Struct archivist_lib::logs::buffer::Cursor
source · pub struct Cursor<T> { /* private fields */ }
Expand description
A weak pointer into the buffer which is being concurrently iterated and modified.
A cursor iterates over nodes in the list, holding the id of the last node seen. If that id is less than the first id found in the deque, the cursor starts at the beginning of the list and first returns a count of items rolled out.
The count is maintained by giving each successive item in a list a monotonically increasing ID and tracking the “high-water mark” of the largest/last ID seen.
§Modes
These IDs are also how we express snapshotting vs. subscribing. The mode determines the minimum and maximum IDs the cursor will yield.
§Wraparound
IDs are stored as u64
and the list would need to receive a new entry once every nanosecond
for ~580 consecutive years before ID allocations will wrap around. This eventuality is not
accounted for in the implementation. If you’re reading this after observing a bug due to that,
congratulations.
Trait Implementations§
source§impl<T> Stream for Cursor<T>
impl<T> Stream for Cursor<T>
Auto Trait Implementations§
impl<T> Freeze for Cursor<T>
impl<T> !RefUnwindSafe for Cursor<T>
impl<T> Send for Cursor<T>
impl<T> Sync for Cursor<T>
impl<T> Unpin for Cursor<T>
impl<T> !UnwindSafe for Cursor<T>
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