iobuf: Increase the size of the buffer. Add iobuf_set_buffer_size.

* common/iobuf.c (IOBUF_BUFFER_SIZE): Rename to
DEFAULT_IOBUF_BUFFER_SIZE and increase to 64k.
(iobuf_buffer_size): New var.  Always use this instead of the macro.
(iobuf_set_buffer_size): New.
(struct file_filter_ctx_t): Add field delayed_rc.
(file_filter) [!W32]: Try to fill the supplied buffer.
--

I did some test to see whether this has an effect.  A test program
piped 100 million random bytes to gpg to symmetric encryption only w/0
compression.  Single read means the old behaviour, multi read the new
behaviour which fills up the buffer when the read(2) returned only 4k
in once call.

8k buffer single read
        User time (seconds): 0.09
        System time (seconds): 0.04
        Percent of CPU this job got: 6%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.04

8k buffer multi read
       User time (seconds): 0.08
       System time (seconds): 0.05
       Percent of CPU this job got: 6%
       Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.04

64k buffer single read
        User time (seconds): 0.09
        System time (seconds): 0.06
        Percent of CPU this job got: 6%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.20

64k buffer multi read
        User time (seconds): 0.11
        System time (seconds): 0.06
        Percent of CPU this job got: 8%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.01

128k buffer single read
        User time (seconds): 0.09
        System time (seconds): 0.05
        Percent of CPU this job got: 7%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.05

128k buffer multi read
        User time (seconds): 0.11
        System time (seconds): 0.05
        Percent of CPU this job got: 8%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.01

512k buffer single read:
        User time (seconds): 0.08
        System time (seconds): 0.08
        Percent of CPU this job got: 7%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.21

512k buffer multi read:
        User time (seconds): 0.10
        System time (seconds): 0.06
        Percent of CPU this job got: 7%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:02.05

Does not make much of a difference :-(.  Maybe it changes depending on
the type of used filters.

Signed-off-by: Werner Koch <wk@gnupg.org>

2 files changed, 89 insertions, 35 deletions

diff --git a/common/iobuf.c b/common/iobuf.c
index 5a9fd7caf..bf5977843 100644
--- a/common/iobuf.c
+++ b/common/iobuf.c
@@ -62,7 +62,7 @@
 /* The size of the internal buffers.
    NOTE: If you change this value you MUST also adjust the regression
    test "armored_key_8192" in armor.test! */
-#define IOBUF_BUFFER_SIZE  8192
+#define DEFAULT_IOBUF_BUFFER_SIZE  (64*1024)
 
 /* To avoid a potential DoS with compression packets we better limit
    the number of filters in a chain.  */
@@ -70,6 +70,10 @@
 
 /*-- End configurable part.  --*/
 
+/* The size of the iobuffers.  This can be chnages using the
+ * iobuf_set_buffer_size fucntion.  */
+static unsigned int iobuf_buffer_size = DEFAULT_IOBUF_BUFFER_SIZE;
+
 
 #ifdef HAVE_W32_SYSTEM
 # ifdef HAVE_W32CE_SYSTEM
@@ -92,6 +96,7 @@ typedef struct
   int keep_open;
   int no_cache;
   int eof_seen;
+  int delayed_rc;
   int print_only_name; /* Flags indicating that fname is not a real file.  */
   char fname[1];       /* Name of the file.  */
 } file_filter_ctx_t;
@@ -167,7 +172,7 @@ static int translate_file_handle (int fd, int for_write);
    to be sent to A's filter function.
 
    If A is a IOBUF_OUTPUT_TEMP filter, then this also enlarges the
-   buffer by IOBUF_BUFFER_SIZE.
+   buffer by iobuf_buffer_size.
 
    May only be called on an IOBUF_OUTPUT or IOBUF_OUTPUT_TEMP filters.  */
 static int filter_flush (iobuf_t a);
@@ -451,12 +456,20 @@ file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
 
   if (control == IOBUFCTRL_UNDERFLOW)
     {
-      assert (size); /* We need a buffer.  */
+      log_assert (size); /* We need a buffer.  */
       if (a->eof_seen)
 	{
 	  rc = -1;
 	  *ret_len = 0;
 	}
+      else if (a->delayed_rc)
+        {
+          rc = a->delayed_rc;
+          a->delayed_rc = 0;
+          if (rc == -1)
+            a->eof_seen = -1;
+	  *ret_len = 0;
+        }
       else
 	{
 #ifdef HAVE_W32_SYSTEM
@@ -487,29 +500,39 @@ file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
 	  int n;
 
 	  nbytes = 0;
-	  do
-	    {
-	      n = read (f, buf, size);
-	    }
-	  while (n == -1 && errno == EINTR);
-	  if (n == -1)
-	    {			/* error */
-	      if (errno != EPIPE)
-		{
-		  rc = gpg_error_from_syserror ();
-		  log_error ("%s: read error: %s\n",
-			     a->fname, strerror (errno));
-		}
-	    }
-	  else if (!n)
-	    {			/* eof */
-	      a->eof_seen = 1;
-	      rc = -1;
-	    }
-	  else
-	    {
-	      nbytes = n;
-	    }
+        read_more:
+          do
+            {
+              n = read (f, buf + nbytes, size - nbytes);
+            }
+          while (n == -1 && errno == EINTR);
+          if (n > 0)
+            {
+              nbytes += n;
+              if (nbytes < size)
+                goto read_more;
+            }
+          else if (!n) /* eof */
+            {
+              if (nbytes)
+                a->delayed_rc = -1;
+              else
+                {
+                  a->eof_seen = 1;
+                  rc = -1;
+                }
+            }
+          else /* error */
+            {
+              rc = gpg_error_from_syserror ();
+              if (gpg_err_code (rc) != GPG_ERR_EPIPE)
+                log_error ("%s: read error: %s\n", a->fname, gpg_strerror (rc));
+              if (nbytes)
+                {
+                  a->delayed_rc = rc;
+                  rc = 0;
+                }
+            }
 #endif
 	  *ret_len = nbytes;
 	}
@@ -569,6 +592,7 @@ file_filter (void *opaque, int control, iobuf_t chain, byte * buf,
   else if (control == IOBUFCTRL_INIT)
     {
       a->eof_seen = 0;
+      a->delayed_rc = 0;
       a->keep_open = 0;
       a->no_cache = 0;
     }
@@ -1053,6 +1077,30 @@ block_filter (void *opaque, int control, iobuf_t chain, byte * buffer,
   return rc;
 }
 
+
+/* Change the default size for all IOBUFs to KILOBYTE.  This needs to
+ * be called before any iobufs are used and can only be used once.
+ * Returns the current value.  Using 0 has no effect except for
+ * returning the current value.  */
+unsigned int
+iobuf_set_buffer_size (unsigned int kilobyte)
+{
+  static int used;
+
+  if (!used && kilobyte)
+    {
+      if (kilobyte < 4)
+        kilobyte = 4;
+      else if (kilobyte > 16*1024)
+        kilobyte = 16*1024;
+
+      iobuf_buffer_size = kilobyte * 1024;
+      used = 1;
+    }
+  return iobuf_buffer_size / 1024;
+}
+
+
 #define MAX_IOBUF_DESC 32
 /*
  * Fill the buffer by the description of iobuf A.
@@ -1105,7 +1153,7 @@ iobuf_alloc (int use, size_t bufsize)
   if (bufsize == 0)
     {
       log_bug ("iobuf_alloc() passed a bufsize of 0!\n");
-      bufsize = IOBUF_BUFFER_SIZE;
+      bufsize = iobuf_buffer_size;
     }
 
   a = xcalloc (1, sizeof *a);
@@ -1213,7 +1261,7 @@ iobuf_cancel (iobuf_t a)
 iobuf_t
 iobuf_temp (void)
 {
-  return iobuf_alloc (IOBUF_OUTPUT_TEMP, IOBUF_BUFFER_SIZE);
+  return iobuf_alloc (IOBUF_OUTPUT_TEMP, iobuf_buffer_size);
 }
 
 iobuf_t
@@ -1288,7 +1336,7 @@ do_open (const char *fname, int special_filenames,
 	return NULL;
     }
 
-  a = iobuf_alloc (use, IOBUF_BUFFER_SIZE);
+  a = iobuf_alloc (use, iobuf_buffer_size);
   fcx = xmalloc (sizeof *fcx + strlen (fname));
   fcx->fp = fp;
   fcx->print_only_name = print_only;
@@ -1335,7 +1383,7 @@ do_iobuf_fdopen (int fd, const char *mode, int keep_open)
   fp = INT2FD (fd);
 
   a = iobuf_alloc (strchr (mode, 'w') ? IOBUF_OUTPUT : IOBUF_INPUT,
-		   IOBUF_BUFFER_SIZE);
+		   iobuf_buffer_size);
   fcx = xmalloc (sizeof *fcx + 20);
   fcx->fp = fp;
   fcx->print_only_name = 1;
@@ -1373,7 +1421,7 @@ iobuf_esopen (estream_t estream, const char *mode, int keep_open)
   size_t len = 0;
 
   a = iobuf_alloc (strchr (mode, 'w') ? IOBUF_OUTPUT : IOBUF_INPUT,
-		   IOBUF_BUFFER_SIZE);
+		   iobuf_buffer_size);
   fcx = xtrymalloc (sizeof *fcx + 30);
   fcx->fp = estream;
   fcx->print_only_name = 1;
@@ -1398,7 +1446,7 @@ iobuf_sockopen (int fd, const char *mode)
   size_t len;
 
   a = iobuf_alloc (strchr (mode, 'w') ? IOBUF_OUTPUT : IOBUF_INPUT,
-		   IOBUF_BUFFER_SIZE);
+		   iobuf_buffer_size);
   scx = xmalloc (sizeof *scx + 25);
   scx->sock = fd;
   scx->print_only_name = 1;
@@ -1599,13 +1647,13 @@ iobuf_push_filter2 (iobuf_t a,
 	 increased accordingly.  We don't need to allocate a 10 MB
 	 buffer for a non-terminal filter.  Just use the default
 	 size.  */
-      a->d.size = IOBUF_BUFFER_SIZE;
+      a->d.size = iobuf_buffer_size;
     }
   else if (a->use == IOBUF_INPUT_TEMP)
     /* Same idea as above.  */
     {
       a->use = IOBUF_INPUT;
-      a->d.size = IOBUF_BUFFER_SIZE;
+      a->d.size = iobuf_buffer_size;
     }
 
   /* The new filter (A) gets a new buffer.
@@ -1922,7 +1970,7 @@ filter_flush (iobuf_t a)
 
   if (a->use == IOBUF_OUTPUT_TEMP)
     {				/* increase the temp buffer */
-      size_t newsize = a->d.size + IOBUF_BUFFER_SIZE;
+      size_t newsize = a->d.size + iobuf_buffer_size;
 
       if (DBG_IOBUF)
 	log_debug ("increasing temp iobuf from %lu to %lu\n",
diff --git a/common/iobuf.h b/common/iobuf.h
index 22e02daad..16156383c 100644
--- a/common/iobuf.h
+++ b/common/iobuf.h
@@ -259,6 +259,12 @@ struct iobuf_struct
 EXTERN_UNLESS_MAIN_MODULE int iobuf_debug_mode;
 
 
+/* Change the default size for all IOBUFs to KILOBYTE.  This needs to
+ * be called before any iobufs are used and can only be used once.
+ * Returns the current value.  Using 0 has no effect except for
+ * returning the current value.  */
+unsigned int iobuf_set_buffer_size (unsigned int kilobyte);
+
 /* Returns whether the specified filename corresponds to a pipe.  In
    particular, this function checks if FNAME is "-" and, if special
    filenames are enabled (see check_special_filename), whether