From: Martin Mares <mj@ucw.cz>
Date: Thu, 19 Aug 2004 13:47:23 +0000 (+0000)
Subject: A better implementation of vbprintf() which avoids copying if there is enough
X-Git-Tag: holmes-import~915
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=9c21b55e57a42cabe0ee81489ce232834885f7b1;p=libucw.git

A better implementation of vbprintf() which avoids copying if there is enough
room in the fastbuf's buffer.
---

diff --git a/lib/ff-printf.c b/lib/ff-printf.c
index 395e04b2..d22d421d 100644
--- a/lib/ff-printf.c
+++ b/lib/ff-printf.c
@@ -16,7 +16,24 @@ int
 vbprintf(struct fastbuf *b, byte *msg, va_list args)
 {
   byte *buf;
-  int r, len = 256;
+  int len, r;
+
+  len = bdirect_write_prepare(b, &buf);
+  if (len >= 16)
+    {
+      r = vsnprintf(buf, len, msg, args);
+      if (r < 0)
+	len = 256;
+      else if (r < len)
+	{
+	  bdirect_write_commit(b, buf+r);
+	  return r;
+	}
+      else
+	len = r+1;
+    }
+  else
+    len = 256;
 
   while (1)
     {
@@ -51,7 +68,8 @@ bprintf(struct fastbuf *b, byte *msg, ...)
 int main(void)
 {
   struct fastbuf *b = bfdopen_shared(1, 65536);
-  bprintf(b, "13=%d str=<%s> msg=%m\n", 13, "str");
+  for (int i=0; i<10000; i++)
+    bprintf(b, "13=%d str=<%s> msg=%m\n", 13, "str");
   bclose(b);
   return 0;
 }