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circuitpython/unix/mpthreadport.c

228 lines
6.8 KiB

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include "py/mpstate.h"
#include "py/mpthread.h"
#include "py/gc.h"
#if MICROPY_PY_THREAD
#include <signal.h>
#include <sched.h>
// this structure forms a linked list, one node per active thread
typedef struct _thread_t {
pthread_t id; // system id of thread
int ready; // whether the thread is ready and running
void *arg; // thread Python args, a GC root pointer
struct _thread_t *next;
} thread_t;
STATIC pthread_key_t tls_key;
// the mutex controls access to the linked list
STATIC pthread_mutex_t thread_mutex = PTHREAD_MUTEX_INITIALIZER;
STATIC thread_t *thread;
// this is used to synchronise the signal handler of the thread
// it's needed because we can't use any pthread calls in a signal handler
STATIC volatile int thread_signal_done;
// this signal handler is used to scan the regs and stack of a thread
STATIC void mp_thread_gc(int signo, siginfo_t *info, void *context) {
(void)info; // unused
(void)context; // unused
if (signo == SIGUSR1) {
void gc_collect_regs_and_stack(void);
gc_collect_regs_and_stack();
// We have access to the context (regs, stack) of the thread but it seems
// that we don't need the extra information, enough is captured by the
// gc_collect_regs_and_stack function above
//gc_collect_root((void**)context, sizeof(ucontext_t) / sizeof(uintptr_t));
thread_signal_done = 1;
}
}
void mp_thread_init(void) {
pthread_key_create(&tls_key, NULL);
pthread_setspecific(tls_key, &mp_state_ctx.thread);
// create first entry in linked list of all threads
thread = malloc(sizeof(thread_t));
thread->id = pthread_self();
thread->ready = 1;
thread->arg = NULL;
thread->next = NULL;
// enable signal handler for garbage collection
struct sigaction sa;
sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = mp_thread_gc;
sigemptyset(&sa.sa_mask);
sigaction(SIGUSR1, &sa, NULL);
}
// This function scans all pointers that are external to the current thread.
// It does this by signalling all other threads and getting them to scan their
// own registers and stack. Note that there may still be some edge cases left
// with race conditions and root-pointer scanning: a given thread may manipulate
// the global root pointers (in mp_state_ctx) while another thread is doing a
// garbage collection and tracing these pointers.
void mp_thread_gc_others(void) {
pthread_mutex_lock(&thread_mutex);
for (thread_t *th = thread; th != NULL; th = th->next) {
gc_collect_root(&th->arg, 1);
if (th->id == pthread_self()) {
continue;
}
if (!th->ready) {
continue;
}
thread_signal_done = 0;
pthread_kill(th->id, SIGUSR1);
while (thread_signal_done == 0) {
sched_yield();
}
}
pthread_mutex_unlock(&thread_mutex);
}
mp_state_thread_t *mp_thread_get_state(void) {
return (mp_state_thread_t*)pthread_getspecific(tls_key);
}
void mp_thread_set_state(void *state) {
pthread_setspecific(tls_key, state);
}
void mp_thread_start(void) {
pthread_mutex_lock(&thread_mutex);
for (thread_t *th = thread; th != NULL; th = th->next) {
if (th->id == pthread_self()) {
th->ready = 1;
break;
}
}
pthread_mutex_unlock(&thread_mutex);
}
void mp_thread_create(void *(*entry)(void*), void *arg, size_t *stack_size) {
// default stack size is 8k machine-words
if (*stack_size == 0) {
*stack_size = 8192 * BYTES_PER_WORD;
}
// minimum stack size is set by pthreads
if (*stack_size < PTHREAD_STACK_MIN) {
*stack_size = PTHREAD_STACK_MIN;
}
// set thread attributes
pthread_attr_t attr;
int ret = pthread_attr_init(&attr);
if (ret != 0) {
goto er;
}
ret = pthread_attr_setstacksize(&attr, *stack_size);
if (ret != 0) {
goto er;
}
pthread_mutex_lock(&thread_mutex);
// create thread
pthread_t id;
ret = pthread_create(&id, &attr, entry, arg);
if (ret != 0) {
pthread_mutex_unlock(&thread_mutex);
goto er;
}
// adjust stack_size to provide room to recover from hitting the limit
// this value seems to be about right for both 32-bit and 64-bit builds
*stack_size -= 8192;
// add thread to linked list of all threads
thread_t *th = malloc(sizeof(thread_t));
th->id = id;
th->ready = 0;
th->arg = arg;
th->next = thread;
thread = th;
pthread_mutex_unlock(&thread_mutex);
return;
er:
nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(ret)));
}
void mp_thread_finish(void) {
pthread_mutex_lock(&thread_mutex);
// TODO unlink from list
for (thread_t *th = thread; th != NULL; th = th->next) {
if (th->id == pthread_self()) {
th->ready = 0;
break;
}
}
pthread_mutex_unlock(&thread_mutex);
}
void mp_thread_mutex_init(mp_thread_mutex_t *mutex) {
pthread_mutex_init(mutex, NULL);
}
int mp_thread_mutex_lock(mp_thread_mutex_t *mutex, int wait) {
int ret;
if (wait) {
ret = pthread_mutex_lock(mutex);
if (ret == 0) {
return 1;
}
} else {
ret = pthread_mutex_trylock(mutex);
if (ret == 0) {
return 1;
} else if (ret == EBUSY) {
return 0;
}
}
return -ret;
}
void mp_thread_mutex_unlock(mp_thread_mutex_t *mutex) {
pthread_mutex_unlock(mutex);
// TODO check return value
}
#endif // MICROPY_PY_THREAD