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# === Pipelining

#

# On HTTP/1.1 servers requests can be pipelined which can reduce response

# time for a series of requests. When pipelining Net::HTTP sends requests

# in the list without waiting for a response then retrieves the responses

# from the server after all requests are issued. The server will return the

# responses in the same order they were issued.

#

# Example:

#

# requests = []

# requests << Net::HTTP::Get.new('/images/bug.png')

# requests << Net::HTTP::Get.new('/images/date.png')

# requests << Net::HTTP::Get.new('/images/find.png')

#

# http = Net::HTTP.start 'localhost' do

# http.pipeline requests do |req, res|

# # ...

# end

# end

#

# Before attempting to pipeline a sequence of requests, Net::HTTP will

# consume one request to check if the server is pipelining-capable. To avoid

# the check set #pipelining to true:

#

# http = Net::HTTP.start 'localhost' do

# http.pipelining = true

# responses = http.pipeline requests

# # ...

#

# For more details see Net::HTTP#pipeline

#

class Error < StandardError; end

class PipelineError < Error

##

# Remaining requests that have not been sent to the HTTP server

attr_reader :requests

##

# Retrieved responses up to the error point

attr_reader :responses

##

# Creates a new Error with +message+, a list of +requests+ that have not

# been sent to the server and a list of +responses+ that have been

# retrieved from the server.

def initialize message, requests, responses

super message

@requests = requests

@responses = responses

end

end

# Raised when the server appears to not support persistent connections

# which are required for pipelining requests.

class PipelinePersistenceError < PipelineError

# Creates a new PipelinePersistenceError with a list of +requests+ that

# have not been sent to the server and a list of +responses+ that have

# been retrieved from the server.

def initialize requests, responses

super 'persistent connections required', requests, responses

end

end

# Raised when the server appears to not support pipelining requests

class PipelineUnsupportedError < PipelineError

# Creates a new PipelineUnsupportedError with a list of +requests+ that

# have not been sent to the server and a list of +responses+ that have

# been retrieved from the server.

def initialize reason = nil, requests, responses

message = 'pipeline connections are not supported'

message << " (#{reason})" if reason

super message, requests, responses

end

end

# Raised if an error occurs while reading responses.

class PipelineResponseError < PipelineError

# The original exception

attr_accessor :original

# Creates a new PipelineResponseError with an original +exception+, a

# list of +requests+ that were in-flight and a list of +responses+ that

# have been retrieved from the server.

def initialize exception, requests, responses

@original = exception

message = "error reading responses: #{original} (#{original.class})"

super message, requests, responses

end

end

@pipelining = nil # nil means unknown

@socket_class = BufferedIO

# Set to true if this server supports pipelining, false if it does not.

# If unset, #pipeline will figure it out

attr_accessor :pipelining

@socket = @socket_class.new(s)

# Closes the connection and rescues any IOErrors this may cause

def reset_pipeline requests, responses

begin

finish

rescue IOError

end

start

rescue Errno::ECONNREFUSED

raise PipelineError.new("connection refused: #{address}:#{port}",

requests, responses)

rescue Errno::EHOSTDOWN

raise PipelineError.new("host down: #{address}:#{port}",

requests, responses)

end

private :reset_pipeline

# Pipelines +requests+ to the HTTP server yielding responses if a block is

# given. Returns all responses received.

#

# Only idempotent sequences of requests will be pipelined. If a

# non-idempotent request (like a POST) is included in a request sequence

# #pipeline will wait for a response before proceeding with further

# sequences of requests.

#

# The Net::HTTP connection must be started (#start must be called) before

# calling #pipeline.

#

# Raises a subclass of the PipelineError exception if the connection is

# not pipeline-capable, if the HTTP session has not been started, or their

# was a problem sending or receiving the +requests+. The remaining

# outstanding requests and returned responses can be retrieved from the

# PipelineError exception.

#

# Example:

#

# requests = []

# requests << Net::HTTP::Get.new('/images/bug.png')

# requests << Net::HTTP::Get.new('/images/date.png')

# requests << Net::HTTP::Get.new('/images/find.png')

#

# http = Net::HTTP.new 'localhost'

# http.start do

# http.pipeline requests do |req, res|

# open File.basename(req.path), 'wb' do |io|

# io.write res.body

# end

# end

# end

def pipeline requests, &block # :yields: response

requests = requests.dup

responses = []

raise PipelineError.new('Net::HTTP not started', requests, responses) unless

started?

pipeline_check requests, responses, &block

retried = responses.length

until requests.empty? do

begin

in_flight = pipeline_send requests

pipeline_receive in_flight, responses, &block

rescue PipelineResponseError => e

e.requests.reverse_each do |request|

requests.unshift request

end

raise if responses.length == retried or not requests.first.idempotent?

retried = responses.length

reset_pipeline requests, responses

retry

end

end

responses

end

# Ensures this connection supports pipelining.

#

# If the server has not been tested for pipelining support one of the

# +requests+ will be consumed and placed in +responses+.

#

# A PersistenceError will be raised if the server does not support

# persistent connections. (The server is HTTP/1.1, but closed the

# connection.)

#

# A PipelineUnsupportedError will be raised if the server does not support

# pipelining. (The server is not HTTP/1.1.)

def pipeline_check requests, responses

unless @pipelining.nil? then # tri-state

return if @pipelining

raise PipelineUnsupportedError.new(requests, responses) unless

@pipelining

else

@pipelining = false

end

if '1.1' > @curr_http_version then

@pipelining = false

reason = "server is HTTP/#{@curr_http_version}"

raise PipelineUnsupportedError.new(reason, requests, responses)

end

req = requests.shift

tried_once = false

begin

res = request(req)

rescue Timeout::Error, EOFError, Errno::ECONNABORTED, Errno::ECONNRESET,

Errno::EPIPE, Net::HTTPBadResponse => e

if tried_once then

requests.unshift req

raise PipelineResponseError.new(e, requests, responses)

end

tried_once = true

reset_pipeline requests, responses

retry

end

responses << res

yield req, res if block_given?

@pipelining = keep_alive? req, res

if '1.1' > @curr_http_version then

@pipelining = false

reason = "server is HTTP/#{@curr_http_version}"

raise PipelineUnsupportedError.new(reason, requests, responses)

elsif not @pipelining then

raise PipelinePersistenceError.new(requests, responses)

end

@close_on_empty_response = false

end

# Receives HTTP responses for the +in_flight+ requests and adds them to

# +responses+

def pipeline_receive in_flight, responses

while req = in_flight.shift do

begin

begin

res = Net::HTTPResponse.read_new @socket

end while res.kind_of? Net::HTTPContinue

res.reading_body @socket, req.response_body_permitted? do

responses << res

yield req, res if block_given?

end

end_transport req, res

rescue StandardError, Timeout::Error

in_flight.unshift req

raise

end

end

responses

rescue Timeout::Error, EOFError, Errno::ECONNABORTED, Errno::ECONNRESET,

Errno::EPIPE, Net::HTTPBadResponse => e

finish

raise PipelineResponseError.new(e, in_flight, responses)

end

# Sends +requests+ to the HTTP server and removes them from the +requests+

# list. Returns the requests that have been pipelined and are in-flight.

#

# If a non-idempotent request is first in +requests+ it will be sent and no

# further requests will be pipelined.

#

# If a non-idempotent request is encountered after an idempotent request it

# will not be sent.

#

# After the response for a non-idempotent request is received another

# series of pipelined requests will be issued via #pipeline.

def pipeline_send requests

in_flight = []

while req = requests.shift do

idempotent = req.idempotent?

unless idempotent or in_flight.empty? then

requests.unshift req

break

end

begin_transport req

req.exec @socket, @curr_http_version, edit_path(req.path)

in_flight << req

break unless idempotent

end

in_flight

end

##

# Is this request idempotent according to RFC 2616?

def idempotent?

case self

when Net::HTTP::Delete, Net::HTTP::Get, Net::HTTP::Head,

Net::HTTP::Options, Net::HTTP::Put, Net::HTTP::Trace then

true

end

end

class TestNetHttp < Test::Unit::TestCase

def test_idempotent_eh

assert Net::HTTP::Delete.new('/').idempotent?

assert Net::HTTP::Get.new('/').idempotent?

assert Net::HTTP::Head.new('/').idempotent?

assert Net::HTTP::Options.new('/').idempotent?

assert Net::HTTP::Put.new('/').idempotent?

assert Net::HTTP::Trace.new('/').idempotent?

refute Net::HTTP::Post.new('/').idempotent?

end

end

class Net::HTTP

attr_accessor :socket_class

end

##

# Records the data Net::BufferedIO sends and receives in write_io and read_io

class TestIO < Net::BufferedIO

attr_reader :read_io

attr_reader :write_io

def self.ios

@ios

end

def self.new(io)

io = super

@ios << io

io

end

def self.reset

@ios = []

end

reset

def initialize(io)

super

@read_io = StringIO.new

@write_io = StringIO.new

end

def rbuf_consume(len)

s = super len

@read_io << s

s

end

def write0(str)

@write_io << str

super

end

end

##

# Raises Errno::ECONNRESET for every request

class ErrorAlways < TestIO

def readline

raise Errno::ECONNRESET

end

end

##

# Raises Errno::ECONNRESET for every request after the first

class ErrorAfterOne < TestIO

def self.reset

@@count = 0

super

end

def readline

@@count += 1

raise Errno::ECONNRESET if @@count >= 2

super

end

end

##

# Raises Errno::ECONNRESET upon the second request

class ErrorAfterOneOnce < TestIO

def self.reset

@@count = 0

super

end

def readline

@@count += 1

raise Errno::ECONNRESET if @@count == 2

super

end

end

##

# Raises Errno::ECONNRESET upon every even request 2, 4, 6

class ErrorEven < TestIO

def self.reset

@@count = 0

super

end

def readline

@@count += 1

raise Errno::ECONNRESET if @@count % 2 == 0

super

end

end

http.socket_class = @net_http_io

TestIO.reset

ErrorAlways.reset

ErrorAfterOne.reset

ErrorAfterOneOnce.reset

ErrorEven.reset

BadOnce.reset

Counter.reset

@net_http_io = TestIO

server_config[:HTTPVersion] = config('http_version') if

config('http_version')

@server.mount('/', Servlet, config('chunked'))

@server.mount('/bad_once', BadOnce)

@server.mount('/close', Closer)

@server.mount('/count', Counter)

@server.mount('/reset_after', ResetAfter)

class BadOnce < WEBrick::HTTPServlet::AbstractServlet

@instance = nil

def self.get_instance(server, *options)

@instance ||= super

end

def self.reset

@instance = nil

end

def initialize(server)

@count = 1

end

def do_GET(req, res)

def res.status_line

"bogus"

end if @count == 1

res.body = "Was bad. Now #{@count}"

@count += 1

end

alias do_POST do_GET

end

class Counter < WEBrick::HTTPServlet::AbstractServlet

@instance = nil

def self.get_instance(server, *options)

@instance ||= super

end

def self.reset

@instance = nil

end

def initialize(server)

@count = 1

end

def do_GET(req, res)

res['Content-Type'] = 'text/plain'

res.body = "Worked #{@count}!"

@count += 1

end

alias do_POST do_GET

end

class Closer < WEBrick::HTTPServlet::AbstractServlet

def do_GET(req, res)

res['Content-Type'] = 'text/plain'

res.body = "closing this connection"

res.close

end

alias do_POST do_GET

end

class ResetAfter < WEBrick::HTTPServlet::AbstractServlet

def do_GET(req, res)

def res._write_data(socket, data)

socket.close_read

socket << data

end

res.body = "Reading has been shut down"

end

alias do_POST do_GET

end

require 'test/unit'

require 'net/http'

require 'stringio'

require 'uri'

require_relative 'utils'

class TestNetHttpPipeline < Test::Unit::TestCase

CONFIG = {

'host' => '127.0.0.1',

'port' => 10083,

'proxy_host' => nil,

'proxy_port' => nil,

'chunked' => true,

}

include TestNetHTTPUtils

def setup

super

@get1 = Net::HTTP::Get.new '/count'

@get2 = Net::HTTP::Get.new '/count'

@get3 = Net::HTTP::Get.new '/count'

@post = Net::HTTP::Post.new '/count'

end

def test_pipeline

requests = [@get1, @get2]

responses = start do |http|

http.pipeline requests

end

assert_equal 'Worked 1!', responses.first.body

assert_equal 'Worked 2!', responses.last.body

refute_empty requests

end

def test_pipeline_block

requests = [@get1, @get2]

responses = []

start do |http|

http.pipeline requests do |req, res| responses << [req, res] end

end

refute_empty requests

assert_equal requests, responses.map { |req,| req }

responses = responses.map { |_, res| res }

assert_equal 'Worked 1!', responses.first.body

assert_equal 'Worked 2!', responses.last.body

end

def test_pipeline_non_idempotent

responses = start do |http|

http.pipelining = true

http.pipeline [@get1, @get2, @post, @get3]

end

assert_equal 'Worked 1!', responses.shift.body

assert_equal 'Worked 2!', responses.shift.body

assert_equal 'Worked 3!', responses.shift.body

assert_equal 'Worked 4!', responses.shift.body

assert responses.empty?

end

def test_pipeline_not_started

@started = false

e = assert_raises Net::HTTP::PipelineError do

http = new

http.pipeline []

end

assert_equal 'Net::HTTP not started', e.message

end

def test_pipeline_retry

requests = [@get1, @get2, @get3]

@net_http_io = ErrorAfterOneOnce

responses = start do |http|

http.pipelining = true

http.pipeline requests

end

assert_equal 'Worked 1!', responses.shift.body

assert_equal 'Worked 3!', responses.shift.body # response 2 was lost

assert_equal 'Worked 4!', responses.shift.body

assert_empty responses

refute_empty requests

end

def test_pipeline_retry_fail_post

@net_http_io = ErrorAlways

requests = [@post]

e = assert_raises Net::HTTP::PipelineResponseError do

start do |http|

http.pipelining = true

http.pipeline requests

end

end

assert_empty e.responses

assert_equal [@post], e.requests

end

def test_pipeline_retry_fail_different

@net_http_io = ErrorEven

requests = [@get1, @get2, @get3]

responses = start do |http|

http.pipelining = true

http.pipeline requests

end

assert_equal 'Worked 1!', responses.shift.body

assert_equal 'Worked 3!', responses.shift.body

assert_equal 'Worked 5!', responses.shift.body

assert_empty responses

refute_empty requests

end

def test_pipeline_retry_fail_same

@net_http_io = ErrorAfterOne

requests = [@get1, @get2, @get3]

e = assert_raises Net::HTTP::PipelineResponseError do

start do |http|

http.pipelining = true

http.pipeline requests

end

end

responses = e.responses

assert_equal 'Worked 1!', responses.shift.body

assert_empty responses

assert_equal [@get2, @get3], e.requests

end

# end #pipeline tests

def test_pipeline_check

requests = [@get1, @get2]

responses = []

start do |http|

http.send :pipeline_check, requests, responses

assert http.pipelining

end

assert_equal [@get2], requests

assert_equal 1, responses.length

assert_equal 'Worked 1!', responses.first.body

end

def test_pipeline_check_again

start do |http|

http.pipelining = false

e = assert_raises Net::HTTP::PipelineUnsupportedError do

http.send :pipeline_check, [@get1, @get2], []

end

assert_equal [@get1, @get2], e.requests

assert_empty e.responses

refute http.pipelining

end

end

def test_pipeline_check_bad_response

bad_once = Net::HTTP::Get.new '/bad_once'

start do |http|

requests = [bad_once, @get2]

responses = []

http.send :pipeline_check, requests, responses

assert_equal [@get2], requests

assert_equal 1, responses.length

assert_equal 'Was bad. Now 2', responses.first.body

assert http.pipelining

end

end

def test_pipeline_check_non_persistent

start do |http|

get1 = Net::HTTP::Get.new '/close'

e = assert_raises Net::HTTP::PipelinePersistenceError do

http.send :pipeline_check, [get1, @get2], []

end

refute http.pipelining

assert_equal [@get2], e.requests

assert_equal 1, e.responses.length

end

end

def test_pipeline_check_pipelining

start do |http|

http.pipelining = true

requests = [@get1, @get2]

responses = []

http.send :pipeline_check, requests, responses

assert_equal [@get1, @get2], requests

assert_empty responses

assert http.pipelining

end

end

def test_pipeline_receive

responses = []

r = start do |http|

in_flight = http.send :pipeline_send, [@get1, @get2]

assert_equal 2, in_flight.length

http.send :pipeline_receive, in_flight, responses

end

assert_equal 'Worked 1!', responses.first.body

assert_equal 'Worked 2!', responses.last.body

assert_same r, responses

end

def test_pipeline_receive_bad_response

bad_once = Net::HTTP::Get.new '/reset_after'

responses = []

start do |http|

in_flight = http.send :pipeline_send, [bad_once, @get2]

e = assert_raises Net::HTTP::PipelineResponseError do

http.send :pipeline_receive, in_flight, responses

end

assert_equal [@get2], e.requests

assert_equal 1, e.responses.length

assert_equal 'Reading has been shut down', e.responses.first.body

assert_kind_of EOFError, e.original

end

end

def test_pipeline_send

requests = [@get1, @get2, @post, @get3]

in_flight = start do |http|

http.send :pipeline_send, requests

end

assert_equal [@get1, @get2], in_flight

assert_equal [@post, @get3], requests

end

def test_pipeline_send_non_idempotent

requests = [@post, @get3]

in_flight = start do |http|

http.send :pipeline_send, requests

end

assert_equal [@post], in_flight

assert_equal [@get3], requests

end

end

class TestNetHttpPipeline_1_0 < Test::Unit::TestCase

CONFIG = {

'host' => '127.0.0.1',

'port' => 10084,

'proxy_host' => nil,

'proxy_port' => nil,

'chunked' => false,

'http_version' => '1.0'

}

include TestNetHTTPUtils

def setup

super

@get1 = Net::HTTP::Get.new '/count'

@get2 = Net::HTTP::Get.new '/count'

end

def test_pipeline_1_0

start do |http|

http.instance_variable_set :@curr_http_version, '1.0'

e = assert_raises Net::HTTP::PipelineUnsupportedError do

http.pipeline [@get1, @get2]

end

assert_equal [@get1, @get2], e.requests

assert_empty e.responses

end

end

def test_pipeline_check_1_0

start do |http|

e = assert_raises Net::HTTP::PipelineUnsupportedError do

http.send :pipeline_check, [@get1, @get2], []

end

assert_match %r%server is HTTP/1\.0%, e.message

assert_equal [@get2], e.requests

assert_equal 1, e.responses.length

assert_equal 'Worked 1!', e.responses.first.body

refute http.pipelining

end

end

end