More microoptimization of the io_uring polling.

diff --git a/io_uring_engine.cpp b/io_uring_engine.cpp
index cadc6c33a79abeb12d2f63387b2f1fa6037b25f2..f8295aacfde48f99e929a4dc2e0656b4f80dcd19 100644 (file)
--- a/io_uring_engine.cpp
+++ b/io_uring_engine.cpp
@@ -71,28 +71,27 @@ void IOUringEngine::finish()
 #ifndef WITHOUT_URING
        bool anything_to_submit = true;
        while (pending_reads > 0) {
-               io_uring_cqe *cqes[queue_depth];
-               int num_sqes = io_uring_peek_batch_cqe(&ring, cqes, queue_depth);
-               if (num_sqes == 0) {
+               io_uring_cqe *cqe;
+               if (io_uring_peek_cqe(&ring, &cqe) != 0) {
                        if (anything_to_submit) {
                                // Nothing ready, so submit whatever is pending and then do a blocking wait.
-                               int ret = io_uring_submit(&ring);
+                               int ret = io_uring_submit_and_wait(&ring, 1);
                                if (ret < 0) {
                                        fprintf(stderr, "io_uring_submit(queued): %s\n", strerror(-ret));
                                        exit(1);
                                }
                                anything_to_submit = false;
+                       } else {
+                               int ret = io_uring_wait_cqe(&ring, &cqe);
+                               if (ret < 0) {
+                                       fprintf(stderr, "io_uring_wait_cqe: %s\n", strerror(-ret));
+                                       exit(1);
+                               }
                        }
-                       int ret = io_uring_wait_cqe(&ring, &cqes[0]);
-                       if (ret < 0) {
-                               fprintf(stderr, "io_uring_wait_cqe: %s\n", strerror(-ret));
-                               exit(1);
-                       }
-                       num_sqes = 1;
                }
 
-               for (int sqe_idx = 0; sqe_idx < num_sqes; ++sqe_idx) {
-                       io_uring_cqe *cqe = cqes[sqe_idx];
+               unsigned head;
+               io_uring_for_each_cqe(&ring, head, cqe) {
                        PendingRead *pending = reinterpret_cast<PendingRead *>(cqe->user_data);
                        if (cqe->res <= 0) {
                                fprintf(stderr, "async read failed: %s\n", strerror(-cqe->res));
@@ -129,19 +128,19 @@ void IOUringEngine::finish()
                                        anything_to_submit = true;
                                }
                        }
+               }
 
-                       // See if there are any queued reads we can submit now.
-                       while (!queued_reads.empty() && pending_reads < queue_depth) {
-                               io_uring_sqe *sqe = io_uring_get_sqe(&ring);
-                               if (sqe == nullptr) {
-                                       fprintf(stderr, "io_uring_get_sqe: %s\n", strerror(errno));
-                                       exit(1);
-                               }
-                               QueuedRead &qr = queued_reads.front();
-                               submit_read_internal(sqe, qr.fd, qr.len, qr.offset, move(qr.cb));
-                               queued_reads.pop();
-                               anything_to_submit = true;
+               // See if there are any queued reads we can submit now.
+               while (!queued_reads.empty() && pending_reads < queue_depth) {
+                       io_uring_sqe *sqe = io_uring_get_sqe(&ring);
+                       if (sqe == nullptr) {
+                               fprintf(stderr, "io_uring_get_sqe: %s\n", strerror(errno));
+                               exit(1);
                        }
+                       QueuedRead &qr = queued_reads.front();
+                       submit_read_internal(sqe, qr.fd, qr.len, qr.offset, move(qr.cb));
+                       queued_reads.pop();
+                       anything_to_submit = true;
                }
        }
 #endif