93 lines
2.5 KiB
Rust
93 lines
2.5 KiB
Rust
use serde::{Deserialize, Serialize};
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use garage_util::data::*;
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use crate::crdt::Crdt;
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/// Trait for field used to partition data
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pub trait PartitionKey {
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/// Get the key used to partition
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fn hash(&self) -> Hash;
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}
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impl PartitionKey for String {
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fn hash(&self) -> Hash {
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blake2sum(self.as_bytes())
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}
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}
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/// Values of type FixedBytes32 are assumed to be random,
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/// either a hash or a random UUID. This means we can use
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/// them directly as an index into the hash table.
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impl PartitionKey for FixedBytes32 {
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fn hash(&self) -> Hash {
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*self
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}
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}
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/// Trait for field used to sort data
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pub trait SortKey {
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/// Get the key used to sort
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fn sort_key(&self) -> &[u8];
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}
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impl SortKey for String {
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fn sort_key(&self) -> &[u8] {
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self.as_bytes()
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}
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}
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impl SortKey for FixedBytes32 {
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fn sort_key(&self) -> &[u8] {
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self.as_slice()
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}
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}
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/// Trait for an entry in a table. It must be sortable and partitionnable.
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pub trait Entry<P: PartitionKey, S: SortKey>:
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Crdt + PartialEq + Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync
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{
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/// Get the key used to partition
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fn partition_key(&self) -> &P;
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/// Get the key used to sort
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fn sort_key(&self) -> &S;
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/// Is the entry a tombstone? Default implementation always return false
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fn is_tombstone(&self) -> bool {
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false
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}
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}
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/// Trait for the schema used in a table
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pub trait TableSchema: Send + Sync {
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/// The name of the table in the database
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const TABLE_NAME: &'static str;
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/// The partition key used in that table
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type P: PartitionKey + Clone + PartialEq + Serialize + for<'de> Deserialize<'de> + Send + Sync;
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/// The sort key used int that table
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type S: SortKey + Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync;
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/// They type for an entry in that table
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type E: Entry<Self::P, Self::S>;
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/// The type for a filter that can be applied to select entries
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/// (e.g. filter out deleted entries)
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type Filter: Clone + Serialize + for<'de> Deserialize<'de> + Send + Sync;
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// Action to take if not able to decode current version:
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// try loading from an older version
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/// Try migrating an entry from an older version
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fn try_migrate(_bytes: &[u8]) -> Option<Self::E> {
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None
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}
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// Updated triggers some stuff downstream, but it is not supposed to block or fail,
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// as the update itself is an unchangeable fact that will never go back
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// due to CRDT logic. Typically errors in propagation of info should be logged
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// to stderr.
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fn updated(&self, _old: Option<Self::E>, _new: Option<Self::E>) {}
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fn matches_filter(entry: &Self::E, filter: &Self::Filter) -> bool;
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}
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