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|
# frozen_string_literal: true
require "active_record/scoping/default"
require "active_record/scoping/named"
module ActiveRecord
# This class is used to create a table that keeps track of values and keys such
# as which environment migrations were run in.
#
# This is enabled by default. To disable this functionality set
# `use_metadata_table` to false in your database configuration.
class InternalMetadata # :nodoc:
class NullInternalMetadata # :nodoc:
end
attr_reader :arel_table
def initialize(pool)
@pool = pool
@arel_table = Arel::Table.new(table_name)
end
def primary_key
"key"
end
def value_key
"value"
end
def table_name
"#{ActiveRecord::Base.table_name_prefix}#{ActiveRecord::Base.internal_metadata_table_name}#{ActiveRecord::Base.table_name_suffix}"
end
def enabled?
@pool.db_config.use_metadata_table?
end
def []=(key, value)
return unless enabled?
@pool.with_connection do |connection|
update_or_create_entry(connection, key, value)
end
end
def [](key)
return unless enabled?
@pool.with_connection do |connection|
if entry = select_entry(connection, key)
entry[value_key]
end
end
end
def delete_all_entries
dm = Arel::DeleteManager.new(arel_table)
@pool.with_connection do |connection|
connection.delete(dm, "#{self.class} Destroy")
end
end
def count
sm = Arel::SelectManager.new(arel_table)
sm.project(*Arel::Nodes::Count.new([Arel.star]))
@pool.with_connection do |connection|
connection.select_values(sm, "#{self.class} Count").first
end
end
def create_table_and_set_flags(environment, schema_sha1 = nil)
return unless enabled?
@pool.with_connection do |connection|
create_table
update_or_create_entry(connection, :environment, environment)
update_or_create_entry(connection, :schema_sha1, schema_sha1) if schema_sha1
end
end
# Creates an internal metadata table with columns +key+ and +value+
def create_table
return unless enabled?
@pool.with_connection do |connection|
unless connection.table_exists?(table_name)
connection.create_table(table_name, id: false) do |t|
t.string :key, **connection.internal_string_options_for_primary_key
t.string :value
t.timestamps
end
end
end
end
def drop_table
return unless enabled?
@pool.with_connection do |connection|
connection.drop_table table_name, if_exists: true
end
end
def table_exists?
@pool.schema_cache.data_source_exists?(table_name)
end
private
def update_or_create_entry(connection, key, value)
entry = select_entry(connection, key)
if entry
if entry[value_key] != value
update_entry(connection, key, value)
else
entry[value_key]
end
else
create_entry(connection, key, value)
end
end
def current_time(connection)
connection.default_timezone == :utc ? Time.now.utc : Time.now
end
def create_entry(connection, key, value)
im = Arel::InsertManager.new(arel_table)
im.insert [
[arel_table[primary_key], key],
[arel_table[value_key], value],
[arel_table[:created_at], current_time(connection)],
[arel_table[:updated_at], current_time(connection)]
]
connection.insert(im, "#{self.class} Create", primary_key, key)
end
def update_entry(connection, key, new_value)
um = Arel::UpdateManager.new(arel_table)
um.set [
[arel_table[value_key], new_value],
[arel_table[:updated_at], current_time(connection)]
]
um.where(arel_table[primary_key].eq(key))
connection.update(um, "#{self.class} Update")
end
def select_entry(connection, key)
sm = Arel::SelectManager.new(arel_table)
sm.project(Arel::Nodes::SqlLiteral.new("*", retryable: true))
sm.where(arel_table[primary_key].eq(Arel::Nodes::BindParam.new(key)))
sm.order(arel_table[primary_key].asc)
sm.limit = 1
connection.select_all(sm, "#{self.class} Load").first
end
end
end
|
