Module: Mongo::Operation::SessionsSupported Private

Do not use. This module is for internal use only.

Relationships & Source Files
Extension / Inclusion / Inheritance Descendants
Included In: `Aggregate::OpMsg`, `Command::OpMsg`, `Count::OpMsg`, `Create::OpMsg`, `CreateIndex::OpMsg`, `CreateSearchIndexes::OpMsg`, `CreateUser::OpMsg`, `Delete::OpMsg`, `Distinct::OpMsg`, `Drop::OpMsg`, `DropDatabase::OpMsg`, `DropIndex::OpMsg`, `DropSearchIndex::OpMsg`, `Explain::OpMsg`, `Find::OpMsg`, `GetMore::OpMsg`, `Indexes::OpMsg`, `Insert::OpMsg`, `KillCursors::OpMsg`, `ListCollections::OpMsg`, `MapReduce::OpMsg`, `OpMsgBase`, `ParallelScan::OpMsg`, `RemoveUser::OpMsg`, `Update::OpMsg`, `UpdateSearchIndex::OpMsg`, `UpdateUser::OpMsg`, `UsersInfo::OpMsg`, `WriteCommand::OpMsg`
Defined in:	lib/mongo/operation/shared/sessions_supported.rb

Overview

Shared behavior of operations that support a session.

Since:

2.5.2

Constant Summary

READ_COMMANDS =

Since:

2.5.2

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 28

%i[
  aggregate
  count
  dbStats
  distinct
  find
  geoNear
  geoSearch
  group
  mapReduce
  parallelCollectionScan
].freeze

ZERO_TIMESTAMP =
Since:
- 2.5.2
# File 'lib/mongo/operation/shared/sessions_supported.rb', line 26
```
BSON::Timestamp.new(0, 0)
```

Instance Method Summary

#add_read_preference(sel, connection) private Internal use only

Adds $readPreference field to the command document.
#add_write_concern!(sel) private Internal use only
#apply_autocommit!(selector) private Internal use only
#apply_causal_consistency!(selector, connection) private Internal use only

Adds causal consistency document to the selector, if one can be constructed and the selector is for a startTransaction command.
#apply_causal_consistency_if_possible(selector, connection) private Internal use only

Adds causal consistency document to the selector, if one can be constructed.
#apply_cluster_time!(selector, connection) private Internal use only
#apply_read_pref!(selector) private Internal use only
#apply_session_options(sel, connection) private Internal use only
#apply_start_transaction!(selector) private Internal use only
#apply_txn_num!(selector) private Internal use only
#apply_txn_opts!(selector) private Internal use only
#build_message(connection, context) private Internal use only
#command(connection) private Internal use only
#flags private Internal use only
#read_command?(sel) ⇒ Boolean private Internal use only
#suppress_read_write_concern!(selector) private Internal use only
#validate_read_preference!(selector) private Internal use only

Instance Method Details

#add_read_preference(sel, connection) (private)

Adds $readPreference field to the command document.

$readPreference is only sent when the server is a mongos, following the rules described in github.com/mongodb/specifications/blob/master/source/server-selection/server-selection.md#passing-read-preference-to-mongos. The topology does not matter for figuring out whether to send $readPreference since the decision is always made based on server type.

$readPreference is sent to OP_MSG-grokking replica set members.

Parameters:

sel (Hash) —

Existing command document which will be mutated.
connection (Server::Connection) —

The connection that the operation will be executed on.

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 161


def add_read_preference(sel, connection)
  Lint.assert_type(connection, Server::Connection)

  # https://github.com/mongodb/specifications/blob/master/source/server-selection/server-selection.md#topology-type-single
  read_doc = if connection.description.standalone?
               # Read preference is never sent to standalones.
               nil
             elsif connection.server.load_balancer?
               read&.to_mongos
             elsif connection.description.mongos?
               # When server is a mongos:
               # - $readPreference is never sent when mode is 'primary'
               # - Otherwise $readPreference is sent
               # When mode is 'secondaryPreferred' $readPreference is currently
               # required to only be sent when a non-mode field (i.e. tag_sets)
               # is present, but this causes wrong behavior (DRIVERS-1642).
               read&.to_mongos
             elsif connection.server.cluster.single?
               # In Single topology:
               # - If no read preference is specified by the application, the driver
               #   adds mode: primaryPreferred.
               # - If a read preference is specified by the application, the driver
               #   replaces the mode with primaryPreferred.
               read_doc = if read
                            BSON::Document.new(read.to_doc)
                          else
                            BSON::Document.new
                          end
               read_doc['mode'] = 'primaryPreferred' if [ nil, 'primary' ].include?(read_doc['mode'])
               read_doc
             else
               # In replica sets, read preference is passed to the server if one
               # is specified by the application, except for primary read preferences.
               read_doc = BSON::Document.new(read&.to_doc || {})
               if [ nil, 'primary' ].include?(read_doc['mode'])
                 nil
               else
                 read_doc
               end
             end

  return unless read_doc

  sel['$readPreference'] = read_doc
end

#add_write_concern!(sel) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 94


def add_write_concern!(sel)
  sel[:writeConcern] = write_concern.options if write_concern
end

#apply_autocommit!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 98


def apply_autocommit!(selector)
  session.add_autocommit!(selector)
end

#apply_causal_consistency!(selector, connection) (private)

Adds causal consistency document to the selector, if one can be constructed and the selector is for a startTransaction command.

When operations are performed in a transaction, only the first operation (the one which starts the transaction via startTransaction) is allowed to have a read concern, and with it the causal consistency document, specified.

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 48


def apply_causal_consistency!(selector, connection)
  return unless selector[:startTransaction]

  apply_causal_consistency_if_possible(selector, connection)
end

#apply_causal_consistency_if_possible(selector, connection) (private)

Adds causal consistency document to the selector, if one can be constructed.

In order for the causal consistency document to be constructed, causal consistency must be enabled for the session and the session must have the current operation time. Also, topology must be replica set or sharded cluster.

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 61


def apply_causal_consistency_if_possible(selector, connection)
  return if connection.description.standalone?

  cc_doc = session.send(:causal_consistency_doc)
  return unless cc_doc

  rc_doc = (selector[:readConcern] || read_concern || {}).merge(cc_doc)
  selector[:readConcern] = Options::Mapper.transform_values_to_strings(
    rc_doc
  )
end

#apply_cluster_time!(selector, connection) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 77


def apply_cluster_time!(selector, connection)
  return if connection.description.standalone?

  cluster_time = [
    connection.cluster_time,
    session&.cluster_time,
  ].compact.max

  return unless cluster_time

  selector['$clusterTime'] = cluster_time
end

#apply_read_pref!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 110


def apply_read_pref!(selector)
  session.apply_read_pref!(selector) if read_command?(selector)
end

#apply_session_options(sel, connection) (private)

Raises:

(Error::SnapshotSessionInvalidServerVersion)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 207


def apply_session_options(sel, connection)
  apply_cluster_time!(sel, connection)
  sel[:txnNumber] = BSON::Int64.new(txn_num) if txn_num
  sel.merge!(lsid: session.session_id)
  apply_start_transaction!(sel)
  apply_causal_consistency!(sel, connection)
  apply_autocommit!(sel)
  apply_txn_opts!(sel)
  suppress_read_write_concern!(sel)
  validate_read_preference!(sel)
  apply_txn_num!(sel)
  if session.recovery_token &&
     (sel[:commitTransaction] || sel[:abortTransaction])
    sel[:recoveryToken] = session.recovery_token
  end

  return unless session.snapshot?
  raise Error::SnapshotSessionInvalidServerVersion unless connection.description.server_version_gte?('5.0')

  sel[:readConcern] = { level: 'snapshot' }
  return unless session.snapshot_timestamp

  sel[:readConcern][:atClusterTime] = session.snapshot_timestamp
end

#apply_start_transaction!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 102


def apply_start_transaction!(selector)
  session.add_start_transaction!(selector)
end

#apply_txn_num!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 106


def apply_txn_num!(selector)
  session.add_txn_num!(selector)
end

#apply_txn_opts!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 114


def apply_txn_opts!(selector)
  session.add_txn_opts!(selector, read_command?(selector), context)
end

#build_message(connection, context) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 232


def build_message(connection, context)
  if session != context.session
    if session
      raise Error::InternalDriverError,
            "Operation session #{session.inspect} does not match context session #{context.session.inspect}"
    else
      # Some operations are not constructed with sessions but are
      # executed in a context where a session is available.
      # This could be OK or a driver issue.
      # TODO investigate.
    end
  end

  super.tap do |message|
    if session = context.session
      # Serialize the message to detect client-side problems,
      # such as invalid BSON keys or too large messages.
      # The message will be serialized again
      # later prior to being sent to the connection.
      buf = BSON::ByteBuffer.new
      message.serialize(buf)
      raise Error::MaxMessageSize.new(connection.max_message_size) if buf.length > connection.max_message_size

      session.update_state!
    end
  end
end

#command(connection) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 126


def command(connection)
  if Lint.enabled? && !connection.is_a?(Server::Connection)
    raise Error::LintError, "Connection is not a Connection instance: #{connection}"
  end

  sel = BSON::Document.new(selector(connection))
  add_write_concern!(sel)
  sel[Protocol::Msg::DATABASE_IDENTIFIER] = db_name

  add_read_preference(sel, connection)

  if connection.description.logical_session_timeout
    apply_cluster_time!(sel, connection)
    apply_session_options(sel, connection) if session && (acknowledged_write? || session.in_transaction?)
  elsif session && session.explicit?
    apply_session_options(sel, connection)
  end

  sel
end

#flags (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 73


def flags
  acknowledged_write? ? [] : [ :more_to_come ]
end

#read_command?(sel) ⇒ `Boolean` (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 90


def read_command?(sel)
  READ_COMMANDS.any? { |c| sel[c] }
end

#suppress_read_write_concern!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 118


def suppress_read_write_concern!(selector)
  session.suppress_read_write_concern!(selector)
end

#validate_read_preference!(selector) (private)

Since:

2.5.2

[ GitHub ]

# File 'lib/mongo/operation/shared/sessions_supported.rb', line 122


def validate_read_preference!(selector)
  session.validate_read_preference!(selector) if read_command?(selector)
end

Module: Mongo::Operation::SessionsSupported Private

Overview

Constant Summary

Instance Method Summary

Instance Method Details

#add_read_preference(sel, connection) (private)

#add_write_concern!(sel) (private)

#apply_autocommit!(selector) (private)

#apply_causal_consistency!(selector, connection) (private)

#apply_causal_consistency_if_possible(selector, connection) (private)

#apply_cluster_time!(selector, connection) (private)

#apply_read_pref!(selector) (private)

#apply_session_options(sel, connection) (private)

#apply_start_transaction!(selector) (private)

#apply_txn_num!(selector) (private)

#apply_txn_opts!(selector) (private)

#build_message(connection, context) (private)

#command(connection) (private)

#flags (private)

#read_command?(sel) ⇒ Boolean (private)

#suppress_read_write_concern!(selector) (private)

#validate_read_preference!(selector) (private)

#read_command?(sel) ⇒ `Boolean` (private)