From 41f3f81a4781a8116d2fe39efc020e9b726b78f7 Mon Sep 17 00:00:00 2001
From: Sebastian Fiedlschuster <sebastian@fiedlschuster.de>
Date: Fri, 3 Apr 2015 22:54:24 +0200
Subject: [PATCH 1/6] =?UTF-8?q?caching:=20increasing=20the=20precision=20o?=
 =?UTF-8?q?f=20the=20timestamps=20in=20the=20database=20to=20=C2=B5s.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

trello: https://trello.com/c/jh6CpwdX/811-caching-zeit-auflosung
---
 config/initializers/datetime_precision.rb     |  8 ++++
 ...rease_datetime_precision_for_timestamps.rb | 37 ++++++++++++++++++
 demo_app/my_platform.rails4/Gemfile.lock      |  4 +-
 ..._precision_for_timestamps.your_platform.rb | 38 +++++++++++++++++++
 demo_app/my_platform.rails4/db/schema.rb      | 27 +++++++------
 .../active_record_cache_extension_spec.rb     | 14 +++++++
 6 files changed, 115 insertions(+), 13 deletions(-)
 create mode 100644 config/initializers/datetime_precision.rb
 create mode 100644 db/migrate/20150403202151_increase_datetime_precision_for_timestamps.rb
 create mode 100644 demo_app/my_platform.rails4/db/migrate/20150403203339_increase_datetime_precision_for_timestamps.your_platform.rb

diff --git a/config/initializers/datetime_precision.rb b/config/initializers/datetime_precision.rb
new file mode 100644
index 000000000..65f8ac442
--- /dev/null
+++ b/config/initializers/datetime_precision.rb
@@ -0,0 +1,8 @@
+# In order to handle cache_keys properly, we need to store timestamps
+# with µs precision.
+#
+# Trello: https://trello.com/c/jh6CpwdX/811-caching-zeit-auflosung
+# 
+# Gist: https://gist.github.com/iamatypeofwalrus/d074d22a736d49459b15
+#
+Time::DATE_FORMATS.merge!({ db: '%Y-%m-%d %H:%M:%S.%6N' })
diff --git a/db/migrate/20150403202151_increase_datetime_precision_for_timestamps.rb b/db/migrate/20150403202151_increase_datetime_precision_for_timestamps.rb
new file mode 100644
index 000000000..4247bb8ca
--- /dev/null
+++ b/db/migrate/20150403202151_increase_datetime_precision_for_timestamps.rb
@@ -0,0 +1,37 @@
+# In order to handle cache_keys properly, we need to store timestamps
+# with µs precision.
+#
+# Trello: https://trello.com/c/jh6CpwdX/811-caching-zeit-auflosung
+# 
+# Gist: https://gist.github.com/iamatypeofwalrus/d074d22a736d49459b15
+#
+class IncreaseDatetimePrecisionForTimestamps < ActiveRecord::Migration
+  # Include non default date stamps here
+  # Key   :table_name
+  # value [:column_names]
+  # NOTE: only MySQL 5.6.4 and above supports DATETIME's with more precision than a second.
+  TABLES_AND_COLUMNS = {
+    users: [:created_at, :updated_at],
+    groups: [:created_at, :updated_at],
+    dag_links: [:created_at, :updated_at],
+    profile_fields: [:created_at, :updated_at],
+    pages: [:created_at, :updated_at]
+  }
+  
+  def up
+    TABLES_AND_COLUMNS.each do |table, columns|
+      columns.each do |column|
+        # MySQL supports time precision down to microseconds -- DATETIME(6)
+        change_column table, column, :datetime, limit: 6
+      end
+    end
+  end
+ 
+  def down
+    TABLES_AND_COLUMNS.each do |table, columns|
+      columns.each do |column|
+        echange_column table, column, :datetime
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/demo_app/my_platform.rails4/Gemfile.lock b/demo_app/my_platform.rails4/Gemfile.lock
index 5cbcdeeda..4bbf8054e 100644
--- a/demo_app/my_platform.rails4/Gemfile.lock
+++ b/demo_app/my_platform.rails4/Gemfile.lock
@@ -32,7 +32,7 @@ GIT
 PATH
   remote: ../..
   specs:
-    your_platform (1.0.0)
+    your_platform (1.0.1)
       acts-as-dag (>= 2.5.7)
       acts_as_tree
       bcrypt (>= 3.0.1)
@@ -227,7 +227,7 @@ GEM
       yajl-ruby
     font-awesome-rails (4.3.0.0)
       railties (>= 3.2, < 5.0)
-    foreigner (1.7.3)
+    foreigner (1.7.4)
       activerecord (>= 3.0.0)
     foreman (0.78.0)
       thor (~> 0.19.1)
diff --git a/demo_app/my_platform.rails4/db/migrate/20150403203339_increase_datetime_precision_for_timestamps.your_platform.rb b/demo_app/my_platform.rails4/db/migrate/20150403203339_increase_datetime_precision_for_timestamps.your_platform.rb
new file mode 100644
index 000000000..698ebebfa
--- /dev/null
+++ b/demo_app/my_platform.rails4/db/migrate/20150403203339_increase_datetime_precision_for_timestamps.your_platform.rb
@@ -0,0 +1,38 @@
+# This migration comes from your_platform (originally 20150403202151)
+# In order to handle cache_keys properly, we need to store timestamps
+# with µs precision.
+#
+# Trello: https://trello.com/c/jh6CpwdX/811-caching-zeit-auflosung
+# 
+# Gist: https://gist.github.com/iamatypeofwalrus/d074d22a736d49459b15
+#
+class IncreaseDatetimePrecisionForTimestamps < ActiveRecord::Migration
+  # Include non default date stamps here
+  # Key   :table_name
+  # value [:column_names]
+  # NOTE: only MySQL 5.6.4 and above supports DATETIME's with more precision than a second.
+  TABLES_AND_COLUMNS = {
+    users: [:created_at, :updated_at],
+    groups: [:created_at, :updated_at],
+    dag_links: [:created_at, :updated_at],
+    profile_fields: [:created_at, :updated_at],
+    pages: [:created_at, :updated_at]
+  }
+  
+  def up
+    TABLES_AND_COLUMNS.each do |table, columns|
+      columns.each do |column|
+        # MySQL supports time precision down to microseconds -- DATETIME(6)
+        change_column table, column, :datetime, limit: 6
+      end
+    end
+  end
+ 
+  def down
+    TABLES_AND_COLUMNS.each do |table, columns|
+      columns.each do |column|
+        echange_column table, column, :datetime
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/demo_app/my_platform.rails4/db/schema.rb b/demo_app/my_platform.rails4/db/schema.rb
index 3fac9d35b..f300c69d5 100644
--- a/demo_app/my_platform.rails4/db/schema.rb
+++ b/demo_app/my_platform.rails4/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20150325105893) do
+ActiveRecord::Schema.define(version: 20150403203339) do
 
   create_table "activities", force: true do |t|
     t.integer  "trackable_id"
@@ -62,8 +62,8 @@
     t.string   "descendant_type"
     t.boolean  "direct"
     t.integer  "count"
-    t.datetime "created_at"
-    t.datetime "updated_at"
+    t.datetime "created_at",      limit: 6
+    t.datetime "updated_at",      limit: 6
     t.datetime "valid_to"
     t.datetime "valid_from"
   end
@@ -112,8 +112,8 @@
 
   create_table "groups", force: true do |t|
     t.string   "name"
-    t.datetime "created_at"
-    t.datetime "updated_at"
+    t.datetime "created_at",     limit: 6
+    t.datetime "updated_at",     limit: 6
     t.string   "token"
     t.string   "extensive_name"
     t.string   "internal_token"
@@ -132,6 +132,10 @@
 
   add_index "last_seen_activities", ["user_id"], name: "last_seen_activities_user_id_fk", using: :btree
 
+  create_table "my_structureables", force: true do |t|
+    t.string "name"
+  end
+
   create_table "nav_nodes", force: true do |t|
     t.string   "url_component"
     t.string   "breadcrumb_item"
@@ -151,8 +155,8 @@
   create_table "pages", force: true do |t|
     t.string   "title"
     t.text     "content"
-    t.datetime "created_at"
-    t.datetime "updated_at"
+    t.datetime "created_at",     limit: 6
+    t.datetime "updated_at",     limit: 6
     t.string   "redirect_to"
     t.integer  "author_user_id"
     t.string   "type"
@@ -181,8 +185,8 @@
     t.string   "label"
     t.string   "type"
     t.text     "value"
-    t.datetime "created_at"
-    t.datetime "updated_at"
+    t.datetime "created_at",       limit: 6
+    t.datetime "updated_at",       limit: 6
     t.string   "profileable_type"
     t.integer  "parent_id"
   end
@@ -245,8 +249,8 @@
     t.string   "alias"
     t.string   "first_name"
     t.string   "last_name"
-    t.datetime "created_at"
-    t.datetime "updated_at"
+    t.datetime "created_at",        limit: 6
+    t.datetime "updated_at",        limit: 6
     t.boolean  "female"
     t.string   "accepted_terms"
     t.datetime "accepted_terms_at"
@@ -286,6 +290,7 @@
     t.datetime "updated_at"
   end
 
+  Foreigner.load
   add_foreign_key "attachments", "users", name: "attachments_author_user_id_fk", column: "author_user_id"
 
   add_foreign_key "bookmarks", "users", name: "bookmarks_user_id_fk"
diff --git a/spec/models/active_record_cache_extension_spec.rb b/spec/models/active_record_cache_extension_spec.rb
index cb0fb749d..36cc6de0f 100644
--- a/spec/models/active_record_cache_extension_spec.rb
+++ b/spec/models/active_record_cache_extension_spec.rb
@@ -9,6 +9,20 @@
     @user = create(:user)
   end
   
+  describe "#cache_key" do
+    subject { @user.cache_key }
+    it "should be the same before and after a reload from the database" do
+      cache_key_before_reload = @user.cache_key
+      @user.reload
+      subject.should == cache_key_before_reload
+    end
+    it "should allow to retrieve the cached value after reload from database" do
+      Rails.cache.write [@user, :foobar], "Value written before reload"
+      @user.reload
+      Rails.cache.read([@user, :foobar]).should == "Value written before reload"
+    end
+  end
+  
   describe "#cached" do
     subject { @user.cached(:title) }
 

From 29981df01161aba8e35a0f7eb3a7ddd8e3cd305e Mon Sep 17 00:00:00 2001
From: Sebastian Fiedlschuster <sebastian@fiedlschuster.de>
Date: Fri, 3 Apr 2015 23:30:56 +0200
Subject: [PATCH 2/6] using mysql 5.6 on travis.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Since
https://github.com/fiedl/your_platform/commit/41f3f81a4781a8116d2fe39efc
020e9b726b78f7 (µs timestamps), we need mysql 5.6.

Travis supports only mysql 5.5 by default at the moment.

Trello: https://trello.com/c/jh6CpwdX/811-caching-zeit-auflosung

See also:
*
https://github.com/piwik/piwik/commit/20bd2e1c24e5d673dce3feb256204ad48c
29f160
* https://github.com/travis-ci/travis-ci/issues/1986
---
 .travis.yml | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/.travis.yml b/.travis.yml
index eae9edcfe..010e9280e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,24 @@ env:
 services:
   - redis-server
 before_install:
+  # INSTALL MYSQL 5.6
+  # (https://github.com/piwik/piwik/commit/20bd2e1c24e5d673dce3feb256204ad48c29f160)
+  # TODO: Remove when mysql 5.6 is provided by travis.
+  # Otherwise, our migrations will raise a syntax error.
+  - "sudo apt-get remove mysql-common mysql-server-5.5 mysql-server-core-5.5 mysql-client-5.5 mysql-client-core-5.5"
+  - "sudo apt-get autoremove"
+  - "sudo apt-get install libaio1"
+  - "wget -O mysql-5.6.14.deb http://dev.mysql.com/get/Downloads/MySQL-5.6/mysql-5.6.14-debian6.0-x86_64.deb/from/http://cdn.mysql.com/"
+  - "sudo dpkg -i mysql-5.6.14.deb"
+  - "sudo cp /opt/mysql/server-5.6/support-files/mysql.server /etc/init.d/mysql.server"
+  - "sudo ln -s /opt/mysql/server-5.6/bin/* /usr/bin/"
+  - "sudo sed -i'' 's/table_cache/table_open_cache/' /etc/mysql/my.cnf"
+  - "sudo sed -i'' 's/log_slow_queries/slow_query_log/' /etc/mysql/my.cnf"
+  - "sudo sed -i'' 's/basedir[^=]\\+=.*$/basedir = \\/opt\\/mysql\\/server-5.6/' /etc/mysql/my.cnf"
+  - "sudo /etc/init.d/mysql.server start"
+  - mysql --version
+  - mysql -e "SELECT VERSION();"
+  # /END MYSQL 5.6
   - travis_retry gem update --system
   - travis_retry gem install bundler
 install:

From 9cbe9b8ce37e313a9b09bee3cceb27b8a5a876fd Mon Sep 17 00:00:00 2001
From: Sebastian Fiedlschuster <sebastian@fiedlschuster.de>
Date: Sat, 4 Apr 2015 13:14:09 +0200
Subject: [PATCH 3/6] travis: removing host option from travis configuration
 after migrating to rails 4.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

trying to avoid „Mysql2::Error: Can't connect to local MySQL server
through socket '/tmp/mysql.sock‘“

see:
http://stackoverflow.com/questions/5499035/ruby-on-rails-3-cant-connect-
to-local-mysql-server-through-socket-tmp-mysql-s
---
 demo_app/my_platform.rails4/config/database.travis.yml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/demo_app/my_platform.rails4/config/database.travis.yml b/demo_app/my_platform.rails4/config/database.travis.yml
index ed9f56fff..9d022f35b 100644
--- a/demo_app/my_platform.rails4/config/database.travis.yml
+++ b/demo_app/my_platform.rails4/config/database.travis.yml
@@ -6,4 +6,3 @@ test:
   pool: 5
   username: root
   password:
-  host: localhost

From 87e0fb317f38d4a525390cc21e23898104f657e4 Mon Sep 17 00:00:00 2001
From: Sebastian Fiedlschuster <sebastian@fiedlschuster.de>
Date: Sat, 4 Apr 2015 15:28:17 +0200
Subject: [PATCH 4/6] specify sock in travis db configuration.

---
 demo_app/my_platform.rails4/config/database.travis.yml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/demo_app/my_platform.rails4/config/database.travis.yml b/demo_app/my_platform.rails4/config/database.travis.yml
index 9d022f35b..b02459519 100644
--- a/demo_app/my_platform.rails4/config/database.travis.yml
+++ b/demo_app/my_platform.rails4/config/database.travis.yml
@@ -6,3 +6,4 @@ test:
   pool: 5
   username: root
   password:
+  sock: /var/run/mysqld/mysql.sock
\ No newline at end of file

From 0a1a30d661fb43f43cdbea9bb6a6f410134ccbe5 Mon Sep 17 00:00:00 2001
From: Sebastian Fiedlschuster <sebastian@fiedlschuster.de>
Date: Sat, 4 Apr 2015 16:01:09 +0200
Subject: [PATCH 5/6] travis: trying to connect to database through 127.0.0.1.

---
 demo_app/my_platform.rails4/config/database.travis.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/demo_app/my_platform.rails4/config/database.travis.yml b/demo_app/my_platform.rails4/config/database.travis.yml
index b02459519..12a62ad32 100644
--- a/demo_app/my_platform.rails4/config/database.travis.yml
+++ b/demo_app/my_platform.rails4/config/database.travis.yml
@@ -1,9 +1,9 @@
 test:
   adapter: mysql2
   encoding: utf8
-  reconnect: false
+  reconnect: true
   database: my_platform_test
   pool: 5
   username: root
   password:
-  sock: /var/run/mysqld/mysql.sock
\ No newline at end of file
+  host: 127.0.0.1
\ No newline at end of file

From f01d42abd7b0dcfb135f598146c74cabe0c0674e Mon Sep 17 00:00:00 2001
From: Sebastian Fiedlschuster <sebastian@fiedlschuster.de>
Date: Mon, 6 Apr 2015 22:06:38 +0200
Subject: [PATCH 6/6] working on dag link cache.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

I’m increasing the test coverage of dag links in the context of cache
invalidation. In Rails 3, we had a special patch there, which might be
unnecessary in Rails 4.

Trello:
*
https://trello.com/c/BEDtKK83/810-caching-delete-cache-fill-cache-renew-
cache
* https://trello.com/c/jh6CpwdX/811-caching-zeit-auflosung
---
 .../active_record_associations_patches.rb     |  1 +
 app/models/active_record_cache_extension.rb   |  2 +-
 spec/models/dag_link_spec.rb                  | 56 ++++++++++++++++++-
 3 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/app/models/active_record_associations_patches.rb b/app/models/active_record_associations_patches.rb
index 3df9ad255..af4b5c56d 100644
--- a/app/models/active_record_associations_patches.rb
+++ b/app/models/active_record_associations_patches.rb
@@ -14,6 +14,7 @@ def destroy(*records)
       through_association.load_target
       records.each do |record|
         through_records_for(record).each do |through_record|
+          p "DELETE CACHE THROUGH HAS THROUGH ASSOCIATION."
           through_record.delete_cache if through_record.respond_to? :delete_cache
         end
       end
diff --git a/app/models/active_record_cache_extension.rb b/app/models/active_record_cache_extension.rb
index 2a0bc433e..1cd583d11 100644
--- a/app/models/active_record_cache_extension.rb
+++ b/app/models/active_record_cache_extension.rb
@@ -110,7 +110,7 @@ def bulk_delete_cached(method_name, objects)
   end
   
   def delete_cache
-    # p "DEBUG DELETE CACHE #{self}"
+    # p "DEBUG DELETE CACHE #{self.cache_key}/*"
     Rails.cache.delete_matched "#{self.cache_key}/*"
   end
   
diff --git a/spec/models/dag_link_spec.rb b/spec/models/dag_link_spec.rb
index 0a2c1008c..e3af52eae 100644
--- a/spec/models/dag_link_spec.rb
+++ b/spec/models/dag_link_spec.rb
@@ -1,5 +1,59 @@
 require 'spec_helper'
 
+describe DagLink do
+  # Changes on dag links are reflected on attributes of dag nodes (e.g. Users, Groups, etc.).
+  # Therefore, it is important to invalidate or renew the cache of these objects.
+  #
+  describe "(Cache Callbacks)" do
+    before do
+      
+      class User
+        def cached_group_names
+          cached { self.groups.pluck(:name) }
+        end
+      end
+      class Group
+        def cached_member_names
+          cached { self.members.collect(&:name) }
+        end
+      end
+      
+      @user = create :user
+      @group = create :group
+      @membership = @group.assign_user @user
+      
+      @user.cached_group_names
+      @group.cached_member_names
+    end
+    
+    describe "after_destroy" do
+      describe "through the parent object" do
+        subject { @group.members.destroy(@user); time_travel(2.seconds); @user.reload; @group.reload }
+        it "should delete the cache of the associated child object" do
+          subject
+          Rails.cache.read([@user, 'cached_group_names']).present?.should be_false
+        end
+        it "should delete the cache of the associated parent object" do
+          subject
+          Rails.cache.read([@group, 'cached_member_names']).present?.should be_false
+        end
+      end
+      describe "through the child object" do
+        subject { @user.groups.destroy(@group); time_travel(2.seconds); @user.reload; @group.reload }
+        it "should delete the cache of the associated child object" do
+          subject
+          Rails.cache.read([@user, 'cached_group_names']).present?.should be_false
+        end
+        it "should delete the cache of the associated parent object" do
+          subject
+          Rails.cache.read([@group, 'cached_member_names']).present?.should be_false
+        end
+      end
+            
+    end
+  end
+end
+
 # The dag link functionality is tested extensively in the corresponding `acts-as-dag` gem.
 # This test is just to make sure that the integration is propery done. Therefore, some basic scenarios are tested here.
 #
@@ -45,4 +99,4 @@ def setup_pages
     end
   end
 
-end
+end
\ No newline at end of file