Commit | Line | Data |
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da51c050 JA |
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 engine.o engine.c | |
7 | * | |
8 | */ | |
9 | #include <stdio.h> | |
10 | #include <stdlib.h> | |
11 | #include <unistd.h> | |
12 | #include <errno.h> | |
13 | #include <assert.h> | |
14 | ||
15 | #include "../fio.h" | |
16 | #include "../os.h" | |
17 | ||
18 | /* | |
19 | * The core of the module is identical to the ones included with fio, | |
20 | * read those. You cannot use register_ioengine() and unregister_ioengine() | |
21 | * for external modules, they should be gotten through dlsym() | |
22 | */ | |
23 | ||
830a78b0 JA |
24 | /* |
25 | * The ->event() hook is called to match an event number with an io_u. | |
26 | * After the core has called ->getevents() and it has returned eg 3, | |
27 | * the ->event() hook must return the 3 events that have completed for | |
28 | * subsequent calls to ->event() with [0-2]. Required. | |
29 | */ | |
30 | static struct io_u *fio_skeleton_event(struct thread_data *td, int event) | |
31 | { | |
32 | return NULL; | |
33 | } | |
34 | ||
35 | /* | |
36 | * The ->getevents() hook is used to reap completion events from an async | |
37 | * io engine. It returns the number of completed events since the last call, | |
38 | * which may then be retrieved by calling the ->event() hook with the event | |
39 | * numbers. Required. | |
40 | */ | |
41 | static int fio_skeleton_getevents(struct thread_data *td, int min, int max, | |
42 | struct timespec *t) | |
43 | { | |
44 | return 0; | |
45 | } | |
46 | ||
47 | /* | |
48 | * The ->cancel() hook attempts to cancel the io_u. Only relevant for | |
49 | * async io engines, and need not be supported. | |
50 | */ | |
51 | static int fio_skeleton_cancel(struct thread_data *td, struct io_u *io_u) | |
52 | { | |
53 | return 0; | |
54 | } | |
55 | ||
56 | /* | |
57 | * The ->queue() hook is responsible for initiating io on the io_u | |
58 | * being passed in. If the io engine is a synchronous one, io may complete | |
59 | * before ->queue() returns. Required. | |
e2a26d2c JA |
60 | * |
61 | * The io engine must transfer in the direction noted by io_u->ddir | |
62 | * to the buffer pointed to by io_u->xfer_buf for as many bytes as | |
63 | * io_u->xfer_buflen. Residual data count may be set in io_u->residual | |
36167d82 | 64 | * for a short read/write. |
830a78b0 JA |
65 | */ |
66 | static int fio_skeleton_queue(struct thread_data *td, struct io_u *io_u) | |
67 | { | |
36167d82 JA |
68 | /* |
69 | * Could return FIO_Q_QUEUED for a queued request, | |
70 | * FIO_Q_COMPLETED for a completed request, and FIO_Q_BUSY | |
71 | * if we could queue no more at this point (you'd have to | |
72 | * define ->commit() to handle that. | |
73 | */ | |
74 | return FIO_Q_COMPLETED; | |
830a78b0 JA |
75 | } |
76 | ||
77 | /* | |
78 | * The ->prep() function is called for each io_u prior to being submitted | |
79 | * with ->queue(). This hook allows the io engine to perform any | |
34403fb1 | 80 | * preparatory actions on the io_u, before being submitted. Not required. |
830a78b0 JA |
81 | */ |
82 | static int fio_skeleton_prep(struct thread_data *td, struct io_u *io_u) | |
83 | { | |
84 | return 0; | |
85 | } | |
86 | ||
87 | /* | |
88 | * The init function is called once per thread/process, and should set up | |
89 | * any structures that this io engine requires to keep track of io. Not | |
90 | * required. | |
91 | */ | |
92 | static int fio_skeleton_init(struct thread_data *td) | |
93 | { | |
94 | return 0; | |
95 | } | |
96 | ||
97 | /* | |
98 | * This is paired with the ->init() funtion and is called when a thread is | |
99 | * done doing io. Should tear down anything setup by the ->init() function. | |
100 | * Not required. | |
101 | */ | |
102 | static void fio_skeleton_cleanup(struct thread_data *td) | |
103 | { | |
104 | } | |
105 | ||
b5af8293 JA |
106 | /* |
107 | * Hook for opening the given file. Unless the engine has special | |
108 | * needs, it usually just provides generic_file_open() as the handler. | |
109 | */ | |
110 | static int fio_skeleton_open(struct thread_data *td, struct fio_file *f) | |
111 | { | |
112 | return generic_file_open(td, f); | |
113 | } | |
114 | ||
115 | /* | |
116 | * Hook for closing a file. See fio_skeleton_open(). | |
117 | */ | |
118 | static int fio_skeleton_close(struct thread_data *td, struct fio_file *f) | |
119 | { | |
120 | generic_file_close(td, f); | |
121 | } | |
122 | ||
da51c050 JA |
123 | /* |
124 | * Note that the structure is exported, so that fio can get it via | |
125 | * dlsym(..., "ioengine"); | |
126 | */ | |
127 | struct ioengine_ops ioengine = { | |
128 | .name = "engine_name", | |
129 | .version = FIO_IOOPS_VERSION, | |
130 | .init = fio_skeleton_init, | |
131 | .prep = fio_skeleton_prep, | |
132 | .queue = fio_skeleton_queue, | |
830a78b0 | 133 | .cancel = fio_skeleton_cancel, |
da51c050 JA |
134 | .getevents = fio_skeleton_getevents, |
135 | .event = fio_skeleton_event, | |
136 | .cleanup = fio_skeleton_cleanup, | |
b5af8293 JA |
137 | .open_file = fio_skeleton_open, |
138 | .close_file = fio_skeleton_close, | |
da51c050 | 139 | }; |