[PATCH] use String#clear for short-lived buffers we create

[PATCH] use String#clear for short-lived buffers we create

[Eric Wong]

This should reduce memory pressure slightly as we can
have finer-grained control of memory usage for buffers which
can be several kilobytes large.

It is not safe to do this for output buffers we get from the
application, as they may reuse that memory themselves.
---
 lib/yahns/http_response.rb    | 6 ++++--
 lib/yahns/max_body/wrapper.rb | 2 ++
 lib/yahns/tee_input.rb        | 1 +
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/yahns/http_response.rb b/lib/yahns/http_response.rb
index 292fab7..4b36db2 100644
--- a/lib/yahns/http_response.rb
+++ b/lib/yahns/http_response.rb
@@ -162,11 +162,13 @@ def http_response_write(status, headers, body)
                     : "Connection: close\r\n\r\n".freeze)
       case rv = kgio_syssend(buf, flags)
       when nil # all done, likely
+        buf.clear
+        buf = nil # recycle any memory we used ASAP
         break
       when String
         flags = MSG_DONTWAIT
-        buf = rv # hope the skb grows
-      when :wait_writable, :wait_readable
+        buf = rv # unlikely, hope the skb grows
+      when :wait_writable, :wait_readable # unlikely
         if k.output_buffering
           alive = hijack ? hijack : alive
           rv = response_header_blocked(rv, buf, body, alive, offset, count)
diff --git a/lib/yahns/max_body/wrapper.rb b/lib/yahns/max_body/wrapper.rb
index b75c3b6..b6ca1a3 100644
--- a/lib/yahns/max_body/wrapper.rb
+++ b/lib/yahns/max_body/wrapper.rb
@@ -48,6 +48,7 @@ def gets
 
       if tmp = checked_read(16384)
         @rbuf << tmp
+        tmp.clear
       elsif @rbuf.empty? # EOF
         return nil
       else # EOF, return whatever is left
@@ -69,6 +70,7 @@ def read_all
     while checked_read(16384, tmp)
       rv << tmp
     end
+    tmp.clear
     rv
   end
 end
diff --git a/lib/yahns/tee_input.rb b/lib/yahns/tee_input.rb
index 55b1604..93ec148 100644
--- a/lib/yahns/tee_input.rb
+++ b/lib/yahns/tee_input.rb
@@ -100,6 +100,7 @@ def consume!
     junk = ''.dup
     rsize = __rsize
     nil while read(rsize, junk)
+    junk.clear
   end
 
   def tee(buffer)
-- 
EW