Class: NeverBlock::DB::Pool

Inherits:
Object
  • Object
show all
Defined in:
lib/neverblock/io/db/pool.rb

Overview

Example:

pool = NeverBlock::Pool.new(:size=>16)do

# connection creation code goes here

end 32.times do

Fiber.new do
  # acquire a connection from the pool
  pool.hold do |conn|
    conn.execute('something') # you can use the connection normally now
  end
end.resume

end

It is the responsibility of client code to release the connection using pool.release(conn)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}, &block) ⇒ Pool

initialize the connection pool using the supplied proc to create the connections You can choose to start them eagerly or lazily (lazy by default) Available options are

:size => the maximum number of connections to be created in the pool
:eager => (true|false) indicates whether connections should be
          created initially or when need



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# File 'lib/neverblock/io/db/pool.rb', line 41

def initialize(options = {}, &block)
	@connections, @busy_connections, @queue = [], {},[]
	@connection_proc = block
	@size = options[:size] || 8
	if options[:eager]
	  @size.times do
	    @connections << @connection_proc.call
	  end
	end
end

Instance Attribute Details

#size ⇒ Object (readonly)

Returns the value of attribute size.



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# File 'lib/neverblock/io/db/pool.rb', line 32

def size
  @size
end

Instance Method Details

#all_connections ⇒ Object 



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# File 'lib/neverblock/io/db/pool.rb', line 79

def all_connections
  (@connections + @busy_connections.values).each {|conn| yield(conn)}
end

#hold ⇒ Object

If a connection is available, pass it to the block, otherwise pass the fiber to the queue till a connection is available



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# File 'lib/neverblock/io/db/pool.rb', line 61

def hold
  fiber = NB::Fiber.current
     conn = acquire(fiber)
     if block_given?
       yield conn
       release(conn)
     else
       conn
     end
end

#release(conn) ⇒ Object

Give the fiber’s connection back to the pool



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# File 'lib/neverblock/io/db/pool.rb', line 73

def release(conn)
  @busy_connections.delete(conn.object_id)
  @connections << conn unless @connections.include? conn
     process_queue
end

#replace_acquired_connection ⇒ Object 



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# File 'lib/neverblock/io/db/pool.rb', line 52

def replace_acquired_connection
  fiber = NB::Fiber.current
  conn = @connection_proc.call
  @busy_connections[fiber] = conn
  fiber[connection_pool_key] = conn
end