)
+      delete_localization(locale, key_without_locale, unless_is_changed)
     end
 
     def load_all_translations
@@ -227,8 +229,9 @@ def find_localization_for_delete(locale, key_without_locale)
           where(localization_key_id: localization_key.id).first
     end
 
-    def delete_localization(locale, key_without_locale)
+    def delete_localization(locale, key_without_locale, unless_is_changed = false)
       localization = find_localization_for_delete(locale, key_without_locale)
+      return if unless_is_changed && localization.try(:is_changed?)
       if localization
         localizations.delete("#{locale.locale}.#{key_without_locale}")
         localization_keys.delete(key_without_locale)
diff --git a/lib/lit/i18n_backend.rb b/lib/lit/i18n_backend.rb
index 641a4c67..0701e716 100644
--- a/lib/lit/i18n_backend.rb
+++ b/lib/lit/i18n_backend.rb
@@ -59,7 +59,6 @@ def lookup(locale, key, scope = [], options = {})
       return content if parts.size <= 1
 
       if should_cache?(key_with_locale)
-        puts "SHOULD CACHE #{key_with_locale}"
         new_content = @cache.init_key_with_value(key_with_locale, content)
         content = new_content if content.nil? # Content can change when Lit.humanize is true for example
 
@@ -84,26 +83,25 @@ def lookup(locale, key, scope = [], options = {})
       content
     end
 
-    def store_item(locale, data, scope = [])
+    def store_item(locale, data, scope = [], unless_is_changed = false)
       if data.respond_to?(:to_hash)
-        # ActiveRecord::Base.transaction do
-          data.to_hash.each do |key, value|
-            store_item(locale, value, scope + [key])
-          end
-        # end
+        data.to_hash.each do |key, value|
+          store_item(locale, value, scope + [key], unless_is_changed)
+        end
       elsif data.respond_to?(:to_str)
         key = ([locale] + scope).join('.')
-        @cache[key] ||= data
+        @cache.update_locale(key, data, false, unless_is_changed)
       elsif data.nil?
         key = ([locale] + scope).join('.')
-        @cache.delete_locale(key)
+        @cache.delete_locale(key, unless_is_changed)
       end
     end
 
     def load_translations_to_cache
       ActiveRecord::Base.transaction do
         (@translations || {}).each do |locale, data|
-          store_item(locale, data) if valid_locale?(locale)
+          # TODO maybe don't store if marked as changed in db? :)
+          store_item(locale, data, [], true) if valid_locale?(locale)
         end
       end
     end

From 1a6cacbde51a8d108b03c5caac4bed350fab4179 Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Fri, 27 May 2016 12:17:46 +0200
Subject: [PATCH 03/10] Properly prefix redis snapshot key

---
 lib/lit/adapters/hybrid_storage.rb | 18 +++++++++++-------
 test/support/clear_snapshots.rb    |  3 +--
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/lib/lit/adapters/hybrid_storage.rb b/lib/lit/adapters/hybrid_storage.rb
index f49d26a1..45153742 100644
--- a/lib/lit/adapters/hybrid_storage.rb
+++ b/lib/lit/adapters/hybrid_storage.rb
@@ -35,7 +35,7 @@ def hash_snapshot= (timestamp)
   end
 
   def redis_snapshot
-    timestamp = Lit.redis.get('lit:_snapshot')
+    timestamp = Lit.redis.get(Lit.prefix + '_snapshot')
     if timestamp.nil?
       timestamp = Time.current.to_s
       Lit.redis_snapshot = timestamp
@@ -44,13 +44,21 @@ def redis_snapshot
   end
 
   def redis_snapshot= (timestamp)
-    Lit.redis.set('lit:_snapshot', timestamp)
+    Lit.redis.set(Lit.prefix + '_snapshot', timestamp)
   end
 
   def determine_redis_provider
     ENV[ENV['REDIS_PROVIDER'] || 'REDIS_URL']
   end
 
+  def prefix
+    pfx = 'lit:'
+    if Lit.storage_options.is_a?(Hash)
+      pfx += "#{Lit.storage_options[:prefix]}:" if Lit.storage_options.key?(:prefix)
+    end
+    pfx
+  end
+
   class HybridStorage
     def initialize
       Lit.redis
@@ -131,11 +139,7 @@ def sort
     private
 
     def _prefix
-      prefix = 'lit:'
-      if Lit.storage_options.is_a?(Hash)
-        prefix += "#{Lit.storage_options[:prefix]}:" if Lit.storage_options.key?(:prefix)
-      end
-      prefix
+      Lit.prefix
     end
 
     def _prefixed_key(key = '')
diff --git a/test/support/clear_snapshots.rb b/test/support/clear_snapshots.rb
index 30d0f6cf..26428371 100644
--- a/test/support/clear_snapshots.rb
+++ b/test/support/clear_snapshots.rb
@@ -1,7 +1,6 @@
 require 'lit/adapters/hybrid_storage'
 def clear_snapshots
-  trace_var :$_hash, proc { |h| print 'hash is now', v }
   Lit.reset_hash if defined?($_hash)
   Lit.hash_snapshot = nil if defined?($_hash_snapshot)
-  Lit.redis.del('lit:_snapshot') if defined?($redis)
+  Lit.redis.del(Lit.prefix + '_snapshot') if defined?($redis)
 end

From e4edfe77cab89575f6b51840109929b9f54fad31 Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Fri, 27 May 2016 13:02:30 +0200
Subject: [PATCH 04/10] Update travis.yml for hybrid storage

---
 .travis.yml | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index f8bceee0..8adde4d7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,22 +1,22 @@
 language: ruby
 sudo: false
 rvm:
-#  - 2.0.0
-#  - 2.1.2
-#  - 2.2.5
-   - 2.3.0
+  - 2.0.0
+  - 2.1.2
+  - 2.2.5
+  - 2.3.0
 gemfile:
-#  - gemfiles/rails_4.gemfile
-#  - gemfiles/rails_4.1.gemfile
+  - gemfiles/rails_4.gemfile
+  - gemfiles/rails_4.1.gemfile
   - gemfiles/rails_4.2.gemfile
 services:
   - redis-server
 env:
-  # - LIT_STORAGE=hash
-  # - LIT_STORAGE=redis
+  - LIT_STORAGE=hash
+  - LIT_STORAGE=redis
   - LIT_STORAGE=hybrid
 before_script:
   - cp test/dummy/config/database.yml.travis test/dummy/config/database.yml
   - psql -c 'create database lit_test;' -U postgres
   - RAILS_ENV=test bundle exec rake db:migrate
-script: "bundle exec rake test" # TEST=test/unit/lit_behaviour_test.rb"
+script: "bundle exec rake test"

From a8d82d7dde803f642c453cd46ec23f057597f77b Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Mon, 30 May 2016 09:53:58 +0200
Subject: [PATCH 05/10] Ensure consistency of time types

---
 lib/lit/adapters/hybrid_storage.rb | 6 +++---
 lib/lit/i18n_backend.rb            | 1 -
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/lit/adapters/hybrid_storage.rb b/lib/lit/adapters/hybrid_storage.rb
index 45153742..61557832 100644
--- a/lib/lit/adapters/hybrid_storage.rb
+++ b/lib/lit/adapters/hybrid_storage.rb
@@ -37,7 +37,7 @@ def hash_snapshot= (timestamp)
   def redis_snapshot
     timestamp = Lit.redis.get(Lit.prefix + '_snapshot')
     if timestamp.nil?
-      timestamp = Time.current.to_s
+      timestamp = DateTime.now.to_s
       Lit.redis_snapshot = timestamp
     end
     DateTime.parse(timestamp)
@@ -105,7 +105,7 @@ def []=(k, v)
     end
 
     def delete(k)
-      Lit.redis_snapshot = Time.current
+      Lit.redis_snapshot = DateTime.now
       Lit._hash.delete(k)
       Lit.redis.del(_prefixed_key_for_array(k))
       Lit.redis.del(_prefixed_key_for_nil(k))
@@ -113,7 +113,7 @@ def delete(k)
     end
 
     def clear
-      Lit.redis_snapshot = Time.current
+      Lit.redis_snapshot = DateTime.now
       Lit._hash.clear
       Lit.redis.del(keys) if keys.length > 0
     end
diff --git a/lib/lit/i18n_backend.rb b/lib/lit/i18n_backend.rb
index 0701e716..2d79b6b3 100644
--- a/lib/lit/i18n_backend.rb
+++ b/lib/lit/i18n_backend.rb
@@ -100,7 +100,6 @@ def store_item(locale, data, scope = [], unless_is_changed = false)
     def load_translations_to_cache
       ActiveRecord::Base.transaction do
         (@translations || {}).each do |locale, data|
-          # TODO maybe don't store if marked as changed in db? :)
           store_item(locale, data, [], true) if valid_locale?(locale)
         end
       end

From 6e01a99b58640ee541593c8066516cf56074bc75 Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Mon, 30 May 2016 10:30:14 +0200
Subject: [PATCH 06/10] Improve timestamp precision

---
 lib/lit/adapters/hybrid_storage.rb | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/lit/adapters/hybrid_storage.rb b/lib/lit/adapters/hybrid_storage.rb
index 61557832..0b6fa952 100644
--- a/lib/lit/adapters/hybrid_storage.rb
+++ b/lib/lit/adapters/hybrid_storage.rb
@@ -27,7 +27,7 @@ def hash_dirty?
   end
 
   def hash_snapshot
-    $_hash_snapshot ||= DateTime.new
+    $_hash_snapshot ||= DateTime.new.to_f.to_d
   end
 
   def hash_snapshot= (timestamp)
@@ -37,16 +37,20 @@ def hash_snapshot= (timestamp)
   def redis_snapshot
     timestamp = Lit.redis.get(Lit.prefix + '_snapshot')
     if timestamp.nil?
-      timestamp = DateTime.now.to_s
+      timestamp = DateTime.now.to_f.to_s
       Lit.redis_snapshot = timestamp
     end
-    DateTime.parse(timestamp)
+    DateTime.strptime(timestamp, '%s').to_f.to_d
   end
 
   def redis_snapshot= (timestamp)
     Lit.redis.set(Lit.prefix + '_snapshot', timestamp)
   end
 
+  def now_timestamp
+    DateTime.now.to_f.to_d
+  end
+
   def determine_redis_provider
     ENV[ENV['REDIS_PROVIDER'] || 'REDIS_URL']
   end
@@ -67,7 +71,7 @@ def initialize
 
     def [](key)
       if Lit.hash_dirty?
-        Lit.hash_snapshot = DateTime.current
+        Lit.hash_snapshot = Lit.now_timestamp
         Lit._hash.clear
       end
       if Lit._hash.key? key
@@ -105,7 +109,7 @@ def []=(k, v)
     end
 
     def delete(k)
-      Lit.redis_snapshot = DateTime.now
+      Lit.redis_snapshot = Lit.now_timestamp
       Lit._hash.delete(k)
       Lit.redis.del(_prefixed_key_for_array(k))
       Lit.redis.del(_prefixed_key_for_nil(k))
@@ -113,7 +117,7 @@ def delete(k)
     end
 
     def clear
-      Lit.redis_snapshot = DateTime.now
+      Lit.redis_snapshot = Lit.now_timestamp
       Lit._hash.clear
       Lit.redis.del(keys) if keys.length > 0
     end

From 3d6d814764d4e98d1bdbbc83219e3e3961db8e41 Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Mon, 30 May 2016 14:40:51 +0200
Subject: [PATCH 07/10] Preserve redis snapshot until end of request

---
 lib/lit/adapters/hybrid_storage.rb | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/lib/lit/adapters/hybrid_storage.rb b/lib/lit/adapters/hybrid_storage.rb
index 0b6fa952..3fafd3c3 100644
--- a/lib/lit/adapters/hybrid_storage.rb
+++ b/lib/lit/adapters/hybrid_storage.rb
@@ -1,6 +1,14 @@
 require 'redis'
 require 'concurrent'
 
+ActionController::Base.class_eval do
+  after_action :clear_saved_redis_snapshot
+
+  def clear_saved_redis_snapshot
+    Lit.saved_redis_snapshot = nil
+  end
+end
+
 module Lit
   extend self
   def redis
@@ -35,18 +43,29 @@ def hash_snapshot= (timestamp)
   end
 
   def redis_snapshot
+    return Lit.saved_redis_snapshot unless Lit.saved_redis_snapshot.nil?
     timestamp = Lit.redis.get(Lit.prefix + '_snapshot')
     if timestamp.nil?
       timestamp = DateTime.now.to_f.to_s
       Lit.redis_snapshot = timestamp
     end
-    DateTime.strptime(timestamp, '%s').to_f.to_d
+    Lit.saved_redis_snapshot = DateTime.strptime(timestamp, '%s').to_f.to_d
   end
 
   def redis_snapshot= (timestamp)
     Lit.redis.set(Lit.prefix + '_snapshot', timestamp)
   end
 
+  def saved_redis_snapshot
+    $saved_redis_snapshot ||= Concurrent::MVar.new(nil)
+    $saved_redis_snapshot.value
+  end
+
+  def saved_redis_snapshot= (snap)
+    $saved_redis_snapshot ||= Concurrent::MVar.new(nil)
+    $saved_redis_snapshot.set!(snap)
+  end
+
   def now_timestamp
     DateTime.now.to_f.to_d
   end

From bf3dc997ee5a7784b185c58baf868f2b1ee4ee1a Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Tue, 31 May 2016 17:19:10 +0200
Subject: [PATCH 08/10] Revert to previously used item preloading

---
 lib/lit/cache.rb        | 11 ++++-------
 lib/lit/i18n_backend.rb | 10 +++++-----
 2 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/lib/lit/cache.rb b/lib/lit/cache.rb
index 622e25c8..aecb554b 100644
--- a/lib/lit/cache.rb
+++ b/lib/lit/cache.rb
@@ -49,12 +49,11 @@ def keys
       localizations.keys
     end
 
-    def update_locale(key, value, force_array = false, unless_is_changed = false)
+    def update_locale(key, value, force_array = false)
       key = key.to_s
       locale_key, key_without_locale = split_key(key)
       locale = find_locale(locale_key)
       localization = find_localization(locale, key_without_locale, value, force_array, true)
-      return localization.get_value if unless_is_changed && localization.is_changed?
       localizations[key] = localization.get_value if localization
     end
 
@@ -63,12 +62,11 @@ def update_cache(key, value)
       localizations[key] = value
     end
 
-    def delete_locale(key, unless_is_changed = false)
-      binding.pry if key.match /abbr_month/
+    def delete_locale(key)
       key = key.to_s
       locale_key, key_without_locale = split_key(key)
       locale = find_locale(locale_key)
-      delete_localization(locale, key_without_locale, unless_is_changed)
+      delete_localization(locale, key_without_locale)
     end
 
     def load_all_translations
@@ -229,9 +227,8 @@ def find_localization_for_delete(locale, key_without_locale)
           where(localization_key_id: localization_key.id).first
     end
 
-    def delete_localization(locale, key_without_locale, unless_is_changed = false)
+    def delete_localization(locale, key_without_locale)
       localization = find_localization_for_delete(locale, key_without_locale)
-      return if unless_is_changed && localization.try(:is_changed?)
       if localization
         localizations.delete("#{locale.locale}.#{key_without_locale}")
         localization_keys.delete(key_without_locale)
diff --git a/lib/lit/i18n_backend.rb b/lib/lit/i18n_backend.rb
index 2d79b6b3..ad1a09c6 100644
--- a/lib/lit/i18n_backend.rb
+++ b/lib/lit/i18n_backend.rb
@@ -83,24 +83,24 @@ def lookup(locale, key, scope = [], options = {})
       content
     end
 
-    def store_item(locale, data, scope = [], unless_is_changed = false)
+    def store_item(locale, data, scope = [])
       if data.respond_to?(:to_hash)
         data.to_hash.each do |key, value|
-          store_item(locale, value, scope + [key], unless_is_changed)
+          store_item(locale, value, scope + [key])
         end
       elsif data.respond_to?(:to_str)
         key = ([locale] + scope).join('.')
-        @cache.update_locale(key, data, false, unless_is_changed)
+        @cache[key] ||= data
       elsif data.nil?
         key = ([locale] + scope).join('.')
-        @cache.delete_locale(key, unless_is_changed)
+        @cache.delete_locale(key)
       end
     end
 
     def load_translations_to_cache
       ActiveRecord::Base.transaction do
         (@translations || {}).each do |locale, data|
-          store_item(locale, data, [], true) if valid_locale?(locale)
+          store_item(locale, data) if valid_locale?(locale)
         end
       end
     end

From 97dbf5f4b90f0fd203b2e50f7e27fb6750c7e0f7 Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Fri, 22 Jul 2016 14:05:22 +0200
Subject: [PATCH 09/10] Add tests for hybrid storage

---
 lib/lit/adapters/hybrid_storage.rb |  2 +-
 test/unit/hybrid_storage_test.rb   | 89 ++++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 test/unit/hybrid_storage_test.rb

diff --git a/lib/lit/adapters/hybrid_storage.rb b/lib/lit/adapters/hybrid_storage.rb
index 3fafd3c3..c2a4b90f 100644
--- a/lib/lit/adapters/hybrid_storage.rb
+++ b/lib/lit/adapters/hybrid_storage.rb
@@ -49,7 +49,7 @@ def redis_snapshot
       timestamp = DateTime.now.to_f.to_s
       Lit.redis_snapshot = timestamp
     end
-    Lit.saved_redis_snapshot = DateTime.strptime(timestamp, '%s').to_f.to_d
+    Lit.saved_redis_snapshot = timestamp.to_f
   end
 
   def redis_snapshot= (timestamp)
diff --git a/test/unit/hybrid_storage_test.rb b/test/unit/hybrid_storage_test.rb
new file mode 100644
index 00000000..1b17f298
--- /dev/null
+++ b/test/unit/hybrid_storage_test.rb
@@ -0,0 +1,89 @@
+require 'test_helper'
+require 'pry'
+
+# Applicable only for LIT_STORAGE=hybrid
+class HybridStorageTest < ActiveSupport::TestCase
+  if ENV['LIT_STORAGE'] == 'hybrid'
+    class Backend < Lit::I18nBackend
+    end
+
+    fixtures :all
+
+    def setup
+      Lit.init
+      Lit::Localization.delete_all
+      Lit::LocalizationKey.delete_all
+      Lit::LocalizationVersion.delete_all
+      @old_humanize_key = Lit.humanize_key
+      Lit.humanize_key = false
+      @old_load_path = I18n.load_path
+      Lit.reset_hash
+      I18n.backend.cache.clear
+      @locale = Lit::Locale.find_by_locale(I18n.locale)
+      super
+    end
+
+    def teardown
+      Lit.loader = @old_loader
+      Lit.humanize_key = @old_humanize_key
+      I18n.backend = @old_backend
+      I18n.load_path = @old_load_path
+      super
+    end
+
+    test 'it should update translation both in hash and in redis' do
+      # assertions to ensure that storage has been properly cleared
+      assert_nil Lit._hash['en.fizz']
+      assert_nil Lit.redis.get(Lit.prefix + 'en.fizz')
+      I18n.t('fizz', default: 'buzz')
+      assert_equal 'buzz', Lit._hash['en.fizz']
+      assert_equal 'buzz', Lit.redis.get(Lit.prefix + 'en.fizz')
+    end
+
+    test 'it should clear hash when loading from redis something not yet in hash' do
+      # let's do something that creates a hash snapshot timestamp
+      assert_nil Lit._hash['en.fizz']
+      old_hash_snapshot = Lit.hash_snapshot
+      I18n.t('fizz', default: 'buzz')
+      assert_operator Lit.hash_snapshot, :>, old_hash_snapshot
+
+      # in the meantime let's create some new translation
+      # simulate as if it were created and redis snapshot has been updated
+      lk = Lit::LocalizationKey.create(localization_key: 'abcd')
+      l = lk.localizations.create!(locale: @locale, default_value: 'efgh')
+
+      Lit.redis.set(Lit.prefix + 'en.abcd', 'efgh')
+      Lit.saved_redis_snapshot = Lit.now_timestamp
+      Lit.redis_snapshot = Lit.saved_redis_snapshot
+      # TODO: consider if this is not too implementation-specific
+
+      # assert that the newly created localization has been fetched into hash
+      assert_equal 'efgh', I18n.t('abcd')
+      assert_equal 'efgh', Lit._hash['en.abcd']
+      assert_equal 'efgh', Lit.redis.get(Lit.prefix + 'en.abcd')
+
+      # assert that hash cache has been cleared
+      assert_nil Lit._hash['en.fizz']
+      I18n.t('fizz')
+
+      # assert that the value then gets loaded into hash again
+      assert_equal 'buzz', Lit._hash['en.fizz']
+    end
+
+    test 'local cache is used even when redis is cleared' do
+      # define a translation by specifying default value
+      assert_nil Lit._hash['en.fizz']
+      I18n.t('fizz', default: 'buzz')
+      assert_equal 'buzz', Lit._hash['en.fizz']
+
+      # clear redis
+      I18n.backend.cache.clear
+
+      # modify local cache and then see if it's used for loading translation
+      Lit._hash['en.fizz'] = 'fizzbuzz'
+      assert_equal 'fizzbuzz', I18n.t('fizz')
+    end
+  else
+    puts 'Skipping hybrid storage test'
+  end
+end

From f8f4da25186e3b2cb9ba87e1f2469cdd7bc1bdfa Mon Sep 17 00:00:00 2001
From: Michal Buszkiewicz <embed1@gmail.com>
Date: Fri, 22 Jul 2016 16:04:56 +0200
Subject: [PATCH 10/10] Cleanup

---
 test/unit/hybrid_storage_test.rb | 1 -
 1 file changed, 1 deletion(-)

diff --git a/test/unit/hybrid_storage_test.rb b/test/unit/hybrid_storage_test.rb
index 1b17f298..3077d3b0 100644
--- a/test/unit/hybrid_storage_test.rb
+++ b/test/unit/hybrid_storage_test.rb
@@ -1,5 +1,4 @@
 require 'test_helper'
-require 'pry'
 
 # Applicable only for LIT_STORAGE=hybrid
 class HybridStorageTest < ActiveSupport::TestCase