garage/src/table/table.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

458 lines
11 KiB
Rust

use std::borrow::Borrow;
use std::collections::{BTreeMap, BTreeSet, HashMap};
use std::sync::Arc;
use std::time::Duration;
use async_trait::async_trait;
use futures::stream::*;
use serde::{Deserialize, Serialize};
use serde_bytes::ByteBuf;
use opentelemetry::{
trace::{FutureExt, TraceContextExt, Tracer},
Context,
};
use garage_db as db;
use garage_util::data::*;
use garage_util::error::Error;
use garage_util::metrics::RecordDuration;
use garage_rpc::system::System;
use garage_rpc::*;
use crate::crdt::Crdt;
use crate::data::*;
use crate::gc::*;
use crate::merkle::*;
use crate::replication::*;
use crate::schema::*;
use crate::sync::*;
use crate::util::*;
pub const TABLE_RPC_TIMEOUT: Duration = Duration::from_secs(10);
pub struct Table<F: TableSchema + 'static, R: TableReplication + 'static> {
pub system: Arc<System>,
pub data: Arc<TableData<F, R>>,
pub merkle_updater: Arc<MerkleUpdater<F, R>>,
pub syncer: Arc<TableSyncer<F, R>>,
endpoint: Arc<Endpoint<TableRpc<F>, Self>>,
}
#[derive(Serialize, Deserialize)]
pub(crate) enum TableRpc<F: TableSchema> {
Ok,
ReadEntry(F::P, F::S),
ReadEntryResponse(Option<ByteBuf>),
// Read range: read all keys in partition P, possibly starting at a certain sort key offset
ReadRange {
partition: F::P,
begin_sort_key: Option<F::S>,
filter: Option<F::Filter>,
limit: usize,
enumeration_order: EnumerationOrder,
},
Update(Vec<Arc<ByteBuf>>),
}
impl<F: TableSchema> Rpc for TableRpc<F> {
type Response = Result<TableRpc<F>, Error>;
}
impl<F, R> Table<F, R>
where
F: TableSchema + 'static,
R: TableReplication + 'static,
{
// =============== PUBLIC INTERFACE FUNCTIONS (new, insert, get, etc) ===============
pub fn new(instance: F, replication: R, system: Arc<System>, db: &db::Db) -> Arc<Self> {
let endpoint = system
.netapp
.endpoint(format!("garage_table/table.rs/Rpc:{}", F::TABLE_NAME));
let data = TableData::new(system.clone(), instance, replication, db);
let merkle_updater = MerkleUpdater::launch(&system.background, data.clone());
let syncer = TableSyncer::launch(system.clone(), data.clone(), merkle_updater.clone());
TableGc::launch(system.clone(), data.clone());
let table = Arc::new(Self {
system,
data,
merkle_updater,
syncer,
endpoint,
});
table.endpoint.set_handler(table.clone());
table
}
pub async fn insert(&self, e: &F::E) -> Result<(), Error> {
let tracer = opentelemetry::global::tracer("garage_table");
let span = tracer.start(format!("{} insert", F::TABLE_NAME));
self.insert_internal(e)
.bound_record_duration(&self.data.metrics.put_request_duration)
.with_context(Context::current_with_span(span))
.await?;
self.data.metrics.put_request_counter.add(1);
Ok(())
}
async fn insert_internal(&self, e: &F::E) -> Result<(), Error> {
let hash = e.partition_key().hash();
let who = self.data.replication.write_nodes(&hash);
//eprintln!("insert who: {:?}", who);
let e_enc = Arc::new(ByteBuf::from(rmp_to_vec_all_named(e)?));
let rpc = TableRpc::<F>::Update(vec![e_enc]);
self.system
.rpc
.try_call_many(
&self.endpoint,
&who[..],
rpc,
RequestStrategy::with_priority(PRIO_NORMAL)
.with_quorum(self.data.replication.write_quorum())
.with_timeout(TABLE_RPC_TIMEOUT),
)
.await?;
Ok(())
}
pub async fn insert_many<I, IE>(&self, entries: I) -> Result<(), Error>
where
I: IntoIterator<Item = IE> + Send + Sync,
IE: Borrow<F::E> + Send + Sync,
{
let tracer = opentelemetry::global::tracer("garage_table");
let span = tracer.start(format!("{} insert_many", F::TABLE_NAME));
self.insert_many_internal(entries)
.bound_record_duration(&self.data.metrics.put_request_duration)
.with_context(Context::current_with_span(span))
.await?;
self.data.metrics.put_request_counter.add(1);
Ok(())
}
async fn insert_many_internal<I, IE>(&self, entries: I) -> Result<(), Error>
where
I: IntoIterator<Item = IE> + Send + Sync,
IE: Borrow<F::E> + Send + Sync,
{
let mut call_list: HashMap<_, Vec<_>> = HashMap::new();
for entry in entries.into_iter() {
let entry = entry.borrow();
let hash = entry.partition_key().hash();
let who = self.data.replication.write_nodes(&hash);
let e_enc = Arc::new(ByteBuf::from(rmp_to_vec_all_named(entry)?));
for node in who {
call_list.entry(node).or_default().push(e_enc.clone());
}
}
let call_futures = call_list.drain().map(|(node, entries)| async move {
let rpc = TableRpc::<F>::Update(entries);
let resp = self
.system
.rpc
.call(
&self.endpoint,
node,
rpc,
RequestStrategy::with_priority(PRIO_NORMAL).with_timeout(TABLE_RPC_TIMEOUT),
)
.await?;
Ok::<_, Error>((node, resp))
});
let mut resps = call_futures.collect::<FuturesUnordered<_>>();
let mut errors = vec![];
while let Some(resp) = resps.next().await {
if let Err(e) = resp {
errors.push(e);
}
}
if errors.len() > self.data.replication.max_write_errors() {
Err(Error::Message("Too many errors".into()))
} else {
Ok(())
}
}
pub async fn get(
self: &Arc<Self>,
partition_key: &F::P,
sort_key: &F::S,
) -> Result<Option<F::E>, Error> {
let tracer = opentelemetry::global::tracer("garage_table");
let span = tracer.start(format!("{} get", F::TABLE_NAME));
let res = self
.get_internal(partition_key, sort_key)
.bound_record_duration(&self.data.metrics.get_request_duration)
.with_context(Context::current_with_span(span))
.await?;
self.data.metrics.get_request_counter.add(1);
Ok(res)
}
async fn get_internal(
self: &Arc<Self>,
partition_key: &F::P,
sort_key: &F::S,
) -> Result<Option<F::E>, Error> {
let hash = partition_key.hash();
let who = self.data.replication.read_nodes(&hash);
let rpc = TableRpc::<F>::ReadEntry(partition_key.clone(), sort_key.clone());
let resps = self
.system
.rpc
.try_call_many(
&self.endpoint,
&who[..],
rpc,
RequestStrategy::with_priority(PRIO_NORMAL)
.with_quorum(self.data.replication.read_quorum())
.with_timeout(TABLE_RPC_TIMEOUT)
.interrupt_after_quorum(true),
)
.await?;
let mut ret = None;
let mut not_all_same = false;
for resp in resps {
if let TableRpc::ReadEntryResponse(value) = resp {
if let Some(v_bytes) = value {
let v = self.data.decode_entry(v_bytes.as_slice())?;
ret = match ret {
None => Some(v),
Some(mut x) => {
if x != v {
not_all_same = true;
x.merge(&v);
}
Some(x)
}
}
}
} else {
return Err(Error::Message("Invalid return value to read".to_string()));
}
}
if let Some(ret_entry) = &ret {
if not_all_same {
let self2 = self.clone();
let ent2 = ret_entry.clone();
self.system
.background
.spawn_cancellable(async move { self2.repair_on_read(&who[..], ent2).await });
}
}
Ok(ret)
}
pub async fn get_range(
self: &Arc<Self>,
partition_key: &F::P,
begin_sort_key: Option<F::S>,
filter: Option<F::Filter>,
limit: usize,
enumeration_order: EnumerationOrder,
) -> Result<Vec<F::E>, Error> {
let tracer = opentelemetry::global::tracer("garage_table");
let span = tracer.start(format!("{} get_range", F::TABLE_NAME));
let res = self
.get_range_internal(
partition_key,
begin_sort_key,
filter,
limit,
enumeration_order,
)
.bound_record_duration(&self.data.metrics.get_request_duration)
.with_context(Context::current_with_span(span))
.await?;
self.data.metrics.get_request_counter.add(1);
Ok(res)
}
async fn get_range_internal(
self: &Arc<Self>,
partition_key: &F::P,
begin_sort_key: Option<F::S>,
filter: Option<F::Filter>,
limit: usize,
enumeration_order: EnumerationOrder,
) -> Result<Vec<F::E>, Error> {
let hash = partition_key.hash();
let who = self.data.replication.read_nodes(&hash);
let rpc = TableRpc::<F>::ReadRange {
partition: partition_key.clone(),
begin_sort_key,
filter,
limit,
enumeration_order,
};
let resps = self
.system
.rpc
.try_call_many(
&self.endpoint,
&who[..],
rpc,
RequestStrategy::with_priority(PRIO_NORMAL)
.with_quorum(self.data.replication.read_quorum())
.with_timeout(TABLE_RPC_TIMEOUT)
.interrupt_after_quorum(true),
)
.await?;
let mut ret: BTreeMap<Vec<u8>, F::E> = BTreeMap::new();
let mut to_repair = BTreeSet::new();
for resp in resps {
if let TableRpc::Update(entries) = resp {
for entry_bytes in entries.iter() {
let entry = self.data.decode_entry(entry_bytes.as_slice())?;
let entry_key = self.data.tree_key(entry.partition_key(), entry.sort_key());
match ret.get_mut(&entry_key) {
Some(e) => {
if *e != entry {
e.merge(&entry);
to_repair.insert(entry_key.clone());
}
}
None => {
ret.insert(entry_key, entry);
}
}
}
} else {
return Err(Error::unexpected_rpc_message(resp));
}
}
if !to_repair.is_empty() {
let self2 = self.clone();
let to_repair = to_repair
.into_iter()
.map(|k| ret.get(&k).unwrap().clone())
.collect::<Vec<_>>();
self.system.background.spawn_cancellable(async move {
for v in to_repair {
self2.repair_on_read(&who[..], v).await?;
}
Ok(())
});
}
// At this point, the `ret` btreemap might contain more than `limit`
// items, because nodes might have returned us each `limit` items
// but for different keys. We have to take only the first `limit` items
// in this map, in the specified enumeration order, for two reasons:
// 1. To return to the user no more than the number of items that they requested
// 2. To return only items for which we have a read quorum: we do not know
// that we have a read quorum for the items after the first `limit`
// of them
let ret_vec = match enumeration_order {
EnumerationOrder::Forward => ret
.into_iter()
.take(limit)
.map(|(_k, v)| v)
.collect::<Vec<_>>(),
EnumerationOrder::Reverse => ret
.into_iter()
.rev()
.take(limit)
.map(|(_k, v)| v)
.collect::<Vec<_>>(),
};
Ok(ret_vec)
}
// =============== UTILITY FUNCTION FOR CLIENT OPERATIONS ===============
async fn repair_on_read(&self, who: &[Uuid], what: F::E) -> Result<(), Error> {
let what_enc = Arc::new(ByteBuf::from(rmp_to_vec_all_named(&what)?));
self.system
.rpc
.try_call_many(
&self.endpoint,
who,
TableRpc::<F>::Update(vec![what_enc]),
RequestStrategy::with_priority(PRIO_NORMAL)
.with_quorum(who.len())
.with_timeout(TABLE_RPC_TIMEOUT),
)
.await?;
Ok(())
}
}
#[async_trait]
impl<F, R> EndpointHandler<TableRpc<F>> for Table<F, R>
where
F: TableSchema + 'static,
R: TableReplication + 'static,
{
async fn handle(
self: &Arc<Self>,
msg: &TableRpc<F>,
_from: NodeID,
) -> Result<TableRpc<F>, Error> {
match msg {
TableRpc::ReadEntry(key, sort_key) => {
let value = self.data.read_entry(key, sort_key)?;
Ok(TableRpc::ReadEntryResponse(value))
}
TableRpc::ReadRange {
partition,
begin_sort_key,
filter,
limit,
enumeration_order,
} => {
let values = self.data.read_range(
partition,
begin_sort_key,
filter,
*limit,
*enumeration_order,
)?;
Ok(TableRpc::Update(values))
}
TableRpc::Update(pairs) => {
self.data.update_many(pairs)?;
Ok(TableRpc::Ok)
}
m => Err(Error::unexpected_rpc_message(m)),
}
}
}