New model for buckets

src/model/permission.rs

@@ -0,0 +1,37 @@
+use std::cmp::Ordering;
+
+use serde::{Deserialize, Serialize};
+
+use garage_util::crdt::*;
+
+/// Permission given to a key in a bucket
+#[derive(PartialOrd, Ord, PartialEq, Eq, Clone, Copy, Debug, Serialize, Deserialize)]
+pub struct BucketKeyPerm {
+	/// Timestamp at which the permission was given
+	pub timestamp: u64,
+
+	/// The key can be used to read the bucket
+	pub allow_read: bool,
+	/// The key can be used to write in the bucket
+	pub allow_write: bool,
+}
+
+impl Crdt for BucketKeyPerm {
+	fn merge(&mut self, other: &Self) {
+		match other.timestamp.cmp(&self.timestamp) {
+			Ordering::Greater => {
+				*self = *other;
+			}
+			Ordering::Equal if other != self => {
+				warn!("Different permission sets with same timestamp: {:?} and {:?}, merging to most restricted permission set.", self, other);
+				if !other.allow_read {
+					self.allow_read = false;
+				}
+				if !other.allow_write {
+					self.allow_write = false;
+				}
+			}
+			_ => (),
+		}
+	}
+}