Class: Makara::Pool

Inherits:
Object
  • Object
show all
Defined in:
lib/makara/pool.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(role, proxy) ⇒ Pool

Returns a new instance of Pool.



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# File 'lib/makara/pool.rb', line 19

def initialize(role, proxy)
  @role             = role
  @proxy            = proxy
  @connections      = []
  @blacklist_errors = []
  @disabled         = false
  if proxy.shard_aware_for(role)
    @strategy = Makara::Strategies::ShardAware.new(self)
    @shard_strategy_class = proxy.strategy_class_for(proxy.strategy_name_for(role))
    @default_shard = proxy.default_shard_for(role)
  else
    @strategy = proxy.strategy_for(role)
  end
end

Instance Attribute Details

#blacklist_errors ⇒ Object (readonly)

Returns the value of attribute blacklist_errors.



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# File 'lib/makara/pool.rb', line 12

def blacklist_errors
  @blacklist_errors
end

#connections ⇒ Object (readonly)

Returns the value of attribute connections.



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# File 'lib/makara/pool.rb', line 14

def connections
  @connections
end

#default_shard ⇒ Object (readonly)

Returns the value of attribute default_shard.



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# File 'lib/makara/pool.rb', line 17

def default_shard
  @default_shard
end

#disabled ⇒ Object

there are cases when we understand the pool is busted and we essentially want to skip all execution



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# File 'lib/makara/pool.rb', line 11

def disabled
  @disabled
end

#role ⇒ Object (readonly)

Returns the value of attribute role.



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# File 'lib/makara/pool.rb', line 13

def role
  @role
end

#shard_strategy_class ⇒ Object (readonly)

Returns the value of attribute shard_strategy_class.



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# File 'lib/makara/pool.rb', line 16

def shard_strategy_class
  @shard_strategy_class
end

#strategy ⇒ Object (readonly)

Returns the value of attribute strategy.



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# File 'lib/makara/pool.rb', line 15

def strategy
  @strategy
end

Instance Method Details

#add(config) ⇒ Object

Add a connection to this pool, wrapping the connection with a Makara::ConnectionWrapper



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# File 'lib/makara/pool.rb', line 42

def add(config)
  config[:name] ||= "#{@role}/#{@connections.length + 1}"

  connection = yield

  # already wrapped because of initial error
  if connection.is_a?(Makara::ConnectionWrapper)
    connection.config = config # to add :name
    wrapper = connection
  else
    wrapper = Makara::ConnectionWrapper.new(@proxy, connection, config)
  end

  @connections << wrapper
  @strategy.connection_added(wrapper)

  wrapper
end

#completely_blacklisted? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/makara/pool.rb', line 34

def completely_blacklisted?
  @connections.each do |connection|
    return false unless connection._makara_blacklisted?
  end
  true
end

#provide ⇒ Object

Provide a connection that is not blacklisted and connected. Handle any errors that may occur within the block.



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# File 'lib/makara/pool.rb', line 100

def provide
  attempt = 0
  begin
    provided_connection = self.next

    # nil implies that it's blacklisted
    if provided_connection

      value = @proxy.error_handler.handle(provided_connection) do
        yield provided_connection
      end

      @blacklist_errors = []

      value

    # if we've made any connections within this pool, we should report the blackout.
    elsif connection_made?
      err = Makara::Errors::AllConnectionsBlacklisted.new(self, @blacklist_errors)
      @blacklist_errors = []
      raise err
    else
      raise Makara::Errors::NoConnectionsAvailable.new(@role) unless @disabled
    end

  # when a connection causes a blacklist error within the provided block, we blacklist it then retry
  rescue Makara::Errors::BlacklistConnection => e
    @blacklist_errors.insert(0, e)
    in_transaction = self.role == "master" && provided_connection._makara_in_transaction?
    provided_connection._makara_blacklist!
    raise Makara::Errors::BlacklistedWhileInTransaction.new(@role) if in_transaction

    attempt += 1
    if attempt < @connections.length
      retry
    elsif connection_made?
      err = Makara::Errors::AllConnectionsBlacklisted.new(self, @blacklist_errors)
      @blacklist_errors = []
      raise err
    else
      raise Makara::Errors::NoConnectionsAvailable.new(@role) unless @disabled
    end
  end
end

#send_to_all(method, *args, &block) ⇒ Object

send this method to all available nodes send nil to just yield with each con if there is block



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# File 'lib/makara/pool.rb', line 63

def send_to_all(method, *args, &block)
  ret = nil
  one_worked = false # actually found one that worked
  errors = []

  @connections.each do |con|
    next if con._makara_blacklisted?

    begin
      ret = @proxy.error_handler.handle(con) do
        if block
          yield con
        else
          con.send(method, *args)
        end
      end

      one_worked = true
    rescue Makara::Errors::BlacklistConnection => e
      errors.insert(0, e)
      con._makara_blacklist!
    end
  end

  if !one_worked
    if connection_made?
      raise Makara::Errors::AllConnectionsBlacklisted.new(self, errors)
    else
      raise Makara::Errors::NoConnectionsAvailable.new(@role) unless @disabled
    end
  end

  ret
end