Changeset 22f94a4 for examples/io/cat.c

Timestamp:

Aug 11, 2020, 4:40:15 PM (5 years ago)

Author:

Thierry Delisle <tdelisle@…>

Branches:

ADT, arm-eh, ast-experimental, enum, forall-pointer-decay, jacob/cs343-translation, master, new-ast, new-ast-unique-expr, pthread-emulation, qualifiedEnum

Children:

0d070ca

Parents:

07d867b (diff), 129674b (diff)
Note: this is a merge changeset, the changes displayed below correspond to the merge itself.
Use the (diff) links above to see all the changes relative to each parent.

Message:

Merge branch 'master' into new-ast

File:

• examples/io/cat.c (moved) (moved from examples/io_uring.c ) (6 diffs)

examples/io/cat.c

@@ +1 @@
+/*
+This is a simple "cat" example that uses io_uring in IORING_SETUP_IOPOLL mode.
+It demonstrates the bare minimum needed to use io_uring in polling mode.
+It uses liburing for simplicity.
+*/
+
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
 #include <fcntl.h>
 #include <liburing.h>
 #include <stdio.h>
+#include <string.h>
 #include <unistd.h>
 
 struct io_uring ring;
+
+__attribute__((aligned(1024))) char data[1024];
 
 int main(int argc,  char * argv[]) {
@@ -12 +26 @@
       }
 
-      int fd = open(argv[1], 0);
+      int fd = open(argv[1], O_DIRECT);
       if(fd < 0) {
             printf("Could not open file %s.\n", argv[1]);
@@ -19 +33 @@
 
       /* prep the array */
-      char data[512];
-      struct iovec iov = { data, 512 };
+      struct iovec iov = { data, 1024 };
 
       /* init liburing */
-      io_uring_queue_init(256, &ring, 0);
+      io_uring_queue_init(256, &ring, IORING_SETUP_IOPOLL);
 
       /* declare required structs */
@@ -32 +45 @@
       sqe = io_uring_get_sqe(&ring);
       io_uring_prep_readv(sqe, fd, &iov, 1, 0);
+      // io_uring_prep_read(sqe, fd, data, 1024, 0);
 
-      sqe->user_data = data;
+      sqe->user_data = (uint64_t)(uintptr_t)data;
 
       /* tell the kernel we have an sqe ready for consumption */
@@ -40 +54 @@
       /* wait for the sqe to complete */
       int ret = io_uring_wait_cqe(&ring, &cqe);
-      
+
       /* read and process cqe event */
       if(ret == 0) {
-            char * out = cqe->user_data;
+            char * out = (char *)(uintptr_t)cqe->user_data;
             signed int len = cqe->res;
             io_uring_cqe_seen(&ring, cqe);
@@ -49 +63 @@
             if(len > 0) {
                   printf("%.*s", len, out);
+            }
+            else if( len < 0 ) {
+                  fprintf(stderr, "readv/read returned error : %s\n", strerror(-len));
             }
       }