Class: HTTPX::Resolver::System

Inherits:
Resolver
  • Object
show all
Defined in:
lib/httpx/resolver/system.rb,
sig/resolver/system.rbs

Overview

Implementation of a synchronous name resolver which relies on the system resolver, which is lib'c getaddrinfo function (abstracted in ruby via Addrinfo.getaddrinfo).

Its main advantage is relying on the reference implementation for name resolution across most/all OSs which deploy ruby (it's what TCPSocket also uses), its main disadvantage is the inability to set timeouts / check socket for readiness events, hence why it relies on using the Timeout module, which poses a lot of problems for the selector loop, specially when network is unstable.

Defined Under Namespace

Classes: AddrinfoTimeoutError

Constant Summary collapse

RESOLV_ERRORS =

Returns:

  • (Array[singleton(StandardError)]) 
[Resolv::ResolvError,
Resolv::DNS::Requester::RequestError,
Resolv::DNS::EncodeError,
Resolv::DNS::DecodeError].freeze
DONE =

Returns:

  • (1) 
1
ERROR =

Returns:

  • (2) 
2

Constants inherited from Resolver

Resolver::FAMILY_TYPES, Resolver::RECORD_TYPES

Constants included from Loggable

Loggable::COLORS, Loggable::USE_DEBUG_LOG

Instance Attribute Summary collapse

Attributes inherited from Resolver

#current_selector, #current_session, #family, #options

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Resolver

#disconnect, #each_connection, #emit_addresses, #emit_connection_error, #emit_resolve_error, #emit_resolved_connection, #handle_error, #inflight?, #initial_call, #on_error, #on_io_error, #resolve_connection, #resolve_error

Methods included from Loggable

#log, #log_exception, log_identifiers, #log_redact, #log_redact_body, #log_redact_headers

Methods included from _Selectable

#initial_call, #on_error, #on_io_error, #terminate

Constructor Details

#initialize(options) ⇒ System

Returns a new instance of System.

Parameters:



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# File 'lib/httpx/resolver/system.rb', line 37

def initialize(options)
  super(0, options)
  @resolver_options = @options.resolver_options
  resolv_options = @resolver_options.dup
  timeouts = resolv_options.delete(:timeouts) || Resolver::RESOLVE_TIMEOUT
  @_timeouts = Array(timeouts)
  @timeouts = Hash.new { |tims, host| tims[host] = @_timeouts.dup }
  resolv_options.delete(:cache)
  @queries = []
  @ips = []
  @pipe_mutex = Thread::Mutex.new
  @state = :idle
end

Instance Attribute Details

#state ⇒ Symbol (readonly)

Returns the value of attribute state.

Returns:

  • (Symbol) 


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# File 'lib/httpx/resolver/system.rb', line 35

def state
  @state
end

Class Method Details

.multi? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/httpx/resolver/system.rb', line 30

def multi?
  false
end

Instance Method Details

#__addrinfo_resolve(host, scheme) ⇒ Array[Addrinfo]

Parameters:

  • host (String)
  • scheme (String)

Returns:

  • (Array[Addrinfo]) 


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# File 'lib/httpx/resolver/system.rb', line 280

def __addrinfo_resolve(host, scheme)
  Addrinfo.getaddrinfo(host, scheme, Socket::AF_UNSPEC, Socket::SOCK_STREAM)
end

#async_resolve(connection, hostname, scheme) ⇒ void

This method returns an undefined value.

Parameters:

  • connection (Connection)
  • hostname (String)
  • scheme (String) 


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# File 'lib/httpx/resolver/system.rb', line 222

def async_resolve(connection, hostname, scheme)
  families = connection.options.ip_families || Resolver.supported_ip_families
  log { "resolver: query for #{hostname}" }
  timeouts = @timeouts[connection.peer.host]
  resolve_timeout = timeouts.first

  Thread.start do
    Thread.current.report_on_exception = false
    begin
      addrs = if resolve_timeout

        Timeout.timeout(resolve_timeout, AddrinfoTimeoutError) do
          __addrinfo_resolve(hostname, scheme)
        end
      else
        __addrinfo_resolve(hostname, scheme)
      end
      addrs = addrs.sort_by(&:afamily).group_by(&:afamily)
      families.each do |family|
        addresses = addrs[family]
        next unless addresses

        addresses.map!(&:ip_address)
        addresses.uniq!
        @pipe_mutex.synchronize do
          @ips.unshift([family, connection, addresses])
          @pipe_write.putc(DONE) unless @pipe_write.closed?
        end
      end
    rescue StandardError => e
      if e.is_a?(AddrinfoTimeoutError)
        timeouts.shift
        retry unless timeouts.empty?
        e = ResolveTimeoutError.new(resolve_timeout, e.message)
        e.set_backtrace(e.backtrace)
      end
      @pipe_mutex.synchronize do
        families.each do |family|
          @ips.unshift([family, connection, e])
          @pipe_write.putc(ERROR) unless @pipe_write.closed?
        end
      end
    end
  end
  Thread.pass
end

#call ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 85

def call
  case @state
  when :open
    consume
  end
  nil
end

#close ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 65

def close
  transition(:closed)
end

#close_or_resolve ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/system.rb', line 269

def close_or_resolve
  # drop already closed connections
  @connections.shift until @connections.empty? || @connections.first.state != :closed

  if (@connections - @queries.map(&:last)).empty?
    disconnect
  else
    resolve
  end
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/httpx/resolver/system.rb', line 77

def closed?
  @state == :closed
end

#consume ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/system.rb', line 159

def consume
  return if @connections.empty?

  event = @pipe_read.read_nonblock(1, exception: false)

  return if event == :wait_readable

  raise ResolveError, "socket pipe closed unexpectedly" if event.nil?

  case event.unpack1("C")
  when DONE
    *pair, addrs = @pipe_mutex.synchronize { @ips.pop }
    if pair
      @queries.delete(pair)
      family, connection = pair
      @connections.delete(connection)

      catch(:coalesced) { emit_addresses(connection, family, addrs) }
    end
  when ERROR
    *pair, error = @pipe_mutex.synchronize { @ips.pop }
    if pair && error
      @queries.delete(pair)
      _, connection = pair
      @connections.delete(connection)

      emit_resolve_error(connection, connection.peer.host, error)
    end
  end

  return disconnect if @connections.empty?

  resolve
rescue StandardError => e
  on_error(e)
end

#early_resolve(_) ⇒ Object

rubocop:disable Naming/PredicateMethod



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# File 'lib/httpx/resolver/system.rb', line 122

def early_resolve(_, **) # rubocop:disable Naming/PredicateMethod
  false
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/httpx/resolver/system.rb', line 61

def empty?
  @connections.empty?
end

#force_close ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 69

def force_close(*)
  close
  @queries.clear
  @timeouts.clear
  @ips.clear
  super
end

#handle_socket_timeout(interval) ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 126

def handle_socket_timeout(interval)
  error = HTTPX::ResolveTimeoutError.new(interval, "timed out while waiting on select")
  error.set_backtrace(caller)
  @queries.each do |_, connection| # rubocop:disable Style/HashEachMethods
    emit_resolve_error(connection, connection.peer.host, error) if @connections.delete(connection)
  end

  while (connection = @connections.shift)
    emit_resolve_error(connection, connection.peer.host, error)
  end

  close_or_resolve
end

#interests ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 93

def interests
  return if @queries.empty?

  :r
end

#lazy_resolve(connection) ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 113

def lazy_resolve(connection)
  @connections << connection
  resolve

  return if empty?

  @current_session.select_resolver(self, @current_selector)
end

#multi ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 57

def multi
  self
end

#resolvers {|_self| ... } ⇒ Object

Yields:

  • (_self)

Yield Parameters:



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# File 'lib/httpx/resolver/system.rb', line 51

def resolvers
  return enum_for(__method__) unless block_given?

  yield self
end

#timeout ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 99

def timeout
  _, connection = @queries.first

  return unless connection

  timeouts = @timeouts[connection.peer.host]

  return if timeouts.empty?

  log(level: 2) { "resolver #{FAMILY_TYPES[@record_type]}: next timeout #{timeouts.first} secs... (#{timeouts.size - 1} left)" }

  timeouts.first
end

#to_io ⇒ Object 



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# File 'lib/httpx/resolver/system.rb', line 81

def to_io
  @pipe_read.to_io
end

#transition(nextstate) ⇒ void

This method returns an undefined value.

Parameters:

  • nextstate (Symbol) 


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# File 'lib/httpx/resolver/system.rb', line 142

def transition(nextstate)
  case nextstate
  when :idle
    @timeouts.clear
  when :open
    return unless @state == :idle

    @pipe_read, @pipe_write = IO.pipe
  when :closed
    return unless @state == :open

    @pipe_write.close
    @pipe_read.close
  end
  @state = nextstate
end