Class: PGMonitor

Inherits:
Object show all
Defined in:
lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb

Overview

A class to encapsulate the PG handles.

Constant Summary collapse

VERSION = 
%q$Id$
LAG_ALERT =

When to consider a slave as ‘behind’, measured in WAL segments. The default WAL segment size is 16, so we’ll alert after missing two WAL files worth of data.

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Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts, hosts) ⇒ PGMonitor

Create a new PGMonitor object.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 40

def initialize( opts, hosts )
	@opts        = opts
	@master      = hosts.shift
	@slaves      = hosts
	@current_wal = {}
	@failures    = []
end

Instance Attribute Details

#current_wal ⇒ Object (readonly)

Returns the value of attribute current_wal.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 48

def current_wal
  @current_wal
end

#failures ⇒ Object (readonly)

Returns the value of attribute failures.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 48

def failures
  @failures
end

#master ⇒ Object (readonly)

Returns the value of attribute master.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 48

def master
  @master
end

#opts ⇒ Object (readonly)

Returns the value of attribute opts.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 48

def opts
  @opts
end

#slaves ⇒ Object (readonly)

Returns the value of attribute slaves.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 48

def slaves
  @slaves
end

Instance Method Details

#check ⇒ Object

Perform the connections and check the lag.



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# File 'lib/rubypitaya/app-template/vendor/bundle/ruby/3.1.0/gems/pg-1.4.5/sample/replication_monitor.rb', line 53

def check
	# clear prior failures, get current xlog info
	@failures = []
	return unless self.get_current_wal

	# check all slaves
	self.slaves.each do |slave|
		begin
			slave_db = PG.connect(
				:dbname   => self.opts.database,
				:host     => slave,
				:port     => self.opts.port,
				:user     => self.opts.user,
				:password => self.opts.pass,
				:sslmode  => 'prefer'
			)

			xlog = slave_db.exec( 'SELECT pg_last_xlog_receive_location()' ).getvalue( 0, 0 )
			slave_db.close

			lag_in_megs = ( self.find_lag( xlog ).to_f / 1024 / 1024 ).abs
			if lag_in_megs >= LAG_ALERT
				failures << { :host => slave,
					:error => "%0.2fMB behind the master." % [ lag_in_megs ] }
			end
		rescue => err
			failures << { :host => slave, :error => err.message }
		end
	end
end