[PATCH 2/2] wbuf_lite: fix write retries for OpenSSL sockets

[Eric Wong <e@80x24.org>]

OpenSSL can't handle write retries if we append to an existing
string.  Thus we must preserve the same string object upon
retrying.

Do that by utilizing the underlying Wbuf class which could
already handles it transparently using trysendfile.
However, we still avoiding the subtlety of wbuf_close_common
reliance we previously used.

ref: commit 551e670281bea77e727a732ba94275265ccae5f6
("fix output buffering with SSL_write")
---
 lib/yahns/wbuf_lite.rb               | 46 ++++++++++++++++--------------------
 test/test_proxy_pass_no_buffering.rb |  7 +++++-
 2 files changed, 26 insertions(+), 27 deletions(-)

diff --git a/lib/yahns/wbuf_lite.rb b/lib/yahns/wbuf_lite.rb
index 5f25b2e..afee1e9 100644
--- a/lib/yahns/wbuf_lite.rb
+++ b/lib/yahns/wbuf_lite.rb
@@ -2,49 +2,43 @@
 # Copyright (C) 2016 all contributors <yahns-public@yhbt.net>
 # License: GPL-3.0+ <https://www.gnu.org/licenses/gpl-3.0.txt>
 # frozen_string_literal: true
-require_relative 'wbuf_common'
+require_relative 'wbuf'
 
 # This is only used for "proxy_buffering: false"
-class Yahns::WbufLite # :nodoc:
-  include Yahns::WbufCommon
+class Yahns::WbufLite < Yahns::Wbuf # :nodoc:
   attr_reader :busy
 
   def initialize(req_res)
+    super(nil, :ignore)
     @req_res = req_res
-    @busy = false
-    @buf = nil
   end
 
-  # called only by proxy_write in proxy_http_response
   def wbuf_write(client, buf)
-    buf = buf.join if Array === buf
-    buf = @buf << buf if @buf # unlikely
-    do_write(client, buf) # try our best to avoid string copying/appending
+    super
+  rescue
+    @req_res = @req_res.close if @req_res
+    raise
   end
 
-  def do_write(client, buf)
-    case rv = client.kgio_trywrite(buf)
-    when String
-      buf = rv # continue looping
-    when :wait_writable, :wait_readable
-      @buf = buf
-      return @busy = rv
-    when nil
-      @buf = nil
-      return @busy = false
-    end while true
+  def wbuf_flush(client)
+    super
+  rescue
+    @req_res = @req_res.close if @req_res
+    raise
   end
 
   # called by Yahns::HttpClient#step_write
-  def wbuf_flush(client)
-    sym = do_write(client, @buf) and return sym # :wait_writable/:wait_readable
+  def wbuf_close(client)
+    wbuf_abort
 
-    # resume reading
-    client.hijack_cleanup
-    Thread.current[:yahns_queue].queue_mod(@req_res, Yahns::Queue::QEV_RD)
+    # resume reading when @blocked is empty
+    if @req_res
+      client.hijack_cleanup
+      Thread.current[:yahns_queue].queue_mod(@req_res, Yahns::Queue::QEV_RD)
+    end
     :ignore
   rescue
-    @req_res.close
+    @req_res = @req_res.close if @req_res
     raise
   end
 end
diff --git a/test/test_proxy_pass_no_buffering.rb b/test/test_proxy_pass_no_buffering.rb
index 48b8241..b2c8b48 100644
--- a/test/test_proxy_pass_no_buffering.rb
+++ b/test/test_proxy_pass_no_buffering.rb
@@ -79,6 +79,7 @@ def test_proxy_pass_no_buffering
     req = "GET /giant-body HTTP/1.1\r\nHost: example.com\r\n" \
           "Connection: close\r\n\r\n"
     s.write(req)
+    bufs = []
     sleep 1
     10.times do
       sleep 0.1
@@ -91,10 +92,14 @@ def test_proxy_pass_no_buffering
         [ deleted1, deleted2 ].each do |ary|
           ary.delete_if { |x| x =~ /\.(?:err|out) \(deleted\)/ }
         end
-        assert_equal 0, deleted1.size, "pid1=#{deleted1.inspect}"
+        assert_equal 1, deleted1.size, "pid1=#{deleted1.inspect}"
         assert_equal 0, deleted2.size, "pid2=#{deleted2.inspect}"
+        bufs.push(deleted1[0])
       end
     end
+    before = bufs.size
+    bufs.uniq!
+    assert bufs.size < before, 'unlinked buffer should not grow'
     buf = ''.dup
     slow = Digest::MD5.new
     ft = Thread.new do