Espressif ESP32-S2 Programming Manual page 843

Chapter 2. API Reference
• pthread_mutexattr_gettype() / pthread_mutexattr_settype()
Static initializer constant PTHREAD_MUTEX_INITIALIZER is supported, but the non-standard static initializer
constants for other mutex types are not supported.
Note: These functions can be called from tasks created using either pthread or FreeRTOS APIs
Condition Variables
• pthread_cond_init() - The attr argument is not implemented and is ignored.
• pthread_cond_destroy()
• pthread_cond_signal()
• pthread_cond_broadcast()
• pthread_cond_wait()
• pthread_cond_timedwait()
Static initializer constant PTHREAD_COND_INITIALIZER is supported.
• The resolution of pthread_cond_timedwait() timeouts is the RTOS tick period (see
FIG_FREERTOS_HZ). Timeouts may be delayed up to one tick period after the requested timeout.
Note: These functions can be called from tasks created using either pthread or FreeRTOS APIs
Read/Write Locks
• pthread_rwlock_init() - The attr argument is not implemented and is ignored.
• pthread_rwlock_destroy()
• pthread_rwlock_rdlock()
• pthread_rwlock_wrlock()
• pthread_rwlock_unlock()
Static initializer constant PTHREAD_RWLOCK_INITIALIZER is supported.
Note: These functions can be called from tasks created using either pthread or FreeRTOS APIs. Note also that the
current pthread reader-writer-locks implementation is based on the condition variable API. The performance is not
optimal when locking only for a minimal amount of time like e.g. accessing a simple variable. In these cases with
minimal locking time, a simple mutex might be faster.
Thread-Specific Data
• pthread_key_create() - The destr_function argument is supported and will be called if a thread
function exits normally, calls pthread_exit(), or if the underlying task is deleted directly using the FreeR-
TOS function vTaskDelete().
• pthread_key_delete()
• pthread_setspecific() / pthread_getspecific()
Note: These functions can be called from tasks created using either pthread or FreeRTOS APIs
Note: There are other options for thread local storage in ESP-IDF, including options with higher performance. See
Thread Local Storage.
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