1 files changed, 330 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
new file mode 100644
index 0000000000..718910b090
--- /dev/null
+++ b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb
@@ -0,0 +1,330 @@
+# frozen_string_literal: true
+
+module ActiveRecord
+  module ConnectionAdapters
+    class TransactionState
+      def initialize(state = nil)
+        @state = state
+        @children = []
+      end
+
+      def add_child(state)
+        @children << state
+      end
+
+      def finalized?
+        @state
+      end
+
+      def committed?
+        @state == :committed || @state == :fully_committed
+      end
+
+      def fully_committed?
+        @state == :fully_committed
+      end
+
+      def rolledback?
+        @state == :rolledback || @state == :fully_rolledback
+      end
+
+      def fully_rolledback?
+        @state == :fully_rolledback
+      end
+
+      def fully_completed?
+        completed?
+      end
+
+      def completed?
+        committed? || rolledback?
+      end
+
+      def set_state(state)
+        ActiveSupport::Deprecation.warn(<<-MSG.squish)
+          The set_state method is deprecated and will be removed in
+          Rails 6.0. Please use rollback! or commit! to set transaction
+          state directly.
+        MSG
+        case state
+        when :rolledback
+          rollback!
+        when :committed
+          commit!
+        when nil
+          nullify!
+        else
+          raise ArgumentError, "Invalid transaction state: #{state}"
+        end
+      end
+
+      def rollback!
+        @children.each { |c| c.rollback! }
+        @state = :rolledback
+      end
+
+      def full_rollback!
+        @children.each { |c| c.rollback! }
+        @state = :fully_rolledback
+      end
+
+      def commit!
+        @state = :committed
+      end
+
+      def full_commit!
+        @state = :fully_committed
+      end
+
+      def nullify!
+        @state = nil
+      end
+    end
+
+    class NullTransaction #:nodoc:
+      def initialize; end
+      def state; end
+      def closed?; true; end
+      def open?; false; end
+      def joinable?; false; end
+      def add_record(record); end
+    end
+
+    class Transaction #:nodoc:
+      attr_reader :connection, :state, :records, :savepoint_name, :isolation_level
+
+      def initialize(connection, options, run_commit_callbacks: false)
+        @connection = connection
+        @state = TransactionState.new
+        @records = []
+        @isolation_level = options[:isolation]
+        @materialized = false
+        @joinable = options.fetch(:joinable, true)
+        @run_commit_callbacks = run_commit_callbacks
+      end
+
+      def add_record(record)
+        records << record
+      end
+
+      def materialize!
+        @materialized = true
+      end
+
+      def materialized?
+        @materialized
+      end
+
+      def rollback_records
+        ite = records.uniq
+        while record = ite.shift
+          record.rolledback!(force_restore_state: full_rollback?)
+        end
+      ensure
+        ite.each do |i|
+          i.rolledback!(force_restore_state: full_rollback?, should_run_callbacks: false)
+        end
+      end
+
+      def before_commit_records
+        records.uniq.each(&:before_committed!) if @run_commit_callbacks
+      end
+
+      def commit_records
+        ite = records.uniq
+        while record = ite.shift
+          if @run_commit_callbacks
+            record.committed!
+          else
+            # if not running callbacks, only adds the record to the parent transaction
+            connection.add_transaction_record(record)
+          end
+        end
+      ensure
+        ite.each { |i| i.committed!(should_run_callbacks: false) }
+      end
+
+      def full_rollback?; true; end
+      def joinable?; @joinable; end
+      def closed?; false; end
+      def open?; !closed?; end
+    end
+
+    class SavepointTransaction < Transaction
+      def initialize(connection, savepoint_name, parent_transaction, *args)
+        super(connection, *args)
+
+        parent_transaction.state.add_child(@state)
+
+        if isolation_level
+          raise ActiveRecord::TransactionIsolationError, "cannot set transaction isolation in a nested transaction"
+        end
+
+        @savepoint_name = savepoint_name
+      end
+
+      def materialize!
+        connection.create_savepoint(savepoint_name)
+        super
+      end
+
+      def rollback
+        connection.rollback_to_savepoint(savepoint_name) if materialized?
+        @state.rollback!
+      end
+
+      def commit
+        connection.release_savepoint(savepoint_name) if materialized?
+        @state.commit!
+      end
+
+      def full_rollback?; false; end
+    end
+
+    class RealTransaction < Transaction
+      def materialize!
+        if isolation_level
+          connection.begin_isolated_db_transaction(isolation_level)
+        else
+          connection.begin_db_transaction
+        end
+
+        super
+      end
+
+      def rollback
+        connection.rollback_db_transaction if materialized?
+        @state.full_rollback!
+      end
+
+      def commit
+        connection.commit_db_transaction if materialized?
+        @state.full_commit!
+      end
+    end
+
+    class TransactionManager #:nodoc:
+      def initialize(connection)
+        @stack = []
+        @connection = connection
+        @has_unmaterialized_transactions = false
+        @materializing_transactions = false
+        @lazy_transactions_enabled = true
+      end
+
+      def begin_transaction(options = {})
+        @connection.lock.synchronize do
+          run_commit_callbacks = !current_transaction.joinable?
+          transaction =
+            if @stack.empty?
+              RealTransaction.new(@connection, options, run_commit_callbacks: run_commit_callbacks)
+            else
+              SavepointTransaction.new(@connection, "active_record_#{@stack.size}", @stack.last, options,
+                                       run_commit_callbacks: run_commit_callbacks)
+            end
+
+          transaction.materialize! unless @connection.supports_lazy_transactions? && lazy_transactions_enabled?
+          @stack.push(transaction)
+          @has_unmaterialized_transactions = true if @connection.supports_lazy_transactions?
+          transaction
+        end
+      end
+
+      def disable_lazy_transactions!
+        materialize_transactions
+        @lazy_transactions_enabled = false
+      end
+
+      def enable_lazy_transactions!
+        @lazy_transactions_enabled = true
+      end
+
+      def lazy_transactions_enabled?
+        @lazy_transactions_enabled
+      end
+
+      def materialize_transactions
+        return if @materializing_transactions
+        return unless @has_unmaterialized_transactions
+
+        @connection.lock.synchronize do
+          begin
+            @materializing_transactions = true
+            @stack.each { |t| t.materialize! unless t.materialized? }
+          ensure
+            @materializing_transactions = false
+          end
+          @has_unmaterialized_transactions = false
+        end
+      end
+
+      def commit_transaction
+        @connection.lock.synchronize do
+          transaction = @stack.last
+
+          begin
+            transaction.before_commit_records
+          ensure
+            @stack.pop
+          end
+
+          transaction.commit
+          transaction.commit_records
+        end
+      end
+
+      def rollback_transaction(transaction = nil)
+        @connection.lock.synchronize do
+          transaction ||= @stack.pop
+          transaction.rollback
+          transaction.rollback_records
+        end
+      end
+
+      def within_new_transaction(options = {})
+        @connection.lock.synchronize do
+          transaction = begin_transaction options
+          yield
+        rescue Exception => error
+          if transaction
+            rollback_transaction
+            after_failure_actions(transaction, error)
+          end
+          raise
+        ensure
+          if !error && transaction
+            if Thread.current.status == "aborting"
+              rollback_transaction
+            else
+              begin
+                commit_transaction
+              rescue Exception
+                rollback_transaction(transaction) unless transaction.state.completed?
+                raise
+              end
+            end
+          end
+        end
+      end
+
+      def open_transactions
+        @stack.size
+      end
+
+      def current_transaction
+        @stack.last || NULL_TRANSACTION
+      end
+
+      private
+
+        NULL_TRANSACTION = NullTransaction.new
+
+        # Deallocate invalidated prepared statements outside of the transaction
+        def after_failure_actions(transaction, error)
+          return unless transaction.is_a?(RealTransaction)
+          return unless error.is_a?(ActiveRecord::PreparedStatementCacheExpired)
+          @connection.clear_cache!
+        end
+    end
+  end
+end