Class: Mongo::Cluster

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
Event::Subscriber, Loggable, Monitoring::Publishable
Defined in:
lib/mongo/cluster.rb,
lib/mongo/cluster/topology.rb,
lib/mongo/cluster/topology.rb,
lib/mongo/cluster/sdam_flow.rb,
lib/mongo/cluster/topology/base.rb,
lib/mongo/cluster/topology/single.rb,
lib/mongo/cluster/topology/sharded.rb,
lib/mongo/cluster/topology/unknown.rb,
lib/mongo/cluster/periodic_executor.rb,
lib/mongo/cluster/reapers/cursor_reaper.rb,
lib/mongo/cluster/reapers/socket_reaper.rb,
lib/mongo/cluster/topology/no_replica_set_options.rb,
lib/mongo/cluster/topology/replica_set_no_primary.rb,
lib/mongo/cluster/topology/replica_set_with_primary.rb

Overview

Copyright (C) 2018-2019 MongoDB, Inc.

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.

Defined Under Namespace

Modules: Topology Classes: CursorReaper, PeriodicExecutor, SdamFlow, SocketReaper

Constant Summary collapse

MAX_READ_RETRIES =

The default number of mongos read retries.

Since:

  • 2.1.1

1
MAX_WRITE_RETRIES =

The default number of mongos write retries.

Since:

  • 2.4.2

1
READ_RETRY_INTERVAL =

The default mongos read retry interval, in seconds.

Since:

  • 2.1.1

5
IDLE_WRITE_PERIOD_SECONDS =

How often an idle primary writes a no-op to the oplog.

Since:

  • 2.4.0

10
CLUSTER_TIME =

The cluster time key in responses from mongos servers.

Since:

  • 2.5.0

'clusterTime'.freeze

Constants included from Loggable

Loggable::PREFIX

Instance Attribute Summary collapse

Attributes included from Event::Subscriber

#event_listeners

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Loggable

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

Methods included from Event::Subscriber

#subscribe_to

Methods included from Monitoring::Publishable

#publish_event, #publish_sdam_event

Constructor Details

#initialize(seeds, monitoring, options = Options::Redacted.new) ⇒ Cluster

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:

Cluster should never be directly instantiated outside of a Client.

Note:

When connecting to a mongodb+srv:// URI, the client expands such a URI into a list of servers and passes that list to the Cluster constructor. When connecting to a standalone mongod, the Cluster constructor receives the corresponding address as an array of one string.

Instantiate the new cluster.

Examples:

Instantiate the cluster.

Mongo::Cluster.new(["127.0.0.1:27017"], monitoring)

Parameters:

  • seeds (Array<String>)

    The addresses of the configured servers

  • monitoring (Monitoring)

    The monitoring.

  • options (Hash) (defaults to: Options::Redacted.new)

    Options. Client constructor forwards its options to Cluster constructor, although Cluster recognizes only a subset of the options recognized by Client.

Options Hash (options):

  • :scan (true, false)

    Whether to scan all seeds in constructor. The default in driver version 2.x is to do so; driver version 3.x will not scan seeds in constructor. Opt in to the new behavior by setting this option to false. Note: setting this option to nil enables scanning seeds in constructor in driver version 2.x. Driver version 3.x will recognize this option but will ignore it and will never scan seeds in the constructor.

  • :monitoring_io (true, false)

    For internal driver use only. Set to false to prevent SDAM-related I/O from being done by this cluster or servers under it. Note: setting this option to false will make the cluster non-functional. It is intended for use in tests which manually invoke SDAM state transitions.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 90

def initialize(seeds, monitoring, options = Options::Redacted.new)
  if options[:monitoring_io] != false && !options[:server_selection_semaphore]
    raise ArgumentError, 'Need server selection semaphore'
  end

  @servers = []
  @monitoring = monitoring
  @event_listeners = Event::Listeners.new
  @options = options.freeze
  @app_metadata = Server::AppMetadata.new(@options)
  @update_lock = Mutex.new
  @sdam_flow_lock = Mutex.new
  @cluster_time = nil
  @cluster_time_lock = Mutex.new
  @topology = Topology.initial(self, monitoring, options)
  Session::SessionPool.create(self)

  # The opening topology is always unknown with no servers.
  # https://github.com/mongodb/specifications/pull/388
  opening_topology = Topology::Unknown.new(options, monitoring, self)

  publish_sdam_event(
    Monitoring::TOPOLOGY_OPENING,
    Monitoring::Event::TopologyOpening.new(opening_topology)
  )

  subscribe_to(Event::DESCRIPTION_CHANGED, Event::DescriptionChanged.new(self))

  @seeds = seeds
  servers = seeds.map do |seed|
    # Server opening events must be sent after topology change events.
    # Therefore separate server addition, done here before topoolgy change
    # event is published, from starting to monitor the server which is
    # done later.
    add(seed, monitor: false)
  end

  if seeds.size >= 1
    # Recreate the topology to get the current server list into it
    @topology = topology.class.new(topology.options, topology.monitoring, self)
    publish_sdam_event(
      Monitoring::TOPOLOGY_CHANGED,
      Monitoring::Event::TopologyChanged.new(opening_topology, @topology)
    )
  end

  servers.each do |server|
    server.start_monitoring
  end

  if options[:monitoring_io] == false
    # Omit periodic executor construction, because without servers
    # no commands can be sent to the cluster and there shouldn't ever
    # be anything that needs to be cleaned up.
    #
    # Also omit legacy single round of SDAM on the main thread,
    # as it would race with tests that mock SDAM responses.
    return
  end

  @cursor_reaper = CursorReaper.new
  @socket_reaper = SocketReaper.new(self)
  @periodic_executor = PeriodicExecutor.new(@cursor_reaper, @socket_reaper)
  @periodic_executor.run!

  ObjectSpace.define_finalizer(self, self.class.finalize({}, @periodic_executor, @session_pool))

  @connecting = false
  @connected = true

  if options[:scan] != false
    server_selection_timeout = options[:server_selection_timeout] || ServerSelector::SERVER_SELECTION_TIMEOUT
    # The server selection timeout can be very short especially in
    # tests, when the client waits for a synchronous scan before
    # starting server selection. Limiting the scan to server selection time
    # then aborts the scan before it can process even local servers.
    # Therefore, allow at least 3 seconds for the scan here.
    if server_selection_timeout < 3
      server_selection_timeout = 3
    end
    start_time = Time.now
    deadline = start_time + server_selection_timeout
    # Wait for the first scan of each server to complete, for
    # backwards compatibility.
    # If any servers are discovered during this SDAM round we are going to
    # wait for these servers to also be queried, and so on, up to the
    # server selection timeout or the 3 second minimum.
    loop do
      servers = servers_list.dup
      if servers.all? { |server| server.description.last_update_time >= start_time }
        break
      end
      if (time_remaining = deadline - Time.now) <= 0
        break
      end
      options[:server_selection_semaphore].wait(time_remaining)
    end
  end
end

Instance Attribute Details

#app_metadataMongo::Server::AppMetadata (readonly)

Returns The application metadata, used for connection handshakes.

Returns:

Since:

  • 2.4.0



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# File 'lib/mongo/cluster.rb', line 225

def 
  @app_metadata
end

#cluster_timeBSON::Document (readonly)

Returns The latest cluster time seen.

Returns:

  • (BSON::Document)

    The latest cluster time seen.

Since:

  • 2.5.0



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# File 'lib/mongo/cluster.rb', line 230

def cluster_time
  @cluster_time
end

#monitoringMonitoring (readonly)

Returns monitoring The monitoring.

Returns:

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 216

def monitoring
  @monitoring
end

#optionsHash (readonly)

Returns The options hash.

Returns:

  • (Hash)

    The options hash.

Since:

  • 2.0.0



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

def options
  @options
end

#sdam_flow_lockObject (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.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 631

def sdam_flow_lock
  @sdam_flow_lock
end

#seedsArray<String> (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 addresses of seed servers. Contains addresses that were given to Cluster when it was instantiated, not current addresses that the cluster is using as a result of SDAM.

Returns:

  • (Array<String>)

    The addresses of seed servers. Contains addresses that were given to Cluster when it was instantiated, not current addresses that the cluster is using as a result of SDAM.

Since:

  • 2.7.0



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# File 'lib/mongo/cluster.rb', line 238

def seeds
  @seeds
end

#session_poolObject (readonly)

Since:

  • 2.5.1



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

def session_pool
  @session_pool
end

#topologyInteger? (readonly)

The logical session timeout value in minutes.

Examples:

Get the logical session timeout in minutes.

cluster.logical_session_timeout

Returns:

  • (Integer, nil)

    The logical session timeout.

Since:

  • 2.5.0



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# File 'lib/mongo/cluster.rb', line 219

def topology
  @topology
end

Class Method Details

.create(client) ⇒ Cluster

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.

Create a cluster for the provided client, for use when we don't want the client's original cluster instance to be the same.

Examples:

Create a cluster for the client.

Cluster.create(client)

Parameters:

  • client (Client)

    The client to create on.

Returns:

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 203

def self.create(client)
  cluster = Cluster.new(
    client.cluster.addresses.map(&:to_s),
    Monitoring.new,
    client.cluster_options,
  )
  client.instance_variable_set(:@cluster, cluster)
end

.finalize(pools, periodic_executor, session_pool) ⇒ Proc

Finalize the cluster for garbage collection.

Examples:

Finalize the cluster.

Cluster.finalize(pools)

Parameters:

Returns:

  • (Proc)

    The Finalizer.

Since:

  • 2.2.0



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# File 'lib/mongo/cluster.rb', line 359

def self.finalize(pools, periodic_executor, session_pool)
  proc do
    session_pool.end_sessions
    periodic_executor.stop!
  end
end

Instance Method Details

#==(other) ⇒ true, false

Determine if this cluster of servers is equal to another object. Checks the servers currently in the cluster, not what was configured.

Examples:

Is the cluster equal to the object?

cluster == other

Parameters:

  • other (Object)

    The object to compare to.

Returns:

  • (true, false)

    If the objects are equal.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 471

def ==(other)
  return false unless other.is_a?(Cluster)
  addresses == other.addresses &&
    options.merge(server_selection_semaphore: nil) ==
      other.options.merge(server_selection_semaphore: nil)
end

#add(host, add_options = nil) ⇒ Server

Add a server to the cluster with the provided address. Useful in auto-discovery of new servers when an existing server executes an ismaster and potentially non-configured servers were included.

Examples:

Add the server for the address to the cluster.

cluster.add('127.0.0.1:27018')

Parameters:

  • host (String)

    The address of the server to add.

  • options (Hash)

    a customizable set of options

Returns:

  • (Server)

    The newly added server, if not present already.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 575

def add(host, add_options=nil)
  address = Address.new(host, options)
  if !addresses.include?(address)
    server = Server.new(address, self, @monitoring, event_listeners, options.merge(
      monitor: false))
    @update_lock.synchronize { @servers.push(server) }
    if add_options.nil? || add_options[:monitor] != false
      server.start_monitoring
    end
    server
  end
end

#addressesArray<Mongo::Address>

The addresses in the cluster.

Examples:

Get the addresses in the cluster.

cluster.addresses

Returns:

Since:

  • 2.0.6



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# File 'lib/mongo/cluster.rb', line 306

def addresses
  servers_list.map(&:address).dup
end

#connected?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.

Whether the cluster object is connected to its cluster.

Returns:

  • (true|false)

    Whether the cluster is connected.

Since:

  • 2.7.0



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# File 'lib/mongo/cluster.rb', line 281

def connected?
  !!@connected
end

#disconnect!(wait = false) ⇒ true

Note:

Applications should call Client#close to disconnect from

Disconnect all servers.

the cluster rather than calling this method. This method is for internal driver use only.

Examples:

Disconnect the cluster's servers.

cluster.disconnect!

Parameters:

  • wait (Boolean) (defaults to: false)

    Whether to wait for background threads to finish running.

Returns:

  • (true)

    Always true.

Since:

  • 2.1.0



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# File 'lib/mongo/cluster.rb', line 381

def disconnect!(wait=false)
  unless @connecting || @connected
    return true
  end
  @periodic_executor.stop!
  @servers.each do |server|
    if server.connected?
      server.disconnect!(wait)
      publish_sdam_event(
        Monitoring::SERVER_CLOSED,
        Monitoring::Event::ServerClosed.new(server.address, topology)
      )
    end
  end
  publish_sdam_event(
    Monitoring::TOPOLOGY_CLOSED,
    Monitoring::Event::TopologyClosed.new(topology)
  )
  @connecting = @connected = false
  true
end

#has_readable_server?(server_selector = nil) ⇒ true, false

Determine if the cluster would select a readable server for the provided read preference.

Examples:

Is a readable server present?

topology.has_readable_server?(server_selector)

Parameters:

  • server_selector (ServerSelector) (defaults to: nil)

    The server selector.

Returns:

  • (true, false)

    If a readable server is present.

Since:

  • 2.4.0



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# File 'lib/mongo/cluster.rb', line 490

def has_readable_server?(server_selector = nil)
  topology.has_readable_server?(self, server_selector)
end

#has_writable_server?true, false

Determine if the cluster would select a writable server.

Examples:

Is a writable server present?

topology.has_writable_server?

Returns:

  • (true, false)

    If a writable server is present.

Since:

  • 2.4.0



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# File 'lib/mongo/cluster.rb', line 502

def has_writable_server?
  topology.has_writable_server?(self)
end

#inspectString

Get the nicer formatted string for use in inspection.

Examples:

Inspect the cluster.

cluster.inspect

Returns:

  • (String)

    The cluster inspection.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 328

def inspect
  "#<Mongo::Cluster:0x#{object_id} servers=#{servers} topology=#{topology.summary}>"
end

#max_read_retriesInteger

Get the maximum number of times the cluster can retry a read operation on a mongos.

Examples:

Get the max read retries.

cluster.max_read_retries

Returns:

  • (Integer)

    The maximum retries.

Since:

  • 2.1.1



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# File 'lib/mongo/cluster.rb', line 258

def max_read_retries
  options[:max_read_retries] || MAX_READ_RETRIES
end

#next_primary(ping = true) ⇒ Mongo::Server

Get the next primary server we can send an operation to.

Examples:

Get the next primary server.

cluster.next_primary

Parameters:

  • ping (true, false) (defaults to: true)

    Whether to ping the server before selection. Deprecated, not necessary with the implementation of the Server Selection specification.

Returns:

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 518

def next_primary(ping = true)
  @primary_selector ||= ServerSelector.get(ServerSelector::PRIMARY)
  @primary_selector.select_server(self)
end

#pool(server) ⇒ Server::ConnectionPool

Deprecated.

Get the connection pool for the server.

Examples:

Get the connection pool.

cluster.pool(server)

Parameters:

  • server (Server)

    The server.

Returns:

Since:

  • 2.2.0



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# File 'lib/mongo/cluster.rb', line 534

def pool(server)
  server.pool
end

#read_retry_intervalFloat

Get the interval, in seconds, in which a mongos read operation is retried.

Examples:

Get the read retry interval.

cluster.read_retry_interval

Returns:

  • (Float)

    The interval.

Since:

  • 2.1.1



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# File 'lib/mongo/cluster.rb', line 271

def read_retry_interval
  options[:read_retry_interval] || READ_RETRY_INTERVAL
end

#reconnect!true

Deprecated.

Use Client#reconnect to reconnect to the cluster instead of calling this method. This method does not send SDAM events.

Reconnect all servers.

Examples:

Reconnect the cluster's servers.

cluster.reconnect!

Returns:

  • (true)

    Always true.

Since:

  • 2.1.0



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# File 'lib/mongo/cluster.rb', line 413

def reconnect!
  @connecting = true
  scan!
  servers.each do |server|
    server.reconnect!
  end
  @periodic_executor.restart!
  @connecting = false
  @connected = true
end

#remove(host) ⇒ true|false

Remove the server from the cluster for the provided address, if it exists.

Examples:

Remove the server from the cluster.

server.remove('127.0.0.1:27017')

Parameters:

  • host (String)

    The host/port or socket address.

Returns:

  • (true|false)

    Whether any servers were removed.

Since:

  • 2.0.0, return value added in 2.7.0



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# File 'lib/mongo/cluster.rb', line 599

def remove(host)
  address = Address.new(host)
  removed_servers = @servers.select { |s| s.address == address }
  @update_lock.synchronize { @servers = @servers - removed_servers }
  removed_servers.each do |server|
    if server.connected?
      server.disconnect!
      publish_sdam_event(
        Monitoring::SERVER_CLOSED,
        Monitoring::Event::ServerClosed.new(address, topology)
      )
    end
  end
  removed_servers.any?
end

#scan!(sync = true) ⇒ true

Note:

In both synchronous and asynchronous scans, each monitor thread maintains a minimum interval between scans, meaning calling this method may not initiate a scan on a particular server the very next instant.

Force a scan of all known servers in the cluster.

If the sync parameter is true which is the default, the scan is performed synchronously in the thread which called this method. Each server in the cluster is checked sequentially. If there are many servers in the cluster or they are slow to respond, this can be a long running operation.

If the sync parameter is false, this method instructs all server monitor threads to perform an immediate scan and returns without waiting for scan results.

Examples:

Force a full cluster scan.

cluster.scan!

Returns:

  • (true)

    Always true.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 447

def scan!(sync=true)
  if sync
    servers_list.each do |server|
      server.scan!
    end
  else
    servers_list.each do |server|
      server.monitor.scan_semaphore.signal
    end
  end
  true
end

#server_selection_semaphoreObject

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:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 343

def server_selection_semaphore
  options[:server_selection_semaphore]
end

#serversArray<Server>

Get a list of server candidates from the cluster that can have operations executed on them.

Examples:

Get the server candidates for an operation.

cluster.servers

Returns:

  • (Array<Server>)

    The candidate servers.

Since:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 294

def servers
  topology.servers(servers_list.compact).compact
end

#servers_listObject

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:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 626

def servers_list
  @update_lock.synchronize { @servers.dup }
end

#summaryObject

Note:

This method is experimental and subject to change.

Since:

  • 2.7.0



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# File 'lib/mongo/cluster.rb', line 336

def summary
  "#<Cluster " +
  "topology=#{topology.summary} "+
  "servers=[#{servers_list.map(&:summary).join(',')}]>"
end

#update_cluster_time(result) ⇒ Object

Update the max cluster time seen in a response.

Examples:

Update the cluster time.

cluster.update_cluster_time(result)

Parameters:

Returns:

  • (Object)

    The cluster time.

Since:

  • 2.5.0



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# File 'lib/mongo/cluster.rb', line 548

def update_cluster_time(result)
  if cluster_time_doc = result.cluster_time
    @cluster_time_lock.synchronize do
      if @cluster_time.nil?
        @cluster_time = cluster_time_doc
      elsif cluster_time_doc[CLUSTER_TIME] > @cluster_time[CLUSTER_TIME]
        @cluster_time = cluster_time_doc
      end
    end
  end
end

#update_topology(new_topology) ⇒ 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:

  • 2.0.0



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# File 'lib/mongo/cluster.rb', line 616

def update_topology(new_topology)
  old_topology = topology
  @topology = new_topology
  publish_sdam_event(
    Monitoring::TOPOLOGY_CHANGED,
    Monitoring::Event::TopologyChanged.new(old_topology, topology)
  )
end