Struct pipebuf::PBufTrip

pub struct PBufTrip(/* private fields */);

Tripwire value used to detect changes

This value is obtained using PipeBuf::tripwire, PBufRd::tripwire or PBufWr::tripwire, which all calculate the same value. See also the tripwire! macro which allows tuples of tripwire values to be created and compared.

The value will change in these cases:

• Data is written to the pipe
• Data is read from the pipe
• A “push” state is set or consumed
• An EOF state is set or consumed

This value can be compared before and after some operation to detect whether a change has occurred. However that operation must be purely a consumer operation or purely a producer operation. If data is both produced and consumed, then the tripwire value may return to the same value and the change wouldn’t be detected.

These scenarios are supported:

• In a consumer, avoiding re-parsing an input buffer when there have been no changes made by the producer. Save a PBufTrip value before returning, and when called the next time, compare it to the current value.

• In the glue code, detect whether a component call has caused changes to a buffer.

• In consumer code, check whether some sub-part of the consumer processing has done something.

• In producer code, check whether some sub-part of the producer processing has done something.

Trait Implementations

impl Clone for PBufTrip

fn clone(&self) -> PBufTrip

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl PartialEq for PBufTrip

fn eq(&self, other: &PBufTrip) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for PBufTrip

impl Eq for PBufTrip

impl StructuralPartialEq for PBufTrip