Add io_uring_peek_batch_cqe()

io_uring_peek_batch_cqe(), get multiple cqe from the queue at once.
Returns the number of cqe gotten.

test/cq-peek-batch.c: tests io_uring_peek_batch_cqe()

Signed-off-by: James Rouzier <rouzier@gmail.com>

2 files changed, 25 insertions, 0 deletions

diff --git a/src/include/liburing.h b/src/include/liburing.h
index 5de8aab..6367307 100644
--- a/src/include/liburing.h
+++ b/src/include/liburing.h
@@ -72,6 +72,8 @@ extern int io_uring_queue_mmap(int fd, struct io_uring_params *p,
 extern void io_uring_queue_exit(struct io_uring *ring);
 extern int io_uring_peek_cqe(struct io_uring *ring,
 	struct io_uring_cqe **cqe_ptr);
+unsigned io_uring_peek_batch_cqe(struct io_uring *ring,
+	struct io_uring_cqe **cqes, unsigned count);
 extern int io_uring_wait_cqe(struct io_uring *ring,
 	struct io_uring_cqe **cqe_ptr);
 extern int io_uring_wait_cqes_timeout(struct io_uring *ring,
diff --git a/src/queue.c b/src/queue.c
index 18040d5..470c3a2 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -53,6 +53,29 @@ int io_uring_peek_cqe(struct io_uring *ring, struct io_uring_cqe **cqe_ptr)
 }
 
 /*
+ * Fill in an array of IO completions up to count, if any are available.
+ * Returns the amount of IO completions filled.
+ */
+unsigned io_uring_peek_batch_cqe(struct io_uring *ring, struct io_uring_cqe **cqes, unsigned count)
+{
+	unsigned ready = io_uring_cq_ready(ring);
+	if (ready) {
+		count = count > ready ? ready : count;
+		unsigned head = *ring->cq.khead;
+		unsigned last = head + count;
+		unsigned mask = *ring->cq.kring_mask;
+		int i = 0;
+		for (;head!=last;head++,i++) {
+			cqes[i] = &ring->cq.cqes[head & mask];
+		}
+
+		return count;
+	}
+
+	return 0;
+}
+
+/*
  * Return an IO completion, waiting for it if necessary. Returns 0 with
  * cqe_ptr filled in on success, -errno on failure.
  */