Class: ConnectionPool

Inherits:
Object
  • Object
show all
Defined in:
lib/active_rdf/federation/connection_pool.rb

Overview

Maintains pool of adapter instances that are connected to datasources. Returns right adapter for a given datasource, by either reusing an existing adapter-instance or creating new a adapter-instance.

Constant Summary collapse

@@adapter_pool =

pool of all adapters

Array.new
@@adapter_parameters =

pool of connection parameters to all adapter

Array.new
@@registered_adapter_types =

adapters-classes known to the pool, registered by the adapter-class itself using register_adapter method, used to select new adapter-instance for requested connection type

Hash.new

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.write_adapter ⇒ Object

Returns the value of attribute write_adapter.



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# File 'lib/active_rdf/federation/connection_pool.rb', line 9

def write_adapter
  @write_adapter
end

Class Method Details

.adapter_types ⇒ Object 



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# File 'lib/active_rdf/federation/connection_pool.rb', line 51

def ConnectionPool.adapter_types
	@@registered_adapter_types.keys
end

.adapters ⇒ Object 



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# File 'lib/active_rdf/federation/connection_pool.rb', line 42

def ConnectionPool.adapters
  @@adapter_pool.dup
end

.add_data_source(connection_params) ⇒ Object Also known as: add

returns adapter-instance for given parameters (either existing or new)



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# File 'lib/active_rdf/federation/connection_pool.rb', line 65

def ConnectionPool.add_data_source(connection_params)
  $activerdflog.info "ConnectionPool: add_data_source with params: #{connection_params.inspect}"

  # either get the adapter-instance from the pool
  # or create new one (and add it to the pool)
  index = @@adapter_parameters.index(connection_params)
  if index.nil?
    # adapter not in the pool yet: create it,
    # register its connection parameters in parameters-array
    # and add it to the pool (at same index-position as parameters)
    $activerdflog.debug("Create a new adapter for parameters #{connection_params.inspect}")
    adapter = create_adapter(connection_params)
    @@adapter_parameters << connection_params
    @@adapter_pool << adapter
  else
    # if adapter parametrs registered already,
    # then adapter must be in the pool, at the same index-position as its parameters
    $activerdflog.debug("Reusing existing adapter")
    adapter = @@adapter_pool[index]
  end

  # sets the adapter as current write-source if it can write
  self.write_adapter = adapter if adapter.writes?

  return adapter
end

.clear ⇒ Object

clears the pool: removes all registered data sources



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# File 'lib/active_rdf/federation/connection_pool.rb', line 35

def ConnectionPool.clear
  $activerdflog.info "ConnectionPool: clear called"
  @@adapter_pool = []
  @@adapter_parameters = []
  self.write_adapter = nil
end

.flush ⇒ Object

flushes all openstanding changes into the original datasource.



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# File 'lib/active_rdf/federation/connection_pool.rb', line 47

def ConnectionPool.flush
	write_adapter.flush
end

.read_adapters ⇒ Object

returns the set of currently registered read-access datasources



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# File 'lib/active_rdf/federation/connection_pool.rb', line 56

def ConnectionPool.read_adapters
  @@adapter_pool.select {|adapter| adapter.reads? }
end

.register_adapter(type, klass) ⇒ Object

adapter-types can register themselves with connection pool by indicating which adapter-type they are



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# File 'lib/active_rdf/federation/connection_pool.rb', line 132

def ConnectionPool.register_adapter(type, klass)
  $activerdflog.info "ConnectionPool: registering adapter of type #{type} for class #{klass}"
  @@registered_adapter_types[type] = klass
end

.remove_data_source(adapter) ⇒ Object

remove one adapter from activerdf



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# File 'lib/active_rdf/federation/connection_pool.rb', line 93

def ConnectionPool.remove_data_source(adapter)
  $activerdflog.info "ConnectionPool: remove_data_source with params: #{adapter.to_s}"
  
  index = @@adapter_pool.index(adapter)

  # remove_data_source mit be called repeatedly, e.g because the adapter object is stale
  unless index.nil?
    @@adapter_parameters.delete_at(index)
    @@adapter_pool.delete_at(index)
    if self.write_adapters.empty?
      self.write_adapter = nil
    else
      self.write_adapter = self.write_adapters.first
    end
  end
  
end

.set_data_source(adapter, connection_params = {}) ⇒ Object

sets adapter-instance for connection parameters (if you want to re-enable an existing adapter)



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# File 'lib/active_rdf/federation/connection_pool.rb', line 112

def ConnectionPool.set_data_source(adapter, connection_params = {})
	index = @@adapter_parameters.index(connection_params)
	if index.nil?
     @@adapter_parameters << connection_params
     @@adapter_pool << adapter
	else
		@@adapter_pool[index] = adapter
	end
	self.write_adapter = adapter if adapter.writes?
	adapter
end

.write_adapters ⇒ Object 



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# File 'lib/active_rdf/federation/connection_pool.rb', line 60

def ConnectionPool.write_adapters
  @@adapter_pool.select {|adapter| adapter.writes? }
end