Class: Neo4j::Core::Database

Inherits:
Object
  • Object
show all
Defined in:
lib/neo4j-core/database.rb

Overview

Wraps both Java Neo4j GraphDatabaseService and Lucene. You can access the raw java neo4j and lucene db’s with the graph and lucene properties.

This class is also responsible for checking if there is already a running neo4j database. If one tries to start an already started database then a read only instance to neo4j will be used. Many of the methods here are delegated from the Neo4j module

Constant Summary collapse

SEMAPHORE = 
Mutex.new

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Database

Returns a new instance of Database.



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# File 'lib/neo4j-core/database.rb', line 33

def initialize()
  @event_handler = EventHandler.new
end

Instance Attribute Details

#event_handler ⇒ Neo4j::EventHandler (readonly)

Returns the event handler listining to commit events.

Returns:

  • (Neo4j::EventHandler) —

    the event handler listining to commit events



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# File 'lib/neo4j-core/database.rb', line 26

def event_handler
  @event_handler
end

#graph ⇒ Java::OrgNeo4jGraphdb::GraphDatabaseService (readonly)

The Java graph database

Returns:

  • (Java::OrgNeo4jGraphdb::GraphDatabaseService)

See Also:



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# File 'lib/neo4j-core/database.rb', line 18

def graph
  @graph
end

#lucene ⇒ Java::OrgNeo4jGraphdbIndex::IndexManager (readonly) Also known as: index

The lucene index manager

Returns:

  • (Java::OrgNeo4jGraphdbIndex::IndexManager)

See Also:



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# File 'lib/neo4j-core/database.rb', line 23

def lucene
  @lucene
end

#storage_path ⇒ String (readonly)

Returns The location of the database.

Returns:

  • (String) —

    The location of the database



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# File 'lib/neo4j-core/database.rb', line 29

def storage_path
  @storage_path
end

Class Method Details

.default_embedded_db ⇒ Object 



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# File 'lib/neo4j-core/database.rb', line 37

def self.default_embedded_db
  @default_embedded_db || Java::OrgNeo4jKernel::EmbeddedGraphDatabase
end

.default_embedded_db=(db) ⇒ Object 



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# File 'lib/neo4j-core/database.rb', line 41

def self.default_embedded_db=(db)
  @default_embedded_db = db
end

.ha_enabled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/neo4j-core/database.rb', line 45

def self.ha_enabled?
  !!Neo4j::Config[:enable_ha]
end

.locked? ⇒ Boolean

check if the database is locked. A neo4j database is locked when the database is running.

Returns:

  • (Boolean) 


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# File 'lib/neo4j-core/database.rb', line 91

def self.locked?
  lock_file = File.join(Neo4j.config.storage_path, 'neostore')
  return false unless File.exist?(lock_file)
  rfile = java.io.RandomAccessFile.new(lock_file, 'rw')
  begin
    lock = rfile.getChannel.tryLock
    lock.release if lock
    return lock == nil # we got the lock, so that means it is not locked.
  rescue Exception => e
    return false
  end
end

Instance Method Details

#_each_node ⇒ Object

See Also:



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# File 'lib/neo4j-core/database.rb', line 143

def _each_node
  iter = @graph.all_nodes.iterator
  while (iter.hasNext)
    yield iter.next
  end
end

#begin_tx ⇒ Object

private method, used from Neo4j::Transaction.new



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# File 'lib/neo4j-core/database.rb', line 130

def begin_tx
  @graph.begin_tx
end

#each_node ⇒ Object

See Also:



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# File 'lib/neo4j-core/database.rb', line 135

def each_node
  iter = @graph.all_nodes.iterator
  while (iter.hasNext)
    yield iter.next.wrapper
  end
end

#management(jmx_clazz) ⇒ Object

See Also:



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# File 'lib/neo4j-core/database.rb', line 124

def management(jmx_clazz)
  @neo4j_manager ||= Java::OrgNeo4jManagement::Neo4jManager.new(@graph.get_management_bean(org.neo4j.jmx.Kernel.java_class))
  @neo4j_manager.getBean(jmx_clazz.java_class)
end

#read_only? ⇒ Boolean

Returns true if the neo4j db was started in read only mode. This can occur if the database was locked (it was already one instance running).

Returns:

  • (Boolean)

See Also:

  • Neo4j#read_only?


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# File 'lib/neo4j-core/database.rb', line 86

def read_only?
  @graph.java_class == Java::OrgNeo4jKernel::EmbeddedReadOnlyGraphDatabase
end

#running? ⇒ Boolean

true if the database has started

Returns:

  • (Boolean) 


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# File 'lib/neo4j-core/database.rb', line 79

def running?
  @running
end

#shutdown ⇒ Object

Internal method, see Neo4j#shutdown



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# File 'lib/neo4j-core/database.rb', line 105

def shutdown
  if @running
    @graph.unregister_transaction_event_handler(@event_handler) unless read_only?
    @event_handler.neo4j_shutdown(self)
    @graph.shutdown
    @graph = nil
    @lucene = nil
    @running = false
    @neo4j_manager = nil
    if self.class.ha_enabled?
      Neo4j.logger.info "Neo4j (HA mode) has been shutdown, machine id: #{Neo4j.config['ha.server_id']} at #{Neo4j.config['ha.server']} db #{@storage_path}"
    else
      Neo4j.logger.info "Neo4j has been shutdown using storage_path: #{@storage_path}"
    end
  end
end

#start ⇒ Object

Private start method, use Neo4j.start instead

See Also:

  • Neo4j#start


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# File 'lib/neo4j-core/database.rb', line 52

def start
  SEMAPHORE.synchronize do
    return if running?
    @storage_path = Config.storage_path
    Java::JavaLang::System.setProperty("neo4j.ext.udc.source", "neo4rb")

    begin
      if self.class.locked?
        start_readonly_graph_db
      elsif self.class.ha_enabled?
        start_ha_graph_db
        Neo4j.migrate! if Neo4j.respond_to?(:migrate!)
      else
        start_local_graph_db
        Neo4j.migrate! if Neo4j.respond_to?(:migrate!)
      end
    rescue
      @running = false
      raise
    end

    at_exit { shutdown }
  end
end

#start_external_db(external_graph_db) ⇒ Object 



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# File 'lib/neo4j-core/database.rb', line 151

def start_external_db(external_graph_db)
  begin
    @graph = external_graph_db
    @graph.register_transaction_event_handler(@event_handler)
    @lucene = @graph.index
    @running = true
    @event_handler.neo4j_started(self)
    Neo4j.logger.info("Started with external db")
  rescue
    @running = false
    raise
  end
end