New buckets for 0.6.0: small changes

- Fix bucket delete

- fix merge of bucket creation date

- Replace deletable with option in aliases
    Rationale: if two aliases point to conflicting bucket, resolving
    by making an arbitrary choice risks making data accessible when it
    shouldn't be. We'd rather resolve to deleting the alias until
    someone puts it back.

4 files changed, 64 insertions, 35 deletions

diff --git a/src/model/bucket_alias_table.rs b/src/model/bucket_alias_table.rs
index 45807178..fce03d04 100644
--- a/src/model/bucket_alias_table.rs
+++ b/src/model/bucket_alias_table.rs
@@ -10,32 +10,23 @@ use garage_table::*;
 #[derive(PartialEq, Clone, Debug, Serialize, Deserialize)]
 pub struct BucketAlias {
 	name: String,
-	pub state: crdt::Lww<crdt::Deletable<AliasParams>>,
-}
-
-#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Debug, Serialize, Deserialize)]
-pub struct AliasParams {
-	pub bucket_id: Uuid,
-}
-
-impl AutoCrdt for AliasParams {
-	const WARN_IF_DIFFERENT: bool = true;
+	pub state: crdt::Lww<Option<Uuid>>,
 }
 
 impl BucketAlias {
-	pub fn new(name: String, ts: u64, bucket_id: Uuid) -> Option<Self> {
+	pub fn new(name: String, ts: u64, bucket_id: Option<Uuid>) -> Option<Self> {
 		if !is_valid_bucket_name(&name) {
 			None
 		} else {
 			Some(BucketAlias {
 				name,
-				state: crdt::Lww::raw(ts, crdt::Deletable::present(AliasParams { bucket_id })),
+				state: crdt::Lww::raw(ts, bucket_id),
 			})
 		}
 	}
 
 	pub fn is_deleted(&self) -> bool {
-		self.state.get().is_deleted()
+		self.state.get().is_none()
 	}
 	pub fn name(&self) -> &str {
 		&self.name
diff --git a/src/model/bucket_table.rs b/src/model/bucket_table.rs
index fef29b62..52c2316c 100644
--- a/src/model/bucket_table.rs
+++ b/src/model/bucket_table.rs
@@ -63,6 +63,7 @@ impl BucketParams {
 
 impl Crdt for BucketParams {
 	fn merge(&mut self, o: &Self) {
+		self.creation_date = std::cmp::min(self.creation_date, o.creation_date);
 		self.authorized_keys.merge(&o.authorized_keys);
 		self.website_config.merge(&o.website_config);
 		self.aliases.merge(&o.aliases);
diff --git a/src/model/helper/bucket.rs b/src/model/helper/bucket.rs
index 8bc54b3f..52cedb12 100644
--- a/src/model/helper/bucket.rs
+++ b/src/model/helper/bucket.rs
@@ -46,7 +46,7 @@ impl<'a> BucketHelper<'a> {
 				.bucket_alias_table
 				.get(&EmptyKey, bucket_name)
 				.await?
-				.map(|x| x.state.get().as_option().map(|x| x.bucket_id))
+				.map(|x| *x.state.get())
 				.flatten())
 		}
 	}
@@ -154,11 +154,11 @@ impl<'a> BucketHelper<'a> {
 		let alias = self.0.bucket_alias_table.get(&EmptyKey, alias_name).await?;
 
 		if let Some(existing_alias) = alias.as_ref() {
-			if let Some(p) = existing_alias.state.get().as_option() {
-				if p.bucket_id != bucket_id {
+			if let Some(p_bucket) = existing_alias.state.get() {
+				if *p_bucket != bucket_id {
 					return Err(Error::BadRequest(format!(
 						"Alias {} already exists and points to different bucket: {:?}",
-						alias_name, p.bucket_id
+						alias_name, p_bucket
 					)));
 				}
 			}
@@ -176,10 +176,10 @@ impl<'a> BucketHelper<'a> {
 		// writes are now done and all writes use timestamp alias_ts
 
 		let alias = match alias {
-			None => BucketAlias::new(alias_name.clone(), alias_ts, bucket_id)
+			None => BucketAlias::new(alias_name.clone(), alias_ts, Some(bucket_id))
 				.ok_or_bad_request(format!("{}: {}", alias_name, INVALID_BUCKET_NAME_MESSAGE))?,
 			Some(mut a) => {
-				a.state = Lww::raw(alias_ts, Deletable::present(AliasParams { bucket_id }));
+				a.state = Lww::raw(alias_ts, Some(bucket_id));
 				a
 			}
 		};
@@ -209,13 +209,7 @@ impl<'a> BucketHelper<'a> {
 			.bucket_alias_table
 			.get(&EmptyKey, alias_name)
 			.await?
-			.filter(|a| {
-				a.state
-					.get()
-					.as_option()
-					.map(|x| x.bucket_id == bucket_id)
-					.unwrap_or(false)
-			})
+			.filter(|a| a.state.get().map(|x| x == bucket_id).unwrap_or(false))
 			.ok_or_message(format!(
 				"Internal error: alias not found or does not point to bucket {:?}",
 				bucket_id
@@ -244,7 +238,7 @@ impl<'a> BucketHelper<'a> {
 		// ---- timestamp-ensured causality barrier ----
 		// writes are now done and all writes use timestamp alias_ts
 
-		alias.state = Lww::raw(alias_ts, Deletable::delete());
+		alias.state = Lww::raw(alias_ts, None);
 		self.0.bucket_alias_table.insert(&alias).await?;
 
 		bucket_state.aliases = LwwMap::raw_item(alias_name.clone(), alias_ts, false);
@@ -253,6 +247,51 @@ impl<'a> BucketHelper<'a> {
 		Ok(())
 	}
 
+	/// Ensures a bucket does not have a certain global alias.
+	/// Contrarily to unset_global_bucket_alias, this does not
+	/// fail on any condition other than:
+	/// - bucket cannot be found (its fine if it is in deleted state)
+	/// - alias cannot be found (its fine if it points to nothing or
+	///   to another bucket)
+	pub async fn purge_global_bucket_alias(
+		&self,
+		bucket_id: Uuid,
+		alias_name: &String,
+	) -> Result<(), Error> {
+		let mut bucket = self.get_internal_bucket(bucket_id).await?;
+
+		let mut alias = self
+			.0
+			.bucket_alias_table
+			.get(&EmptyKey, alias_name)
+			.await?
+			.ok_or_message(format!("Alias {} not found", alias_name))?;
+
+		// Checks ok, remove alias
+		let alias_ts = match bucket.state.as_option() {
+			Some(bucket_state) => increment_logical_clock_2(
+				alias.state.timestamp(),
+				bucket_state.aliases.get_timestamp(alias_name),
+			),
+			None => increment_logical_clock(alias.state.timestamp()),
+		};
+
+		// ---- timestamp-ensured causality barrier ----
+		// writes are now done and all writes use timestamp alias_ts
+
+		if alias.state.get() == &Some(bucket_id) {
+			alias.state = Lww::raw(alias_ts, None);
+			self.0.bucket_alias_table.insert(&alias).await?;
+		}
+
+		if let Some(mut bucket_state) = bucket.state.as_option_mut() {
+			bucket_state.aliases = LwwMap::raw_item(alias_name.clone(), alias_ts, false);
+			self.0.bucket_table.insert(&bucket).await?;
+		}
+
+		Ok(())
+	}
+
 	/// Sets a new alias for a bucket in the local namespace of a key.
 	/// This function fails if:
 	/// - alias name is not valid according to S3 spec
@@ -277,7 +316,7 @@ impl<'a> BucketHelper<'a> {
 
 		let mut key_param = key.state.as_option_mut().unwrap();
 
-		if let Some(Deletable::Present(existing_alias)) = key_param.local_aliases.get(alias_name) {
+		if let Some(Some(existing_alias)) = key_param.local_aliases.get(alias_name) {
 			if *existing_alias != bucket_id {
 				return Err(Error::BadRequest(format!("Alias {} already exists in namespace of key {} and points to different bucket: {:?}", alias_name,  key.key_id, existing_alias)));
 			}
@@ -301,8 +340,7 @@ impl<'a> BucketHelper<'a> {
 		// ---- timestamp-ensured causality barrier ----
 		// writes are now done and all writes use timestamp alias_ts
 
-		key_param.local_aliases =
-			LwwMap::raw_item(alias_name.clone(), alias_ts, Deletable::present(bucket_id));
+		key_param.local_aliases = LwwMap::raw_item(alias_name.clone(), alias_ts, Some(bucket_id));
 		self.0.key_table.insert(&key).await?;
 
 		bucket_p.local_aliases = LwwMap::raw_item(bucket_p_local_alias_key, alias_ts, true);
@@ -334,8 +372,8 @@ impl<'a> BucketHelper<'a> {
 			.unwrap()
 			.local_aliases
 			.get(alias_name)
-			.map(|x| x.as_option())
-			.flatten() != Some(&bucket_id)
+			.cloned()
+			.flatten() != Some(bucket_id)
 		{
 			return Err(GarageError::Message(format!(
 				"Bucket {:?} does not have alias {} in namespace of key {}",
@@ -372,8 +410,7 @@ impl<'a> BucketHelper<'a> {
 		// ---- timestamp-ensured causality barrier ----
 		// writes are now done and all writes use timestamp alias_ts
 
-		key_param.local_aliases =
-			LwwMap::raw_item(alias_name.clone(), alias_ts, Deletable::delete());
+		key_param.local_aliases = LwwMap::raw_item(alias_name.clone(), alias_ts, None);
 		self.0.key_table.insert(&key).await?;
 
 		bucket_p.local_aliases = LwwMap::raw_item(bucket_p_local_alias_key, alias_ts, false);
diff --git a/src/model/key_table.rs b/src/model/key_table.rs
index 7afa0337..c25f2da4 100644
--- a/src/model/key_table.rs
+++ b/src/model/key_table.rs
@@ -31,7 +31,7 @@ pub struct Key {
 pub struct KeyParams {
 	pub allow_create_bucket: crdt::Lww<bool>,
 	pub authorized_buckets: crdt::Map<Uuid, BucketKeyPerm>,
-	pub local_aliases: crdt::LwwMap<String, crdt::Deletable<Uuid>>,
+	pub local_aliases: crdt::LwwMap<String, Option<Uuid>>,
 }
 
 impl KeyParams {