1/*
2 * null engine
3 *
4 * IO engine that doesn't do any real IO transfers, it just pretends to.
5 * The main purpose is to test fio itself.
6 *
7 * It also can act as external C++ engine - compiled with:
8 *
9 * g++ -O2 -g -shared -rdynamic -fPIC -o null.so null.c -DFIO_EXTERNAL_ENGINE
10 *
11 */
12#include <stdio.h>
13#include <stdlib.h>
14#include <unistd.h>
15#include <errno.h>
16#include <assert.h>
17
18#include "../fio.h"
19
20struct null_data {
21	struct io_u **io_us;
22	int queued;
23	int events;
24};
25
26static struct io_u *fio_null_event(struct thread_data *td, int event)
27{
28	struct null_data *nd = (struct null_data *) td->io_ops_data;
29
30	return nd->io_us[event];
31}
32
33static int fio_null_getevents(struct thread_data *td, unsigned int min_events,
34			      unsigned int fio_unused max,
35			      const struct timespec fio_unused *t)
36{
37	struct null_data *nd = (struct null_data *) td->io_ops_data;
38	int ret = 0;
39
40	if (min_events) {
41		ret = nd->events;
42		nd->events = 0;
43	}
44
45	return ret;
46}
47
48static int fio_null_commit(struct thread_data *td)
49{
50	struct null_data *nd = (struct null_data *) td->io_ops_data;
51
52	if (!nd->events) {
53#ifndef FIO_EXTERNAL_ENGINE
54		io_u_mark_submit(td, nd->queued);
55#endif
56		nd->events = nd->queued;
57		nd->queued = 0;
58	}
59
60	return 0;
61}
62
63static int fio_null_queue(struct thread_data *td, struct io_u *io_u)
64{
65	struct null_data *nd = (struct null_data *) td->io_ops_data;
66
67	fio_ro_check(td, io_u);
68
69	if (td->io_ops->flags & FIO_SYNCIO)
70		return FIO_Q_COMPLETED;
71	if (nd->events)
72		return FIO_Q_BUSY;
73
74	nd->io_us[nd->queued++] = io_u;
75	return FIO_Q_QUEUED;
76}
77
78static int fio_null_open(struct thread_data fio_unused *td,
79			 struct fio_file fio_unused *f)
80{
81	return 0;
82}
83
84static void fio_null_cleanup(struct thread_data *td)
85{
86	struct null_data *nd = (struct null_data *) td->io_ops_data;
87
88	if (nd) {
89		free(nd->io_us);
90		free(nd);
91	}
92}
93
94static int fio_null_init(struct thread_data *td)
95{
96	struct null_data *nd = (struct null_data *) malloc(sizeof(*nd));
97
98	memset(nd, 0, sizeof(*nd));
99
100	if (td->o.iodepth != 1) {
101		nd->io_us = (struct io_u **) malloc(td->o.iodepth * sizeof(struct io_u *));
102		memset(nd->io_us, 0, td->o.iodepth * sizeof(struct io_u *));
103	} else
104		td->io_ops->flags |= FIO_SYNCIO;
105
106	td->io_ops_data = nd;
107	return 0;
108}
109
110#ifndef __cplusplus
111static struct ioengine_ops ioengine = {
112	.name		= "null",
113	.version	= FIO_IOOPS_VERSION,
114	.queue		= fio_null_queue,
115	.commit		= fio_null_commit,
116	.getevents	= fio_null_getevents,
117	.event		= fio_null_event,
118	.init		= fio_null_init,
119	.cleanup	= fio_null_cleanup,
120	.open_file	= fio_null_open,
121	.flags		= FIO_DISKLESSIO | FIO_FAKEIO,
122};
123
124static void fio_init fio_null_register(void)
125{
126	register_ioengine(&ioengine);
127}
128
129static void fio_exit fio_null_unregister(void)
130{
131	unregister_ioengine(&ioengine);
132}
133
134#else
135
136#ifdef FIO_EXTERNAL_ENGINE
137extern "C" {
138static struct ioengine_ops ioengine;
139void get_ioengine(struct ioengine_ops **ioengine_ptr)
140{
141	*ioengine_ptr = &ioengine;
142
143	ioengine.name           = "cpp_null";
144	ioengine.version        = FIO_IOOPS_VERSION;
145	ioengine.queue          = fio_null_queue;
146	ioengine.commit         = fio_null_commit;
147	ioengine.getevents      = fio_null_getevents;
148	ioengine.event          = fio_null_event;
149	ioengine.init           = fio_null_init;
150	ioengine.cleanup        = fio_null_cleanup;
151	ioengine.open_file      = fio_null_open;
152	ioengine.flags          = FIO_DISKLESSIO | FIO_FAKEIO;
153}
154}
155#endif /* FIO_EXTERNAL_ENGINE */
156
157#endif /* __cplusplus */
158