Merge pull request googleapis#1452 from blowmage/spanner-transaction-…

…rerty-info

Spanner Transaction Improvements

google-cloud-spanner/.rubocop.yml

@@ -44,3 +44,5 @@ Style/TrivialAccessors:
   Enabled: false
 Style/FileName:
   Enabled: false # for lib/google-cloud-spanner.rb file
+Lint/HandleExceptions:
+  Enabled: false

google-cloud-spanner/lib/google/cloud/spanner/client.rb

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 
-require "google/cloud/errors"
+require "google/cloud/spanner/errors"
 require "google/cloud/spanner/project"
 require "google/cloud/spanner/pool"
 require "google/cloud/spanner/session"
@@ -446,6 +446,9 @@ def delete table, *id
         # a single logical point in time across columns, rows, and tables in a
         # database.
         #
+        # @param [Numeric] deadline The total amount of time in seconds the
+        #   transaction has to succeed.
+        #
         # @yield [transaction] The block for reading and writing data.
         # @yieldparam [Google::Cloud::Spanner::Transaction] transaction The
         #   Transaction object.
@@ -464,19 +467,32 @@ def delete table, *id
         #     end
         #   end
         #
-        def transaction &block
+        def transaction deadline: 120, &block
           ensure_service!
+
+          deadline = validate_deadline deadline
+          backoff = 1.0
+          start_time = current_time
+
           @pool.with_session do |session|
-            tx_grpc = @project.service.begin_transaction session.path
-            tx = Transaction.from_grpc(tx_grpc, session)
+            tx = create_transaction! session
             begin
               block.call tx
-            rescue Google::Cloud::AbortedError
-              # TODO: retrieve delay from ABORTED error
-              # Retry the entire transaction
-              tx2_grpc = @project.service.begin_transaction session.path
-              tx2 = Transaction.from_grpc(tx2_grpc, session)
-              block.call tx2
+            rescue Google::Cloud::AbortedError => err
+              # Re-raise if deadline has passed
+              raise err if current_time - start_time > deadline
+              # Sleep the amount from RetryDelay, or incremental backoff
+              sleep(delay_from_aborted(err) || backoff *= 1.3)
+              # Create new transaction and retry the block
+              tx = create_transaction! session
+              retry
+            rescue RollbackError
+              # Transaction block was interrupted, allow to continue
+            rescue => err
+              # Rollback transaction when handling unexpeced error
+              # Don't use Transaction#rollback since it raises
+              session.rollback tx.send(:transaction_id)
+              raise err
             end
           end
           nil
@@ -568,6 +584,11 @@ def ensure_service!
           fail "Must have active connection to service" unless @project.service
         end
 
+        def create_transaction! session
+          tx_grpc = @project.service.begin_transaction session.path
+          Transaction.from_grpc(tx_grpc, session)
+        end
+
         ##
         # Check for valid snapshot arguments
         def validate_single_use_args! timestamp: nil, staleness: nil
@@ -599,6 +620,37 @@ def validate_snapshot_args! strong: nil, timestamp: nil, staleness: nil
                "Can only provide one of the following arguments: " \
                "(strong, timestamp, staleness)"
         end
+
+        def validate_deadline deadline
+          return 120 unless deadline.is_a? Numeric
+          return 120 if deadline < 0
+          deadline
+        end
+
+        ##
+        # Defer to this method so we have something to mock for tests
+        def current_time
+          Time.now
+        end
+
+        ##
+        # Retrieves the delay value from Google::Cloud::AbortedError
+        def delay_from_aborted err
+          return nil if err.nil?
+          if err.respond_to?(:metadata) && err.metadata["retryDelay"]
+            # a correct metadata will look like this:
+            # "{\"retryDelay\":{\"seconds\":60}}"
+            seconds = err.metadata["retryDelay"]["seconds"].to_i
+            nanos = err.metadata["retryDelay"]["nanos"].to_i
+            return seconds if nanos.zero?
+            return seconds + (nanos / 1000000000.0)
+          end
+          # No metadata? Try the inner error
+          delay_from_aborted(err.cause)
+        rescue
+          # Any error indicates the backoff should be handled elsewhere
+          return nil
+        end
       end
     end
   end

google-cloud-spanner/lib/google/cloud/spanner/errors.rb

@@ -0,0 +1,29 @@
+# Copyright 2017 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+require "google/cloud/errors"
+
+module Google
+  module Cloud
+    module Spanner
+      ##
+      # # TransactionError
+      #
+      # General error for Transaction problems.
+      class RollbackError < Google::Cloud::Error
+      end
+    end
+  end
+end

google-cloud-spanner/lib/google/cloud/spanner/policy.rb

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 
-require "google/cloud/errors"
+require "google/cloud/spanner/errors"
 
 module Google
   module Cloud

google-cloud-spanner/lib/google/cloud/spanner/project.rb

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 
-require "google/cloud/errors"
+require "google/cloud/spanner/errors"
 require "google/cloud/env"
 require "google/cloud/spanner/service"
 require "google/cloud/spanner/client"

google-cloud-spanner/lib/google/cloud/spanner/results.rb

@@ -14,7 +14,7 @@
 
 
 require "google/cloud/spanner/convert"
-require "google/cloud/errors"
+require "google/cloud/spanner/errors"
 
 module Google
   module Cloud

google-cloud-spanner/lib/google/cloud/spanner/service.rb

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 
-require "google/cloud/errors"
+require "google/cloud/spanner/errors"
 require "google/cloud/spanner/credentials"
 require "google/cloud/spanner/version"
 require "google/cloud/spanner/v1"
@@ -362,6 +362,13 @@ def commit session_name, mutations = [], transaction_id: nil
           end
         end
 
+        def rollback session_name, transaction_id
+          opts = default_options_from_session session_name
+          execute do
+            service.rollback session_name, transaction_id, options: opts
+          end
+        end
+
         def begin_transaction session_name
           tx_opts = Google::Spanner::V1::TransactionOptions.new(read_write:
             Google::Spanner::V1::TransactionOptions::ReadWrite.new)

google-cloud-spanner/lib/google/cloud/spanner/session.rb

@@ -442,6 +442,12 @@ def delete table, *id, transaction_id: nil
           service.commit path, commit.mutations, transaction_id: transaction_id
         end
 
+        ##
+        # Rolls back the transaction, releasing any locks it holds.
+        def rollback transaction_id
+          service.rollback path, transaction_id
+        end
+
         ##
         # @private
         # Keeps the session alive by calling SELECT 1

google-cloud-spanner/lib/google/cloud/spanner/transaction.rb

@@ -13,6 +13,7 @@
 # limitations under the License.
 
 
+require "google/cloud/spanner/errors"
 require "google/cloud/spanner/results"
 require "google/cloud/spanner/commit"
 
@@ -356,6 +357,26 @@ def delete table, *id
           session.delete table, id, transaction_id: transaction_id
         end
 
+        ##
+        # Rolls back the transaction, releasing any locks it holds. It is a good
+        # idea to call this for any transaction that includes one or more `read`
+        # or `execute` requests and ultimately decides not to commit.
+        #
+        # @example
+        #   require "google/cloud/spanner"
+        #
+        #   spanner = Google::Cloud::Spanner.new
+        #   db = spanner.client "my-instance", "my-database"
+        #
+        #   db.transaction { |tx| tx.rollback }
+        #
+        def rollback
+          ensure_session!
+          session.rollback transaction_id
+          # Raise RollbackError so the client can stop the transaction.
+          fail RollbackError
+        end
+
         ##
         # @private Creates a new Transaction instance from a
         # Google::Spanner::V1::Transaction.