boinc/samples/multi_thread/multi_thread.cpp

287 lines
7.5 KiB
C++

// This file is part of BOINC.
// http://boinc.berkeley.edu
// Copyright (C) 2008 University of California
//
// BOINC is free software; you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License
// as published by the Free Software Foundation,
// either version 3 of the License, or (at your option) any later version.
//
// BOINC is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
// See the GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with BOINC. If not, see <http://www.gnu.org/licenses/>.
// Example multi-thread BOINC application.
// It does 64 "units" of computation, where each units is about 1 GFLOP.
// It divides this among N "worker" threads.
// N is passed in the command line, and defaults to 1.
//
// The main issue is how to suspend/resume the threads.
// The standard BOINC API doesn't work - it assumes that
// the initial thread is the only one.
// On Linux, there's no API to suspend/resume threads.
// All you can do is SIGSTOP/SIGCONT, which affects the whole process.
// So we use the following process/thread structure:
//
// Windows:
// Initial thread:
// - launches worker threads,
// - in polling loop, checks for suspend/resume messages
// from the BOINC client, and handles them itself.
// Unix:
// Initial process
// - forks worker process
// - in polling loop, checks for worker process completion
// - doesn't send status msgs
// Worker process
// Initial thread:
// - forks worker threads, wait for them to finish, exit
// - uses BOINC runtime to send status messages (frac done, CPU time)
//
// Doesn't do checkpointing.
#include <stdio.h>
#include <vector>
#ifdef _WIN32
#include "boinc_win.h"
#else
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <pthread.h>
#endif
#include "util.h"
#include "str_util.h"
#include "boinc_api.h"
using std::vector;
#define DEFAULT_NTHREADS 1
#define TOTAL_UNITS 64
int units_per_thread;
#ifdef _WIN32
typedef HANDLE THREAD_ID;
typedef UINT (__stdcall *THREAD_FUNC)(void*);
#else
typedef void* (*THREAD_FUNC)(void*);
typedef pthread_t THREAD_ID;
#endif
#define THREAD_ID_NULL 0
// An abstraction of threads.
// A thread function is passed a pointer to its own object,
// and sets its ID to THREAD_ID_NULL when it's finished.
//
struct THREAD {
THREAD_ID id;
int index;
int units_done;
THREAD(THREAD_FUNC func, int i) {
index = i;
units_done = 0;
#ifdef _WIN32
id = (HANDLE) _beginthreadex(
NULL,
16384,
func,
this,
0,
NULL
);
if (!id) {
fprintf(stderr, "%s Can't start thread\n", boinc_msg_prefix());
exit(1);
}
#else
int retval;
retval = pthread_create(&id, 0, func, (void*)this);
if (retval) {
fprintf(stderr, "%s can't start thread\n", boinc_msg_prefix());
exit(1);
}
#endif
}
#ifdef _WIN32
void suspend(bool if_susp) {
if (if_susp) {
SuspendThread(id);
} else {
ResumeThread(id);
}
}
#endif
};
struct THREAD_SET {
vector<THREAD*> threads;
#ifdef _WIN32
void suspend(bool if_susp) {
for (unsigned int i=0; i<threads.size(); i++) {
THREAD* t = threads[i];
if (t->id != THREAD_ID_NULL) t->suspend(if_susp);
}
fprintf(stderr, "%s suspended all\n", boinc_msg_prefix());
}
#endif
bool all_done() {
for (unsigned int i=0; i<threads.size(); i++) {
if (threads[i]->id != THREAD_ID_NULL) return false;
}
return true;
}
int units_done() {
int count = 0;
for (unsigned int i=0; i<threads.size(); i++) {
count += threads[i]->units_done;
}
return count;
}
};
// do a billion floating-point ops
// (note: I needed to add an arg to this;
// otherwise the MS C++ compiler optimizes away
// all but the first call to it!)
//
static double do_a_giga_flop(int foo) {
double x = 3.14159*foo;
int i;
for (i=0; i<500000000; i++) {
x += 5.12313123;
x *= 0.5398394834;
}
return x;
}
#ifdef _WIN32
UINT WINAPI worker(void* p) {
#else
void* worker(void* p) {
#endif
THREAD* t = (THREAD*)p;
for (int i=0; i<units_per_thread; i++) {
double x = do_a_giga_flop(i);
t->units_done++;
fprintf(stderr, "%s thread %d finished %d: %f\n",
boinc_msg_prefix(), t->index, i, x
);
}
t->id = THREAD_ID_NULL;
#ifdef _WIN32
return 0;
#endif
}
void main_thread(int nthreads) {
int i;
#ifdef _WIN32
static BOINC_STATUS status;
#endif
THREAD_SET thread_set;
for (i=0; i<nthreads; i++) {
thread_set.threads.push_back(new THREAD(worker, i));
}
while (1) {
double f = thread_set.units_done()/((double)TOTAL_UNITS);
boinc_fraction_done(f);
if (thread_set.all_done()) break;
#ifdef _WIN32
int old_susp = status.suspended;
boinc_get_status(&status);
if (status.quit_request || status.abort_request || status.no_heartbeat) {
exit(0);
}
if (status.suspended != old_susp) {
thread_set.suspend(status.suspended != 0);
}
boinc_sleep(0.1);
#else
boinc_sleep(1.0);
#endif
}
}
int main(int argc, char** argv) {
BOINC_OPTIONS options;
int nthreads = DEFAULT_NTHREADS;
double start_time = dtime();
boinc_options_defaults(options);
options.direct_process_action = 0;
for (int i=1; i<argc; i++) {
if (!strcmp(argv[i], "--nthreads")) {
nthreads = atoi(argv[++i]);
} else {
fprintf(stderr, "%s unrecognized arg: %s\n",
boinc_msg_prefix(), argv[i]
);
}
}
units_per_thread = TOTAL_UNITS/nthreads;
#ifdef _WIN32
boinc_init_options(&options);
main_thread(nthreads);
#else
options.send_status_msgs = 0;
boinc_init_options(&options);
int pid = fork();
if (pid) { // parent
BOINC_STATUS status;
boinc_get_status(&status);
int exit_status;
while (1) {
bool old_susp = status.suspended;
boinc_get_status(&status);
if (status.quit_request || status.abort_request || status.no_heartbeat) {
kill(pid, SIGKILL);
exit(0);
}
if (status.suspended != old_susp) {
kill(pid, status.suspended?SIGSTOP:SIGCONT);
}
if (waitpid(pid, &exit_status, WNOHANG) == pid) {
break;
}
boinc_sleep(0.1);
}
} else { // child (worker)
memset(&options, 0, sizeof(options));
options.send_status_msgs = 1;
boinc_init_options(&options);
main_thread(nthreads);
}
#endif
double elapsed_time = dtime()-start_time;
fprintf(stderr,
"%s All done. Used %d threads. Elapsed time %f\n",
boinc_msg_prefix(), nthreads, elapsed_time
);
boinc_finish(0);
}
#ifdef _WIN32
int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInst, LPSTR Args, int WinMode) {
LPSTR command_line;
char* argv[100];
int argc;
command_line = GetCommandLine();
argc = parse_command_line( command_line, argv );
return main(argc, argv);
}
#endif