server: Use ringbuffer for socket backlog
Currently, the socket handler uses a linear buffer for the backlog data;
this means we need to shift up to 128kB of data after each socket
write().
This change introduces a single-producer-multiple-consumer ringbuffer,
to avoid the need for memmove()ing data around; we can simply update
pointers instead of shifting data.
We add this as a new file (ringbuffer.c), to make it a little more
modular. To mitigate the risk of subtle pointer arithmetic issues, we
add a set of tests too.
Change-Id: Ib7c5151d3cf1f588436f5461000b6fed22d0681c
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
diff --git a/test/test-ringbuffer-boundary-poll.c b/test/test-ringbuffer-boundary-poll.c
new file mode 100644
index 0000000..6f6ddc7
--- /dev/null
+++ b/test/test-ringbuffer-boundary-poll.c
@@ -0,0 +1,51 @@
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include "ringbuffer.c"
+#include "ringbuffer-test-utils.c"
+
+void test_boundary_poll(void)
+{
+ uint8_t in_buf[] = { 'a', 'b', 'c', 'd', 'e', 'f' };
+ struct rb_test_ctx _ctx, *ctx = &_ctx;
+ struct ringbuffer *rb;
+ int rc;
+
+ ringbuffer_test_context_init(ctx);
+
+ rb = ringbuffer_init(10);
+
+ ctx->rbc = ringbuffer_consumer_register(rb,
+ ringbuffer_poll_append_all, ctx);
+
+ /* don't consume initial data in the poll callback */
+ ctx->ignore_poll = true;
+
+ /* queue and dequeue, so our tail is non-zero */
+ ringbuffer_queue(rb, in_buf, sizeof(in_buf));
+ ringbuffer_dequeue_commit(ctx->rbc, sizeof(in_buf));
+
+ /* start queueing data */
+ ctx->ignore_poll = false;
+
+ /* ensure we're getting the second batch of data back */
+ in_buf[0] = 'A';
+
+ rc = ringbuffer_queue(rb, in_buf, sizeof(in_buf));
+ assert(!rc);
+
+ assert(ctx->count == 1);
+ assert(ctx->len == sizeof(in_buf));
+ assert(!memcmp(in_buf, ctx->data, ctx->len));
+
+ ringbuffer_fini(rb);
+ ringbuffer_test_context_fini(ctx);
+}
+
+int main(void)
+{
+ test_boundary_poll();
+ return EXIT_SUCCESS;
+}