From 6475525f3176698d6d8902b32af62ffd23ddd9e3 Mon Sep 17 00:00:00 2001 From: Thibaut Girka Date: Wed, 20 Nov 2019 17:03:25 +0100 Subject: Monkey-patch Rails' migrator to ignore duplicate migrations across Mastodon and glitch-soc --- config/initializers/0_duplicate_migrations.rb | 28 +++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 config/initializers/0_duplicate_migrations.rb (limited to 'config/initializers') diff --git a/config/initializers/0_duplicate_migrations.rb b/config/initializers/0_duplicate_migrations.rb new file mode 100644 index 000000000..4c7440fa4 --- /dev/null +++ b/config/initializers/0_duplicate_migrations.rb @@ -0,0 +1,28 @@ +ALLOWED_DUPLICATES = [20180410220657, 20180831171112].freeze + +module ActiveRecord + class Migrator + old_initialize = instance_method(:initialize) + + define_method(:initialize) do |direction, migrations, target_version| + migrated = Set.new(Base.connection.migration_context.get_all_versions) + + migrations.group_by(&:name).each do |name, duplicates| + if duplicates.length > 1 && duplicates.all? { |m| ALLOWED_DUPLICATES.include?(m.version) } + # We have a set of allowed duplicates. Keep the migrated one, if any. + non_migrated = duplicates.reject { |m| migrated.include?(m.version.to_i) } + + if duplicates.length == non_migrated.length + # There weren't any migrated one, so we have to pick one “canonical” migration + migrations = migrations - duplicates[1..-1] + else + # Just reject every duplicate which hasn't been migrated yet + migrations = migrations - non_migrated + end + end + end + + old_initialize.bind(self).(direction, migrations, target_version) + end + end +end -- cgit From 33c2a7e23c3e53f05ac93ec533e2c9b238e2cc34 Mon Sep 17 00:00:00 2001 From: Thibaut Girka Date: Wed, 20 Nov 2019 17:18:00 +0100 Subject: Add documentation about the migration hack --- config/initializers/0_duplicate_migrations.rb | 14 ++++++++++++++ db/migrate/20180410220657_create_bookmarks.rb | 10 ++++++++-- db/migrate/20180831171112_create_bookmarks.rb | 3 +++ 3 files changed, 25 insertions(+), 2 deletions(-) (limited to 'config/initializers') diff --git a/config/initializers/0_duplicate_migrations.rb b/config/initializers/0_duplicate_migrations.rb index 4c7440fa4..d15d2b24a 100644 --- a/config/initializers/0_duplicate_migrations.rb +++ b/config/initializers/0_duplicate_migrations.rb @@ -1,3 +1,17 @@ +# Some migrations have been present in glitch-soc for a long time and have then +# been merged in upstream Mastodon, under a different version number. +# +# This puts us in an uneasy situation in which if we remove upstream's +# migration file, people migrating from upstream will end up having a conflict +# with their already-ran migration. +# +# On the other hand, if we keep upstream's migration and remove our own, +# any current glitch-soc user will have a conflict during migration. +# +# For lack of a better solution, as those migrations are indeed identical, +# we decided monkey-patching Rails' Migrator to completely ignore the duplicate, +# keeping only the one that has run, or an arbitrary one. + ALLOWED_DUPLICATES = [20180410220657, 20180831171112].freeze module ActiveRecord diff --git a/db/migrate/20180410220657_create_bookmarks.rb b/db/migrate/20180410220657_create_bookmarks.rb index 08d22c10d..bc79022e4 100644 --- a/db/migrate/20180410220657_create_bookmarks.rb +++ b/db/migrate/20180410220657_create_bookmarks.rb @@ -1,3 +1,6 @@ +# This migration is a duplicate of 20180831171112 and may get ignored, see +# config/initializers/0_duplicate_migrations.rb + class CreateBookmarks < ActiveRecord::Migration[5.1] def change create_table :bookmarks do |t| @@ -7,8 +10,11 @@ class CreateBookmarks < ActiveRecord::Migration[5.1] t.timestamps end - safety_assured { add_foreign_key :bookmarks, :accounts, column: :account_id, on_delete: :cascade } - safety_assured { add_foreign_key :bookmarks, :statuses, column: :status_id, on_delete: :cascade } + safety_assured do + add_foreign_key :bookmarks, :accounts, column: :account_id, on_delete: :cascade + add_foreign_key :bookmarks, :statuses, column: :status_id, on_delete: :cascade + end + add_index :bookmarks, [:account_id, :status_id], unique: true end end diff --git a/db/migrate/20180831171112_create_bookmarks.rb b/db/migrate/20180831171112_create_bookmarks.rb index 27c7339c9..5d587b7e9 100644 --- a/db/migrate/20180831171112_create_bookmarks.rb +++ b/db/migrate/20180831171112_create_bookmarks.rb @@ -1,3 +1,6 @@ +# This migration is a duplicate of 20180410220657 and may get ignored, see +# config/initializers/0_duplicate_migrations.rb + class CreateBookmarks < ActiveRecord::Migration[5.1] def change create_table :bookmarks do |t| -- cgit From 1064a9d827b5ec773e13c9bd10459f598b6ef84f Mon Sep 17 00:00:00 2001 From: Thibaut Girka Date: Wed, 20 Nov 2019 17:31:22 +0100 Subject: Override Migrator.new instead of Migrator#initialize, it's easier to understand --- config/initializers/0_duplicate_migrations.rb | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'config/initializers') diff --git a/config/initializers/0_duplicate_migrations.rb b/config/initializers/0_duplicate_migrations.rb index d15d2b24a..509a069e6 100644 --- a/config/initializers/0_duplicate_migrations.rb +++ b/config/initializers/0_duplicate_migrations.rb @@ -16,9 +16,7 @@ ALLOWED_DUPLICATES = [20180410220657, 20180831171112].freeze module ActiveRecord class Migrator - old_initialize = instance_method(:initialize) - - define_method(:initialize) do |direction, migrations, target_version| + def self.new(direction, migrations, target_version = nil) migrated = Set.new(Base.connection.migration_context.get_all_versions) migrations.group_by(&:name).each do |name, duplicates| @@ -36,7 +34,7 @@ module ActiveRecord end end - old_initialize.bind(self).(direction, migrations, target_version) + super(direction, migrations, target_version) end end end -- cgit From e87cc59811fab285033cc78d97ad7f0b8df9c081 Mon Sep 17 00:00:00 2001 From: Thibaut Girka Date: Wed, 20 Nov 2019 19:19:32 +0100 Subject: Fix weird edge case in load_schema --- config/initializers/0_duplicate_migrations.rb | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'config/initializers') diff --git a/config/initializers/0_duplicate_migrations.rb b/config/initializers/0_duplicate_migrations.rb index 509a069e6..4ab806587 100644 --- a/config/initializers/0_duplicate_migrations.rb +++ b/config/initializers/0_duplicate_migrations.rb @@ -24,7 +24,7 @@ module ActiveRecord # We have a set of allowed duplicates. Keep the migrated one, if any. non_migrated = duplicates.reject { |m| migrated.include?(m.version.to_i) } - if duplicates.length == non_migrated.length + if duplicates.length == non_migrated.length || non_migrated.length == 0 # There weren't any migrated one, so we have to pick one “canonical” migration migrations = migrations - duplicates[1..-1] else -- cgit