| --- |
| layout: doc |
| title: "Starboard Module Reference: once.h" |
| --- |
| |
| Onces represent initializations that should only ever happen once per process, |
| in a thread-safe way. |
| |
| ## Macros ## |
| |
| ### SB_ONCE_MAX_SIZE ### |
| |
| Max size of the SbOnceControl type. |
| |
| ## Typedefs ## |
| |
| ### SbOnceControl ### |
| |
| An opaque handle to a once control type with reserved memory buffer of size |
| SB_ONCE_MAX_SIZE and aligned at void pointer type. |
| |
| #### Definition #### |
| |
| ``` |
| typedef union SbOnceControl SbOnceControl |
| ``` |
| |
| ### SbOnceInitRoutine ### |
| |
| Function pointer type for methods that can be called via the SbOnce() system. |
| |
| #### Definition #### |
| |
| ``` |
| typedef void(* SbOnceInitRoutine) (void) |
| ``` |
| |
| ## Functions ## |
| |
| ### SbOnce ### |
| |
| Thread-safely runs `init_routine` only once. |
| |
| * If this `once_control` has not run a function yet, this function runs |
| `init_routine` in a thread-safe way and then returns `true`. |
| |
| * If SbOnce() was called with `once_control` before, the function returns |
| `true` immediately. |
| |
| * If `once_control` or `init_routine` is invalid, the function returns |
| `false`. |
| |
| #### Declaration #### |
| |
| ``` |
| bool SbOnce(SbOnceControl *once_control, SbOnceInitRoutine init_routine) |
| ``` |
| |
