Class: N::Db

Inherits:
Object
  • Object
show all
Defined in:
lib/n/db.rb

Overview

Database

Design:

  • This is NOT a singleton, an application may access multiple databases.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config) ⇒ Db

Initialize the database interface.



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# File 'lib/n/db.rb', line 83

def initialize(config)
	@config = config
	
	if backend = config[:backend]
		require "n/db/#{backend}"
	else
		require "n/db/psql"
	end

	$log.info "Connecting to database '#{config[:database]}'."
	
	@pool = N::Pool.new
	@fields = N::SafeHash.new
	
	for i in (0...config[:connection_count])
		@pool << DbConnection.new(config)
	end
end

Instance Attribute Details

#cache ⇒ Object

Entities cache.



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# File 'lib/n/db.rb', line 76

def cache
  @cache
end

#config ⇒ Object

hash of configuration options.



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# File 'lib/n/db.rb', line 70

def config
  @config
end

#fields ⇒ Object

Managed classes fields. A hash of hashes.



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# File 'lib/n/db.rb', line 79

def fields
  @fields
end

#pool ⇒ Object

Pool of connections to the backend.



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# File 'lib/n/db.rb', line 73

def pool
  @pool
end

Instance Method Details

#connect(deserialize = nil, &block) ⇒ Object Also known as: open

Utility method, automatically restores a connection to the pool.



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# File 'lib/n/db.rb', line 125

def connect(deserialize = nil, &block)
	result = nil
	
	begin
		db = @pool.pop()
		db.deserialize = deserialize unless deserialize.nil?
		
		result = yield(db)
		
		db.deserialize = true
	ensure
		@pool.push(db)
	end

	return result
end

#entity_from_row(row, klass) ⇒ Object

Utility method, creates an entity from a row



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# File 'lib/n/db.rb', line 166

def entity_from_row(row, klass)
	entity = klass.new()
	entity.__db_read_row__(row)
	return entity
end

#get_connection ⇒ Object

Get a connection from the pool to access the database.



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# File 'lib/n/db.rb', line 113

def get_connection
	return @pool.pop()
end

#put_connection(connection) ⇒ Object

Restore an unused connection to the pool.



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# File 'lib/n/db.rb', line 119

def put_connection(connection)
	return @pool.push(connection)
end

#shutdown ⇒ Object Also known as: close

Shutdown the database interface.



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# File 'lib/n/db.rb', line 104

def shutdown
	for con in @pool
		con.close()
	end
end

#transaction(deserialize = nil, &block) ⇒ Object

Utility method, gets connection and encloses in transaction.



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# File 'lib/n/db.rb', line 145

def transaction(deserialize = nil, &block) 
	result = nil
	
	begin
		db = @pool.pop()
		db.deserialize = deserialize if deserialize
		
		db.start()
		result = yield(db)
		db.commit()
		
		db.deserialize = true
	ensure
		@pool.push(db)
	end

	return result
end