Class: RR::Committers::BufferedCommitter

Inherits:
DefaultCommitter show all
Defined in:
lib/rubyrep/committers/buffered_committer.rb

Overview

This committer periodically commits transactions. It can be used for pre-replication syncs as it

  • updates the activity marker table.

  • switches existing triggers to filter out rubyrep activity

Constant Summary collapse

DEFAULT_COMMIT_FREQUENCY =

Unless overwritten via configuration, transactions are commited after the given number of record changes

1000

Instance Attribute Summary

Attributes inherited from DefaultCommitter

#connections, #session

Instance Method Summary collapse

Constructor Details

#initialize(session) ⇒ BufferedCommitter

A new committer is created for each table sync.

  • session: a Session object representing the current database session



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 102

def initialize(session)
  super
  begin_db_transactions
end

Instance Method Details

#activity_marker_table ⇒ Object

Returns the name of the activity marker table



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 31

def activity_marker_table
  @activity_marker_table ||= "#{session.configuration.options[:rep_prefix]}_running_flags"
end

#begin_db_transactions ⇒ Object

Begins new transactions in both databases. After starting the transaction, marks the activity of rubyrep.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 67

def begin_db_transactions
  [:left, :right].each do |database|
    session.send(database).begin_db_transaction
    if maintain_activity_status?
      session.send(database).execute("insert into #{activity_marker_table} values(1)")
    end
  end
end

#commit ⇒ Object

Commits the open tranactions and starts new one if the #commit_frequency number of record changes have been executed.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 84

def commit
  @change_counter ||= 0
  @change_counter += 1
  if @change_counter == commit_frequency
    @change_counter = 0
    commit_db_transactions
    begin_db_transactions
  end
end

#commit_db_transactions ⇒ Object

Commits the open transactions in both databases. Before committing, clears the rubyrep activity marker.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 56

def commit_db_transactions
  [:left, :right].each do |database|
    if maintain_activity_status?
      session.send(database).execute("delete from #{activity_marker_table}")
    end
    session.send(database).commit_db_transaction
  end
end

#commit_frequency ⇒ Object

Returns the number of changes, after which the open transactions should be committed and new transactions be started.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 46

def commit_frequency
  unless @commit_frequency
    @commit_frequency = session.configuration.options[:commit_frequency]
    @commit_frequency ||= DEFAULT_COMMIT_FREQUENCY
  end
  @commit_frequency
end

#delete_record(database, table, values) ⇒ Object

Deletes the specified record in the specified database.

  • database: identifying the database (either :left or :right)

  • table: name of the table

  • values: a hash of column_name => value pairs (must only contain primary key columns).



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 134

def delete_record(database, table, values)
  exclude_rr_activity database, table
  super
  commit
end

#exclude_rr_activity(database, table) ⇒ Object

Switches the trigger mode of the specified table in the specified database to ignore rubyrep activity.

  • database: identifying the database (either :left or :right)

  • table: name of the table



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 21

def exclude_rr_activity(database, table)
  trigger_mode_switcher.exclude_rr_activity database, table
end

#finalize(success = true) ⇒ Object

Is called after the last insert / update / delete query.

  • success: should be true if there were no problems, false otherwise.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 142

def finalize(success = true)
  if success
    commit_db_transactions
  else
    rollback_db_transactions
  end
end

#insert_record(database, table, values) ⇒ Object

Inserts the specified record in the specified database.

  • database: identifying the database (either :left or :right)

  • table: name of the table

  • values: a hash of column_name => value pairs.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 111

def insert_record(database, table, values)
  exclude_rr_activity database, table
  super
  commit
end

#maintain_activity_status? ⇒ Boolean

Returns true if the activity marker table should be maintained.

Returns:

  • (Boolean) 


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# File 'lib/rubyrep/committers/buffered_committer.rb', line 36

def maintain_activity_status?
  unless @activity_status_checked
    @activity_status_checked = true
    @maintain_activity_status = session.left.tables.include?(activity_marker_table)
  end
  @maintain_activity_status
end

#new_transaction? ⇒ Boolean

Returns true if a new transaction was started since the last insert / update / delete.

Returns:

  • (Boolean) 


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# File 'lib/rubyrep/committers/buffered_committer.rb', line 96

def new_transaction?
  @change_counter == 0
end

#rollback_db_transactions ⇒ Object

Rolls back the open transactions in both databases.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 77

def rollback_db_transactions
  session.left.rollback_db_transaction
  session.right.rollback_db_transaction
end

#trigger_mode_switcher ⇒ Object

Returns the TriggerModeSwitcher (creates it if necessary)



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 26

def trigger_mode_switcher
  @trigger_mode_switcher ||= TriggerModeSwitcher.new session
end

#update_record(database, table, values, old_key = nil) ⇒ Object

Updates the specified record in the specified database.

  • database: identifying the database (either :left or :right)

  • table: name of the table

  • values: a hash of column_name => value pairs.

  • old_key: A column_name => value hash identifying original primary key. If nil, then the primary key must be contained in values.



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# File 'lib/rubyrep/committers/buffered_committer.rb', line 124

def update_record(database, table, values, old_key = nil)
  exclude_rr_activity database, table
  super
  commit
end