From a256a05fe3785c245f77761db19658c8bbc2b87a Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Tue, 24 Sep 2002 21:38:21 +0000
Subject: [PATCH] After a lot of benchmarking replaced the old super-smart
 bbcopy() by a much simpler solution based on the bdirect interface and
 inlined the fast path. Surprisingly, the new version is faster under real
 load (the explanation is very simple: we use very large buffers for the
 indexer and hence the bbcopy optimizations triggered rarely) and it also
 works on all fastbuf streams, not only file-based ones.

Also, made bdirect_* inline.
---
 lib/fastbuf.c | 41 ++++++++++++++++-------------------------
 lib/fastbuf.h | 49 ++++++++++++++++++++++++++++++++++++++++++++-----
 lib/fb-file.c | 45 ---------------------------------------------
 3 files changed, 60 insertions(+), 75 deletions(-)

diff --git a/lib/fastbuf.c b/lib/fastbuf.c
index 1b89a813..2631be06 100644
--- a/lib/fastbuf.c
+++ b/lib/fastbuf.c
@@ -284,32 +284,23 @@ bgets0(struct fastbuf *f, byte *b, uns l)
   die("%s: Line too long", f->name);
 }
 
-int
-bdirect_read_prepare(struct fastbuf *f, byte **buf)
-{
-  if (f->bptr == f->bstop && !f->refill(f))
-    return EOF;
-  *buf = f->bptr;
-  return f->bstop - f->bptr;
-}
-
 void
-bdirect_read_commit(struct fastbuf *f, byte *pos)
-{
-  f->bptr = pos;
-}
-
-int
-bdirect_write_prepare(struct fastbuf *f, byte **buf)
+bbcopy_slow(struct fastbuf *f, struct fastbuf *t, uns l)
 {
-  if (f->bptr == f->bufend)
-    f->spout(f);
-  *buf = f->bptr;
-  return f->bufend - f->bptr;
-}
+  while (l)
+    {
+      byte *fptr, *tptr;
+      uns favail, tavail, n;
 
-void
-bdirect_write_commit(struct fastbuf *f, byte *pos)
-{
-  f->bptr = pos;
+      favail = bdirect_read_prepare(f, &fptr);
+      if (favail == (uns)EOF)
+	die("bbcopy: source exhausted");
+      tavail = bdirect_write_prepare(t, &tptr);
+      n = MIN(l, favail);
+      n = MIN(n, tavail);
+      memcpy(tptr, fptr, n);
+      bdirect_read_commit(f, fptr + n);
+      bdirect_write_commit(t, tptr + n);
+      l -= n;
+    }
 }
diff --git a/lib/fastbuf.h b/lib/fastbuf.h
index 7baa5013..4f6c5e66 100644
--- a/lib/fastbuf.h
+++ b/lib/fastbuf.h
@@ -77,7 +77,6 @@ struct fastbuf *bopen(byte *name, uns mode, uns buffer);
 struct fastbuf *bopen_tmp(uns buffer);
 struct fastbuf *bfdopen(int fd, uns buffer);
 struct fastbuf *bfdopen_shared(int fd, uns buffer);
-void bbcopy(struct fastbuf *f, struct fastbuf *t, uns l);
 #define FB_IS_TEMP_FILE(f) FB_FILE(f)->is_temp_file
 
 /* FastIO on in-memory streams */
@@ -286,6 +285,21 @@ bputsn(struct fastbuf *f, byte *b)
   bputc(f, '\n');
 }
 
+void bbcopy_slow(struct fastbuf *f, struct fastbuf *t, uns l);
+static inline void
+bbcopy(struct fastbuf *f, struct fastbuf *t, uns l)
+{
+  if (f->bptr + l <= f->bstop &&
+      t->bptr + l <= t->bufend)
+    {
+      memcpy(t->bptr, f->bptr, l);
+      t->bptr += l;
+      f->bptr += l;
+    }
+  else
+    bbcopy_slow(f, t, l);
+}
+
 /* I/O on addr_int_t */
 
 #ifdef CPU_64BIT_POINTERS
@@ -298,9 +312,34 @@ bputsn(struct fastbuf *f, byte *b)
 
 /* Direct I/O on buffers */
 
-int bdirect_read_prepare(struct fastbuf *f, byte **buf);
-void bdirect_read_commit(struct fastbuf *f, byte *pos);
-int bdirect_write_prepare(struct fastbuf *f, byte **buf);
-void bdirect_write_commit(struct fastbuf *f, byte *pos);
+static inline int
+bdirect_read_prepare(struct fastbuf *f, byte **buf)
+{
+  if (f->bptr == f->bstop && !f->refill(f))
+    return EOF;
+  *buf = f->bptr;
+  return f->bstop - f->bptr;
+}
+
+static inline void
+bdirect_read_commit(struct fastbuf *f, byte *pos)
+{
+  f->bptr = pos;
+}
+
+static inline int
+bdirect_write_prepare(struct fastbuf *f, byte **buf)
+{
+  if (f->bptr == f->bufend)
+    f->spout(f);
+  *buf = f->bptr;
+  return f->bufend - f->bptr;
+}
+
+static inline void
+bdirect_write_commit(struct fastbuf *f, byte *pos)
+{
+  f->bptr = pos;
+}
 
 #endif
diff --git a/lib/fb-file.c b/lib/fb-file.c
index 73a2f143..b5e6b646 100644
--- a/lib/fb-file.c
+++ b/lib/fb-file.c
@@ -126,51 +126,6 @@ bfdopen_shared(int fd, uns buffer)
   return f;
 }
 
-void bbcopy(struct fastbuf *f, struct fastbuf *t, uns l)
-{
-  uns rf = f->bstop - f->bptr;
-  uns tbuflen = t->bufend - t->buffer;
-
-  ASSERT(f->close == bfd_close);
-  ASSERT(t->close == bfd_close);
-  if (!l)
-    return;
-  if (rf)
-    {
-      uns k = MIN(rf, l);
-      bwrite(t, f->bptr, k);
-      f->bptr += k;
-      l -= k;
-      if (!l)
-	return;
-    }
-  while (l >= tbuflen)
-    {
-      t->spout(t);
-      if ((uns) read(FB_FILE(f)->fd, t->buffer, tbuflen) != tbuflen)
-	die("bbcopy: %s exhausted", f->name);
-      f->pos += tbuflen;
-      f->bstop = f->bptr = f->buffer;
-      t->bptr = t->bufend;
-      l -= tbuflen;
-    }
-  while (l)
-    {
-      uns k = t->bufend - t->bptr;
-
-      if (!k)
-	{
-	  t->spout(t);
-	  k = t->bufend - t->bptr;
-	}
-      if (k > l)
-	k = l;
-      bread(f, t->bptr, k);
-      t->bptr += k;
-      l -= k;
-    }
-}
-
 #ifdef TEST
 
 int main(int argc, char **argv)
-- 
2.39.2