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      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 
     20 struct null_data {
     21 	struct io_u **io_us;
     22 	int queued;
     23 	int events;
     24 };
     25 
     26 static 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 
     33 static 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 
     48 static 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 
     63 static 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 
     78 static int fio_null_open(struct thread_data fio_unused *td,
     79 			 struct fio_file fio_unused *f)
     80 {
     81 	return 0;
     82 }
     83 
     84 static 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 
     94 static 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
    111 static 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 
    124 static void fio_init fio_null_register(void)
    125 {
    126 	register_ioengine(&ioengine);
    127 }
    128 
    129 static void fio_exit fio_null_unregister(void)
    130 {
    131 	unregister_ioengine(&ioengine);
    132 }
    133 
    134 #else
    135 
    136 #ifdef FIO_EXTERNAL_ENGINE
    137 extern "C" {
    138 static struct ioengine_ops ioengine;
    139 void 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