wbuf: only enable bypass if we've truncated

The first time we call wbuf_write, we do so because we already hit
:wait_writable in the caller.  So we can avoid the extra
still-highly-likely-to-return-:wait_*) kgio_trywrite by writing to
the VFS, first.

1 files changed, 10 insertions, 10 deletions

diff --git a/lib/yahns/wbuf.rb b/lib/yahns/wbuf.rb
index 10312db..8b2b82e 100644
--- a/lib/yahns/wbuf.rb
+++ b/lib/yahns/wbuf.rb
@@ -11,20 +11,19 @@ class Yahns::Wbuf # :nodoc:
     @sf_offset = @sf_count = 0
     @wbuf_persist = persist # whether or not we keep the connection alive
     @body = body
+    @bypass = false
   end
 
   def wbuf_write(client, buf)
     # try to bypass the VFS layer if we're all caught up
-    if @sf_count == 0
-      case rv = client.kgio_trywrite(buf)
-      when String
-        buf = rv # retry in loop
-      when nil
-        return nil # yay! hopefully we don't have to buffer again
-      when :wait_writable, :wait_readable
-        break # ugh, continue to buffering to file
-      end while true
-    end
+    case rv = client.kgio_trywrite(buf)
+    when String
+      buf = rv # retry in loop
+    when nil
+      return # yay! hopefully we don't have to buffer again
+    when :wait_writable, :wait_readable
+      @bypass = false # ugh, continue to buffering to file
+    end while @bypass
 
     @sf_count += @tmpio.write(buf)
     case rv = client.trysendfile(@tmpio, @sf_offset, @sf_count)
@@ -42,6 +41,7 @@ class Yahns::Wbuf # :nodoc:
     # to disk if we can help it.
     @tmpio.truncate(@sf_offset = 0)
     @tmpio.rewind
+    @bypass = true
     nil
   end