92 行
3.2 KiB
Ruby
92 行
3.2 KiB
Ruby
require 'digest'
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class SharedResourceIdAllocator
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SPACES = {
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'tags' => ['tags', 'external_tags'],
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'wiki' => ['tag_descriptions', 'tag_groups'],
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'wiki_history' => ['tag_description_versions', 'tag_group_versions'] }.freeze
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HISTORY_IDS = {
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'tags' => [
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['tag_versions', 'tag_id'],
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['nico_tag_versions', 'tag_id'],
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['tag_description_versions', 'tag_id']],
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'wiki' => [['tag_group_versions', 'tag_group_id']] }.freeze
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LOCK_TIMEOUT = 10
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def self.assign! record
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space, tables = SPACES.find { |_name, names| names.include?(record.class.table_name) }
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raise ArgumentError, 'Unknown shared ID resource' unless tables
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connection = record.class.connection
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transaction = record.class.current_transaction
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unless transaction.open?
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raise ActiveRecord::ActiveRecordError, 'Shared ID requires a transaction'
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end
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database = connection.pool.db_config.database
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name = "btrc:ids:#{ Digest::SHA256.hexdigest(database)[0, 16] }:#{ space }"
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quoted_name = connection.quote(name)
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acquired = record.class.uncached do
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connection.select_value("SELECT GET_LOCK(#{ quoted_name }, #{ LOCK_TIMEOUT })")
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end
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unless acquired.to_i == 1
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raise ActiveRecord::LockWaitTimeout, "Shared ID lock unavailable: #{ space }"
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end
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release = lambda do
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result = record.class.uncached do
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connection.select_value("SELECT RELEASE_LOCK(#{ quoted_name })")
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end
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unless result.to_i == 1
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raise ActiveRecord::ActiveRecordError, "Shared ID lock release failed: #{ space }"
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end
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end
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begin
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transaction.after_commit(&release)
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transaction.after_rollback(&release)
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rescue StandardError
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release.call
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raise
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end
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# 明示-tic な Id. 指定は許可する．
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return if record.id.present?
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next_id = record.class.uncached do
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historical_max = HISTORY_IDS.fetch(space, []).map { |table, column|
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quoted_table = connection.quote_table_name(table)
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quoted_column = connection.quote_column_name(column)
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connection.select_value("SELECT MAX(#{ quoted_column }) FROM #{ quoted_table }").to_i
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}.max.to_i
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[next_ids(connection, tables).max, historical_max + 1].max
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end
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record.id = next_id
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end
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def self.next_ids connection, tables
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expiry = connection.select_value('SELECT @@SESSION.information_schema_stats_expiry').to_i
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begin
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connection.execute('SET SESSION information_schema_stats_expiry = 0')
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quoted_tables = tables.map { connection.quote(_1) }.join(', ')
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rows = connection.select_all(<<~SQL).to_a
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SELECT TABLE_NAME, ENGINE, AUTO_INCREMENT
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FROM information_schema.tables
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WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME IN (#{ quoted_tables })
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SQL
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persistent = rows.all? do |row|
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row['ENGINE'] == 'InnoDB' && row['AUTO_INCREMENT'].to_i.positive?
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end
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unless rows.size == tables.size && persistent
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raise ActiveRecord::ActiveRecordError, 'Persistent InnoDB counters are required'
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end
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rows.map { _1.fetch('AUTO_INCREMENT').to_i }
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ensure
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connection.execute("SET SESSION information_schema_stats_expiry = #{ expiry }")
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end
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end
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private_class_method :next_ids
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end
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