Reduce slightly allocations when reading/writing HTTP messages (#950)

* Avoid creating additional string when writing headers

* Define our own simpler Version type

* Update src/Messages.jl

Co-authored-by: Jacob Quinn <[email protected]>

* Update src/Messages.jl

Co-authored-by: Jacob Quinn <[email protected]>

* Test we don't allocate

* Tidy tests

* Remove unused code

* Update src/clientlayers/MessageRequest.jl

* Write headers to temporary buffer first

- ...before flushing to socket, to avoid task switching
  mid writing to the socket itself.

* Remove unneeded temp buffer in Stream startwrite

* Make loopback test less flaky by using Event instead of sleep

* Don't connect a socket for Loopback test

- unnecessary and was leading to occasional DNS Errors

Co-authored-by: Jacob Quinn <[email protected]>

src/ConnectionPool.jl

@@ -72,6 +72,7 @@ mutable struct Connection <: IO
     timestamp::Float64
     readable::Bool
     writable::Bool
+    writebuffer::IOBuffer
     state::Any # populated & used by Servers code
 end
 
@@ -92,7 +93,7 @@ Connection(host::AbstractString, port::AbstractString,
     Connection(host, port, idle_timeout,
                 require_ssl_verification,
                 safe_getpeername(io)..., localport(io),
-                io, client, PipeBuffer(), time(), false, false, nothing)
+                io, client, PipeBuffer(), time(), false, false, IOBuffer(), nothing)
 
 Connection(io; require_ssl_verification::Bool=true) =
     Connection("", "", 0, require_ssl_verification, io, false)

src/Messages.jl

@@ -61,6 +61,7 @@ export Message, Request, Response,
 
 using URIs, CodecZlib
 using ..Pairs, ..IOExtras, ..Parsers, ..Strings, ..Forms, ..Conditions
+using ..ConnectionPool
 
 const nobody = UInt8[]
 const unknown_length = typemax(Int)
@@ -77,7 +78,7 @@ abstract type Message end
 
 Represents an HTTP response message with fields:
 
-- `version::VersionNumber`
+- `version::HTTPVersion`
    [RFC7230 2.6](https://tools.ietf.org/html/rfc7230#section-2.6)
 
 - `status::Int16`
@@ -94,14 +95,14 @@ Represents an HTTP response message with fields:
 
 """
 mutable struct Response <: Message
-    version::VersionNumber
+    version::HTTPVersion
     status::Int16
     headers::Headers
     body::Any # Usually Vector{UInt8} or IO
     request::Union{Message, Nothing} # Union{Request, Nothing}
 end
 
-function Response(status::Integer, headers, body; version::VersionNumber=v"1.1", request=nothing)
+function Response(status::Integer, headers, body; version=HTTPVersion(1, 1), request=nothing)
     b = isbytes(body) ? bytes(body) : something(body, nobody)
     @assert (request isa Request || request === nothing)
     return Response(version, status, mkheaders(headers), b, request)
@@ -119,7 +120,7 @@ Response(body) = Response(200; body=body)
 Base.convert(::Type{Response}, s::AbstractString) = Response(s)
 
 function reset!(r::Response)
-    r.version = v"1.1"
+    r.version = HTTPVersion(1, 1)
     r.status = 0
     if !isempty(r.headers)
         empty!(r.headers)
@@ -136,8 +137,10 @@ body(r::Response) = getfield(r, :body)
 const Context = Dict{Symbol, Any}
 
 """
-    HTTP.Request(method, target, headers=[], body=nobody;
-        version=v"1.1", url::URI=URI(), responsebody=nothing, parent=nothing, context=HTTP.Context())
+    HTTP.Request(
+        method, target, headers=[], body=nobody;
+        version=v"1.1", url::URI=URI(), responsebody=nothing, parent=nothing, context=HTTP.Context()
+    )
 
 Represents a HTTP Request Message with fields:
 
@@ -147,7 +150,7 @@ Represents a HTTP Request Message with fields:
 - `target::String`
    [RFC7230 5.3](https://tools.ietf.org/html/rfc7230#section-5.3)
 
-- `version::VersionNumber`
+- `version::HTTPVersion`
    [RFC7230 2.6](https://tools.ietf.org/html/rfc7230#section-2.6)
 
 - `headers::HTTP.Headers`
@@ -170,7 +173,7 @@ Represents a HTTP Request Message with fields:
 mutable struct Request <: Message
     method::String
     target::String
-    version::VersionNumber
+    version::HTTPVersion
     headers::Headers
     body::Any # Usually Vector{UInt8} or some kind of IO
     response::Response
@@ -181,8 +184,10 @@ end
 
 Request() = Request("", "")
 
-function Request(method::String, target, headers=[], body=nobody;
-                 version=v"1.1", url::URI=URI(), responsebody=nothing, parent=nothing, context=Context())
+function Request(
+    method::String, target, headers=[], body=nobody;
+    version=HTTPVersion(1, 1), url::URI=URI(), responsebody=nothing, parent=nothing, context=Context()
+)
     b = isbytes(body) ? bytes(body) : body
     r = Request(method, target == "" ? "/" : target, version,
                 mkheaders(headers), b, Response(0; body=responsebody),
@@ -463,26 +468,19 @@ function decode(m::Message, encoding::String="gzip")::Vector{UInt8}
 end
 
 # Writing HTTP Messages to IO streams
-"""
-    HTTP.httpversion(::Message)
-
-e.g. `"HTTP/1.1"`
-"""
-httpversion(m::Message) = "HTTP/$(m.version.major).$(m.version.minor)"
+Base.write(io::IO, v::HTTPVersion) = write(io, "HTTP/", string(v.major), ".", string(v.minor))
 
 """
     writestartline(::IO, ::Message)
 
 e.g. `"GET /path HTTP/1.1\\r\\n"` or `"HTTP/1.1 200 OK\\r\\n"`
 """
 function writestartline(io::IO, r::Request)
-    write(io, "$(r.method) $(r.target) $(httpversion(r))\r\n")
-    return
+    return write(io, r.method, " ", r.target, " ", r.version, "\r\n")
 end
 
 function writestartline(io::IO, r::Response)
-    write(io, "$(httpversion(r)) $(r.status) $(statustext(r.status))\r\n")
-    return
+    return write(io, r.version, " ", string(r.status), " ", statustext(r.status), "\r\n")
 end
 
 """
@@ -491,14 +489,18 @@ end
 Write `Message` start line and
 a line for each "name: value" pair and a trailing blank line.
 """
-function writeheaders(io::IO, m::Message)
-    writestartline(io, m)
+writeheaders(io::IO, m::Message) = writeheaders(io, m, IOBuffer())
+writeheaders(io::Connection, m::Message) = writeheaders(io, m, io.writebuffer)
+
+function writeheaders(io::IO, m::Message, buf::IOBuffer)
+    writestartline(buf, m)
     for (name, value) in m.headers
         # match curl convention of not writing empty headers
-        !isempty(value) && write(io, "$name: $value\r\n")
+        !isempty(value) && write(buf, name, ": ", value, "\r\n")
     end
-    write(io, "\r\n")
-    return
+    write(buf, "\r\n")
+    nwritten = write(io, take!(buf))
+    return nwritten
 end
 
 """
@@ -507,15 +509,15 @@ end
 Write start line, headers and body of HTTP Message.
 """
 function Base.write(io::IO, m::Message)
-    writeheaders(io, m)
-    write(io, m.body)
-    return
+    nwritten = writeheaders(io, m)
+    nwritten += write(io, m.body)
+    return nwritten
 end
 
 function Base.String(m::Message)
     io = IOBuffer()
     write(io, m)
-    String(take!(io))
+    return String(take!(io))
 end
 
 # Reading HTTP Messages from IO streams
@@ -589,7 +591,7 @@ end
 function compactstartline(m::Message)
     b = IOBuffer()
     writestartline(b, m)
-    strip(String(take!(b)))
+    return strip(String(take!(b)))
 end
 
 # temporary replacement for isvalid(String, s), until the

src/Parsers.jl

@@ -191,7 +191,7 @@ function parse_request_line!(bytes::AbstractString, request)::SubString{String}
     end
     request.method = group(1, re, bytes)
     request.target = group(2, re, bytes)
-    request.version = VersionNumber(group(3, re, bytes))
+    request.version = HTTPVersion(group(3, re, bytes))
     return nextbytes(re, bytes)
 end
 
@@ -205,7 +205,7 @@ function parse_status_line!(bytes::AbstractString, response)::SubString{String}
     if !exec(re, bytes)
         throw(ParseError(:INVALID_STATUS_LINE, bytes))
     end
-    response.version = VersionNumber(group(1, re, bytes))
+    response.version = HTTPVersion(group(1, re, bytes))
     response.status = parse(Int, group(2, re, bytes))
     return nextbytes(re, bytes)
 end

src/Servers.jl

@@ -494,7 +494,7 @@ function check_readtimeout(c, readtimeout, wait_for_timeout)
         if inactiveseconds(c) > readtimeout
             @warnv 2 "Connection Timeout: $c"
             try
-                writeheaders(c.io, Response(408, ["Connection" => "close"]))
+                writeheaders(c, Response(408, ["Connection" => "close"]))
             finally
                 closeconnection(c)
             end

src/Streams.jl

@@ -76,9 +76,7 @@ function IOExtras.startwrite(http::Stream)
     else
         http.writechunked = ischunked(m)
     end
-    buf = IOBuffer()
-    writeheaders(buf, m)
-    n = write(http.stream, take!(buf))
+    n = writeheaders(http.stream, m)
     # nwritten starts at -1 so that we can tell if we've written anything yet
     http.nwritten = 0 # should not include headers
     return n

src/Strings.jl

@@ -1,9 +1,88 @@
 module Strings
 
-export escapehtml, tocameldash, iso8859_1_to_utf8, ascii_lc_isequal
+export HTTPVersion, escapehtml, tocameldash, iso8859_1_to_utf8, ascii_lc_isequal
 
 using ..IOExtras
 
+# A `Base.VersionNumber` is a SemVer spec, whereas a HTTP versions is just 2 digits,
+# This allows us to use a smaller type and more importantly write a simple parse method
+# that avoid allocations.
+"""
+    HTTPVersion(major, minor)
+
+The HTTP version number consists of two digits separated by a
+"." (period or decimal point). The first digit (`major` version)
+indicates the HTTP messaging syntax, whereas the second digit (`minor`
+version) indicates the highest minor version within that major
+version to which the sender is conformant and able to understand for
+future communication.
+
+See [RFC7230 2.6](https://tools.ietf.org/html/rfc7230#section-2.6)
+"""
+struct HTTPVersion
+    major::UInt8
+    minor::UInt8
+end
+
+HTTPVersion(major::Integer) = HTTPVersion(major, 0x00)
+HTTPVersion(v::AbstractString) = parse(HTTPVersion, v)
+HTTPVersion(v::VersionNumber) = convert(HTTPVersion, v)
+# Lossy conversion. We ignore patch/prerelease/build parts even if non-zero/non-empty,
+# because we don't want to add overhead for a case that should never be relevant.
+Base.convert(::Type{HTTPVersion}, v::VersionNumber) = HTTPVersion(v.major, v.minor)
+Base.VersionNumber(v::HTTPVersion) = VersionNumber(v.major, v.minor)
+
+Base.show(io::IO, v::HTTPVersion) = print(io, "HTTPVersion(\"", string(v.major), ".", string(v.minor), "\")")
+
+Base.:(==)(va::VersionNumber, vb::HTTPVersion) = va == VersionNumber(vb)
+Base.:(==)(va::HTTPVersion, vb::VersionNumber) = VersionNumber(va) == vb
+
+Base.isless(va::VersionNumber, vb::HTTPVersion) = isless(va, VersionNumber(vb))
+Base.isless(va::HTTPVersion, vb::VersionNumber) = isless(VersionNumber(va), vb)
+function Base.isless(va::HTTPVersion, vb::HTTPVersion)
+    va.major < vb.major && return true
+    va.major > vb.major && return false
+    va.minor < vb.minor && return true
+    return false
+end
+
+function Base.parse(::Type{HTTPVersion}, v::AbstractString)
+    ver = tryparse(HTTPVersion, v)
+    ver === nothing && throw(ArgumentError("invalid HTTP version string: $(repr(v))"))
+    return ver
+end
+
+# We only support single-digits for major and minor versions
+# - we can parse 0.9 but not 0.10
+# - we can parse 9.0 but not 10.0
+function Base.tryparse(::Type{HTTPVersion}, v::AbstractString)
+    isempty(v) && return nothing
+    len = ncodeunits(v)
+
+    i = firstindex(v)
+    d1 = v[i]
+    if isdigit(d1)
+        major = parse(UInt8, d1)
+    else
+        return nothing
+    end
+
+    i = nextind(v, i)
+    i > len && return HTTPVersion(major)
+    dot = v[i]
+    dot == '.' || return nothing
+
+    i = nextind(v, i)
+    i > len && return HTTPVersion(major)
+    d2 = v[i]
+    if isdigit(d2)
+        minor = parse(UInt8, d2)
+    else
+        return nothing
+    end
+    return HTTPVersion(major, minor)
+end
+
 """
     escapehtml(i::String)
 

src/clientlayers/MessageRequest.jl

@@ -2,6 +2,8 @@ module MessageRequest
 
 using URIs
 using ..IOExtras, ..Messages, ..Parsers, ..Exceptions
+using ..Messages, ..Parsers
+using ..Strings: HTTPVersion
 
 export messagelayer
 
@@ -12,7 +14,7 @@ Construct a [`Request`](@ref) object from method, url, headers, and body.
 Hard-coded as the first layer in the request pipeline.
 """
 function messagelayer(handler)
-    return function(method::String, url::URI, headers::Headers, body; response_stream=nothing, http_version=v"1.1", kw...)
+    return function(method::String, url::URI, headers::Headers, body; response_stream=nothing, http_version=HTTPVersion(1, 1), kw...)
         req = Request(method, resource(url), headers, body; url=url, version=http_version, responsebody=response_stream)
         local resp
         try

test/httpversion.jl

@@ -0,0 +1,31 @@
+@testset "HTTPVersion" begin
+
+# Constructors
+@test HTTPVersion(1) == HTTPVersion(1, 0)
+@test HTTPVersion(1) == HTTPVersion("1")
+@test HTTPVersion(1) == HTTPVersion("1.0")
+@test HTTPVersion(1) == HTTPVersion(v"1")
+@test HTTPVersion(1) == HTTPVersion(v"1.0")
+
+@test HTTPVersion(1, 1) == HTTPVersion("1.1")
+@test HTTPVersion(1, 1) == HTTPVersion(v"1.1")
+@test HTTPVersion(1, 1) == HTTPVersion(v"1.1.0")
+
+@test VersionNumber(HTTPVersion(1)) == v"1"
+@test VersionNumber(HTTPVersion(1, 1)) == v"1.1"
+
+# Important that we can parse a string into a `HTTPVersion` without allocations,
+# as we do this for every request/response. Similarly if we then want a `VersionNumber`.
+@test @allocated(HTTPVersion("1.1")) == 0
+@test @allocated(VersionNumber(HTTPVersion("1.1"))) == 0
+
+# Test comparisons with `VersionNumber`s
+req = HTTP.Request("GET", "http://httpbin.org/anything")
+res = HTTP.Response(200)
+for r in (req, res)
+    @test r.version == v"1.1"
+    @test r.version <= v"1.1"
+    @test r.version < v"1.2"
+end
+
+end # testset

test/loopback.jl

@@ -43,7 +43,7 @@ Base.readavailable(fio::FunctionIO) = (call(fio); readavailable(fio.buf))
 Base.readavailable(lb::Loopback) = readavailable(lb.io)
 Base.unsafe_read(lb::Loopback, p::Ptr, n::Integer) = unsafe_read(lb.io, p, n)
 
-HTTP.IOExtras.tcpsocket(::Loopback) = Sockets.connect("$httpbin", 80)
+HTTP.IOExtras.tcpsocket(::Loopback) = TCPSocket()
 
 lbreq(req, headers, body; method="GET", kw...) =
       HTTP.request(method, "http://test/$req", headers, body; config..., kw...)
@@ -262,8 +262,9 @@ end
         @test_throws HTTP.StatusError begin
             r = lbopen("abort", []) do http
                 @sync begin
+                    event = Base.Event()
                     @async try
-                        sleep(0.1)
+                        wait(event)
                         write(http, "Hello World!")
                         closewrite(http)
                         body_sent = true
@@ -278,6 +279,7 @@ end
                     startread(http)
                     body = read(http)
                     closeread(http)
+                    notify(event)
                 end
             end
         end