waiting not twice

1 files changed, 7 insertions, 0 deletions

diff --git a/src/document/changes.rs b/src/document/changes.rs
index 1091261..9a07fc0 100644
--- a/src/document/changes.rs
+++ b/src/document/changes.rs
@@ -8,6 +8,13 @@ use anyhow::{Context, Result, anyhow, bail};
 
 use super::{Change, ChangeHash, Document, ReadDoc};
 
+/// Whether `doc` has every change of `heads`.
+pub(crate) fn holds_all(doc: &Document, heads: &[ChangeHash]) -> bool {
+    heads
+        .iter()
+        .all(|head| doc.get_change_by_hash(head).is_some())
+}
+
 /// Whether the history of `theirs` (of them, those `doc` has) holds all of `ours`
 /// (heads of `doc`): a peer at `theirs` has every change we have.
 pub(crate) fn covers(doc: &Document, theirs: &[ChangeHash], ours: &[ChangeHash]) -> bool {