## nng_mtx_alloc

Allocate mutex.

### Synopsis

```c
#include <nng/nng.h>
#include <nng/supplemental/util/platform.h>

typedef struct nng_mtx nng_mtx;

int nng_mtx_alloc(nng_mtx **mtxp);
```

### Description

The `nng_mtx_alloc` function allocates mutex and returns it in _mtxp_.

The mutex objects created by this function are suitable only for simple lock and unlock operations, and are not recursive.
Every effort has been made to use light-weight underlying primitives when available.

Mutex (mutual exclusion) objects can be thought of as binary semaphores,
where only a single thread of execution is permitted to acquire the semaphore.

Furthermore, a mutex can only be unlocked by the thread that locked it.

### Return Values

This function returns 0 on success, and non-zero otherwise.

### Errors

[horizontal]
`NNG_ENOMEM`:: Insufficient free memory exists.

### See Also

xref:nng_mtx_free.adoc[nng_mtx_free],
xref:nng_mtx_lock.adoc[nng_mtx_lock]
