X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lib%2Ffb-file.c;h=66227ed1b3ef3935ae09c97710b2403b26d66ef7;hb=d5e8872563f6fde8299db971ffb6494c2438c590;hp=0d1cc96cbd8cca573086d4302f76355398271142;hpb=2c9aa505622e524dd4fa031981da1b432c8fadef;p=libucw.git

diff --git a/lib/fb-file.c b/lib/fb-file.c
index 0d1cc96c..66227ed1 100644
--- a/lib/fb-file.c
+++ b/lib/fb-file.c
@@ -2,6 +2,7 @@
  *	UCW Library -- Fast Buffered I/O on Files
  *
  *	(c) 1997--2004 Martin Mares <mj@ucw.cz>
+ *	(c) 2007 Pavel Charvat <pchar@ucw.cz>
  *
  *	This software may be freely distributed and used according to the terms
  *	of the GNU Lesser General Public License.
@@ -20,6 +21,9 @@ struct fb_file {
   struct fastbuf fb;
   int fd;				/* File descriptor */
   int is_temp_file;			/* 0=normal file, 1=temporary file, delete on close, -1=shared FD */
+  int keep_back_buf;			/* Optimize for backwards reading */
+  sh_off_t wpos;			/* Real file position */
+  uns wlen;				/* Window size */
 };
 #define FB_FILE(f) ((struct fb_file *)(f)->is_fastbuf)
 #define FB_BUFFER(f) (byte *)(FB_FILE(f) + 1)
@@ -27,22 +31,124 @@ struct fb_file {
 static int
 bfd_refill(struct fastbuf *f)
 {
-  f->bptr = f->buffer = FB_BUFFER(f);
-  int l = read(FB_FILE(f)->fd, f->buffer, f->bufend-f->buffer);
-  if (l < 0)
-    die("Error reading %s: %m", f->name);
-  f->bstop = f->buffer + l;
-  f->pos += l;
-  return l;
+  struct fb_file *F = FB_FILE(f);
+  byte *read_ptr = (f->buffer = FB_BUFFER(f));
+  uns blen = f->bufend - f->buffer, back = F->keep_back_buf ? blen >> 2 : 0, read_len = blen;
+  /* Forward or no seek */
+  if (F->wpos <= f->pos)
+    {
+      sh_off_t diff = f->pos - F->wpos;
+      if (diff > ((sh_off_t)blen << 2)) /* FIXME: Formula for long forward seeks */
+        {
+long_seek:
+	  f->bptr = f->buffer + back;
+	  f->bstop = f->buffer + blen;
+	  goto seek;
+	}
+      if ((uns)diff < back) /* Reuse part of previous window (also F->wpos == f->pos) */
+        {
+	  uns keep = back - (uns)diff;
+	  if (keep >= F->wlen)
+	    back = diff + (keep = F->wlen);
+	  else
+	    memmove(f->buffer, f->buffer + F->wlen - keep, keep);
+	  read_len -= keep;
+	  read_ptr += keep;
+	}
+      else /* Short forward seek */
+        {
+	  uns skip = diff - back;
+	  F->wpos += skip;
+	  while (skip)
+	    {
+	      int l = read(F->fd, f->buffer, MIN(skip, blen));
+	      if (unlikely(l <= 0))
+		if (l < 0)
+		  die("Error reading %s: %m", f->name);
+		else
+		  {
+		    F->wpos -= skip;
+		    goto eof;
+		  }
+	      skip -= l;
+	    }
+	}
+      f->bptr = f->buffer + back;
+      f->bstop = f->buffer + blen;
+    }
+  /* Backwards seek */
+  else
+    {
+      sh_off_t diff = F->wpos - f->pos;
+      if (diff > ((sh_off_t)blen << 1)) /* FIXME: Formula for long backwards seeks */
+        {
+	  if ((sh_off_t)back > f->pos)
+	    back = f->pos;
+	  goto long_seek;
+	}
+      if ((uns)diff <= F->wlen) /* Seek into previous window (for example brewind) */
+        {
+	  f->bstop = f->buffer + F->wlen;
+	  f->bptr = f->bstop - diff;
+	  f->pos = F->wpos;
+	  return 1;
+	}
+      back *= 3;
+      if ((sh_off_t)back > f->pos)
+	back = f->pos;
+      f->bptr = f->buffer + back;
+      read_len = back + diff - F->wlen;
+      if (F->wlen && read_len < blen) /* Reuse part of previous window */
+        {
+	  uns keep = MIN(F->wlen, blen - read_len);
+	  memmove(f->buffer + read_len, f->buffer, keep);
+	  f->bstop = f->buffer + read_len + keep;
+	}
+      else
+	f->bstop = f->buffer + (read_len = blen);
+seek:
+      F->wpos = f->pos + (f->buffer - f->bptr);
+      if (sh_seek(F->fd, F->wpos, SEEK_SET) < 0)
+	die("Error seeking %s: %m", f->name);
+    }
+  do
+    {
+      int l = read(F->fd, read_ptr, read_len);
+      if (unlikely(l < 0))
+	die("Error reading %s: %m", f->name);
+      if (!l)
+	if (unlikely(read_ptr < f->bptr))
+	  goto eof;
+	else
+	  break; /* Incomplete read because of EOF */
+      read_ptr += l;
+      read_len -= l;
+      F->wpos += l;
+    }
+  while (read_ptr <= f->bptr);
+  if (read_len)
+    f->bstop = read_ptr;
+  f->pos += f->bstop - f->bptr;
+  F->wlen = f->bstop - f->buffer;
+  return f->bstop - f->bptr;
+eof:
+  /* Seeked behind EOF */
+  f->bptr = f->bstop = f->buffer;
+  F->wlen = 0;
+  return 0;
 }
 
 static void
 bfd_spout(struct fastbuf *f)
 {
+  if (FB_FILE(f)->wpos != f->pos && sh_seek(FB_FILE(f)->fd, f->pos, SEEK_SET) < 0)
+    die("Error seeking %s: %m", f->name);
+
   int l = f->bptr - f->buffer;
   byte *c = f->buffer;
 
-  f->pos += l;
+  FB_FILE(f)->wpos = (f->pos += l);
+  FB_FILE(f)->wlen = 0;
   while (l)
     {
       int z = write(FB_FILE(f)->fd, c, l);
@@ -57,11 +163,28 @@ bfd_spout(struct fastbuf *f)
 static int
 bfd_seek(struct fastbuf *f, sh_off_t pos, int whence)
 {
-  sh_off_t l = sh_seek(FB_FILE(f)->fd, pos, whence);
-  if (l < 0)
-    return 0;
-  f->pos = l;
-  return 1;
+  sh_off_t l;
+  switch (whence)
+    {
+      case SEEK_SET:
+	f->pos = pos;
+	return 1;
+      case SEEK_CUR:
+	l = f->pos + pos;
+	if ((pos > 0) ^ (l > f->pos))
+	  return 0;
+	f->pos = l;
+	return 1;
+      case SEEK_END:
+	l = sh_seek(FB_FILE(f)->fd, pos, SEEK_END);
+	if (l < 0)
+	  return 0;
+	FB_FILE(f)->wpos = f->pos = l;
+	FB_FILE(f)->wlen = 0;
+	return 1;
+      default:
+	ASSERT(0);
+    }
 }
 
 static void
@@ -73,7 +196,8 @@ bfd_close(struct fastbuf *f)
       if (unlink(f->name) < 0)
 	log(L_ERROR, "unlink(%s): %m", f->name);
     case 0:
-      close(FB_FILE(f)->fd);
+      if (close(FB_FILE(f)->fd))
+	die("close(%s): %m", f->name);
     }
   xfree(f);
 }
@@ -83,22 +207,25 @@ bfd_config(struct fastbuf *f, uns item, int value)
 {
   switch (item)
     {
-    case BCONFIG_IS_TEMP_FILE:
-      FB_FILE(f)->is_temp_file = value;
-      return 0;
-    default:
-      return -1;
+      case BCONFIG_IS_TEMP_FILE:
+	FB_FILE(f)->is_temp_file = value;
+	return 0;
+      case BCONFIG_KEEP_BACK_BUF:
+	FB_FILE(f)->keep_back_buf = value;
+	return 0;
+      default:
+	return -1;
     }
 }
 
-static struct fastbuf *
-bfdopen_internal(int fd, uns buflen, byte *name)
+struct fastbuf *
+bfdopen_internal(int fd, byte *name, uns buflen)
 {
+  ASSERT(buflen);
   int namelen = strlen(name) + 1;
-  struct fb_file *F = xmalloc(sizeof(struct fb_file) + buflen + namelen);
+  struct fb_file *F = xmalloc_zero(sizeof(struct fb_file) + buflen + namelen);
   struct fastbuf *f = &F->fb;
 
-  ASSERT(buflen);
   bzero(F, sizeof(*F));
   f->buffer = (byte *)(F+1);
   f->bptr = f->bstop = f->buffer;
@@ -118,34 +245,19 @@ bfdopen_internal(int fd, uns buflen, byte *name)
 struct fastbuf *
 bopen_try(byte *name, uns mode, uns buflen)
 {
-  int fd = sh_open(name, mode, 0666);
-  if (fd < 0)
-    return NULL;
-  struct fastbuf *b = bfdopen_internal(fd, buflen, name);
-  if (mode & O_APPEND)
-    bfd_seek(b, 0, SEEK_END);
-  return b;
+  return bopen_file_try(name, mode, &(struct fb_params){ .type = FB_STD, .buffer_size = buflen });
 }
 
 struct fastbuf *
 bopen(byte *name, uns mode, uns buflen)
 {
-  if (!buflen)
-    return bopen_mm(name, mode);
-  struct fastbuf *b = bopen_try(name, mode, buflen);
-  if (!b)
-    die("Unable to %s file %s: %m",
-	(mode & O_CREAT) ? "create" : "open", name);
-  return b;
+  return bopen_file(name, mode, &(struct fb_params){ .type = FB_STD, .buffer_size = buflen });
 }
 
 struct fastbuf *
 bfdopen(int fd, uns buflen)
 {
-  byte x[32];
-
-  sprintf(x, "fd%d", fd);
-  return bfdopen_internal(fd, buflen, x);
+  return bopen_fd(fd, &(struct fb_params){ .type = FB_STD, .buffer_size = buflen });
 }
 
 struct fastbuf *