Module: Activerecord::Mysql::Reconnect

Defined in:
lib/activerecord/mysql/reconnect/version.rb,
lib/activerecord/mysql/reconnect.rb

Constant Summary collapse

VERSION = 
'0.3.3'
DEFAULT_EXECUTION_TRIES = 
3
DEFAULT_EXECUTION_RETRY_WAIT = 
0.5
WITHOUT_RETRY_KEY = 
'activerecord-mysql-reconnect-without-retry'
RETRYABLE_TRANSACTION_KEY = 
'activerecord-mysql-reconnect-transaction-retry'
HANDLE_ERROR = 
[
  ActiveRecord::StatementInvalid,
  Mysql2::Error,
]
HANDLE_R_ERROR_MESSAGES = 
[
  'Lost connection to MySQL server during query',
]
HANDLE_RW_ERROR_MESSAGES = 
[
  'MySQL server has gone away',
  'Server shutdown in progress',
  'closed MySQL connection',
  "Can't connect to MySQL server",
  'Query execution was interrupted',
  'Access denied for user',
  'The MySQL server is running with the --read-only option',
]
HANDLE_ERROR_MESSAGES = 
HANDLE_R_ERROR_MESSAGES + HANDLE_RW_ERROR_MESSAGES
READ_SQL_REGEXP = 
/\A\s*(?:SELECT|SHOW|SET)\b/i
RETRY_MODES = 
[:r, :rw, :force]
DEFAULT_RETRY_MODE = 
:r

Class Method Summary collapse

Class Method Details

.enable_retry ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 64

def enable_retry
  !!ActiveRecord::Base.enable_retry
end

.execution_retry_wait ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 59

def execution_retry_wait
  wait = ActiveRecord::Base.execution_retry_wait || DEFAULT_EXECUTION_RETRY_WAIT
  wait.kind_of?(BigDecimal) ? wait : BigDecimal(wait.to_s)
end

.execution_tries ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 55

def execution_tries
  ActiveRecord::Base.execution_tries || DEFAULT_EXECUTION_TRIES
end

.logger ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 114

def logger
  if defined?(Rails)
    Rails.logger || ActiveRecord::Base.logger || Logger.new($stderr)
  else
    ActiveRecord::Base.logger || Logger.new($stderr)
  end
end

.retry_mode ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 76

def retry_mode
  @activerecord_mysql_reconnect_retry_mode || DEFAULT_RETRY_MODE
end

.retry_mode=(v) ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 68

def retry_mode=(v)
  unless RETRY_MODES.include?(v)
    raise "Invalid retry_mode. Please set one of the following: #{RETRY_MODES.map {|i| i.inspect }.join(', ')}"
  end

  @activerecord_mysql_reconnect_retry_mode = v
end

.retryable(opts) ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 80

def retryable(opts)
  block     = opts.fetch(:proc)
  on_error  = opts[:on_error]
  conn      = opts[:connection]
  tries     = self.execution_tries
  retval    = nil

  retryable_loop(tries) do |n|
    begin
      retval = block.call
      break
    rescue => e
      if enable_retry and (tries.zero? or n < tries) and should_handle?(e, opts)
        on_error.call if on_error
        wait = self.execution_retry_wait * n

        opt_msgs = ["cause: #{e} [#{e.class}]"]

        if conn and conn.kind_of?(Mysql2::Client)
          opt_msgs << 'connection: ' + [:host, :database, :username].map {|k| "#{k}=#{conn.query_options[k]}" }.join(";")
        end

        logger.warn("MySQL server has gone away. Trying to reconnect in #{wait.to_f} seconds. (#{opt_msgs.join(', ')})")
        sleep(wait)
        next
      else
        raise e
      end
    end
  end

  return retval
end

.retryable_transaction ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 135

def retryable_transaction
  begin
    Thread.current[RETRYABLE_TRANSACTION_KEY] = []

    ActiveRecord::Base.transaction do
      yield
    end
  ensure
    Thread.current[RETRYABLE_TRANSACTION_KEY] = nil
  end
end

.retryable_transaction_buffer ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 147

def retryable_transaction_buffer
  Thread.current[RETRYABLE_TRANSACTION_KEY]
end

.without_retry ⇒ Object 



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# File 'lib/activerecord/mysql/reconnect.rb', line 122

def without_retry
  begin
    Thread.current[WITHOUT_RETRY_KEY] = true
    yield
  ensure
    Thread.current[WITHOUT_RETRY_KEY] = nil
  end
end

.without_retry? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/activerecord/mysql/reconnect.rb', line 131

def without_retry?
  !!Thread.current[WITHOUT_RETRY_KEY]
end