Alex
b44d3fc796
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- [x] Design interface - [x] Implement Sled backend - [x] Re-implement the SledCountedTree hack ~~on Sled backend~~ on all backends (i.e. over the abstraction) - [x] Convert Garage code to use generic interface - [x] Proof-read converted Garage code - [ ] Test everything well - [x] Implement sqlite backend - [x] Implement LMDB backend - [ ] (Implement Persy backend?) - [ ] (Implement other backends? (like RocksDB, ...)) - [x] Implement backend choice in config file and garage server module - [x] Add CLI for converting between DB formats - Exploit the new interface to put more things in transactions - [x] `.updated()` trigger on Garage tables Fix #284 **Bugs** - [x] When exporting sqlite, trees iterate empty?? - [x] LMDB doesn't work **Known issues for various back-ends** - Sled: - Eats all my RAM and also all my disk space - `.len()` has to traverse the whole table - Is actually quite slow on some operations - And is actually pretty bad code... - Sqlite: - Requires a lock to be taken on all operations. The lock is also taken when iterating on a table with `.iter()`, and the lock isn't released until the iterator is dropped. This means that we must be VERY carefull to not do anything else inside a `.iter()` loop or else we will have a deadlock! Most such cases have been eliminated from the Garage codebase, but there might still be some that remain. If your Garage-over-Sqlite seems to hang/freeze, this is the reason. - (adapter uses a bunch of unsafe code) - Heed (LMDB): - Not suited for 32-bit machines as it has to map the whole DB in memory. - (adpater uses a tiny bit of unsafe code) **My recommendation:** avoid 32-bit machines and use LMDB as much as possible. **Converting databases** is actually quite easy. For example from Sled to LMDB: ```bash cd src/db cargo run --features cli --bin convert -- -i path/to/garage/meta/db -a sled -o path/to/garage/meta/db.lmdb -b lmdb ``` Then, just add this to your `config.toml`: ```toml db_engine = "lmdb" ``` Co-authored-by: Alex Auvolat <alex@adnab.me> Reviewed-on: #322 Co-authored-by: Alex <alex@adnab.me> Co-committed-by: Alex <alex@adnab.me>
102 lines
2.7 KiB
Rust
102 lines
2.7 KiB
Rust
use serde::{Deserialize, Serialize};
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use garage_db as db;
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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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/// Actions triggered by data changing in a table. If such actions
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/// include updates to the local database that should be applied
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/// atomically with the item update itself, a db transaction is
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/// provided on which these changes should be done.
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/// This function can return a DB error but that's all.
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fn updated(
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&self,
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_tx: &mut db::Transaction,
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_old: Option<&Self::E>,
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_new: Option<&Self::E>,
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) -> db::TxOpResult<()> {
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Ok(())
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}
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fn matches_filter(entry: &Self::E, filter: &Self::Filter) -> bool;
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}
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