Add request pool to improve delivery performance (#10353)
* Add request pool to improve delivery performance Fix #7909 * Ensure connection is closed when exception interrupts execution * Remove Timeout#timeout from socket connection * Fix infinite retrial loop on HTTP::ConnectionError * Close sockets on failure, reduce idle time to 90 seconds * Add MAX_REQUEST_POOL_SIZE option to limit concurrent connections to the same server * Use a shared pool size, 512 by default, to stay below open file limit * Add some tests * Add more tests * Reduce MAX_IDLE_TIME from 90 to 30 seconds, reap every 30 seconds * Use a shared pool that returns preferred connection but re-purposes other ones when needed * Fix wrong connection being returned on subsequent calls within the same thread * Reduce mutex calls on flushes from 2 to 1 and add test for reaping
This commit is contained in:
Eugen Rochko
GitHub
63
app/lib/connection_pool/shared_connection_pool.rb
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63
app/lib/connection_pool/shared_connection_pool.rb
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@ -0,0 +1,63 @@
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# frozen_string_literal: true
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require 'connection_pool'
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require_relative './shared_timed_stack'
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class ConnectionPool::SharedConnectionPool < ConnectionPool
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def initialize(options = {}, &block)
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super(options, &block)
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@available = ConnectionPool::SharedTimedStack.new(@size, &block)
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end
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delegate :size, :flush, to: :@available
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def with(preferred_tag, options = {})
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Thread.handle_interrupt(Exception => :never) do
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conn = checkout(preferred_tag, options)
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begin
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Thread.handle_interrupt(Exception => :immediate) do
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yield conn
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end
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ensure
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checkin(preferred_tag)
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end
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end
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end
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def checkout(preferred_tag, options = {})
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if ::Thread.current[key(preferred_tag)]
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::Thread.current[key_count(preferred_tag)] += 1
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::Thread.current[key(preferred_tag)]
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else
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::Thread.current[key_count(preferred_tag)] = 1
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::Thread.current[key(preferred_tag)] = @available.pop(preferred_tag, options[:timeout] || @timeout)
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end
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end
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def checkin(preferred_tag)
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if ::Thread.current[key(preferred_tag)]
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if ::Thread.current[key_count(preferred_tag)] == 1
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@available.push(::Thread.current[key(preferred_tag)])
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::Thread.current[key(preferred_tag)] = nil
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else
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::Thread.current[key_count(preferred_tag)] -= 1
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end
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else
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raise ConnectionPool::Error, 'no connections are checked out'
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end
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nil
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end
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private
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def key(tag)
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:"#{@key}-#{tag}"
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end
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def key_count(tag)
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:"#{@key_count}-#{tag}"
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end
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end
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95
app/lib/connection_pool/shared_timed_stack.rb
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95
app/lib/connection_pool/shared_timed_stack.rb
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@ -0,0 +1,95 @@
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# frozen_string_literal: true
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class ConnectionPool::SharedTimedStack
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def initialize(max = 0, &block)
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@create_block = block
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@max = max
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@created = 0
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@queue = []
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@tagged_queue = Hash.new { |hash, key| hash[key] = [] }
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@mutex = Mutex.new
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@resource = ConditionVariable.new
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end
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def push(connection)
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@mutex.synchronize do
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store_connection(connection)
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@resource.broadcast
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end
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end
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alias << push
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def pop(preferred_tag, timeout = 5.0)
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deadline = current_time + timeout
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@mutex.synchronize do
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loop do
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return fetch_preferred_connection(preferred_tag) unless @tagged_queue[preferred_tag].empty?
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connection = try_create(preferred_tag)
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return connection if connection
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to_wait = deadline - current_time
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raise Timeout::Error, "Waited #{timeout} sec" if to_wait <= 0
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@resource.wait(@mutex, to_wait)
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end
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end
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end
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def empty?
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size.zero?
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end
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def size
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@mutex.synchronize do
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@queue.size
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end
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end
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def flush
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@mutex.synchronize do
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@queue.delete_if do |connection|
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delete = !connection.in_use && (connection.dead || connection.seconds_idle >= RequestPool::MAX_IDLE_TIME)
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if delete
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@tagged_queue[connection.site].delete(connection)
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connection.close
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@created -= 1
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end
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delete
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end
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end
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end
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private
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def try_create(preferred_tag)
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if @created == @max && !@queue.empty?
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throw_away_connection = @queue.pop
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@tagged_queue[throw_away_connection.site].delete(throw_away_connection)
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@create_block.call(preferred_tag)
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elsif @created != @max
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connection = @create_block.call(preferred_tag)
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@created += 1
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connection
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end
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end
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def fetch_preferred_connection(preferred_tag)
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connection = @tagged_queue[preferred_tag].pop
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@queue.delete(connection)
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connection
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end
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def current_time
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Process.clock_gettime(Process::CLOCK_MONOTONIC)
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end
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def store_connection(connection)
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@tagged_queue[connection.site].push(connection)
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@queue.push(connection)
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end
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end
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@ -17,15 +17,21 @@ end
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class Request
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REQUEST_TARGET = '(request-target)'
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# We enforce a 5s timeout on DNS resolving, 5s timeout on socket opening
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# and 5s timeout on the TLS handshake, meaning the worst case should take
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# about 15s in total
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TIMEOUT = { connect: 5, read: 10, write: 10 }.freeze
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include RoutingHelper
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def initialize(verb, url, **options)
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raise ArgumentError if url.blank?
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@verb = verb
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@url = Addressable::URI.parse(url).normalize
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@options = options.merge(use_proxy? ? Rails.configuration.x.http_client_proxy : { socket_class: Socket })
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@headers = {}
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@verb = verb
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@url = Addressable::URI.parse(url).normalize
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@http_client = options.delete(:http_client)
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@options = options.merge(use_proxy? ? Rails.configuration.x.http_client_proxy : { socket_class: Socket })
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@headers = {}
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raise Mastodon::HostValidationError, 'Instance does not support hidden service connections' if block_hidden_service?
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@ -50,15 +56,24 @@ class Request
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def perform
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begin
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response = http_client.headers(headers).public_send(@verb, @url.to_s, @options)
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response = http_client.public_send(@verb, @url.to_s, @options.merge(headers: headers))
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rescue => e
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raise e.class, "#{e.message} on #{@url}", e.backtrace[0]
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end
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begin
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yield response.extend(ClientLimit) if block_given?
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response = response.extend(ClientLimit)
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# If we are using a persistent connection, we have to
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# read every response to be able to move forward at all.
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# However, simply calling #to_s or #flush may not be safe,
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# as the response body, if malicious, could be too big
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# for our memory. So we use the #body_with_limit method
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response.body_with_limit if http_client.persistent?
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yield response if block_given?
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ensure
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http_client.close
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http_client.close unless http_client.persistent?
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end
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end
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@ -76,6 +91,10 @@ class Request
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%w(http https).include?(parsed_url.scheme) && parsed_url.host.present?
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end
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def http_client
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HTTP.use(:auto_inflate).timeout(:per_operation, TIMEOUT.dup).follow(max_hops: 2)
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end
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end
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private
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@ -116,16 +135,8 @@ class Request
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end
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end
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def timeout
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# We enforce a 1s timeout on DNS resolving, 10s timeout on socket opening
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# and 5s timeout on the TLS handshake, meaning the worst case should take
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# about 16s in total
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{ connect: 5, read: 10, write: 10 }
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end
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def http_client
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@http_client ||= HTTP.use(:auto_inflate).timeout(:per_operation, timeout).follow(max_hops: 2)
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@http_client ||= Request.http_client
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end
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def use_proxy?
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@ -169,20 +180,41 @@ class Request
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return super(host, *args) if thru_hidden_service?(host)
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outer_e = nil
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port = args.first
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Resolv::DNS.open do |dns|
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dns.timeouts = 5
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addresses = dns.getaddresses(host).take(2)
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time_slot = 10.0 / addresses.size
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addresses.each do |address|
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begin
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raise Mastodon::HostValidationError if PrivateAddressCheck.private_address?(IPAddr.new(address.to_s))
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::Timeout.timeout(time_slot, HTTP::TimeoutError) do
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return super(address.to_s, *args)
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sock = ::Socket.new(::Socket::AF_INET, ::Socket::SOCK_STREAM, 0)
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sockaddr = ::Socket.pack_sockaddr_in(port, address.to_s)
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sock.setsockopt(::Socket::IPPROTO_TCP, ::Socket::TCP_NODELAY, 1)
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begin
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sock.connect_nonblock(sockaddr)
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rescue IO::WaitWritable
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if IO.select(nil, [sock], nil, Request::TIMEOUT[:connect])
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begin
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sock.connect_nonblock(sockaddr)
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rescue Errno::EISCONN
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# Yippee!
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rescue
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sock.close
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raise
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end
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else
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sock.close
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raise HTTP::TimeoutError, "Connect timed out after #{Request::TIMEOUT[:connect]} seconds"
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end
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end
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return sock
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rescue => e
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outer_e = e
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end
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114
app/lib/request_pool.rb
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114
app/lib/request_pool.rb
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@ -0,0 +1,114 @@
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# frozen_string_literal: true
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require_relative './connection_pool/shared_connection_pool'
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class RequestPool
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def self.current
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@current ||= RequestPool.new
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end
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class Reaper
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attr_reader :pool, :frequency
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def initialize(pool, frequency)
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@pool = pool
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@frequency = frequency
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end
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def run
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return unless frequency&.positive?
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Thread.new(frequency, pool) do |t, p|
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loop do
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sleep t
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p.flush
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end
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end
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end
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end
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MAX_IDLE_TIME = 30
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WAIT_TIMEOUT = 5
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MAX_POOL_SIZE = ENV.fetch('MAX_REQUEST_POOL_SIZE', 512).to_i
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class Connection
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attr_reader :site, :last_used_at, :created_at, :in_use, :dead, :fresh
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def initialize(site)
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@site = site
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@http_client = http_client
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@last_used_at = nil
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@created_at = current_time
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@dead = false
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@fresh = true
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end
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def use
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@last_used_at = current_time
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@in_use = true
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retries = 0
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begin
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yield @http_client
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rescue HTTP::ConnectionError
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# It's possible the connection was closed, so let's
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# try re-opening it once
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close
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if @fresh || retries.positive?
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raise
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else
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@http_client = http_client
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retries += 1
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retry
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end
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rescue StandardError
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# If this connection raises errors of any kind, it's
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# better if it gets reaped as soon as possible
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close
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@dead = true
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raise
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end
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ensure
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@fresh = false
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@in_use = false
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end
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def seconds_idle
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current_time - (@last_used_at || @created_at)
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end
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def close
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@http_client.close
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end
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private
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def http_client
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Request.http_client.persistent(@site, timeout: MAX_IDLE_TIME)
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end
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def current_time
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Process.clock_gettime(Process::CLOCK_MONOTONIC)
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end
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end
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def initialize
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@pool = ConnectionPool::SharedConnectionPool.new(size: MAX_POOL_SIZE, timeout: WAIT_TIMEOUT) { |site| Connection.new(site) }
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@reaper = Reaper.new(self, 30)
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@reaper.run
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end
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def with(site, &block)
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@pool.with(site) do |connection|
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ActiveSupport::Notifications.instrument('with.request_pool', miss: connection.fresh, host: connection.site) do
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connection.use(&block)
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end
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end
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end
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delegate :size, :flush, to: :@pool
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end
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