add an offline precompile workload

Project.toml

@@ -14,6 +14,7 @@ LoggingExtras = "e6f89c97-d47a-5376-807f-9c37f3926c36"
 MbedTLS = "739be429-bea8-5141-9913-cc70e7f3736d"
 NetworkOptions = "ca575930-c2e3-43a9-ace4-1e988b2c1908"
 OpenSSL = "4d8831e6-92b7-49fb-bdf8-b643e874388c"
+PrecompileTools = "aea7be01-6a6a-4083-8856-8a6e6704d82a"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 SimpleBufferStream = "777ac1f9-54b0-4bf8-805c-2214025038e7"
 Sockets = "6462fe0b-24de-5631-8697-dd941f90decc"
@@ -27,6 +28,7 @@ ExceptionUnwrapping = "0.1"
 LoggingExtras = "0.4.9,1"
 MbedTLS = "0.6.8, 0.7, 1"
 OpenSSL = "1.3"
+PrecompileTools = "1.2.1"
 SimpleBufferStream = "1.1"
 URIs = "1.3"
 julia = "1.6"
@@ -37,9 +39,9 @@ Deno_jll = "04572ae6-984a-583e-9378-9577a1c2574d"
 Distributed = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 InteractiveUtils = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
 JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
+NetworkOptions = "ca575930-c2e3-43a9-ace4-1e988b2c1908"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
-NetworkOptions = "ca575930-c2e3-43a9-ace4-1e988b2c1908"
 
 [targets]
 test = ["BufferedStreams", "Deno_jll", "Distributed", "InteractiveUtils", "JSON", "Test", "Unitful", "NetworkOptions"]

src/HTTP.jl

@@ -631,4 +631,9 @@ function Base.parse(::Type{T}, str::AbstractString)::T where T <: Message
     return m
 end
 
+# only run if precompiling
+if ccall(:jl_generating_output, Cint, ()) == 1
+    include("precompile.jl")
+end
+
 end # module

src/precompile.jl

@@ -0,0 +1,30 @@
+using PrecompileTools: @setup_workload, @compile_workload
+
+@setup_workload begin
+    # These need to be safe to call here and bake into the pkgimage, i.e. called twice.
+    Connections.__init__()
+    MultiPartParsing.__init__()
+    Parsers.__init__()
+
+    # Doesn't seem to be needed here, and might not be safe to call twice (here and during runtime)
+    # ConnectionRequest.__init__()
+
+    gzip_data(data::String) = read(GzipCompressorStream(IOBuffer(data)))
+
+    # random port in the dynamic/private range (49152–65535) which are are
+    # least likely to be used by well-known services
+    _port = 57813
+
+    server = HTTP.serve!("0.0.0.0", _port; verbose = -1, listenany=true) do req
+        HTTP.Response(200,  ["Content-Encoding" => "gzip"], gzip_data("dummy response"))
+    end
+    # listenany allows changing port if that one is already in use, so check the actual port
+    _port = HTTP.port(server)
+
+    @compile_workload begin
+        HTTP.get("http://localhost:$_port")
+    end
+
+    HTTP.forceclose(server)
+    server = nothing
+end