garage/src/table/metrics.rs
Alex b44d3fc796 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: Deuxfleurs/garage#322
Co-authored-by: Alex <alex@adnab.me>
Co-committed-by: Alex <alex@adnab.me>
2022-06-08 10:01:44 +02:00

95 lines
3.4 KiB
Rust

use opentelemetry::{global, metrics::*, KeyValue};
use garage_db as db;
use garage_db::counted_tree_hack::CountedTree;
/// TableMetrics reference all counter used for metrics
pub struct TableMetrics {
pub(crate) _merkle_todo_len: ValueObserver<u64>,
pub(crate) _gc_todo_len: ValueObserver<u64>,
pub(crate) get_request_counter: BoundCounter<u64>,
pub(crate) get_request_duration: BoundValueRecorder<f64>,
pub(crate) put_request_counter: BoundCounter<u64>,
pub(crate) put_request_duration: BoundValueRecorder<f64>,
pub(crate) internal_update_counter: BoundCounter<u64>,
pub(crate) internal_delete_counter: BoundCounter<u64>,
pub(crate) sync_items_sent: Counter<u64>,
pub(crate) sync_items_received: Counter<u64>,
}
impl TableMetrics {
pub fn new(table_name: &'static str, merkle_todo: db::Tree, gc_todo: CountedTree) -> Self {
let meter = global::meter(table_name);
TableMetrics {
_merkle_todo_len: meter
.u64_value_observer(
"table.merkle_updater_todo_queue_length",
move |observer| {
if let Ok(v) = merkle_todo.len() {
observer.observe(
v as u64,
&[KeyValue::new("table_name", table_name)],
);
}
},
)
.with_description("Merkle tree updater TODO queue length")
.init(),
_gc_todo_len: meter
.u64_value_observer(
"table.gc_todo_queue_length",
move |observer| {
observer.observe(
gc_todo.len() as u64,
&[KeyValue::new("table_name", table_name)],
);
},
)
.with_description("Table garbage collector TODO queue length")
.init(),
get_request_counter: meter
.u64_counter("table.get_request_counter")
.with_description("Number of get/get_range requests internally made on this table")
.init()
.bind(&[KeyValue::new("table_name", table_name)]),
get_request_duration: meter
.f64_value_recorder("table.get_request_duration")
.with_description("Duration of get/get_range requests internally made on this table, in seconds")
.init()
.bind(&[KeyValue::new("table_name", table_name)]),
put_request_counter: meter
.u64_counter("table.put_request_counter")
.with_description("Number of insert/insert_many requests internally made on this table")
.init()
.bind(&[KeyValue::new("table_name", table_name)]),
put_request_duration: meter
.f64_value_recorder("table.put_request_duration")
.with_description("Duration of insert/insert_many requests internally made on this table, in seconds")
.init()
.bind(&[KeyValue::new("table_name", table_name)]),
internal_update_counter: meter
.u64_counter("table.internal_update_counter")
.with_description("Number of value updates where the value actually changes (includes creation of new key and update of existing key)")
.init()
.bind(&[KeyValue::new("table_name", table_name)]),
internal_delete_counter: meter
.u64_counter("table.internal_delete_counter")
.with_description("Number of value deletions in the tree (due to GC or repartitioning)")
.init()
.bind(&[KeyValue::new("table_name", table_name)]),
sync_items_sent: meter
.u64_counter("table.sync_items_sent")
.with_description("Number of data items sent to other nodes during resync procedures")
.init(),
sync_items_received: meter
.u64_counter("table.sync_items_received")
.with_description("Number of data items received from other nodes during resync procedures")
.init(),
}
}
}