-
-
Notifications
You must be signed in to change notification settings - Fork 2.3k
/
Pool.zig
217 lines (176 loc) · 5.85 KB
/
Pool.zig
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
const std = @import("std");
const builtin = @import("builtin");
const Pool = @This();
const WaitGroup = @import("WaitGroup.zig");
mutex: std.Thread.Mutex = .{},
cond: std.Thread.Condition = .{},
run_queue: RunQueue = .{},
is_running: bool = true,
allocator: std.mem.Allocator,
threads: []std.Thread,
const RunQueue = std.SinglyLinkedList(Runnable);
const Runnable = struct {
runFn: RunProto,
};
const RunProto = *const fn (*Runnable) void;
pub const Options = struct {
allocator: std.mem.Allocator,
n_jobs: ?u32 = null,
};
pub fn init(pool: *Pool, options: Options) !void {
const allocator = options.allocator;
pool.* = .{
.allocator = allocator,
.threads = &[_]std.Thread{},
};
if (builtin.single_threaded) {
return;
}
const thread_count = options.n_jobs orelse @max(1, std.Thread.getCpuCount() catch 1);
// kill and join any threads we spawned and free memory on error.
pool.threads = try allocator.alloc(std.Thread, thread_count);
var spawned: usize = 0;
errdefer pool.join(spawned);
for (pool.threads) |*thread| {
thread.* = try std.Thread.spawn(.{}, worker, .{pool});
spawned += 1;
}
}
pub fn deinit(pool: *Pool) void {
pool.join(pool.threads.len); // kill and join all threads.
pool.* = undefined;
}
fn join(pool: *Pool, spawned: usize) void {
if (builtin.single_threaded) {
return;
}
{
pool.mutex.lock();
defer pool.mutex.unlock();
// ensure future worker threads exit the dequeue loop
pool.is_running = false;
}
// wake up any sleeping threads (this can be done outside the mutex)
// then wait for all the threads we know are spawned to complete.
pool.cond.broadcast();
for (pool.threads[0..spawned]) |thread| {
thread.join();
}
pool.allocator.free(pool.threads);
}
/// Runs `func` in the thread pool, calling `WaitGroup.start` beforehand, and
/// `WaitGroup.finish` after it returns.
///
/// In the case that queuing the function call fails to allocate memory, or the
/// target is single-threaded, the function is called directly.
pub fn spawnWg(pool: *Pool, wait_group: *WaitGroup, comptime func: anytype, args: anytype) void {
wait_group.start();
if (builtin.single_threaded) {
@call(.auto, func, args);
wait_group.finish();
return;
}
const Args = @TypeOf(args);
const Closure = struct {
arguments: Args,
pool: *Pool,
run_node: RunQueue.Node = .{ .data = .{ .runFn = runFn } },
wait_group: *WaitGroup,
fn runFn(runnable: *Runnable) void {
const run_node: *RunQueue.Node = @fieldParentPtr("data", runnable);
const closure: *@This() = @alignCast(@fieldParentPtr("run_node", run_node));
@call(.auto, func, closure.arguments);
closure.wait_group.finish();
// The thread pool's allocator is protected by the mutex.
const mutex = &closure.pool.mutex;
mutex.lock();
defer mutex.unlock();
closure.pool.allocator.destroy(closure);
}
};
{
pool.mutex.lock();
const closure = pool.allocator.create(Closure) catch {
pool.mutex.unlock();
@call(.auto, func, args);
wait_group.finish();
return;
};
closure.* = .{
.arguments = args,
.pool = pool,
.wait_group = wait_group,
};
pool.run_queue.prepend(&closure.run_node);
pool.mutex.unlock();
}
// Notify waiting threads outside the lock to try and keep the critical section small.
pool.cond.signal();
}
pub fn spawn(pool: *Pool, comptime func: anytype, args: anytype) !void {
if (builtin.single_threaded) {
@call(.auto, func, args);
return;
}
const Args = @TypeOf(args);
const Closure = struct {
arguments: Args,
pool: *Pool,
run_node: RunQueue.Node = .{ .data = .{ .runFn = runFn } },
fn runFn(runnable: *Runnable) void {
const run_node: *RunQueue.Node = @fieldParentPtr("data", runnable);
const closure: *@This() = @alignCast(@fieldParentPtr("run_node", run_node));
@call(.auto, func, closure.arguments);
// The thread pool's allocator is protected by the mutex.
const mutex = &closure.pool.mutex;
mutex.lock();
defer mutex.unlock();
closure.pool.allocator.destroy(closure);
}
};
{
pool.mutex.lock();
defer pool.mutex.unlock();
const closure = try pool.allocator.create(Closure);
closure.* = .{
.arguments = args,
.pool = pool,
};
pool.run_queue.prepend(&closure.run_node);
}
// Notify waiting threads outside the lock to try and keep the critical section small.
pool.cond.signal();
}
fn worker(pool: *Pool) void {
pool.mutex.lock();
defer pool.mutex.unlock();
while (true) {
while (pool.run_queue.popFirst()) |run_node| {
// Temporarily unlock the mutex in order to execute the run_node
pool.mutex.unlock();
defer pool.mutex.lock();
const runFn = run_node.data.runFn;
runFn(&run_node.data);
}
// Stop executing instead of waiting if the thread pool is no longer running.
if (pool.is_running) {
pool.cond.wait(&pool.mutex);
} else {
break;
}
}
}
pub fn waitAndWork(pool: *Pool, wait_group: *WaitGroup) void {
while (!wait_group.isDone()) {
if (blk: {
pool.mutex.lock();
defer pool.mutex.unlock();
break :blk pool.run_queue.popFirst();
}) |run_node| {
run_node.data.runFn(&run_node.data);
continue;
}
wait_group.wait();
return;
}
}