class GenePool
Generic connection pool class
Attributes
Public Class Methods
Creates a gene_pool. The passed block will be used to initialize a single instance of the item being pooled (i.e., socket connection or whatever) options -
name - The name used in logging messages. pool_size - The maximum number of instances that will be created (Defaults to 1). timeout - Will raise a Timeout exception if waiting on a connection for this many seconds. timeout_class - Exception class to raise if timeout error, defaults to Timeout::Error warn_timeout - Displays an error message if a checkout takes longer that the given time (used to give hints to increase the pool size). idle_timeout - If set, the connection will be renewed if it hasn't been used in this amount of time (seconds). logger - The logger used for log messages, defaults to STDERR. close_proc - The process or method used to close a pooled instance when it is removed. Defaults to :close. Set to nil for no-op or a symbol for a method or a proc that takes an argument for the instance.
# File lib/gene_pool.rb, line 24 def initialize(options={}, &connect_block) @connect_block = connect_block @name = options[:name] || 'GenePool' @pool_size = options[:pool_size] || 1 @timeout = options[:timeout] @timeout_class = options[:timeout_class] || Timeout::Error @warn_timeout = options[:warn_timeout] || 5.0 @idle_timeout = options[:idle_timeout] @logger = options[:logger] @close_proc = options[:close_proc] || (!options.has_key?(:close_proc) && :close) unless @logger @logger = Logger.new(STDERR) @logger.level = Logger::INFO end @connections = [] @checked_out = [] # Map the original connections object_id within the with_connection method to the final connection. # This could change if the connection is renew'ed. @with_map = Concurrent::Hash.new setup_mutex end
Public Instance Methods
Return a connection to the pool.
# File lib/gene_pool.rb, line 112 def checkin(connection) @mutex.synchronize do @checked_out.delete(connection) if @pool_size < @connections.size remove_and_close(connection) @logger.info "#{@name}: Checkin connection #{connection}(#{connection.object_id}) has been removed due to pool size reduction" else connection._last_used = Time.now @condition.signal end end @logger.debug {"#{@name}: Checkin connection #{connection}(#{connection.object_id}) self=#{self}"} end
Check out a connection from the pool, creating it if necessary.
# File lib/gene_pool.rb, line 71 def checkout start_time = Time.now connection = nil reserved_connection_placeholder = Thread.current begin @mutex.synchronize do raise "Can't perform checkout, #{@name} has been closed" if @pool_size == 0 until connection do if @checked_out.size < @connections.size connection = (@connections - @checked_out).first @checked_out << connection elsif @connections.size < @pool_size # Perform the actual connection outside the mutex connection = reserved_connection_placeholder @connections << connection @checked_out << connection @logger.debug {"#{@name}: Created connection ##{@connections.size} #{connection}(#{connection.object_id}) for #{name}"} else @logger.info "#{@name}: Waiting for an available connection, all #{@pool_size} connections are checked out." wait_mutex(start_time) end end end ensure delta = Time.now - start_time if delta > @warn_timeout @logger.warn "#{@name}: It took #{delta} seconds to obtain a connection. Consider raising the pool size which is " + "currently set to #{@pool_size}." end end if connection == reserved_connection_placeholder connection = renew(reserved_connection_placeholder) elsif @idle_timeout && (Time.now - connection._last_used) >= @idle_timeout connection = renew(connection) end @logger.debug {"#{@name}: Checkout connection #{connection}(#{connection.object_id}) self=#{self}"} return connection end
Close all connections and wait for active connections to complete
Parameters:
timeout: Maximum time to wait for connections to close before returning
# File lib/gene_pool.rb, line 246 def close(timeout=10) # Prevent any new connections from being handed out self.pool_size = 0 start_time = Time.now while (Time.now - start_time) < timeout sleep 1 @mutex.synchronize do return if @connections.empty? @logger.info "#{@name}: Waiting to close, #{@connections.size} connections are still in use" end end @logger.warn "#{@name}: Timed out while waiting to close, #{@connections.size} connections are still in use" end
Return a copy of all the current connections
# File lib/gene_pool.rb, line 234 def connections connections = @mutex.synchronize { connections = @connections.dup } connections.delete_if { |c| c.kind_of?(Thread) } connections.freeze connections end
Perform the given block for each connection. Note that close should be used for safely closing all connections This should probably only ever be used to allow interrupt of a connection that is checked out?
# File lib/gene_pool.rb, line 226 def each @mutex.synchronize do # Don't include the ones in a reserved_placeholder state because that object is meaningless @connections.each { |connection| yield connection unless connection.kind_of?(Thread) } end end
# File lib/gene_pool.rb, line 56 def pool_size=(size) @mutex.synchronize do return if @pool_size == size @pool_size = size if @pool_size < @connections.size old_connections = (@connections - @checked_out).last(@connections.size - @pool_size) old_connections.each do |connection| remove_and_close(connection) @logger.info "#{@name}: Connection #{connection}(#{connection.object_id}) has been removed due to pool size reduction" end end end end
Remove an existing connection from the pool
# File lib/gene_pool.rb, line 180 def remove(connection) @mutex.synchronize do @connections.delete(connection) @checked_out.delete(connection) @condition.signal end close_connection(connection) @logger.debug {"#{@name}: Removed connection #{connection}(#{connection.object_id}) self=#{self}"} end
# File lib/gene_pool.rb, line 260 def remove_idle(idle_time=60) @mutex.synchronize do (@connections - @checked_out).each do |idle_connection| if (Time.now - idle_connection._last_used) >= idle_time remove_and_close(idle_connection) @logger.debug {"#{@name}: Removed idle connection=#{idle_connection}(#{idle_connection.object_id})"} end end end end
If a connection needs to be renewed for some reason, reassign it here
# File lib/gene_pool.rb, line 191 def renew(old_connection) new_connection = begin @connect_block.call rescue Exception remove old_connection raise end class << new_connection attr_accessor :_last_used end @mutex.synchronize do index = @checked_out.index(old_connection) raise Error.new("Can't reassign non-checked out connection for #{@name}") unless index @checked_out[index] = new_connection @connections[@connections.index(old_connection)] = new_connection # If this is part of a with_connection block, then track our new connection if @with_map.respond_to?(:key) with_key = @with_map.key(old_connection) else # 1.8 compatibility with_key = @with_map.index(old_connection) end @with_map[with_key] = new_connection if with_key end # Since connection has been removed, it can be closed outside the mutex close_connection(old_connection) @logger.debug {"#{@name}: Renewed connection old=#{old_connection.inspect} new=#{new_connection.inspect}"} return new_connection end
# File lib/gene_pool.rb, line 50 def size @mutex.synchronize do return @connections.size end end
# File lib/gene_pool.rb, line 271 def to_s conn = chk = with = nil @mutex.synchronize do conn = @connections.map{|c| c.object_id}.join(',') chk = @checked_out.map{|c| c.object_id}.join(',') with = @with_map.keys.map{|k| "#{k}=#{@with_map[k].object_id}"}.join(',') end "connections=#{conn} checked_out=#{chk} with_map=#{with}" end
Create a scope for checking out a connection The client should handle cleanup on exception which should be something similar to the following:
rescue Exception => e @gene_pool.remove(connection) raise end
Note that with_connection_auto_remove
automatically does this
# File lib/gene_pool.rb, line 133 def with_connection connection = checkout @with_map[connection.object_id] = connection begin yield connection ensure # Update connection for any renew's that have occurred connection = @with_map.delete(connection.object_id) checkin(connection) if connection end end
Create a scope for checking out a connection while automatically removing this connection on exception
# File lib/gene_pool.rb, line 146 def with_connection_auto_remove with_connection do |connection| begin yield connection rescue Exception remove(connection) raise end end end
Create a scope for checking out a connection while automatically retrying on exception
# File lib/gene_pool.rb, line 159 def with_connection_auto_retry with_connection do |connection| begin yield connection rescue Exception => e if e.kind_of?(Timeout::Error) || e.kind_of?(@timeout_class) || e.message =~ /expired/ remove(connection) raise end connection = renew(connection) begin yield connection rescue Exception => e remove(connection) raise end end end end
Private Instance Methods
# File lib/gene_pool.rb, line 285 def close_connection(connection) return unless @close_proc # Thread is used as a reserved_connection_placeholder so don't close the connection if it's actually a thread return if connection.kind_of?(Thread) if @close_proc.kind_of?(Symbol) connection.__send__(@close_proc) else @close_proc.call(connection) end rescue NoMethodError @logger.warn "Unable to close, you should explicitly set :close_proc => nil in the gene_pool options" rescue Exception => e @logger.warn "Exception trying to close #{connection}(#{connection.object_id}): #{e.message}\n\t#{e.backtrace.join("\n\t")}" end
Clients should have obtained the mutex before calling this!
# File lib/gene_pool.rb, line 301 def remove_and_close(connection) @connections.delete(connection) close_connection(connection) end
# File lib/gene_pool.rb, line 306 def setup_mutex @connections.extend(MonitorMixin) # Mutex for synchronizing pool access @mutex = @connections # Condition variable for waiting for an available connection @condition = @mutex.new_cond end
# File lib/gene_pool.rb, line 314 def wait_mutex(start_time) return @condition.wait unless @timeout delta = @timeout - (Time.now - start_time) raise @timeout_class if delta <= 0.0 @condition.wait(delta) delta = @timeout - (Time.now - start_time) raise @timeout_class if delta <= 0.0 end