add cooperative threading example

pull/21/head
Ariadne Conill 3 years ago
parent a52354e640
commit cc2b4da24a

@ -37,6 +37,8 @@ LIBUCONTEXT_STATIC_PATH = ${LIBDIR}/${LIBUCONTEXT_STATIC_NAME}
LIBUCONTEXT_HEADERS = \
include/libucontext/libucontext.h \
include/libucontext/bits.h
LIBUCONTEXT_EXAMPLES = \
examples/cooperative_threading
all: ${LIBUCONTEXT_SONAME} ${LIBUCONTEXT_STATIC_NAME} ${LIBUCONTEXT_PC}
@ -98,6 +100,10 @@ check: test_libucontext ${LIBUCONTEXT_SONAME}
test_libucontext: test_libucontext.c ${LIBUCONTEXT_NAME}
$(CC) -std=c99 -D_BSD_SOURCE ${CFLAGS} ${CPPFLAGS} $@.c -o $@ -L. -lucontext
examples: ${LIBUCONTEXT_EXAMPLES}
examples/cooperative_threading: examples/cooperative_threading.c ${LIBUCONTEXT_NAME}
$(CC) -std=c99 -D_BSD_SOURCE ${CFLAGS} ${CPPFLAGS} $@.c -o $@ -L. -lucontext
ifeq ($(FREESTANDING),no)
include/libucontext/bits.h: arch/common/bits.h

@ -0,0 +1,94 @@
#include <assert.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <libucontext/libucontext.h>
libucontext_ucontext_t mainctx = {};
libucontext_ucontext_t *curthr = &mainctx;
libucontext_ucontext_t *threads = NULL;
size_t thrcount = 0;
void
yieldto(libucontext_ucontext_t *target)
{
libucontext_ucontext_t *oldthr = curthr;
curthr = target;
libucontext_swapcontext(oldthr, curthr);
}
void
yield(void)
{
libucontext_ucontext_t *newthr;
/* we set uc_flags to non-zero to signal thread completion. */
do
newthr = &threads[random() % thrcount];
while (newthr == curthr || newthr->uc_flags);
srandom(time(NULL));
yieldto(newthr);
}
void
worker(size_t multiple)
{
size_t accum = 1;
for (size_t i = 0; i < 10; i++)
{
accum += (multiple * i);
printf("[%p] accumulated %zu\n", curthr, accum);
yield();
}
/* mark thread as completed, so we don't return here */
curthr->uc_flags = 1;
}
void
create(size_t multiple)
{
libucontext_ucontext_t *cursor;
thrcount += 1;
threads = realloc(threads, sizeof(*threads) * thrcount);
cursor = &threads[thrcount - 1];
memset(cursor, '\0', sizeof *cursor);
/* initialize the new thread's values to our current context */
libucontext_getcontext(cursor);
/* set up uc_link */
cursor->uc_link = thrcount > 1 ? &threads[thrcount - 2] : &mainctx;
/* set up a stack */
cursor->uc_stack.ss_size = 8192;
cursor->uc_stack.ss_sp = calloc(1, cursor->uc_stack.ss_size);
/* set up the function call */
libucontext_makecontext(cursor, worker, 1, multiple);
}
int
main(int argc, const char *argv[])
{
srandom(time(NULL));
libucontext_getcontext(&mainctx);
for (size_t i = 1; i < 4; i++)
create(i);
/* start the threads off by yielding to the last one */
yieldto(&threads[thrcount - 1]);
return EXIT_SUCCESS;
}
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