Class: Mongo::Session

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
ClusterTime::Consumer, Loggable, Retryable
Defined in:
lib/mongo/session.rb,
lib/mongo/session/session_pool.rb,
lib/mongo/session/server_session.rb,
lib/mongo/session/server_session/dirtyable.rb

Overview

Note:

Session objects are not thread-safe. An application may use a session from only one thread or process at a time.

A logical session representing a set of sequential operations executed by an application that are related in some way.

Since:

  • 2.5.0

Defined Under Namespace

Classes: ServerSession, SessionPool

Constant Summary collapse

MISMATCHED_CLUSTER_ERROR_MSG =

Error message indicating that the session was retrieved from a client with a different cluster than that of the client through which it is currently being used.

Since:

  • 2.5.0

'The configuration of the client used to create this session does not match that ' +
'of the client owning this operation. Please only use this session for operations through its parent ' +
'client.'.freeze
SESSION_ENDED_ERROR_MSG =

Error message describing that the session cannot be used because it has already been ended.

Since:

  • 2.5.0

'This session has ended and cannot be used. Please create a new one.'.freeze
SESSIONS_NOT_SUPPORTED =
Deprecated.

Error message describing that sessions are not supported by the server version.

Since:

  • 2.5.0

'Sessions are not supported by the connected servers.'.freeze
NO_TRANSACTION_STATE =

The state of a session in which the last operation was not related to any transaction or no operations have yet occurred.

Since:

  • 2.6.0

:no_transaction
STARTING_TRANSACTION_STATE =

The state of a session in which a user has initiated a transaction but no operations within the transactions have occurred yet.

Since:

  • 2.6.0

:starting_transaction
TRANSACTION_IN_PROGRESS_STATE =

The state of a session in which a transaction has been started and at least one operation has occurred, but the transaction has not yet been committed or aborted.

Since:

  • 2.6.0

:transaction_in_progress
TRANSACTION_COMMITTED_STATE =

The state of a session in which the last operation executed was a transaction commit.

Since:

  • 2.6.0

:transaction_committed
TRANSACTION_ABORTED_STATE =

The state of a session in which the last operation executed was a transaction abort.

Since:

  • 2.6.0

:transaction_aborted
UNLABELED_WRITE_CONCERN_CODES =

This constant is part of a private API. You should avoid using this constant if possible, as it may be removed or be changed in the future.

Since:

  • 2.5.0

[
  79,  # UnknownReplWriteConcern
  100, # CannotSatisfyWriteConcern,
].freeze

Constants included from Loggable

Loggable::PREFIX

Instance Attribute Summary collapse

Attributes included from ClusterTime::Consumer

#cluster_time

Instance Method Summary collapse

Methods included from ClusterTime::Consumer

#advance_cluster_time

Methods included from Loggable

#log_debug, #log_error, #log_fatal, #log_info, #log_warn, #logger

Methods included from Retryable

#read_worker, #select_server, #write_worker

Constructor Details

#initialize(server_session, client, options = {}) ⇒ Session

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Note:

Applications should use Client#start_session to begin a session. This constructor is for internal driver use only.

Initialize a Session.

A session can be explicit or implicit. Lifetime of explicit sessions is managed by the application - applications explicitry create such sessions and explicitly end them. Implicit sessions are created automatically by the driver when sending operations to servers that support sessions (3.6+), and their lifetime is managed by the driver.

When an implicit session is created, it cannot have a server session associated with it. The server session will be checked out of the session pool when an operation using this session is actually executed. When an explicit session is created, it must reference a server session that is already allocated.

Parameters:

  • server_session (ServerSession | nil) —

    The server session this session is associated with. If the :implicit option is true, this must be nil.

  • client (Client) —

    The client through which this session is created.

  • options (Hash) (defaults to: {}) —

    The options for this session.

Options Hash (options):

  • :causal_consistency (true|false) —

    Whether to enable causal consistency for this session.

  • :default_timeout_ms (Integer) —

    The timeoutMS value for the following operations executed on the session:

    • commitTransaction

    • abortTransaction

    • withTransaction

    • endSession

  • :default_transaction_options (Hash) —

    Options to pass to start_transaction by default, can contain any of the options that start_transaction accepts.

  • :implicit (true|false) —

    For internal driver use only - specifies whether the session is implicit. If this is true, the server_session will be nil. This is done so that the server session is only checked out after the connection is checked out.

  • :read_preference (Hash) —

    The read preference options hash, with the following optional keys:

    • :mode – the read preference as a string or symbol; valid values are :primary, :primary_preferred, :secondary, :secondary_preferred and :nearest.

  • :snapshot (true | false) —

    Set up the session for snapshot reads.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 83

def initialize(server_session, client, options = {})
  if options[:causal_consistency] && options[:snapshot]
    raise ArgumentError, ':causal_consistency and :snapshot options cannot be both set on a session'
  end

  if options[:implicit]
    unless server_session.nil?
      raise ArgumentError, 'Implicit session cannot reference server session during construction'
    end
  else
    if server_session.nil?
      raise ArgumentError, 'Explicit session must reference server session during construction'
    end
  end

  @server_session = server_session
  options = options.dup

  @client = client.use(:admin)
  @options = options.dup.freeze
  @cluster_time = nil
  @state = NO_TRANSACTION_STATE
  @with_transaction_deadline = nil
end

Instance Attribute Details

#client ⇒ Client (readonly)

Returns The client through which this session was created.

Returns:

  • (Client) —

    The client through which this session was created.

Since:

  • 2.5.1



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# File 'lib/mongo/session.rb', line 116

def client
  @client
end

#operation_time ⇒ BSON::Timestamp (readonly)

Returns The latest seen operation time for this session.

Returns:

  • (BSON::Timestamp) —

    The latest seen operation time for this session.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 131

def operation_time
  @operation_time
end

#options ⇒ Hash (readonly)

Returns The options for this session.

Returns:

  • (Hash) —

    The options for this session.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 111

def options
  @options
end

#pinned_connection_global_id ⇒ Integer | nil (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns The connection global id that this session is pinned to, if any.

Returns:

  • (Integer | nil) —

    The connection global id that this session is pinned to, if any.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 284

def pinned_connection_global_id
  @pinned_connection_global_id
end

#pinned_server ⇒ Server | nil (readonly)

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns The server (which should be a mongos) that this session is pinned to, if any.

Returns:

  • (Server | nil) —

    The server (which should be a mongos) that this session is pinned to, if any.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 278

def pinned_server
  @pinned_server
end

#recovery_token ⇒ BSON::Document | nil

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Recovery token for the sharded transaction being executed on this session, if any.

Returns:

  • (BSON::Document | nil) —

    Recovery token for the sharded transaction being executed on this session, if any.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 290

def recovery_token
  @recovery_token
end

#snapshot_timestamp ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1192

def snapshot_timestamp
  @snapshot_timestamp
end

#with_transaction_deadline ⇒ Object (readonly)

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1194

def with_transaction_deadline
  @with_transaction_deadline
end

Instance Method Details

#abort_transaction(options = nil) ⇒ Object

Abort the currently active transaction without making any changes to the database.

Examples:

Abort the transaction.

session.abort_transaction

Parameters:

  • options (Hash) (defaults to: nil) —

    a customizable set of options

Options Hash (options):

  • :timeout_ms (Integer) —

    The operation timeout in milliseconds. Must be a non-negative integer. An explicit value of 0 means infinite. The default value is unset which means the value is inherited from the client.

Raises:

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 730

def abort_transaction(options = nil)
  QueryCache.clear

  check_if_ended!
  check_if_no_transaction!

  if within_states?(TRANSACTION_COMMITTED_STATE)
    raise Mongo::Error::InvalidTransactionOperation.new(
      Mongo::Error::InvalidTransactionOperation.cannot_call_after_msg(
        :commitTransaction, :abortTransaction))
  end

  if within_states?(TRANSACTION_ABORTED_STATE)
    raise Mongo::Error::InvalidTransactionOperation.new(
      Mongo::Error::InvalidTransactionOperation.cannot_call_twice_msg(:abortTransaction))
  end

  options ||= {}

  begin
    unless starting_transaction?
      @aborting_transaction = true
      context = Operation::Context.new(
        client: @client,
        session: self,
        operation_timeouts: operation_timeouts(options)
      )
      write_with_retry(txn_options[:write_concern],
        ending_transaction: true, context: context,
      ) do |connection, txn_num, context|
        begin
          Operation::Command.new(
            selector: { abortTransaction: 1 },
            db_name: 'admin',
            session: self,
            txn_num: txn_num
          ).execute_with_connection(connection, context: context)
        ensure
          unpin
        end
      end
    end

    @state = TRANSACTION_ABORTED_STATE
  rescue Mongo::Error::InvalidTransactionOperation
    raise
  rescue Mongo::Error
    @state = TRANSACTION_ABORTED_STATE
  rescue Exception
    @state = TRANSACTION_ABORTED_STATE
    raise
  ensure
    @aborting_transaction = false
  end

  # No official return value, but return true so that in interactive
  # use the method hints that it succeeded.
  true
end

#aborting_transaction? ⇒ true | false

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Whether the session is currently aborting a transaction.

Returns:

  • (true | false) —

    Whether the session is currently aborting a transaction.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 819

def aborting_transaction?
  !!@aborting_transaction
end

#add_autocommit!(command) ⇒ Hash, BSON::Document

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Add the autocommit field to a command document if applicable.

Examples:

session.add_autocommit!(cmd)

Returns:

  • (Hash, BSON::Document) —

    The command document.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 899

def add_autocommit!(command)
  command.tap do |c|
    c[:autocommit] = false if in_transaction?
  end
end

#add_start_transaction!(command) ⇒ Hash, BSON::Document

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Add the startTransaction field to a command document if applicable.

Examples:

session.add_start_transaction!(cmd)

Returns:

  • (Hash, BSON::Document) —

    The command document.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 914

def add_start_transaction!(command)
  command.tap do |c|
    if starting_transaction?
      c[:startTransaction] = true
    end
  end
end

#add_txn_num!(command) ⇒ Hash, BSON::Document

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Add the transaction number to a command document if applicable.

Examples:

session.add_txn_num!(cmd)

Returns:

  • (Hash, BSON::Document) —

    The command document.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 931

def add_txn_num!(command)
  command.tap do |c|
    c[:txnNumber] = BSON::Int64.new(@server_session.txn_num) if in_transaction?
  end
end

#add_txn_opts!(command, read, context) ⇒ Hash, BSON::Document

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Add the transactions options if applicable.

Examples:

session.add_txn_opts!(cmd)

Returns:

  • (Hash, BSON::Document) —

    The command document.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 946

def add_txn_opts!(command, read, context)
  command.tap do |c|
    # The read concern should be added to any command that starts a transaction.
    if starting_transaction?
      # https://jira.mongodb.org/browse/SPEC-1161: transaction's
      # read concern overrides collection/database/client read concerns,
      # even if transaction's read concern is not set.
      # Read concern here is the one sent to the server and may
      # include afterClusterTime.
      if rc = c[:readConcern]
        rc = rc.dup
        rc.delete(:level)
      end
      if txn_read_concern
        if rc
          rc.update(txn_read_concern)
        else
          rc = txn_read_concern.dup
        end
      end
      if rc.nil? || rc.empty?
        c.delete(:readConcern)
      else
        c[:readConcern ] = Options::Mapper.transform_values_to_strings(rc)
      end
    end

    # We need to send the read concern level as a string rather than a symbol.
    if c[:readConcern]
      c[:readConcern] = Options::Mapper.transform_values_to_strings(c[:readConcern])
    end

    if c[:commitTransaction]
      if max_time_ms = txn_options[:max_commit_time_ms]
        c[:maxTimeMS] = max_time_ms
      end
    end

    # The write concern should be added to any abortTransaction or commitTransaction command.
    if (c[:abortTransaction] || c[:commitTransaction])
      if @already_committed
        wc = BSON::Document.new(c[:writeConcern] || txn_write_concern || {})
        wc.merge!(w: :majority)
        wc[:wtimeout] ||= 10000
        c[:writeConcern] = wc
      elsif txn_write_concern
        c[:writeConcern] ||= txn_write_concern
      end
    end

    # A non-numeric write concern w value needs to be sent as a string rather than a symbol.
    if c[:writeConcern] && c[:writeConcern][:w] && c[:writeConcern][:w].is_a?(Symbol)
      c[:writeConcern][:w] = c[:writeConcern][:w].to_s
    end

    # Ignore wtimeout if csot
    if context&.csot?
      c[:writeConcern]&.delete(:wtimeout)
    end

    # We must not send an empty (server default) write concern.
    c.delete(:writeConcern) if c[:writeConcern]&.empty?
  end
end

#advance_operation_time(new_operation_time) ⇒ BSON::Timestamp

Advance the cached operation time for this session.

Examples:

Advance the operation time.

session.advance_operation_time(timestamp)

Parameters:

  • new_operation_time (BSON::Timestamp) —

    The new operation time.

Returns:

  • (BSON::Timestamp) —

    The max operation time, considering the current and new times.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1123

def advance_operation_time(new_operation_time)
  if @operation_time
    @operation_time = [ @operation_time, new_operation_time ].max
  else
    @operation_time = new_operation_time
  end
end

#cluster ⇒ Object

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 118

def cluster
  @client.cluster
end

#commit_transaction(options = nil) ⇒ Object

Commit the currently active transaction on the session.

Examples:

Commits the transaction.

session.commit_transaction

Parameters:

  • options (Hash) (defaults to: nil) —

    a customizable set of options

Options Hash (options):

  • :write_concern (nil | WriteConcern::Base) —

    The write concern to use for this operation.

  • :timeout_ms (Integer) —

    The operation timeout in milliseconds. Must be a non-negative integer. An explicit value of 0 means infinite. The default value is unset which means the value is inherited from the client.

Raises:

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 648

def commit_transaction(options=nil)
  QueryCache.clear
  check_if_ended!
  check_if_no_transaction!

  if within_states?(TRANSACTION_ABORTED_STATE)
    raise Mongo::Error::InvalidTransactionOperation.new(
      Mongo::Error::InvalidTransactionOperation.cannot_call_after_msg(
        :abortTransaction, :commitTransaction))
  end

  options ||= {}

  begin
    # If commitTransaction is called twice, we need to run the same commit
    # operation again, so we revert the session to the previous state.
    if within_states?(TRANSACTION_COMMITTED_STATE)
      @state = @last_commit_skipped ? STARTING_TRANSACTION_STATE : TRANSACTION_IN_PROGRESS_STATE
      @already_committed = true
    end

    if starting_transaction?
      @last_commit_skipped = true
    else
      @last_commit_skipped = false
      @committing_transaction = true

      write_concern = options[:write_concern] || txn_options[:write_concern]
      if write_concern && !write_concern.is_a?(WriteConcern::Base)
        write_concern = WriteConcern.get(write_concern)
      end

      context = Operation::Context.new(
        client: @client,
        session: self,
        operation_timeouts: operation_timeouts(options)
      )
      write_with_retry(write_concern, ending_transaction: true,
        context: context,
      ) do |connection, txn_num, context|
        if context.retry?
          if write_concern
            wco = write_concern.options.merge(w: :majority)
            wco[:wtimeout] ||= 10000
            write_concern = WriteConcern.get(wco)
          else
            write_concern = WriteConcern.get(w: :majority, wtimeout: 10000)
          end
        end
        spec = {
          selector: { commitTransaction: 1 },
          db_name: 'admin',
          session: self,
          txn_num: txn_num,
          write_concern: write_concern,
        }
        Operation::Command.new(spec).execute_with_connection(connection, context: context)
      end
    end
  ensure
    @state = TRANSACTION_COMMITTED_STATE
    @committing_transaction = false
  end

  # No official return value, but return true so that in interactive
  # use the method hints that it succeeded.
  true
end

#committing_transaction? ⇒ true | false

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns Whether the session is currently committing a transaction.

Returns:

  • (true | false) —

    Whether the session is currently committing a transaction.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 811

def committing_transaction?
  !!@committing_transaction
end

#dirty!(mark = true) ⇒ Object

Sets the dirty state to the given value for the underlying server session. If there is no server session, this does nothing.

Parameters:

  • mark (true | false) (defaults to: true) —

    whether to mark the server session as dirty, or not.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 138

def dirty!(mark = true)
  @server_session&.dirty!(mark)
end

#dirty? ⇒ true | false | nil

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns whether the underlying server session is dirty. If no server session exists for this session, returns nil.

Returns:

  • (true | false | nil) —

    whether the underlying server session is dirty. If no server session exists for this session, returns nil.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 146

def dirty?
  @server_session&.dirty?
end

#end_session ⇒ nil

End this session.

If there is an in-progress transaction on this session, the transaction is aborted. The server session associated with this session is returned to the server session pool. Finally, this session is marked ended and is no longer usable.

If this session is already ended, this method does nothing.

Note that this method does not directly issue an endSessions command to this server, contrary to what its name might suggest.

Examples:

session.end_session

Returns:

  • (nil) —

    Always nil.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 377

def end_session
  if !ended? && @client
    if within_states?(TRANSACTION_IN_PROGRESS_STATE)
      begin
        abort_transaction
      rescue Mongo::Error, Error::AuthError
      end
    end
    if @server_session
      @client.cluster.session_pool.checkin(@server_session)
    end
  end
ensure
  @server_session = nil
  @ended = true
end

#ended? ⇒ true, false

Whether this session has ended.

Examples:

session.ended?

Returns:

  • (true, false) —

    Whether the session has ended.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 243

def ended?
  !!@ended
end

#explicit? ⇒ true, false

Is this session an explicit one (i.e. user-created).

Examples:

Is the session explicit?

session.explicit?

Returns:

  • (true, false) —

    Whether this session is explicit.

Since:

  • 2.5.2



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# File 'lib/mongo/session.rb', line 178

def explicit?
  !implicit?
end

#implicit? ⇒ true, false

Is this session an implicit one (not user-created).

Examples:

Is the session implicit?

session.implicit?

Returns:

  • (true, false) —

    Whether this session is implicit.

Since:

  • 2.5.1



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# File 'lib/mongo/session.rb', line 166

def implicit?
  @implicit ||= !!(@options.key?(:implicit) && @options[:implicit] == true)
end

#in_transaction? ⇒ true | false

Whether or not the session is currently in a transaction.

Examples:

Is the session in a transaction?

session.in_transaction?

Returns:

  • (true | false) —

    Whether or not the session in a transaction.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 803

def in_transaction?
  within_states?(STARTING_TRANSACTION_STATE, TRANSACTION_IN_PROGRESS_STATE)
end

#inspect ⇒ String

Get a formatted string for use in inspection.

Examples:

Inspect the session object.

session.inspect

Returns:

  • (String) —

    The session inspection.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 355

def inspect
  "#<Mongo::Session:0x#{object_id} session_id=#{session_id} options=#{@options}>"
end

#materialize_if_needed ⇒ Session

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

If not already set, populate a session objects’s server_session by checking out a session from the session pool.

Returns:

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1137

def materialize_if_needed
  if ended?
    raise Error::SessionEnded
  end

  return unless implicit? && !@server_session

  @server_session = cluster.session_pool.checkout

  self
end

#materialized? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean)

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1150

def materialized?
  if ended?
    raise Error::SessionEnded
  end

  !@server_session.nil?
end

#next_txn_num ⇒ Integer

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Increment and return the next transaction number.

Examples:

Get the next transaction number.

session.next_txn_num

Returns:

  • (Integer) —

    The next transaction number.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1167

def next_txn_num
  if ended?
    raise Error::SessionEnded
  end

  @server_session.next_txn_num
end

#pin_to_connection(connection_global_id) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Pins this session to the specified connection.

this session to.

Parameters:

  • connection_global_id (Integer) —

    The global id of connection to pin

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 846

def pin_to_connection(connection_global_id)
  if connection_global_id.nil?
    raise ArgumentError, 'Cannot pin to a nil connection id'
  end
  @pinned_connection_global_id = connection_global_id
end

#pin_to_server(server) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Pins this session to the specified server, which should be a mongos.

Parameters:

  • server (Server) —

    The server to pin this session to.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 828

def pin_to_server(server)
  if server.nil?
    raise ArgumentError, 'Cannot pin to a nil server'
  end
  if Lint.enabled?
    unless server.mongos?
      raise Error::LintError, "Attempted to pin the session to server #{server.summary} which is not a mongos"
    end
  end
  @pinned_server = server
end

#process(result) ⇒ Operation::Result

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Process a response from the server that used this session.

Examples:

Process a response from the server.

session.process(result)

Parameters:

Returns:

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1095

def process(result)
  unless implicit?
    set_operation_time(result)
    if cluster_time_doc = result.cluster_time
      advance_cluster_time(cluster_time_doc)
    end
  end
  @server_session.set_last_use!

  if doc = result.reply && result.reply.documents.first
    if doc[:recoveryToken]
      self.recovery_token = doc[:recoveryToken]
    end
  end

  result
end

#retry_reads? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Whether reads executed with this session can be retried according to the modern retryable reads specification.

If this method returns true, the modern retryable reads have been requested by the application. If the server selected for a read operation supports modern retryable reads, they will be used for that particular operation. If the server selected for a read operation does not support modern retryable reads, the read will not be retried.

If this method returns false, legacy retryable reads have been requested by the application. Legacy retryable read logic will be used regardless of server version of the server(s) that the client is connected to. The number of read retries is given by :max_read_retries client option, which is 1 by default and can be set to 0 to disable legacy read retries.

Returns:

  • (Boolean)

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 198

def retry_reads?
  client.options[:retry_reads] != false
end

#retry_writes? ⇒ true, false

Note:

Retryable writes are only available on server versions at least 3.6 and with sharded clusters, replica sets, or load-balanced topologies.

Will writes executed with this session be retried.

Examples:

Will writes be retried.

session.retry_writes?

Returns:

  • (true, false) —

    If writes will be retried.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 213

def retry_writes?
  !!client.options[:retry_writes] && (cluster.replica_set? || cluster.sharded? || cluster.load_balanced?)
end

#session_id ⇒ BSON::Document

Get the server session id of this session, if the session has not been ended. If the session had been ended, raises Error::SessionEnded.

Returns:

  • (BSON::Document) —

    The server session id.

Raises:

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 255

def session_id
  if ended?
    raise Error::SessionEnded
  end

  # An explicit session will always have a session_id, because during
  # construction a server session must be provided. An implicit session
  # will not have a session_id until materialized, thus calls to
  # session_id might fail. An application should not have an opportunity
  # to experience this failure because an implicit session shouldn't be
  # accessible to applications due to its lifetime being constrained to
  # operation execution, which is done entirely by the driver.
  unless materialized?
    raise Error::SessionNotMaterialized
  end

  @server_session.session_id
end

#snapshot? ⇒ true | false

Returns Whether the session is configured for snapshot reads.

Returns:

  • (true | false) —

    Whether the session is configured for snapshot reads.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 124

def snapshot?
  !!options[:snapshot]
end

#start_transaction(options = nil) ⇒ Object

Places subsequent operations in this session into a new transaction.

Note that the transaction will not be started on the server until an operation is performed after start_transaction is called.

Examples:

Start a new transaction

session.start_transaction(options)

Parameters:

  • options (Hash) (defaults to: nil) —

    The options for the transaction being started.

Options Hash (options):

  • :max_commit_time_ms (Integer) —

    The maximum amount of time to allow a single commitTransaction command to run, in milliseconds. This options is deprecated, use :timeout_ms instead.

  • :read_concern (Hash) —

    The read concern options hash, with the following optional keys:

    • :level – the read preference level as a symbol; valid values

      are *:local*, *:majority*, and *:snapshot*
  • :write_concern (Hash) —

    The write concern options. Can be :w => Integer|String, :fsync => Boolean, :j => Boolean.

  • :read (Hash) —

    The read preference options. The hash may have the following items:

    • :mode – read preference specified as a symbol; the only valid value is :primary.

  • :timeout_ms (Integer) —

    The operation timeout in milliseconds. Must be a non-negative integer. An explicit value of 0 means infinite. The default value is unset which means the value is inherited from the client.

Raises:

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 583

def start_transaction(options = nil)
  check_transactions_supported!

  if options
    Lint.validate_read_concern_option(options[:read_concern])

=begin
    # It would be handy to detect invalid read preferences here, but
    # some of the spec tests require later detection of invalid read prefs.
    # Maybe we can do this when lint mode is on.
    mode = options[:read] && options[:read][:mode].to_s
    if mode && mode != 'primary'
      raise Mongo::Error::InvalidTransactionOperation.new(
        "read preference in a transaction must be primary (requested: #{mode})"
      )
    end
=end
  end

  if snapshot?
    raise Mongo::Error::SnapshotSessionTransactionProhibited
  end

  check_if_ended!

  if within_states?(STARTING_TRANSACTION_STATE, TRANSACTION_IN_PROGRESS_STATE)
    raise Mongo::Error::InvalidTransactionOperation.new(
      Mongo::Error::InvalidTransactionOperation::TRANSACTION_ALREADY_IN_PROGRESS)
  end

  unpin

  next_txn_num
  @txn_options = (@options[:default_transaction_options] || {}).merge(options || {})

  if txn_write_concern && !WriteConcern.get(txn_write_concern).acknowledged?
    raise Mongo::Error::InvalidTransactionOperation.new(
      Mongo::Error::InvalidTransactionOperation::UNACKNOWLEDGED_WRITE_CONCERN)
  end

  @state = STARTING_TRANSACTION_STATE
  @already_committed = false

  # This method has no explicit return value.
  # We could return nil here but true indicates to the user that the
  # operation succeeded. This is intended for interactive use.
  # Note that the return value is not documented.
  true
end

#starting_transaction? ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Returns:

  • (Boolean)

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 791

def starting_transaction?
  within_states?(STARTING_TRANSACTION_STATE)
end

#suppress_read_write_concern!(command) ⇒ Hash, BSON::Document

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Remove the read concern and/or write concern from the command if not applicable.

Examples:

session.suppress_read_write_concern!(cmd)

Returns:

  • (Hash, BSON::Document) —

    The command document.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 1020

def suppress_read_write_concern!(command)
  command.tap do |c|
    next unless in_transaction?

    c.delete(:readConcern) unless starting_transaction?
    c.delete(:writeConcern) unless c[:commitTransaction] || c[:abortTransaction]
  end
end

#txn_num ⇒ Integer

Get the current transaction number.

Examples:

Get the current transaction number.

session.txn_num

Returns:

  • (Integer) —

    The current transaction number.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 1183

def txn_num
  if ended?
    raise Error::SessionEnded
  end

  @server_session.txn_num
end

#txn_options ⇒ Hash

on this session.

Returns:

  • (Hash) —

    The options for the transaction currently being executed

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 154

def txn_options
  @txn_options or raise ArgumentError, "There is no active transaction"
end

#txn_read_preference ⇒ Hash

Get the read preference the session will use in the currently active transaction.

This is a driver style hash with underscore keys.

Examples:

Get the transaction’s read preference

session.txn_read_preference

Returns:

  • (Hash) —

    The read preference of the transaction.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 228

def txn_read_preference
  rp = txn_options[:read] ||
    @client.read_preference
  Mongo::Lint.validate_underscore_read_preference(rp)
  rp
end

#unpin(connection = nil) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Unpins this session from the pinned server or connection, if the session was pinned.

Parameters:

  • connection (Connection | nil) (defaults to: nil) —

    Connection to unpin from.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 859

def unpin(connection = nil)
  @pinned_server = nil
  @pinned_connection_global_id = nil
  connection.unpin unless connection.nil?
end

#unpin_maybe(error, connection = nil) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Unpins this session from the pinned server or connection, if the session was pinned and the specified exception instance and the session’s transaction state require it to be unpinned.

The exception instance should already have all of the labels set on it (both client- and server-side generated ones).

Parameters:

  • error (Error) —

    The exception instance to process.

  • connection (Connection | nil) (defaults to: nil) —

    Connection to unpin from.

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 876

def unpin_maybe(error, connection = nil)
  if !within_states?(Session::NO_TRANSACTION_STATE) &&
    error.label?('TransientTransactionError')
  then
    unpin(connection)
  end

  if committing_transaction? &&
    error.label?('UnknownTransactionCommitResult')
  then
    unpin(connection)
  end
end

#update_state! ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Update the state of the session due to a (non-commit and non-abort) operation being run.

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 1056

def update_state!
  case @state
  when STARTING_TRANSACTION_STATE
    @state = TRANSACTION_IN_PROGRESS_STATE
  when TRANSACTION_COMMITTED_STATE, TRANSACTION_ABORTED_STATE
    @state = NO_TRANSACTION_STATE
  end
end

#validate!(client) ⇒ Session

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Validate the session for use by the specified client.

The session must not be ended and must have been created by a client with the same cluster as the client that the session is to be used with.

Parameters:

  • client (Client) —

    The client the session is to be used with.

Returns:

  • (Session) —

    self, if the session is valid.

Raises:

Since:

  • 2.5.0



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# File 'lib/mongo/session.rb', line 1078

def validate!(client)
  check_matching_cluster!(client)
  check_if_ended!
  self
end

#validate_read_preference!(command) ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Ensure that the read preference of a command primary.

Examples:

session.validate_read_preference!(command)

Raises:

Since:

  • 2.6.0



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# File 'lib/mongo/session.rb', line 1039

def validate_read_preference!(command)
  return unless in_transaction?
  return unless command['$readPreference']

  mode = command['$readPreference']['mode'] || command['$readPreference'][:mode]

  if mode && mode != 'primary'
    raise Mongo::Error::InvalidTransactionOperation.new(
      "read preference in a transaction must be primary (requested: #{mode})"
    )
  end
end

#with_transaction(options = nil) ⇒ Object

Note:

with_transaction contains a loop, therefore the if with_transaction itself is placed in a loop, its block should not call next or break to control the outer loop because this will instead affect the loop in with_transaction. The driver will warn and abort the transaction if it detects this situation.

Executes the provided block in a transaction, retrying as necessary.

Returns the return value of the block.

Exact number of retries and when they are performed are implementation details of the driver; the provided block should be idempotent, and should be prepared to be called more than once. The driver may retry the commit command within an active transaction or it may repeat the transaction and invoke the block again, depending on the error encountered if any. Note also that the retries may be executed against different servers.

Transactions cannot be nested - InvalidTransactionOperation will be raised if this method is called when the session already has an active transaction.

Exceptions raised by the block which are not derived from Mongo::Error stop processing, abort the transaction and are propagated out of with_transaction. Exceptions derived from Mongo::Error may be handled by with_transaction, resulting in retries of the process.

Currently, with_transaction will retry commits and block invocations until at least 120 seconds have passed since with_transaction started executing. This timeout is not configurable and may change in a future driver version.

Examples:

Execute a statement in a transaction

session.with_transaction(write_concern: {w: :majority}) do
  collection.update_one({ id: 3 }, { '$set' => { status: 'Inactive'} },
                        session: session)

end

Execute a statement in a transaction, limiting total time consumed

Timeout.timeout(5) do
  session.with_transaction(write_concern: {w: :majority}) do
    collection.update_one({ id: 3 }, { '$set' => { status: 'Inactive'} },
                          session: session)

  end
end

Parameters:

  • options (Hash) (defaults to: nil) —

    The options for the transaction being started. These are the same options that start_transaction accepts.

Raises:

Since:

  • 2.7.0



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# File 'lib/mongo/session.rb', line 448

def with_transaction(options = nil)
  if timeout_ms = (options || {})[:timeout_ms]
    timeout_sec = timeout_ms / 1_000.0
    deadline = Utils.monotonic_time + timeout_sec
    @with_transaction_deadline = deadline
  elsif default_timeout_ms = @options[:default_timeout_ms]
    timeout_sec = default_timeout_ms / 1_000.0
    deadline = Utils.monotonic_time + timeout_sec
    @with_transaction_deadline = deadline
  elsif @client.timeout_sec
    deadline = Utils.monotonic_time + @client.timeout_sec
    @with_transaction_deadline = deadline
  else
    deadline = Utils.monotonic_time + 120
  end
  transaction_in_progress = false
  loop do
    commit_options = {}
    if options
      commit_options[:write_concern] = options[:write_concern]
    end
    start_transaction(options)
    transaction_in_progress = true
    begin
      rv = yield self
    rescue Exception => e
      if within_states?(STARTING_TRANSACTION_STATE, TRANSACTION_IN_PROGRESS_STATE)
        log_warn("Aborting transaction due to #{e.class}: #{e}")
        @with_transaction_deadline = nil
        abort_transaction
        transaction_in_progress = false
      end

      if Utils.monotonic_time >= deadline
        transaction_in_progress = false
        raise
      end

      if e.is_a?(Mongo::Error) && e.label?('TransientTransactionError')
        next
      end

      raise
    else
      if within_states?(TRANSACTION_ABORTED_STATE, NO_TRANSACTION_STATE, TRANSACTION_COMMITTED_STATE)
        transaction_in_progress = false
        return rv
      end

      begin
        commit_transaction(commit_options)
        transaction_in_progress = false
        return rv
      rescue Mongo::Error => e
        if e.label?('UnknownTransactionCommitResult')
          if Utils.monotonic_time >= deadline ||
            e.is_a?(Error::OperationFailure::Family) && e.max_time_ms_expired?
          then
            transaction_in_progress = false
            raise
          end
          wc_options = case v = commit_options[:write_concern]
            when WriteConcern::Base
              v.options
            when nil
              {}
            else
              v
            end
          commit_options[:write_concern] = wc_options.merge(w: :majority)
          retry
        elsif e.label?('TransientTransactionError')
          if Utils.monotonic_time >= deadline
            transaction_in_progress = false
            raise
          end
          @state = NO_TRANSACTION_STATE
          next
        else
          transaction_in_progress = false
          raise
        end
      rescue Error::AuthError
        transaction_in_progress = false
        raise
      end
    end
  end

  # No official return value, but return true so that in interactive
  # use the method hints that it succeeded.
  true
ensure
  if transaction_in_progress
    log_warn('with_transaction callback broke out of with_transaction loop, aborting transaction')
    begin
      abort_transaction
    rescue Error::OperationFailure::Family, Error::InvalidTransactionOperation
    end
  end
  @with_transaction_deadline = nil
end