| 1 | /* |
| 2 | * Skeleton for a sample external io engine |
| 3 | * |
| 4 | * Should be compiled with: |
| 5 | * |
| 6 | * gcc -Wall -O2 -g -shared -rdynamic -fPIC -o skeleton_external.o skeleton_external.c |
| 7 | * (also requires -D_GNU_SOURCE -DCONFIG_STRSEP on Linux) |
| 8 | * |
| 9 | */ |
| 10 | #include <stdio.h> |
| 11 | #include <stdlib.h> |
| 12 | #include <unistd.h> |
| 13 | #include <errno.h> |
| 14 | #include <assert.h> |
| 15 | |
| 16 | #include "../fio.h" |
| 17 | #include "../optgroup.h" |
| 18 | |
| 19 | /* |
| 20 | * The core of the module is identical to the ones included with fio, |
| 21 | * read those. You cannot use register_ioengine() and unregister_ioengine() |
| 22 | * for external modules, they should be gotten through dlsym() |
| 23 | */ |
| 24 | |
| 25 | /* |
| 26 | * The io engine can define its own options within the io engine source. |
| 27 | * The option member must not be at offset 0, due to the way fio parses |
| 28 | * the given option. Just add a padding pointer unless the io engine has |
| 29 | * something usable. |
| 30 | */ |
| 31 | struct fio_skeleton_options { |
| 32 | void *pad; /* avoid ->off1 of fio_option becomes 0 */ |
| 33 | unsigned int dummy; |
| 34 | }; |
| 35 | |
| 36 | static struct fio_option options[] = { |
| 37 | { |
| 38 | .name = "dummy", |
| 39 | .lname = "ldummy", |
| 40 | .type = FIO_OPT_STR_SET, |
| 41 | .off1 = offsetof(struct fio_skeleton_options, dummy), |
| 42 | .help = "Set dummy", |
| 43 | .category = FIO_OPT_C_ENGINE, /* always use this */ |
| 44 | .group = FIO_OPT_G_INVALID, /* this can be different */ |
| 45 | }, |
| 46 | { |
| 47 | .name = NULL, |
| 48 | }, |
| 49 | }; |
| 50 | |
| 51 | /* |
| 52 | * The ->event() hook is called to match an event number with an io_u. |
| 53 | * After the core has called ->getevents() and it has returned eg 3, |
| 54 | * the ->event() hook must return the 3 events that have completed for |
| 55 | * subsequent calls to ->event() with [0-2]. Required. |
| 56 | */ |
| 57 | static struct io_u *fio_skeleton_event(struct thread_data *td, int event) |
| 58 | { |
| 59 | return NULL; |
| 60 | } |
| 61 | |
| 62 | /* |
| 63 | * The ->getevents() hook is used to reap completion events from an async |
| 64 | * io engine. It returns the number of completed events since the last call, |
| 65 | * which may then be retrieved by calling the ->event() hook with the event |
| 66 | * numbers. Required. |
| 67 | */ |
| 68 | static int fio_skeleton_getevents(struct thread_data *td, unsigned int min, |
| 69 | unsigned int max, const struct timespec *t) |
| 70 | { |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * The ->cancel() hook attempts to cancel the io_u. Only relevant for |
| 76 | * async io engines, and need not be supported. |
| 77 | */ |
| 78 | static int fio_skeleton_cancel(struct thread_data *td, struct io_u *io_u) |
| 79 | { |
| 80 | return 0; |
| 81 | } |
| 82 | |
| 83 | /* |
| 84 | * The ->queue() hook is responsible for initiating io on the io_u |
| 85 | * being passed in. If the io engine is a synchronous one, io may complete |
| 86 | * before ->queue() returns. Required. |
| 87 | * |
| 88 | * The io engine must transfer in the direction noted by io_u->ddir |
| 89 | * to the buffer pointed to by io_u->xfer_buf for as many bytes as |
| 90 | * io_u->xfer_buflen. Residual data count may be set in io_u->resid |
| 91 | * for a short read/write. |
| 92 | */ |
| 93 | static enum fio_q_status fio_skeleton_queue(struct thread_data *td, |
| 94 | struct io_u *io_u) |
| 95 | { |
| 96 | /* |
| 97 | * Double sanity check to catch errant write on a readonly setup |
| 98 | */ |
| 99 | fio_ro_check(td, io_u); |
| 100 | |
| 101 | /* |
| 102 | * Could return FIO_Q_QUEUED for a queued request, |
| 103 | * FIO_Q_COMPLETED for a completed request, and FIO_Q_BUSY |
| 104 | * if we could queue no more at this point (you'd have to |
| 105 | * define ->commit() to handle that. |
| 106 | */ |
| 107 | return FIO_Q_COMPLETED; |
| 108 | } |
| 109 | |
| 110 | /* |
| 111 | * The ->prep() function is called for each io_u prior to being submitted |
| 112 | * with ->queue(). This hook allows the io engine to perform any |
| 113 | * preparatory actions on the io_u, before being submitted. Not required. |
| 114 | */ |
| 115 | static int fio_skeleton_prep(struct thread_data *td, struct io_u *io_u) |
| 116 | { |
| 117 | return 0; |
| 118 | } |
| 119 | |
| 120 | /* |
| 121 | * The init function is called once per thread/process, and should set up |
| 122 | * any structures that this io engine requires to keep track of io. Not |
| 123 | * required. |
| 124 | */ |
| 125 | static int fio_skeleton_init(struct thread_data *td) |
| 126 | { |
| 127 | return 0; |
| 128 | } |
| 129 | |
| 130 | /* |
| 131 | * This is paired with the ->init() function and is called when a thread is |
| 132 | * done doing io. Should tear down anything setup by the ->init() function. |
| 133 | * Not required. |
| 134 | */ |
| 135 | static void fio_skeleton_cleanup(struct thread_data *td) |
| 136 | { |
| 137 | } |
| 138 | |
| 139 | /* |
| 140 | * Hook for opening the given file. Unless the engine has special |
| 141 | * needs, it usually just provides generic_open_file() as the handler. |
| 142 | */ |
| 143 | static int fio_skeleton_open(struct thread_data *td, struct fio_file *f) |
| 144 | { |
| 145 | return generic_open_file(td, f); |
| 146 | } |
| 147 | |
| 148 | /* |
| 149 | * Hook for closing a file. See fio_skeleton_open(). |
| 150 | */ |
| 151 | static int fio_skeleton_close(struct thread_data *td, struct fio_file *f) |
| 152 | { |
| 153 | return generic_close_file(td, f); |
| 154 | } |
| 155 | |
| 156 | /* |
| 157 | * Note that the structure is exported, so that fio can get it via |
| 158 | * dlsym(..., "ioengine"); for (and only for) external engines. |
| 159 | */ |
| 160 | struct ioengine_ops ioengine = { |
| 161 | .name = "engine_name", |
| 162 | .version = FIO_IOOPS_VERSION, |
| 163 | .init = fio_skeleton_init, |
| 164 | .prep = fio_skeleton_prep, |
| 165 | .queue = fio_skeleton_queue, |
| 166 | .cancel = fio_skeleton_cancel, |
| 167 | .getevents = fio_skeleton_getevents, |
| 168 | .event = fio_skeleton_event, |
| 169 | .cleanup = fio_skeleton_cleanup, |
| 170 | .open_file = fio_skeleton_open, |
| 171 | .close_file = fio_skeleton_close, |
| 172 | .options = options, |
| 173 | .option_struct_size = sizeof(struct fio_skeleton_options), |
| 174 | }; |