Gate-keeper class for code that should only execute once per process.
Declared in <bslmt_once.h>
class Once;This class is a POD-type and can be statically initialized to the value of the BSLMT_ONCE_INITIALIZE macro. For this reason, it does not have any explicitly-declared constructors or destructor.
| Name | Description |
|---|---|
OnceLock | Special token created by a single thread to pass to the enter, leave, and cancel methods. |
| Name | Description |
|---|---|
callOnce | Call function at most once across all threads for this object. |
cancel | Abort incomplete one-time execution and unlock the internal mutex. |
enter | Attempt to enter the one-time execution region for this object. |
isMaybeUninitialized | Return true if this object may not be in the "done" state (that is, leave has not been called). |
leave | Mark one-time execution as complete and unlock the internal mutex. |
| Name | Description |
|---|---|
d_mutex | Mutex used to synchronize one-time execution. Public for static initialization, but do not access directly. |
d_state | One-time execution state. Public for static initialization, but do not access directly. |