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author | Alex <alex@adnab.me> | 2022-06-08 10:01:44 +0200 |
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committer | Alex <alex@adnab.me> | 2022-06-08 10:01:44 +0200 |
commit | b44d3fc796484a50cd6854f20c9b46e5fddedc9d (patch) | |
tree | 29f6da0e8dc68485edf713aaa7331536f4ff4fde /src/model/k2v | |
parent | 7eed3ceda9cf964e3435f22fc1852e27f4f5a8ae (diff) | |
download | garage-b44d3fc796484a50cd6854f20c9b46e5fddedc9d.tar.gz garage-b44d3fc796484a50cd6854f20c9b46e5fddedc9d.zip |
Abstract database behind generic interface and implement alternative drivers (#322)
- [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: https://git.deuxfleurs.fr/Deuxfleurs/garage/pulls/322
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>
Diffstat (limited to 'src/model/k2v')
-rw-r--r-- | src/model/k2v/item_table.rs | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/src/model/k2v/item_table.rs b/src/model/k2v/item_table.rs index 8b7cc08a..991fe66d 100644 --- a/src/model/k2v/item_table.rs +++ b/src/model/k2v/item_table.rs @@ -2,6 +2,7 @@ use serde::{Deserialize, Serialize}; use std::collections::BTreeMap; use std::sync::Arc; +use garage_db as db; use garage_util::data::*; use garage_table::crdt::*; @@ -221,7 +222,12 @@ impl TableSchema for K2VItemTable { type E = K2VItem; type Filter = ItemFilter; - fn updated(&self, old: Option<&Self::E>, new: Option<&Self::E>) { + fn updated( + &self, + tx: &mut db::Transaction, + old: Option<&Self::E>, + new: Option<&Self::E>, + ) -> db::TxOpResult<()> { // 1. Count let (old_entries, old_conflicts, old_values, old_bytes) = match old { None => (0, 0, 0, 0), @@ -239,7 +245,8 @@ impl TableSchema for K2VItemTable { .map(|e| &e.partition.partition_key) .unwrap_or_else(|| &new.unwrap().partition.partition_key); - if let Err(e) = self.counter_table.count( + let counter_res = self.counter_table.count( + tx, &count_pk, count_sk, &[ @@ -248,14 +255,23 @@ impl TableSchema for K2VItemTable { (VALUES, new_values - old_values), (BYTES, new_bytes - old_bytes), ], - ) { - error!("Could not update K2V counter for bucket {:?} partition {}; counts will now be inconsistent. {}", count_pk, count_sk, e); + ); + if let Err(e) = db::unabort(counter_res)? { + // This result can be returned by `counter_table.count()` for instance + // if messagepack serialization or deserialization fails at some step. + // Warn admin but ignore this error for now, that's all we can do. + error!( + "Unable to update K2V item counter for bucket {:?} partition {}: {}. Index values will be wrong!", + count_pk, count_sk, e + ); } // 2. Notify if let Some(new_ent) = new { self.subscriptions.notify(new_ent); } + + Ok(()) } #[allow(clippy::nonminimal_bool)] |