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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
|
//
// Threading example program for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2025 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file. If this
// file is missing or damaged, see the license at:
//
// https://www.fltk.org/COPYING.php
//
// Please see the following page on how to report bugs and issues:
//
// https://www.fltk.org/bugs.php
//
#include <config.h>
#if defined(HAVE_PTHREAD) || defined(_WIN32)
# include <FL/Fl.H>
# include <FL/Fl_Double_Window.H>
# include <FL/Fl_Terminal.H>
# include <FL/Fl_Output.H>
# include <FL/fl_ask.H>
# include "threads.h"
# include <stdio.h>
# include <math.h>
# include <vector>
// min. time in seconds before calling Fl::awake(...)
#define DELTA 0.25
// struct to collect primes until at least <DELTA> seconds passed.
// Two such structs per thread are used as alternate buffers.
struct prime {
int idx; // thread index: 0 or {1..6}
int done; // set to 1 after it was worked on
Fl_Terminal *terminal; // widget to write output to
unsigned long max_prime; // highest prime found so far
Fl_Output *value; // highest prime output widget
std::vector<unsigned long> primes; // collected primes within time frame
};
Fl_Thread prime_thread;
Fl_Terminal *tty1, *tty2;
Fl_Output *value1, *value2;
int start2 = 3;
void magic_number_cb(void *p) {
Fl_Output *w = (Fl_Output*)p;
w->labelcolor(FL_RED);
w->parent()->redraw();
// if (w == value1) Fl::hide_all_windows(); // TEST: terminate early to measure time
}
// This is called indirectly by Fl::awake(update_handler, (void *)prime)
// in the context of the main (FLTK GUI) thread.
void update_handler(void *v) {
char max_buf[32];
struct prime *pr = (struct prime *)v;
for (auto n : pr->primes) {
pr->terminal->printf("prime: %10lu\n", n);
if (n > pr->max_prime)
pr->max_prime = n;
}
snprintf(max_buf, sizeof(max_buf), "%9lu", pr->max_prime);
pr->value->value(max_buf);
pr->done = 1;
}
extern "C" void* prime_func(void* p) {
Fl_Terminal* terminal = (Fl_Terminal*)p;
Fl_Output *value;
unsigned long n;
unsigned long max_value = 0;
int step;
char proud = 0;
// initialize thread variables
if (terminal == tty2) { // multiple threads
Fl::lock(); // lock to prevent race condition on `start2`
n = start2;
start2 += 2;
Fl::unlock();
step = 12;
value = value2;
} else { // single thread
n = 3;
step = 2;
value = value1;
}
// initialize alternate buffers (struct prime) to store primes
struct prime pr[2];
pr[0].idx = pr[1].idx = ((int)n/2 - 1);
pr[0].done = 0;
pr[1].done = 1;
pr[0].terminal = pr[1].terminal = terminal;
pr[0].max_prime = pr[1].max_prime = 0;
pr[0].value = pr[1].value = value;
pr[0].primes.clear();
pr[1].primes.clear();
int pi = 0; // prime buffer index
Fl_Timestamp last = Fl::now();
// very simple prime number calculator !
//
// The return at the end of this function can never be reached and thus
// will generate a warning with some compilers, however we need to have
// a return statement or other compilers will complain there is no return
// statement. To avoid warnings on all compilers, we fool the smart ones into
// believing that there is a chance that we reach the end by testing n > 0,
// knowing that logically, n will never be less than 3 in this context.
if (n > 0) for (;;) {
int pp;
int hn = (int)sqrt((double)n);
for (pp = 3; pp <= hn; pp += 2) {
if (n % pp == 0)
break;
}
if (pp > hn) { // n is a prime
pr[pi].primes.push_back(n);
// Send a message to the main thread, at which point it will
// process any pending updates.
double ssl = Fl::seconds_since(last);
if (ssl > DELTA && pr[1-pi].done) { // ready to switch buffers
last = Fl::now();
Fl::awake(update_handler, (void *)(&pr[pi]));
pi = 1 - pi; // switch to alternate buffer
pr[pi].primes.clear(); // clear primes
}
if (n > max_value) {
pr[pi].max_prime = n;
}
n += step;
if (n > 5 * 1000 * 1000 && !proud) {
proud = 1;
Fl::awake(magic_number_cb, value);
}
} else {
// This should not be necessary since "n" and "step" are local variables,
// however it appears that at least MacOS X has some threading issues
// that cause semi-random corruption of the (stack) variables.
Fl::lock();
n += step;
Fl::unlock();
}
}
return 0L;
}
// close all windows when the user closes one of the windows
void close_cb(Fl_Widget *w, void *v) {
Fl::hide_all_windows();
printf("Max prime number with 1 thread : %s\n", value1->value());
printf("Max prime number with 6 threads: %s\n", value2->value());
return;
}
int main(int argc, char **argv)
{
// First window: single thread
Fl_Double_Window* w = new Fl_Double_Window(200, 200, "Single Thread");
tty1 = new Fl_Terminal(0, 0, 200, 175);
tty1->color(FL_BACKGROUND2_COLOR);
tty1->textcolor(FL_FOREGROUND_COLOR);
w->resizable(tty1);
value1 = new Fl_Output(100, 175, 98, 23, "Max Prime:");
value1->textfont(FL_COURIER);
w->callback(close_cb);
w->end();
w->show(argc, argv);
// Second window: multiple threads
w = new Fl_Double_Window(200, 200, "Six Threads");
tty2 = new Fl_Terminal(0, 0, 200, 175);
tty2->color(FL_BACKGROUND2_COLOR);
tty2->textcolor(FL_FOREGROUND_COLOR);
w->resizable(tty2);
value2 = new Fl_Output(100, 175, 98, 23, "Max Prime:");
value2->textfont(FL_COURIER);
w->callback(close_cb);
w->end();
w->show();
tty1->printf("Prime numbers:\n");
tty2->printf("Prime numbers:\n");
// Enable multi-thread support by locking from the main thread.
// Fl::wait() and Fl::run() call Fl::unlock() and Fl::lock() as needed
// to release control to the child threads when it is safe to do so...
Fl::lock();
// Start threads...
// One thread displaying in one terminal
fl_create_thread(prime_thread, prime_func, tty1);
// Six threads displaying in another terminal
fl_create_thread(prime_thread, prime_func, tty2);
fl_create_thread(prime_thread, prime_func, tty2);
fl_create_thread(prime_thread, prime_func, tty2);
fl_create_thread(prime_thread, prime_func, tty2);
fl_create_thread(prime_thread, prime_func, tty2);
fl_create_thread(prime_thread, prime_func, tty2);
Fl::run();
return 0;
}
#else
# include <FL/fl_ask.H>
int main() {
fl_alert("Sorry, threading not supported on this platform!");
}
#endif // HAVE_PTHREAD || _WIN32
|
