# mtx_trylock

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< c‎ | thread

Defined in header `<threads.h>` |  |
int mtx_trylock( mtx_t *mutex ); |  | (since C11)

Tries to lock the mutex pointed to by `mutex` without blocking. Returns immediately if the mutex is already locked.

Prior calls to mtx_unlock on the same mutex synchronize-with this operation (if this operation succeeds), and all lock/unlock operations on any given mutex form a single total order (similar to the modification order of an atomic)

### Parameters

mutex | - | pointer to the mutex to lock

### Return value

thrd_success if successful, thrd_busy if the mutex has already been locked or due to a spurious failure to acquire an available mutex, thrd_error if an error occurs.

### Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C standards.

DR | Applied to | Behavior as published | Correct behavior
--- | --- | --- | ---
DR 470 | C11 | `mtx_trylock` was not allowed to fail spuriously | allowed

### References

- C17 standard (ISO/IEC 9899:2018):

  - 7.26.4.5 The mtx_trylock function (p: 278-279)

- C11 standard (ISO/IEC 9899:2011):

  - 7.26.4.5 The mtx_trylock function (p: 382)

### See also

mtx_lock (C11) | blocks until locks a mutex (function)
mtx_timedlock (C11) | blocks until locks a mutex or times out (function)
mtx_unlock (C11) | unlocks a mutex (function)

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