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			      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		if (nd->io_us)
90			free(nd->io_us);
91		free(nd);
92	}
93}
94
95static int fio_null_init(struct thread_data *td)
96{
97	struct null_data *nd = (struct null_data *) malloc(sizeof(*nd));
98
99	memset(nd, 0, sizeof(*nd));
100
101	if (td->o.iodepth != 1) {
102		nd->io_us = (struct io_u **) malloc(td->o.iodepth * sizeof(struct io_u *));
103		memset(nd->io_us, 0, td->o.iodepth * sizeof(struct io_u *));
104	} else
105		td->io_ops->flags |= FIO_SYNCIO;
106
107	td->io_ops->data = nd;
108	return 0;
109}
110
111#ifndef __cplusplus
112static struct ioengine_ops ioengine = {
113	.name		= "null",
114	.version	= FIO_IOOPS_VERSION,
115	.queue		= fio_null_queue,
116	.commit		= fio_null_commit,
117	.getevents	= fio_null_getevents,
118	.event		= fio_null_event,
119	.init		= fio_null_init,
120	.cleanup	= fio_null_cleanup,
121	.open_file	= fio_null_open,
122	.flags		= FIO_DISKLESSIO,
123};
124
125static void fio_init fio_null_register(void)
126{
127	register_ioengine(&ioengine);
128}
129
130static void fio_exit fio_null_unregister(void)
131{
132	unregister_ioengine(&ioengine);
133}
134
135#else
136
137#ifdef FIO_EXTERNAL_ENGINE
138extern "C" {
139void get_ioengine(struct ioengine_ops **ioengine_ptr)
140{
141	struct ioengine_ops *ioengine;
142
143	*ioengine_ptr = (struct ioengine_ops *) malloc(sizeof(struct ioengine_ops));
144	ioengine = *ioengine_ptr;
145
146	strcpy(ioengine->name, "cpp_null");
147	ioengine->version        = FIO_IOOPS_VERSION;
148	ioengine->queue          = fio_null_queue;
149	ioengine->commit         = fio_null_commit;
150	ioengine->getevents      = fio_null_getevents;
151	ioengine->event          = fio_null_event;
152	ioengine->init           = fio_null_init;
153	ioengine->cleanup        = fio_null_cleanup;
154	ioengine->open_file      = fio_null_open;
155	ioengine->flags	         = FIO_DISKLESSIO;
156}
157}
158#endif /* FIO_EXTERNAL_ENGINE */
159
160#endif /* __cplusplus */
161