# PRCallOnceType

Structure for tracking initialization.

## Syntax

```{code}
#include <prinit.h>

typedef struct PRCallOnceType {
  PRIntn initialized;
  PRInt32 inProgress;
  PRStatus status;
} PRCallOnceType;
```

### Fields

The structure has these fields:

`initialized`

: If not zero, the initialization process has been completed.

`inProgress`

: If not zero, the initialization process is currently being executed.
  Calling threads that observe this status block until inProgress is
  zero.

`status`

: An indication of the outcome of the initialization process.

## Description

The client is responsible for initializing the {ref}`PRCallOnceType`
structure to all zeros. This initialization must be accomplished before
any threading issues exist.