This struct provides a simple data type for ensuring a block of code is executed (only) once. Note that this is defined as a struct to allow constant initialization in a global or static context using BSLS_BSLONCE_INITIALIZER.
Declared in <bsls_bslonce.h>
struct BslOnce;| Name | Description |
|---|---|
enter | Enter the one-time block of code. Return true if the one-time block of code has been entered, and false if the one-time block of code has already been executed. If this function returns false then the thread of execution in which enter returned true has already called leave -- i.e., the one-time block of code is guaranteed to have completed execution. The behavior is undefined unless this object was originally initialized to BSLS_BSLONCE_INITIALIZER. Note that a successful enter locks a spin-lock; it is imperative that leave be called quickly. |
leave | Exit the one-time block of code. The behavior is undefined unless the caller had previously called enter, and enter had returned true. |
| Name | Description |
|---|---|
d_onceState | State of the one-time block of code managed by this object. |