1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
use crossbeam_utils::thread;
use std::any::Any;
use std::env;
use std::io;
#[derive(Debug)]
pub enum Error<E> {
IOError(io::Error),
BuildError(E),
BuildPanic(Box<dyn Any + Send + 'static>),
}
fn compile_object<T, R, E, F>(f: F, obj: &T) -> Result<R, Error<E>>
where
T: 'static + Sync,
R: 'static + Sync + Send,
E: 'static + Sync + Send,
F: Fn(&T) -> Result<R, E> + Sync + Send,
{
f(obj).map_err(Error::BuildError)
}
pub fn compile_objects<T, R, E, F>(f: &F, objs: &[T]) -> Result<Vec<R>, Error<E>>
where
T: 'static + Sync,
R: 'static + Sync + Send,
E: 'static + Sync + Send,
F: Fn(&T) -> Result<R, E> + Sync + Send,
{
use std::sync::atomic::{AtomicBool, Ordering::SeqCst};
use std::sync::Once;
let server = jobserver();
let reacquire = server.release_raw().is_ok();
let res = thread::scope(|s| {
let error = AtomicBool::new(false);
let mut handles = Vec::new();
for obj in objs {
if error.load(SeqCst) {
break;
}
let token = server.acquire().map_err(Error::IOError)?;
let state = State { obj, error: &error };
let state = unsafe { std::mem::transmute::<State<T>, State<'static, T>>(state) };
handles.push(s.spawn(|_| {
let state: State<T> = state;
let result = compile_object(f, state.obj);
if result.is_err() {
state.error.store(true, SeqCst);
}
drop(token);
result
}));
}
let mut output = Vec::new();
for handle in handles {
match handle.join().map_err(Error::BuildPanic)? {
Ok(r) => output.push(r),
Err(err) => return Err(err),
}
}
Ok(output)
})
.map_err(Error::BuildPanic)?;
if reacquire {
server.acquire_raw().map_err(Error::IOError)?;
}
return res;
struct State<'a, O> {
obj: &'a O,
error: &'a AtomicBool,
}
fn jobserver() -> &'static jobserver::Client {
static INIT: Once = Once::new();
static mut JOBSERVER: Option<jobserver::Client> = None;
fn _assert_sync<T: Sync>() {}
_assert_sync::<jobserver::Client>();
unsafe {
INIT.call_once(|| {
let server = default_jobserver();
JOBSERVER = Some(server);
});
JOBSERVER.as_ref().unwrap()
}
}
unsafe fn default_jobserver() -> jobserver::Client {
if let Some(client) = jobserver::Client::from_env() {
return client;
}
let mut parallelism = num_cpus::get();
if let Ok(amt) = env::var("NUM_JOBS") {
if let Ok(amt) = amt.parse() {
parallelism = amt;
}
}
let client = jobserver::Client::new(parallelism).expect("failed to create jobserver");
client.acquire_raw().expect("failed to acquire initial");
client
}
}
#[test]
fn it_works() {
struct Object;
let mut v = Vec::new();
for _ in 0..4000 {
v.push(Object);
}
compile_objects::<Object, (), (), _>(
&|_| {
println!("compile {:?}", std::thread::current().id());
Ok(())
},
&v,
)
.unwrap();
}
#[test]
fn test_build_error() {
struct Object;
let mut v = Vec::new();
v.push(Object);
let err = compile_objects::<Object, (), (), _>(
&|_| {
return Err(());
},
&v,
)
.unwrap_err();
match err {
Error::BuildError(_) => {},
_ => panic!("Unexpected error."),
}
}
#[test]
fn test_build_panic() {
struct Object;
let mut v = Vec::new();
v.push(Object);
let err = compile_objects::<Object, (), (), _>(
&|_| {
panic!("Panic.");
},
&v,
)
.unwrap_err();
match err {
Error::BuildPanic(_) => {},
_ => panic!("Unexpected error."),
}
}