introduce :buffer_size option

this allows to tweak connection buffer sizes, which may help optimizing
memory usage, and in this case, test the resumable retries.

wip

lib/httpx/connection.rb

@@ -39,8 +39,6 @@ module HTTPX
     require "httpx/connection/http2"
     require "httpx/connection/http1"
 
-    BUFFER_SIZE = 1 << 14
-
     def_delegator :@io, :closed?
 
     def_delegator :@write_buffer, :empty?
@@ -57,8 +55,8 @@ module HTTPX
       @origin = Utils.to_uri(uri.origin)
       @options = Options.new(options)
       @window_size = @options.window_size
-      @read_buffer = Buffer.new(BUFFER_SIZE)
-      @write_buffer = Buffer.new(BUFFER_SIZE)
+      @read_buffer = Buffer.new(@options.buffer_size)
+      @write_buffer = Buffer.new(@options.buffer_size)
       @pending = []
       on(:error, &method(:on_error))
       if @options.io

lib/httpx/options.rb

@@ -4,6 +4,7 @@ require "socket"
 
 module HTTPX
   class Options
+    BUFFER_SIZE = 1 << 14
     WINDOW_SIZE = 1 << 14 # 16K
     MAX_BODY_THRESHOLD_SIZE = (1 << 10) * 112 # 112K
     CONNECT_TIMEOUT = 60
@@ -41,6 +42,7 @@ module HTTPX
       },
       :headers => {},
       :window_size => WINDOW_SIZE,
+      :buffer_size => BUFFER_SIZE,
       :body_threshold_size => MAX_BODY_THRESHOLD_SIZE,
       :request_class => Class.new(Request),
       :response_class => Class.new(Response),
@@ -178,7 +180,19 @@ module HTTPX
     end
 
     def option_window_size(value)
-      Integer(value)
+      value = Integer(value)
+
+      raise TypeError, ":window_size must be positive" unless value.positive?
+
+      value
+    end
+
+    def option_buffer_size(value)
+      value = Integer(value)
+
+      raise TypeError, ":buffer_size must be positive" unless value.positive?
+
+      value
     end
 
     def option_body_threshold_size(value)

sig/connection.rbs

@@ -19,7 +19,6 @@ module HTTPX
     include Callbacks
     include HTTPX::Registry[String, Class]
 
-    BUFFER_SIZE: Integer
 
     attr_reader type: io_type
     attr_reader origin: URI::Generic

sig/options.rbs

@@ -2,6 +2,7 @@ module HTTPX
   class Options
     # include _ToHash
 
+    BUFFER_SIZE: Integer
     WINDOW_SIZE: Integer
     MAX_BODY_THRESHOLD_SIZE: Integer
     CONNECT_TIMEOUT: Integer
@@ -38,6 +39,9 @@ module HTTPX
     # window_size
     attr_reader window_size: Integer
 
+    # buffer_size
+    attr_reader buffer_size: Integer
+
     # body_threshold_size
     attr_reader body_threshold_size: Integer
 

test/options_test.rb

@@ -100,6 +100,7 @@ class OptionsTest < Minitest::Test
       :json => nil,
       :xml => nil,
       :body => nil,
+      :buffer_size => 16_384,
       :window_size => 16_384,
       :body_threshold_size => 114_688,
       :form => { foo: "foo", :bar => "bar" },

test/support/requests/plugins/retries.rb

@@ -98,7 +98,7 @@ module Requests
       end
 
       def test_plugin_retries_resumable
-        resumable_uri = build_uri("/range/200")
+        resumable_uri = build_uri("/range/200?chunk_size=100")
         full_payload = HTTPX.get(resumable_uri).raise_for_status.to_s
 
         retries_session = HTTPX
@@ -106,7 +106,9 @@ module Requests
                           .plugin(RequestFailAfter100Bytes)
                           .plugin(:retries)
                           .max_retries(2)
-                          .with(retry_on: ->(res) { res.error.is_a?(RequestFailAfter100Bytes::BiggerThan100Bytes) }, window_size: 100)
+                          .with(retry_on: ->(res) {
+                            res.error && res.error.message == "over 100 bytes"
+                          }, window_size: 50, buffer_size: 50, http2_settings: { settings_initial_window_size: 100 })
         retries_response = retries_session.get(resumable_uri)
         verify_status(retries_response, 200)
         assert retries_response.to_s == full_payload
@@ -128,7 +130,7 @@ module Requests
           def write(chunk)
             val = super
 
-            raise(BiggerThan100Bytes, "ouch") if (100..199).cover?(@length)
+            raise(BiggerThan100Bytes, "over 100 bytes") if (100..199).cover?(@length)
 
             val
           end