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RUBY-314 initial implementation of replica set health checking via background thread

This commit is contained in:
Kyle Banker 2011-08-24 18:34:00 -04:00
parent 9ea718522f
commit 1090dd3873
9 changed files with 450 additions and 127 deletions
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1
lib/mongo.rb
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@ -57,6 +57,7 @@ require 'mongo/util/conversions'
require 'mongo/util/support'
require 'mongo/util/core_ext'
require 'mongo/util/pool'
require 'mongo/util/pool_manager'
require 'mongo/util/server_version'
require 'mongo/util/uri_parser'

4
lib/mongo/connection.rb
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@ -35,8 +35,8 @@ module Mongo
STANDARD_HEADER_SIZE = 16
RESPONSE_HEADER_SIZE = 20
attr_reader :logger, :size, :auths, :primary, :safe, :primary_pool,
:host_to_try, :pool_size, :connect_timeout
attr_reader :logger, :size, :auths, :primary, :safe, :host_to_try,
:pool_size, :connect_timeout, :primary_pool
# Counter for generating unique request ids.
@@current_request_id = 0

18
lib/mongo/node.rb
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@ -18,6 +18,10 @@ module Mongo
end
alias :== :eql?
def host_string
"#{@host}:#{@port}"
end
# Create a connection to the provided node,
# and, if successful, return the socket. Otherwise,
# return nil.
@ -55,6 +59,15 @@ module Mongo
self.socket != nil
end
def active?
begin
result = self.connection['admin'].command({:ping => 1}, :socket => self.socket)
return result['ok'] == 1
rescue OperationFailure, SocketError, SystemCallError, IOError => ex
return nil
end
end
# Get the configuration for the provided node as returned by the
# ismaster command. Additionally, check that the replica set name
# matches with the name provided.
@ -78,7 +91,9 @@ module Mongo
# Note: this excludes arbiters.
def node_list
connect unless connected?
return [] unless self.config
set_config
return [] unless config
nodes = []
nodes += config['hosts'] if config['hosts']
@ -88,6 +103,7 @@ module Mongo
def arbiters
connect unless connected?
return [] unless config['arbiters']
config['arbiters'].map do |arbiter|
split_nodes(arbiter)

217
lib/mongo/repl_set_connection.rb
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@ -20,8 +20,8 @@ module Mongo
# Instantiates and manages connections to a MongoDB replica set.
class ReplSetConnection < Connection
attr_reader :nodes, :secondaries, :arbiters, :read_pool, :secondary_pools,
:replica_set_name, :ping_ranges
attr_reader :nodes, :secondaries, :arbiters, :secondary_pools,
:replica_set_name, :read_pool
# Create a connection to a MongoDB replica set.
#
@ -51,6 +51,12 @@ module Mongo
# Disabled by default.
# @option opts [Float] :connect_timeout (nil) The number of seconds to wait before timing out a
# connection attempt.
# @option opts [Boolean] :auto_refresh (false) Set this to true to enable a background thread that
# periodically updates the state of the connection. If, for example, you initially connect while a secondary
# is down, :auto_refresh will reconnect to that secondary behind the scenes to
# prevent you from having to reconnect manually.
# @option opts [Integer] :refresh_interval (90) If :auto_refresh is enabled, this is the number of seconds
# that the background thread will sleep between calls to check the replica set's state.
#
# @example Connect to a replica set and provide two seed nodes. Note that the number of seed nodes does
# not have to be equal to the number of replica set members. The purpose of seed nodes is to permit
@ -75,16 +81,16 @@ module Mongo
end
unless args.length > 0
raise MongoArgumentError, "A ReplSetConnection requires at least one node."
raise MongoArgumentError, "A ReplSetConnection requires at least one seed node."
end
# Get the list of seed nodes
# The list of seed nodes
@seeds = args
# The members of the replica set, stored as instances of Mongo::Node.
@nodes = []
# Connection pool for primay node
# Connection pool for primary node
@primary = nil
@primary_pool = nil
@ -93,17 +99,26 @@ module Mongo
@secondary_pools = []
# The secondary pool to which we'll be sending reads.
# This may be identical to the primary pool.
@read_pool = nil
# A list of arbiter address (for client information only)
# A list of arbiter addresses (for client information only)
@arbiters = []
# An array mapping secondaries by proximity
@ping_ranges = Array.new(3) { |i| Array.new }
# Refresh
@auto_refresh = opts.fetch(:auto_refresh, true)
@refresh_interval = opts[:refresh_interval] || 90
# Are we allowing reads from secondaries?
@read_secondary = opts.fetch(:read_secondary, false)
# Lock around changes to the global config
@connection_lock = Mutex.new
@connected = false
# Store the refresher thread
@refresh_thread = nil
# Replica set name
if opts[:rs_name]
warn ":rs_name option has been deprecated and will be removed in 2.0. " +
@ -116,29 +131,58 @@ module Mongo
setup(opts)
end
# Use the provided seed nodes to initiate a connection
# to the replica set.
# Initiate a connection to the replica set.
def connect
connect_to_members
initialize_pools
@connection_lock.synchronize do
return if @connected
manager = PoolManager.new(self, @seeds)
manager.connect
if connected?
choose_node_for_reads
update_seed_list
BSON::BSON_CODER.update_max_bson_size(self)
else
close
update_config(manager)
#BSON::BSON_CODER.update_max_bson_size(self)
initiate_auto_refresh
if @primary.nil?
if @primary.nil? #TODO: in v2.0, we'll let this be optional and do a lazy connect.
raise ConnectionFailure, "Failed to connect to primary node."
else
raise ConnectionFailure, "Failed to connect to any given member."
@connected = true
end
end
end
# Note: this method must be called from within
# a locked @connection_lock
def update_config(manager)
@arbiters = manager.arbiters.nil? ? [] : manager.arbiters.dup
@primary = manager.primary.nil? ? nil : manager.primary.dup
@secondaries = manager.secondaries.dup
@primary_pool = manager.primary_pool
@read_pool = manager.read_pool
@secondary_pools = manager.secondary_pools
@seeds = manager.seeds
@manager = manager
@hosts = manager.hosts
end
# If ismaster doesn't match our current view
# then create a new PoolManager, passing in our
# existing view. It should be able to do the diff.
# Then take out the connection lock and replace
# our current values.
def refresh
background_manager = PoolManager.new(self, @seeds)
if update_struct = background_manager.update_required?(@hosts)
@connection_lock.synchronize do
background_manager.update(@manager, update_struct)
update_config(background_manager)
end
end
end
def connected?
@primary_pool || (!@secondary_pools.empty? && @read_secondary)
@connected && !@connection_lock.locked?
end
# @deprecated
@ -165,21 +209,31 @@ module Mongo
#
# @return [Boolean]
def read_primary?
!@read_pool
@read_pool == @primary_pool
end
alias :primary? :read_primary?
# Close the connection to the database.
def close
super
@connected = false
if @refresh_thread
@refresh_thread.kill
@refresh_thread = nil
end
@nodes.each do |member|
member.disconnect
end
@nodes = []
@read_pool = nil
@secondary_pools.each do |pool|
pool.close
end
@secondaries = []
@secondary_pools = []
@arbiters = []
@ -217,102 +271,34 @@ module Mongo
private
# Iterate through the list of provided seed
# nodes until we've gotten a response from the
# replica set we're trying to connect to.
#
# If we don't get a response, raise an exception.
def get_valid_seed_node
@seeds.each do |seed|
node = Mongo::Node.new(self, seed)
if node.connect && node.set_config
return node
def initiate_auto_refresh
return if @refresh_thread && @refresh_thread.alive?
@refresh_thread = Thread.new do
sleep(@refresh_interval)
refresh
end
end
raise ConnectionFailure, "Cannot connect to a replica set using seeds " +
"#{@seeds.map {|s| "#{s[0]}:#{s[1]}" }.join(', ')}"
end
# Connect to each member of the replica set
# as reported by the given seed node, and cache
# those connections in the @nodes array.
def connect_to_members
seed = get_valid_seed_node
seed.node_list.each do |host|
node = Mongo::Node.new(self, host)
if node.connect && node.set_config
@nodes << node
end
end
end
# Initialize the connection pools to the primary and secondary nodes.
def initialize_pools
if @nodes.empty?
raise ConnectionFailure, "Failed to connect to any given member."
end
@arbiters = @nodes.first.arbiters
@nodes.each do |member|
if member.primary?
@primary = member.host_port
@primary_pool = Pool.new(self, member.host, member.port,
:size => @pool_size,
:timeout => @timeout,
:node => member)
elsif member.secondary? && !@secondaries.include?(member.host_port)
@secondaries << member.host_port
@secondary_pools << Pool.new(self, member.host, member.port,
:size => @pool_size,
:timeout => @timeout,
:node => member)
end
end
end
# Pick a node from the set of possible secondaries.
# If more than one node is available, use the ping
# time to figure out which nodes to choose from.
def choose_node_for_reads
return if @secondary_pools.empty?
if @secondary_pools.size == 1
@read_pool = @secondary_pools.first
else
@secondary_pools.each do |pool|
case pool.ping_time
when 0..150
@ping_ranges[0] << pool
when 150..1000
@ping_ranges[1] << pool
else
@ping_ranges[2] << pool
end
end
for list in @ping_ranges do
break if !list.empty?
end
@read_pool = list[rand(list.length)]
end
end
def update_seed_list
@seeds = @nodes.map { |n| n.host_port }
end
# Checkout a socket for reading (i.e., a secondary node).
# Note that @read_pool might point to the primary pool
# if no read pool has been defined. That's okay; we don't
# want to have to check for the existence of the @read_pool
# because that introduces concurrency issues.
def checkout_reader
connect unless connected?
if @read_secondary && @read_pool
@read_pool.checkout
else
checkout_writer
begin
return @read_pool.checkout
rescue NoMethodError
warn "Read pool was not available."
end
end
begin
return @primary_pool.checkout
rescue NoMethodError
raise ConnectionFailure, "Not connected to any nodes."
end
end
@ -320,12 +306,19 @@ module Mongo
def checkout_writer
connect unless connected?
@primary_pool.checkout
if @primary_pool
begin
return @primary_pool.checkout
rescue NoMethodError
end
end
raise ConnectionFailure, "Failed to connect to primary node."
end
# Checkin a socket used for reading.
def checkin_reader(socket)
if @read_secondary && @read_pool
if @read_secondary
@read_pool.checkin(socket)
else
checkin_writer(socket)

4
lib/mongo/util/pool.rb
View File

@ -63,6 +63,10 @@ module Mongo
@checked_out.clear
end
def host_string
"#{@host}:#{@port}"
end
# Return the time it takes on average
# to do a round-trip against this node.
def ping_time

219
lib/mongo/util/pool_manager.rb Normal file
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@ -0,0 +1,219 @@
module Mongo
class PoolManager
attr_reader :connection, :seeds, :arbiters, :primary, :secondaries,
:primary_pool, :read_pool, :secondary_pools, :hosts
def initialize(connection, seeds)
@connection = connection
@seeds = seeds
end
def connect
initialize_data
nodes = connect_to_members
initialize_pools(nodes)
update_seed_list(nodes)
end
# Ensure that the view of the replica set is current by
# running the ismaster command and checking to see whether
# we've connected to all known nodes. If not, automatically
# connect to these unconnected nodes. This is handy when we've
# connected to a replica set with no primary or when a secondary
# node comes up after we've connected.
#
# If we're connected to nodes that are no longer part of the set,
# remove these from our set of secondary pools.
def update_required?(hosts)
node = Thread.current[:refresher_node]
if !node || !node.active?
begin
node = get_valid_seed_node
Thread.current[:refresher_node] = node
rescue ConnectionFailure
warn "Could not refresh config because no valid seed node was unavailable."
end
end
node_list = node.node_list
unconnected_nodes = node_list - hosts
removed_nodes = hosts - node_list
if unconnected_nodes.empty? && removed_nodes.empty?
return false
else
{:unconnected => unconnected_nodes, :removed => removed_nodes}
end
end
def update(manager, node_struct)
reference_manager_data(manager)
unconnected_nodes = node_struct[:unconnected]
removed_nodes = node_struct[:removed]
if !removed_nodes.empty?
removed_nodes.each do |node|
if @primary_pool && @primary_pool.host_string == node
@primary = nil
@primary_pool.close
@primary_pool = nil
elsif rejected_pool = @secondary_pools.reject! {|pool| pool.host_string == node}
@secondaries.reject! do |secondary|
secondary.port == rejected_pool.port && secondary.host == rejected_pool.host
end
end
end
end
if !unconnected_nodes.empty?
nodes = []
unconnected_nodes.each do |host_port|
node = Mongo::Node.new(self.connection, host_port)
if node.connect && node.set_config
nodes << node
end
end
if !nodes.empty?
initialize_pools(nodes)
end
end
end
private
# Note that @arbiters and @read_pool will be
# assigned automatically.
def reference_manager_data(manager)
@primary = manager.primary
@primary_pool = manager.primary_pool
@secondaries = manager.secondaries
@secondary_pools = manager.secondary_pools
@read_pool = manager.read_pool
@arbiters = manager.arbiters
@hosts = manager.hosts
end
def initialize_data
@primary = nil
@primary_pool = nil
@read_pool = nil
@arbiters = []
@secondaries = []
@secondary_pools = []
@hosts = []
end
def connected_nodes
nodes = []
if @primary_pool
nodes << "#{@primary_pool.host}:#{@primary_pool.port}"
end
@secondary_pools.each do |pool|
nodes << "#{pool.host}:#{pool.port}"
end
nodes
end
# Connect to each member of the replica set
# as reported by the given seed node, and return
# as a list of Mongo::Node objects.
def connect_to_members
nodes = []
seed = get_valid_seed_node
seed.node_list.each do |host|
node = Mongo::Node.new(self.connection, host)
if node.connect && node.set_config
nodes << node
end
end
if nodes.empty?
raise ConnectionFailure, "Failed to connect to any given member."
end
nodes
end
# Initialize the connection pools for the primary and secondary nodes.
def initialize_pools(nodes)
nodes.each do |member|
@hosts << member.host_string
if member.primary?
@primary = member.host_port
@primary_pool = Pool.new(self.connection, member.host, member.port,
:size => self.connection.pool_size,
:timeout => self.connection.connect_timeout,
:node => member)
elsif member.secondary? && !@secondaries.include?(member.host_port)
@secondaries << member.host_port
@secondary_pools << Pool.new(self.connection, member.host, member.port,
:size => self.connection.pool_size,
:timeout => self.connection.connect_timeout,
:node => member)
end
end
@arbiters = nodes.first.arbiters
choose_read_pool
end
# Pick a node from the set of possible secondaries.
# If more than one node is available, use the ping
# time to figure out which nodes to choose from.
def choose_read_pool
if @secondary_pools.empty?
@read_pool = @primary_pool
elsif @secondary_pools.size == 1
@read_pool = @secondary_pools[0]
else
ping_ranges = Array.new(3) { |i| Array.new }
@secondary_pools.each do |pool|
case pool.ping_time
when 0..150
ping_ranges[0] << pool
when 150..1000
ping_ranges[1] << pool
else
ping_ranges[2] << pool
end
end
for list in ping_ranges do
break if !list.empty?
end
@read_pool = list[rand(list.length)]
end
end
# Iterate through the list of provided seed
# nodes until we've gotten a response from the
# replica set we're trying to connect to.
#
# If we don't get a response, raise an exception.
def get_valid_seed_node
@seeds.each do |seed|
node = Mongo::Node.new(self.connection, seed)
if node.connect && node.set_config
return node
end
end
raise ConnectionFailure, "Cannot connect to a replica set using seeds " +
"#{@seeds.map {|s| "#{s[0]}:#{s[1]}" }.join(', ')}"
end
def update_seed_list(nodes)
@seeds = nodes.map { |n| n.host_port }
end
end
end

70
test/replica_sets/refresh_test.rb Normal file
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@ -0,0 +1,70 @@
$:.unshift(File.join(File.dirname(__FILE__), '..', 'lib'))
require './test/replica_sets/rs_test_helper'
require 'benchmark'
# NOTE: This test expects a replica set of three nodes to be running on RS.host,
# on ports TEST_PORT, RS.ports[1], and TEST + 2.
class ReplicaSetRefreshTest < Test::Unit::TestCase
include Mongo
def setup
#RS.restart_killed_nodes
end
def teardown
RS.restart_killed_nodes
end
def test_connect_and_manual_refresh_with_secondaries_down
RS.kill_all_secondaries
rescue_connection_failure do
@conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
[RS.host, RS.ports[2]], :auto_refresh => false)
end
assert_equal [], @conn.secondaries
assert @conn.connected?
assert_equal @conn.read_pool, @conn.primary_pool
# Refresh with no change to set
@conn.refresh
assert_equal [], @conn.secondaries
assert @conn.connected?
assert_equal @conn.read_pool, @conn.primary_pool
RS.restart_killed_nodes
assert_equal [], @conn.secondaries
assert @conn.connected?
assert_equal @conn.read_pool, @conn.primary_pool
# Refresh with everything up
@conn.refresh
assert @conn.read_pool
assert @conn.secondaries.length > 0
end
def test_automated_refresh_with_secondaries_down
RS.kill_all_secondaries
rescue_connection_failure do
@conn = ReplSetConnection.new([RS.host, RS.ports[0]], [RS.host, RS.ports[1]],
[RS.host, RS.ports[2]], :refresh_interval => 2, :auto_refresh => true)
end
assert_equal [], @conn.secondaries
assert @conn.connected?
assert_equal @conn.read_pool, @conn.primary_pool
RS.restart_killed_nodes
sleep(3)
assert @conn.read_pool != @conn.primary_pool, "Read pool and primary pool are identical."
assert @conn.secondaries.length > 0, "No secondaries have been added."
end
def test_automated_refresh_with_removed_node
end
end

1
test/replica_sets/rs_test_helper.rb
View File

@ -17,7 +17,6 @@ class Test::Unit::TestCase
yield
rescue Mongo::ConnectionFailure => ex
puts "Rescue attempt #{retries}: from #{ex}"
puts ex.backtrace
retries += 1
raise ex if retries > max_retries
sleep(1)

23
test/tools/repl_set_manager.rb
View File

@ -154,6 +154,15 @@ class ReplSetManager
return node
end
def kill_all_secondaries
nodes = get_all_nodes_with_state(2)
if nodes
nodes.each do |n|
kill(n)
end
end
end
def restart_killed_nodes
nodes = @mongods.keys.select do |key|
@mongods[key]['up'] == false
@ -228,13 +237,25 @@ class ReplSetManager
end
end
def get_all_nodes_with_state(state)
status = ensure_up
nodes = status['members'].select {|m| m['state'] == state}
nodes = nodes.map do |node|
host_port = node['name'].split(':')
port = host_port[1] ? host_port[1].to_i : 27017
@mongods.keys.detect {|key| @mongods[key]['port'] == port}
end
nodes == [] ? false : nodes
end
def get_node_with_state(state)
status = ensure_up
node = status['members'].detect {|m| m['state'] == state}
if node
host_port = node['name'].split(':')
port = host_port[1] ? host_port[1].to_i : 27017
key = @mongods.keys.detect {|key| @mongods[key]['port'] == port}
key = @mongods.keys.detect {|n| @mongods[n]['port'] == port}
return key
else
return false