Class: Mongo::Server::Monitor Private

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

Relationships & Source Files
Namespace Children
Classes: `AppMetadata`, `Connection`
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, Forwardable
Instance Chain: self, `::Mongo::BackgroundThread`, `::Mongo::Event::Publisher`, `::Mongo::Loggable`
Inherits:	Object
Defined in:	lib/mongo/server/monitor.rb, lib/mongo/server/monitor/app_metadata.rb, lib/mongo/server/monitor/connection.rb

Overview

Responsible for periodically polling a server via hello commands to keep the server’s status up to date.

Does all work in a background thread so as to not interfere with other operations performed by the driver.

Since:

2.0.0

Constant Summary

DEFAULT_HEARTBEAT_INTERVAL =

The default interval between server status refreshes is 10 seconds.
Since:
- 2.0.0
# File 'lib/mongo/server/monitor.rb', line 38
```
10.freeze
```
MIN_SCAN_INTERVAL =

The minimum time between forced server scans. Is minHeartbeatFrequencyMS in the SDAM spec.
Since:
- 2.0.0
# File 'lib/mongo/server/monitor.rb', line 44
```
0.5.freeze
```
RTT_WEIGHT_FACTOR =

Deprecated.

Will be removed in version 3.0.

The weighting factor (alpha) for calculating the average moving round trip time.
Since:
- 2.0.0
# File 'lib/mongo/server/monitor.rb', line 50
```
0.2.freeze
```

`::Mongo::Loggable` - Included

PREFIX

Class Method Summary

.new(server, event_listeners, monitoring, options = {}) ⇒ Monitor constructor Internal use only

Create the new server monitor.

Instance Attribute Summary

#connection ⇒ Mongo::Server::Monitor::Connection readonly Internal use only
#monitoring ⇒ Monitoring readonly Internal use only
#options ⇒ Hash readonly Internal use only
#server ⇒ Server readonly Internal use only

`::Mongo::BackgroundThread` - Included

#running?

`::Mongo::Event::Publisher` - Included

#event_listeners

Instance Method Summary

#create_push_monitor!(topology_version) Internal use only
#do_work Internal use only

Perform a check of the server.
#heartbeat_interval ⇒ Float Internal use only

The interval between regular server checks.
#push_monitor ⇒ Server::PushMonitor | nil Internal use only
#restart! ⇒ Thread Internal use only

Restarts the server monitor unless the current thread is alive.
#run_sdam_flow(result, awaited: false, scan_error: nil) Internal use only
#scan! ⇒ Description Internal use only

Perform a check of the server with throttling, and update the server’s description and average round trip time.
#stop! ⇒ true | false

Stop the background thread and wait for it to terminate for a reasonable amount of time.
#stop_push_monitor! Internal use only
#to_s Internal use only
#check private Internal use only
#do_scan private Internal use only
#pre_stop private Internal use only
#throttle_scan_frequency! private Internal use only

`::Mongo::BackgroundThread` - Included

#run!	Start the background thread.
#stop!	Stop the background thread and wait for to terminate for a reasonable amount of time.
#do_work	Override this method to do the work in the background thread.
#pre_stop	Override this method to perform additional signaling for the background thread to stop.
#start!,
#wait_for_stop	Waits for the thread to die, with a timeout.

`::Mongo::Event::Publisher` - Included

#publish

Publish the provided event.

`::Mongo::Loggable` - Included

#log_debug	Convenience method to log debug messages with the standard prefix.
#log_error	Convenience method to log error messages with the standard prefix.
#log_fatal	Convenience method to log fatal messages with the standard prefix.
#log_info	Convenience method to log info messages with the standard prefix.
#log_warn	Convenience method to log warn messages with the standard prefix.
#logger	Get the logger instance.
#_mongo_log_prefix, #format_message

Instance Attribute Details

#connection ⇒ Mongo::Server::Monitor::Connection (readonly)

Returns:

(Mongo::Server::Monitor::Connection) —

connection The connection to use.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 103


attr_reader :connection

#monitoring ⇒ Monitoring (readonly)

Returns:

(Monitoring) —

monitoring The monitoring.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 125


attr_reader :monitoring

#options ⇒ `Hash` (readonly)

Returns:

(Hash) —

options The server options.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 106


attr_reader :options

#server ⇒ Server (readonly)

Returns:

(Server) —

server The server that this monitor is monitoring.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 100


attr_reader :server

Instance Method Details

#check (private)

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 301


def check
  if @connection && @connection.pid != Process.pid
    log_warn("Detected PID change - Mongo client should have been reconnected (old pid #{@connection.pid}, new pid #{Process.pid}")
    @connection.disconnect!
    @connection = nil
  end

  if @connection
    result = server.round_trip_time_averager.measure do
      begin
        doc = @connection.check_document
        cmd = Protocol::Query.new(
          Database::ADMIN, Database::COMMAND, doc, :limit => -1
        )
        message = @connection.dispatch_bytes(cmd.serialize.to_s)
        message.documents.first
      rescue Mongo::Error
        @connection.disconnect!
        @connection = nil
        raise
      end
    end
  else
    connection = Connection.new(server.address, options)
    connection.connect!
    result = server.round_trip_time_averager.measure do
      connection.handshake!
    end
    @connection = connection
    if tv_doc = result['topologyVersion']
      # Successful response, server 4.4+
      create_push_monitor!(TopologyVersion.new(tv_doc))
      push_monitor.run!
    else
      # Failed response or pre-4.4 server
      stop_push_monitor!
    end
    result
  end
  result
end

#create_push_monitor!(topology_version)

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 173


def create_push_monitor!(topology_version)
  @update_mutex.synchronize do
    if @push_monitor && !@push_monitor.running?
      @push_monitor = nil
    end

    @push_monitor ||= PushMonitor.new(
      self,
      topology_version,
      monitoring,
      **Utils.shallow_symbolize_keys(options.merge(
        socket_timeout: heartbeat_interval + connection.socket_timeout,
        app_metadata: options[:push_monitor_app_metadata],
        check_document: @connection.check_document
      )),
    )
  end
end

#do_scan (private)

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 285


def do_scan
  begin
    monitoring.publish_heartbeat(server) do
      check
    end
  rescue => exc
    msg = "Error checking #{server.address}"
    Utils.warn_bg_exception(msg, exc,
      logger: options[:logger],
      log_prefix: options[:log_prefix],
      bg_error_backtrace: options[:bg_error_backtrace],
    )
    raise exc
  end
end

#do_work

Perform a check of the server.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 138


def do_work
  scan!
  # @next_wanted_scan may be updated by the push monitor.
  # However we need to check for termination flag so that the monitor
  # thread exits when requested.
  loop do
    delta = @next_wanted_scan - Time.now
    if delta > 0
      signaled = server.scan_semaphore.wait(delta)
      if signaled || @stop_requested
        break
      end
    else
      break
    end
  end
end

#heartbeat_interval ⇒ `Float`

The interval between regular server checks.

Returns:

(Float) —

The heartbeat interval, in seconds.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 111


def heartbeat_interval
  options[:heartbeat_interval] || DEFAULT_HEARTBEAT_INTERVAL
end

#pre_stop (private)

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 281


def pre_stop
  server.scan_semaphore.signal
end

#push_monitor ⇒ Server::PushMonitor | `nil`

Returns:

(Server::PushMonitor | nil) —

The push monitor, if one is being used.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 129


def push_monitor
  @update_mutex.synchronize do
    @push_monitor
  end
end

#restart! ⇒ `Thread`

Restarts the server monitor unless the current thread is alive.

Examples:

Restart the monitor.

monitor.restart!

Returns:

(Thread) —

The thread the monitor runs on.

Since:

2.1.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 267


def restart!
  if @thread && @thread.alive?
    @thread
  else
    run!
  end
end

#run_sdam_flow(result, awaited: false, scan_error: nil)

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 236


def run_sdam_flow(result, awaited: false, scan_error: nil)
  @sdam_mutex.synchronize do
    old_description = server.description

    new_description = Description.new(server.address, result,
      average_round_trip_time: server.round_trip_time_averager.average_round_trip_time
    )

    server.cluster.run_sdam_flow(server.description, new_description, awaited: awaited, scan_error: scan_error)

    server.description.tap do |new_description|
      unless awaited
        if new_description.unknown? && !old_description.unknown?
          @next_earliest_scan = @next_wanted_scan = Time.now
        else
          @next_earliest_scan = Time.now + MIN_SCAN_INTERVAL
          @next_wanted_scan = Time.now + heartbeat_interval
        end
      end
    end
  end
end

#scan! ⇒ Description

Note:

If the system clock moves backwards, this method can sleep for a very long time.

Note:

The return value of this method is deprecated. In version 3.0.0 this method will not have a return value.

Perform a check of the server with throttling, and update the server’s description and average round trip time.

If the server was checked less than MIN_SCAN_INTERVAL seconds ago, sleep until MIN_SCAN_INTERVAL seconds have passed since the last check. Then perform the check which involves running hello on the server being monitored and updating the server description as a result.

Returns:

(Description) —

The updated description.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 219


def scan!
  # Ordinarily the background thread would invoke this method.
  # But it is also possible to invoke scan! directly on a monitor.
  # Allow only one scan to be performed at a time.
  @mutex.synchronize do
    throttle_scan_frequency!

    begin
      result = do_scan
    rescue => e
      run_sdam_flow({}, scan_error: e)
    else
      run_sdam_flow(result)
    end
  end
end

#stop! ⇒ `true` | `false`

Stop the background thread and wait for it to terminate for a reasonable amount of time.

Returns:

(true | false) —

Whether the thread was terminated.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 162


def stop!
  stop_push_monitor!

  # Forward super's return value
  super.tap do
    # Important: disconnect should happen after the background thread
    # terminates.
    connection&.disconnect!
  end
end

#stop_push_monitor!

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 192


def stop_push_monitor!
  @update_mutex.synchronize do
    if @push_monitor
      @push_monitor.stop!
      @push_monitor = nil
    end
  end
end

#throttle_scan_frequency! (private)

Note:

If the system clock is set to a time in the past, this method can sleep for a very long time.

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 345


def throttle_scan_frequency!
  delta = @next_earliest_scan - Time.now
  if delta > 0
    sleep(delta)
  end
end

#to_s

Since:

2.0.0

[ GitHub ]

# File 'lib/mongo/server/monitor.rb', line 275


def to_s
  "#<#{self.class.name}:#{object_id} #{server.address}>"
end

Class: Mongo::Server::Monitor Private

Overview

Constant Summary

::Mongo::Loggable - Included

Class Method Summary

Instance Attribute Summary

::Mongo::BackgroundThread - Included

::Mongo::Event::Publisher - Included

Instance Method Summary

::Mongo::BackgroundThread - Included

::Mongo::Event::Publisher - Included

::Mongo::Loggable - Included

Instance Attribute Details

#connection ⇒ Mongo::Server::Monitor::Connection (readonly)

#monitoring ⇒ Monitoring (readonly)

#options ⇒ Hash (readonly)

#server ⇒ Server (readonly)

Instance Method Details

#check (private)

#create_push_monitor!(topology_version)

#do_scan (private)

#do_work

#heartbeat_interval ⇒ Float

#pre_stop (private)

#push_monitor ⇒ Server::PushMonitor | nil

#restart! ⇒ Thread

#run_sdam_flow(result, awaited: false, scan_error: nil)

#scan! ⇒ Description

#stop! ⇒ true | false

#stop_push_monitor!

#throttle_scan_frequency! (private)

#to_s

`::Mongo::Loggable` - Included

`::Mongo::BackgroundThread` - Included

`::Mongo::Event::Publisher` - Included

`::Mongo::BackgroundThread` - Included

`::Mongo::Event::Publisher` - Included

`::Mongo::Loggable` - Included

#options ⇒ `Hash` (readonly)

#heartbeat_interval ⇒ `Float`

#push_monitor ⇒ Server::PushMonitor | `nil`

#restart! ⇒ `Thread`

#stop! ⇒ `true` | `false`