Type Alias someday::Timestamp

pub type Timestamp = usize;

An incrementing usize representing a new versions of data.

In Commit objects, there is a Timestamp that represents that data’s “version”.

It is just an incrementing usize starting at 0.

Every time the Writer calls a commit operation like Writer::commit(), or Writer::overwrite() the data’s Timestamp is incremented by 1, thus the timestamp is also how many commits there are.

An invariant that can be relied upon is that the Writer can never “rebase” (as in, go back in time with their Commit) more further back than the current Reader’s Timestamp.

This means the Writer’s timestamp will always be greater than or equal to the Reader’s timestamp.

Example

let v = vec![];
let (r, mut w) = someday::new::<Vec<&str>>(v);

// Writer writes some data, but does not commit.
w.add(Patch::Ptr(|w, _| w.push("a")));
// Timestamp is still 0.
assert_eq!(w.timestamp(), 0);

w.add(Patch::Ptr(|w, _| w.push("b")));
assert_eq!(w.timestamp(), 0);

w.add(Patch::Ptr(|w, _| w.push("b")));
assert_eq!(w.timestamp(), 0);

// Now we commit.
w.commit();
assert_eq!(w.timestamp(), 1);

// We haven't pushed though, so
// readers will see timestamp of 0
assert_eq!(r.head().timestamp, 0);