use serde::{Deserialize, Serialize}; use garage_db as db; use garage_util::data::*; use garage_util::migrate::Migrate; use crate::crdt::Crdt; // =================================== PARTITION KEYS /// Trait for field used to partition data pub trait PartitionKey: Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + Send + Sync + 'static { /// Get the key used to partition fn hash(&self) -> Hash; } impl PartitionKey for String { fn hash(&self) -> Hash { blake2sum(self.as_bytes()) } } /// Values of type FixedBytes32 are assumed to be random, /// either a hash or a random UUID. This means we can use /// them directly as an index into the hash table. impl PartitionKey for FixedBytes32 { fn hash(&self) -> Hash { *self } } // =================================== SORT KEYS /// Trait for field used to sort data pub trait SortKey: Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync + 'static { /// Get the key used to sort fn sort_key(&self) -> &[u8]; } impl SortKey for String { fn sort_key(&self) -> &[u8] { self.as_bytes() } } impl SortKey for FixedBytes32 { fn sort_key(&self) -> &[u8] { self.as_slice() } } // =================================== SCHEMA /// Trait for an entry in a table. It must be sortable and partitionnable. pub trait Entry<P: PartitionKey, S: SortKey>: Crdt + PartialEq + Clone + Migrate + Send + Sync + 'static { /// Get the key used to partition fn partition_key(&self) -> &P; /// Get the key used to sort fn sort_key(&self) -> &S; /// Is the entry a tombstone? Default implementation always return false fn is_tombstone(&self) -> bool { false } } /// Trait for the schema used in a table pub trait TableSchema: Send + Sync + 'static { /// The name of the table in the database const TABLE_NAME: &'static str; /// The partition key used in that table type P: PartitionKey; /// The sort key used int that table type S: SortKey; /// They type for an entry in that table type E: Entry<Self::P, Self::S>; /// The type for a filter that can be applied to select entries /// (e.g. filter out deleted entries) type Filter: Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync + 'static; /// Actions triggered by data changing in a table. If such actions /// include updates to the local database that should be applied /// atomically with the item update itself, a db transaction is /// provided on which these changes should be done. /// This function can return a DB error but that's all. fn updated( &self, _tx: &mut db::Transaction, _old: Option<&Self::E>, _new: Option<&Self::E>, ) -> db::TxOpResult<()> { Ok(()) } fn matches_filter(entry: &Self::E, filter: &Self::Filter) -> bool; }