Minimize allocations for frame tvbuffs and Buffers.

Try to minimize the number of times we allocate memory for Buffers and
Buffer data.

Change-Id: I738fdc64e571772ef4ba6335d49087277dd7b430
Reviewed-on: https://code.wireshark.org/review/16577
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

2 files changed, 32 insertions, 7 deletions

diff --git a/frame_tvbuff.c b/frame_tvbuff.c
index 311653ce1a..9af5d2ff4d 100644
--- a/frame_tvbuff.c
+++ b/frame_tvbuff.c
@@ -69,6 +69,8 @@ frame_read(struct tvb_frame *frame_tvb, struct wtap_pkthdr *phdr, Buffer *buf)
 	return TRUE;
 }
 
+static GPtrArray *buffer_cache = NULL;
+
 static void
 frame_cache(struct tvb_frame *frame_tvb)
 {
@@ -77,9 +79,14 @@ frame_cache(struct tvb_frame *frame_tvb)
 	wtap_phdr_init(&phdr);
 
 	if (frame_tvb->buf == NULL) {
-		frame_tvb->buf = (struct Buffer *) g_malloc(sizeof(struct Buffer));
+		if G_UNLIKELY(!buffer_cache) buffer_cache = g_ptr_array_sized_new(1024);
+
+		if (buffer_cache->len > 0) {
+			frame_tvb->buf = (struct Buffer *) g_ptr_array_remove_index(buffer_cache, buffer_cache->len - 1);
+		} else {
+			frame_tvb->buf = (struct Buffer *) g_malloc(sizeof(struct Buffer));
+		}
 
-		/* XXX, register frame_tvb to some list which frees from time to time not used buffers :] */
 		ws_buffer_init(frame_tvb->buf, frame_tvb->tvb.length + frame_tvb->offset);
 
 		if (!frame_read(frame_tvb, &phdr, frame_tvb->buf))
@@ -98,8 +105,7 @@ frame_free(tvbuff_t *tvb)
 
 	if (frame_tvb->buf) {
 		ws_buffer_free(frame_tvb->buf);
-
-		g_free(frame_tvb->buf);
+		g_ptr_array_add(buffer_cache, frame_tvb->buf);
 	}
 }
 
diff --git a/wsutil/buffer.c b/wsutil/buffer.c
index 5f9daf25f3..7d9d44b1b4 100644
--- a/wsutil/buffer.c
+++ b/wsutil/buffer.c
@@ -25,12 +25,27 @@
 
 #include "buffer.h"
 
+#define SMALL_BUFFER_SIZE (2 * 1024) /* Everyone still uses 1500 byte frames, right? */
+static GPtrArray *small_buffers = NULL; /* Guaranteed to be at least SMALL_BUFFER_SIZE */
+/* XXX - Add medium and large buffers? */
+
 /* Initializes a buffer with a certain amount of allocated space */
 void
 ws_buffer_init(Buffer* buffer, gsize space)
 {
-	buffer->data = (guint8*)g_malloc(space);
-	buffer->allocated = space;
+	if G_UNLIKELY(!small_buffers) small_buffers = g_ptr_array_sized_new(1024);
+
+	if (space <= SMALL_BUFFER_SIZE) {
+		if (small_buffers->len > 0) {
+			buffer->data = (guint8*) g_ptr_array_remove_index(small_buffers, small_buffers->len - 1);
+		} else {
+			buffer->data = (guint8*)g_malloc(SMALL_BUFFER_SIZE);
+		}
+		buffer->allocated = SMALL_BUFFER_SIZE;
+	} else {
+		buffer->data = (guint8*)g_malloc(space);
+		buffer->allocated = space;
+	}
 	buffer->start = 0;
 	buffer->first_free = 0;
 }
@@ -39,7 +54,11 @@ ws_buffer_init(Buffer* buffer, gsize space)
 void
 ws_buffer_free(Buffer* buffer)
 {
-	g_free(buffer->data);
+	if (buffer->allocated == SMALL_BUFFER_SIZE) {
+		g_ptr_array_add(small_buffers, buffer->data);
+	} else {
+		g_free(buffer->data);
+	}
 	buffer->data = NULL;
 }