Class: ActiveRecordSpannerAdapter::Transaction

Inherits:
Object
  • Object
show all
Defined in:
lib/activerecord_spanner_adapter/transaction.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(connection, isolation) ⇒ Transaction

Returns a new instance of Transaction.



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 11

def initialize connection, isolation
  @connection = connection
  @isolation = isolation
  @committable = ![:read_only, :pdml].include?(isolation) && !isolation.is_a?(Hash)
  @state = :INITIALIZED
  @sequence_number = 0
  @mutations = []
end

Instance Attribute Details

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 9

def state
  @state
end

Instance Method Details

#_transaction_isolation_level_to_grpc(isolation) ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 79

def _transaction_isolation_level_to_grpc isolation
  case isolation
  when :serializable
    Google::Cloud::Spanner::V1::TransactionOptions::IsolationLevel::SERIALIZABLE
  when :repeatable_read
    Google::Cloud::Spanner::V1::TransactionOptions::IsolationLevel::REPEATABLE_READ
  end
end

#active? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 20

def active?
  @state == :STARTED
end

#begin ⇒ Object

Begins the transaction.

Read-only and PDML transactions are started by executing a BeginTransaction RPC. Read/write transactions are not really started by this method, and instead a transaction selector is prepared that will be included with the first statement on the transaction.



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 39

def begin
  raise "Nested transactions are not allowed" if @state != :INITIALIZED
  begin
    case @isolation
    when Hash
      if @isolation[:timestamp]
        @grpc_transaction = @connection.session.create_snapshot timestamp: @isolation[:timestamp]
      elsif @isolation[:staleness]
        @grpc_transaction = @connection.session.create_snapshot staleness: @isolation[:staleness]
      elsif @isolation[:strong]
        @grpc_transaction = @connection.session.create_snapshot strong: true
      else
        raise "Invalid snapshot argument: #{@isolation}"
      end
    when :read_only
      @grpc_transaction = @connection.session.create_snapshot strong: true
    when :pdml
      @grpc_transaction = @connection.session.create_pdml
    else
      grpc_isolation = _transaction_isolation_level_to_grpc @isolation
      @begin_transaction_selector = Google::Cloud::Spanner::V1::TransactionSelector.new \
        begin: Google::Cloud::Spanner::V1::TransactionOptions.new(
          read_write: Google::Cloud::Spanner::V1::TransactionOptions::ReadWrite.new,
          isolation_level: grpc_isolation
        )
    end
    @state = :STARTED
  rescue Google::Cloud::NotFoundError => e
    if @connection.session_not_found? e
      @connection.reset!
      retry
    end
    @state = :FAILED
    raise
  rescue StandardError
    @state = :FAILED
    raise
  end
end

#buffer(mutation) ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 29

def buffer mutation
  @mutations << mutation
end

#commit ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 98

def commit
  raise "This transaction is not active" unless active?

  begin
    # Start a transaction with an explicit BeginTransaction RPC if the transaction only contains mutations.
    force_begin_read_write if @committable && !@mutations.empty? && !@grpc_transaction

    @connection.session.commit_transaction @grpc_transaction, @mutations if @committable && @grpc_transaction
    @state = :COMMITTED
  rescue Google::Cloud::NotFoundError => e
    if @connection.session_not_found? e
      shoot_and_forget_rollback
      @connection.reset!
      @connection.raise_aborted_err
    end
    @state = :FAILED
    raise
  rescue StandardError
    @state = :FAILED
    raise
  end
end

#force_begin_read_write ⇒ Object

Forces a BeginTransaction RPC for a read/write transaction. This is used by a connection if the first statement of a transaction failed.



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 90

def force_begin_read_write
  @grpc_transaction = @connection.session.create_transaction
end

#grpc_transaction=(grpc) ⇒ Object

Sets the underlying gRPC transaction to use for this Transaction. This is used for queries/DML statements that inlined the BeginTransaction option and returned a transaction in the metadata.



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 147

def grpc_transaction= grpc
  @grpc_transaction = Google::Cloud::Spanner::Transaction.from_grpc grpc, @connection.session
end

#isolation ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 24

def isolation
  return nil unless active?
  @isolation
end

#mark_aborted ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 140

def mark_aborted
  @state = :ABORTED
end

#next_sequence_number ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 94

def next_sequence_number
  @sequence_number += 1 if @committable
end

#rollback ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 121

def rollback
  # Allow rollback after abort and/or a failed commit.
  raise "This transaction is not active" unless active? || @state == :FAILED || @state == :ABORTED
  if active? && @grpc_transaction
    # We do a shoot-and-forget rollback here, as the error that caused the transaction to be rolled back could
    # also have invalidated the transaction (e.g. `Session not found`). If the rollback fails for any other
    # reason, we also do not need to retry it or propagate the error to the application, as the transaction will
    # automatically be aborted by Cloud Spanner after 10 seconds anyways.
    shoot_and_forget_rollback
  end
  @state = :ROLLED_BACK
end

#shoot_and_forget_rollback ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 134

def shoot_and_forget_rollback
  @connection.session.rollback @grpc_transaction.transaction_id if @committable
rescue StandardError
  # Ignored
end

#transaction_selector ⇒ Object 



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# File 'lib/activerecord_spanner_adapter/transaction.rb', line 151

def transaction_selector
  return unless active?

  # Use the transaction that has been started by a BeginTransaction RPC or returned by a
  # statement, if present.
  return Google::Cloud::Spanner::V1::TransactionSelector.new id: @grpc_transaction.transaction_id \
      if @grpc_transaction

  # Return a transaction selector that will instruct the statement to also start a transaction
  # and return its id as a side effect.
  @begin_transaction_selector
end