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/*
* SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <time.h>
#include <errno.h>
#include <pthread.h>
#include <string.h>
#include <stdatomic.h>
#include "esp_err.h"
#include "esp_attr.h"
#include "sys/queue.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "soc/soc_memory_layout.h"
#include "pthread_internal.h"
#include "esp_pthread.h"
#include "esp_log.h"
const static char *TAG = "pthread_rw_lock";
/** pthread rw_mutex FreeRTOS wrapper */
typedef struct {
/**
*
*/
pthread_cond_t cv;
pthread_mutex_t resource_mutex;
/**
* Number of current readers holding this lock, negative number means waiting readers
*/
int8_t active_readers;
uint8_t active_writers;
uint8_t waiting_writers;
} esp_pthread_rwlock_t;
#define WRITER_QUEUE_SIZE 4
#define READER_QUEUE_SIZE 4
int pthread_rwlock_init(pthread_rwlock_t *rwlock,
const pthread_rwlockattr_t *attr)
{
int result;
if (!rwlock) {
return EINVAL;
}
if (attr) {
// TODO: implement attributes in IDF-4284
return ENOSYS;
}
esp_pthread_rwlock_t *esp_rwlock = (esp_pthread_rwlock_t*) calloc(1, sizeof(esp_pthread_rwlock_t));
if (esp_rwlock == NULL) {
return ENOMEM;
}
result = pthread_mutex_init(&esp_rwlock->resource_mutex, NULL);
if (result != 0) {
free(esp_rwlock);
return ENOMEM;
}
result = pthread_cond_init(&esp_rwlock->cv, NULL);
if (result != 0) {
pthread_mutex_destroy(&esp_rwlock->resource_mutex);
free(esp_rwlock);
return ENOMEM;
}
esp_rwlock->active_readers = 0;
esp_rwlock->active_writers = 0;
esp_rwlock->waiting_writers = 0;
*rwlock = (pthread_rwlock_t) esp_rwlock;
return 0;
}
static int pthread_rwlock_init_if_static(pthread_rwlock_t *rwlock)
{
int res = 0;
if ((intptr_t) *rwlock == PTHREAD_RWLOCK_INITIALIZER) {
portENTER_CRITICAL(&pthread_lazy_init_lock);
if ((intptr_t) *rwlock == PTHREAD_RWLOCK_INITIALIZER) {
res = pthread_rwlock_init(rwlock, NULL);
}
portEXIT_CRITICAL(&pthread_lazy_init_lock);
}
return res;
}
int pthread_rwlock_destroy(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
ESP_LOGV(TAG, "%s %p", __FUNCTION__, rwlock);
if (!rwlock) {
return EINVAL;
}
if ((intptr_t) *rwlock == PTHREAD_RWLOCK_INITIALIZER) {
return 0; // Static rwlock was never initialized
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
if (esp_rwlock == NULL) {
return EINVAL;
}
// TODO: necessary?
pthread_mutex_lock(&esp_rwlock->resource_mutex);
if (esp_rwlock->active_readers != 0 || esp_rwlock->active_writers > 0 || esp_rwlock->waiting_writers > 0) {
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
return EBUSY;
}
// delete whole lock
pthread_cond_destroy(&esp_rwlock->cv);
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
pthread_mutex_destroy(&esp_rwlock->resource_mutex);
free(esp_rwlock);
return 0;
}
static int checkrw_lock(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
int res;
if (rwlock == NULL) {
return EINVAL;
}
res = pthread_rwlock_init_if_static(rwlock);
if (res != 0) {
return res;
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
if (esp_rwlock == NULL) {
return EINVAL;
}
return 0;
}
int pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
int res;
res = checkrw_lock(rwlock);
if (res != 0) {
return res;
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
res = pthread_mutex_lock(&esp_rwlock->resource_mutex);
if (res != 0) {
return res;
}
if (esp_rwlock->active_writers == 0) {
esp_rwlock->active_readers++;
} else {
while (true) {
pthread_cond_wait(&esp_rwlock->cv, &esp_rwlock->resource_mutex);
if (esp_rwlock->active_writers == 0 && esp_rwlock->waiting_writers == 0) {
esp_rwlock->active_readers++;
break;
}
}
}
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
return 0;
}
int pthread_rwlock_tryrdlock(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
int res;
res = checkrw_lock(rwlock);
if (res != 0) {
return res;
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
res = pthread_mutex_trylock(&esp_rwlock->resource_mutex);
if (res != 0) {
return res;
}
if (esp_rwlock->active_writers == 0) {
esp_rwlock->active_readers++;
res = 0;
} else {
res = EBUSY;
}
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
return res;
}
int pthread_rwlock_wrlock(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
int res;
res = checkrw_lock(rwlock);
if (res != 0) {
return res;
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
res = pthread_mutex_lock(&esp_rwlock->resource_mutex);
if (res != 0) {
return res;
}
esp_rwlock->waiting_writers++;
while (esp_rwlock->active_readers > 0 || esp_rwlock->active_writers > 0) {
pthread_cond_wait(&esp_rwlock->cv, &esp_rwlock->resource_mutex);
}
esp_rwlock->waiting_writers--;
esp_rwlock->active_writers++;
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
return 0;
}
int pthread_rwlock_trywrlock(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
int res;
res = checkrw_lock(rwlock);
if (res != 0) {
return res;
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
res = pthread_mutex_trylock(&esp_rwlock->resource_mutex);
if (res != 0) {
return res;
}
if (esp_rwlock->active_readers > 0 ||
esp_rwlock->active_writers > 0 ||
esp_rwlock->waiting_writers > 0) { // the last check for waiting_writers is to avoid skipping the queue
res = EBUSY;
} else {
esp_rwlock->active_writers++;
res = 0;
}
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
return res;
}
int pthread_rwlock_unlock(pthread_rwlock_t *rwlock)
{
esp_pthread_rwlock_t *esp_rwlock;
int res;
res = checkrw_lock(rwlock);
if (res != 0) {
return res;
}
esp_rwlock = (esp_pthread_rwlock_t *)*rwlock;
res = pthread_mutex_lock(&esp_rwlock->resource_mutex);
if (res != 0) {
return res;
}
assert(!(esp_rwlock->active_readers > 0 && esp_rwlock->active_writers > 0));
if (esp_rwlock->active_readers > 0) {
// we are a reader
esp_rwlock->active_readers--;
if (esp_rwlock->active_readers == 0) {
pthread_cond_broadcast(&esp_rwlock->cv);
}
} else {
// we are a writer
esp_rwlock->active_writers = 0;
pthread_cond_broadcast(&esp_rwlock->cv);
}
pthread_mutex_unlock(&esp_rwlock->resource_mutex);
return 0;
}
/* Hook function to force linking this file */
void pthread_include_pthread_rwlock_impl(void)
{
}
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