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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/11/18 11:00:28 UTC
[GitHub] [arrow-ballista] thinkharderdev commented on a diff in pull request #523: Provide a memory StateBackendClient
thinkharderdev commented on code in PR #523:
URL: https://github.com/apache/arrow-ballista/pull/523#discussion_r1026287065
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ballista/scheduler/src/state/backend/memory.rs:
##########
@@ -0,0 +1,395 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use crate::state::backend::utils::sled_subscriber::{Subscriber, Subscribers};
+use crate::state::backend::{
+ Keyspace, Lock, Operation, StateBackendClient, Watch, WatchEvent,
+};
+use ballista_core::error::Result;
+use dashmap::DashMap;
+use futures::{FutureExt, Stream};
+use log::warn;
+use std::collections::{BTreeMap, HashSet};
+use std::sync::Arc;
+use tokio::sync::Mutex;
+
+type KeySpaceState = BTreeMap<String, Vec<u8>>;
+type KeyLock = Arc<Mutex<()>>;
+
+/// A [`StateBackendClient`] implementation that uses in memory map to save cluster state.
+#[derive(Clone, Default)]
+pub struct MemoryBackendClient {
+ /// The key is the KeySpace. For every KeySpace, there will be a tree map which is better for prefix filtering
+ states: DashMap<String, KeySpaceState>,
+ /// The key is the full key formatted like "/KeySpace/key". It's a flatted map
+ locks: DashMap<String, KeyLock>,
+ subscribers: Arc<Subscribers>,
+}
+
+impl MemoryBackendClient {
+ pub fn new() -> Self {
+ Self::default()
+ }
+
+ fn get_space_key(keyspace: &Keyspace) -> String {
+ format!("/{:?}", keyspace)
+ }
+
+ fn get_flat_key(keyspace: &Keyspace, key: &str) -> String {
+ format!("/{:?}/{}", keyspace, key)
+ }
+}
+
+#[tonic::async_trait]
+impl StateBackendClient for MemoryBackendClient {
+ async fn get(&self, keyspace: Keyspace, key: &str) -> Result<Vec<u8>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| space_state.value().get(key).cloned().unwrap_or_default())
+ .unwrap_or_default())
+ }
+
+ async fn get_from_prefix(
+ &self,
+ keyspace: Keyspace,
+ prefix: &str,
+ ) -> Result<Vec<(String, Vec<u8>)>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| {
+ space_state
+ .value()
+ .range(prefix.to_owned()..)
+ .take_while(|(k, _)| k.starts_with(prefix))
+ .map(|e| (format!("{}/{}", space_key, e.0), e.1.clone()))
+ .collect()
+ })
+ .unwrap_or_default())
+ }
+
+ async fn scan(
+ &self,
+ keyspace: Keyspace,
+ limit: Option<usize>,
+ ) -> Result<Vec<(String, Vec<u8>)>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| {
+ if let Some(limit) = limit {
+ space_state
+ .value()
+ .iter()
+ .take(limit)
+ .map(|e| (format!("{}/{}", space_key, e.0), e.1.clone()))
+ .collect::<Vec<(String, Vec<u8>)>>()
+ } else {
+ space_state
+ .value()
+ .iter()
+ .map(|e| (format!("{}/{}", space_key, e.0), e.1.clone()))
+ .collect::<Vec<(String, Vec<u8>)>>()
+ }
+ })
+ .unwrap_or_default())
+ }
+
+ async fn scan_keys(&self, keyspace: Keyspace) -> Result<HashSet<String>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| {
+ space_state
+ .value()
+ .iter()
+ .map(|e| format!("{}/{}", space_key, e.0))
+ .collect::<HashSet<String>>()
+ })
+ .unwrap_or_default())
+ }
+
+ async fn put(&self, keyspace: Keyspace, key: String, value: Vec<u8>) -> Result<()> {
+ let space_key = Self::get_space_key(&keyspace);
+ if !self.states.contains_key(&space_key) {
+ self.states.insert(space_key.clone(), BTreeMap::default());
+ }
+ self.states
+ .get_mut(&space_key)
+ .unwrap()
+ .value_mut()
+ .insert(key.clone(), value.clone());
+
+ // Notify subscribers
+ let full_key = format!("{}/{}", space_key, key);
+ if let Some(res) = self.subscribers.reserve(&full_key) {
+ let event = WatchEvent::Put(full_key, value);
+ res.complete(&event);
+ }
+
+ Ok(())
+ }
+
+ async fn apply_txn(&self, ops: Vec<(Operation, Keyspace, String)>) -> Result<()> {
+ let mut locks = vec![];
+ for (_, keyspace, key) in ops.iter() {
+ locks.push(self.lock(keyspace.clone(), key).await?);
+ }
+
+ for (op, keyspace, key) in ops.into_iter() {
+ match op {
+ Operation::Delete => {
+ self.delete(keyspace, &key).await?;
+ }
+ Operation::Put(value) => {
+ self.put(keyspace, key, value).await?;
+ }
+ };
+ }
+
+ Ok(())
+ }
+
+ async fn mv(
+ &self,
+ from_keyspace: Keyspace,
+ to_keyspace: Keyspace,
+ key: &str,
+ ) -> Result<()> {
+ let from_space_key = Self::get_space_key(&from_keyspace);
+
+ if let Some(from_space_state) = self.states.get(&from_space_key) {
+ if let Some(state) = from_space_state.value().get(key) {
+ let ops = vec![
+ (Operation::Delete, from_keyspace, key.to_owned()),
+ (Operation::Put(state.clone()), to_keyspace, key.to_owned()),
+ ];
+ self.apply_txn(ops).await
+ } else {
+ // TODO should this return an error?
Review Comment:
I think this should be consistent with the Sled and Etcd backends which I believe would both return an error in this scenario
##########
ballista/scheduler/src/state/backend/utils/mod.rs:
##########
@@ -0,0 +1,21 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#[allow(dead_code)]
+mod sled_oneshot;
+#[allow(dead_code)]
+pub(crate) mod sled_subscriber;
Review Comment:
Confused about the naming here. Why is this called `sled_subscriber`? It's used by the memory backend right?
##########
ballista/scheduler/src/state/backend/memory.rs:
##########
@@ -0,0 +1,395 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use crate::state::backend::utils::sled_subscriber::{Subscriber, Subscribers};
+use crate::state::backend::{
+ Keyspace, Lock, Operation, StateBackendClient, Watch, WatchEvent,
+};
+use ballista_core::error::Result;
+use dashmap::DashMap;
+use futures::{FutureExt, Stream};
+use log::warn;
+use std::collections::{BTreeMap, HashSet};
+use std::sync::Arc;
+use tokio::sync::Mutex;
+
+type KeySpaceState = BTreeMap<String, Vec<u8>>;
+type KeyLock = Arc<Mutex<()>>;
+
+/// A [`StateBackendClient`] implementation that uses in memory map to save cluster state.
+#[derive(Clone, Default)]
+pub struct MemoryBackendClient {
+ /// The key is the KeySpace. For every KeySpace, there will be a tree map which is better for prefix filtering
+ states: DashMap<String, KeySpaceState>,
+ /// The key is the full key formatted like "/KeySpace/key". It's a flatted map
+ locks: DashMap<String, KeyLock>,
+ subscribers: Arc<Subscribers>,
+}
+
+impl MemoryBackendClient {
+ pub fn new() -> Self {
+ Self::default()
+ }
+
+ fn get_space_key(keyspace: &Keyspace) -> String {
+ format!("/{:?}", keyspace)
+ }
+
+ fn get_flat_key(keyspace: &Keyspace, key: &str) -> String {
+ format!("/{:?}/{}", keyspace, key)
+ }
+}
+
+#[tonic::async_trait]
+impl StateBackendClient for MemoryBackendClient {
+ async fn get(&self, keyspace: Keyspace, key: &str) -> Result<Vec<u8>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| space_state.value().get(key).cloned().unwrap_or_default())
+ .unwrap_or_default())
+ }
+
+ async fn get_from_prefix(
+ &self,
+ keyspace: Keyspace,
+ prefix: &str,
+ ) -> Result<Vec<(String, Vec<u8>)>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| {
+ space_state
+ .value()
+ .range(prefix.to_owned()..)
+ .take_while(|(k, _)| k.starts_with(prefix))
+ .map(|e| (format!("{}/{}", space_key, e.0), e.1.clone()))
+ .collect()
+ })
+ .unwrap_or_default())
+ }
+
+ async fn scan(
+ &self,
+ keyspace: Keyspace,
+ limit: Option<usize>,
+ ) -> Result<Vec<(String, Vec<u8>)>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| {
+ if let Some(limit) = limit {
+ space_state
+ .value()
+ .iter()
+ .take(limit)
+ .map(|e| (format!("{}/{}", space_key, e.0), e.1.clone()))
+ .collect::<Vec<(String, Vec<u8>)>>()
+ } else {
+ space_state
+ .value()
+ .iter()
+ .map(|e| (format!("{}/{}", space_key, e.0), e.1.clone()))
+ .collect::<Vec<(String, Vec<u8>)>>()
+ }
+ })
+ .unwrap_or_default())
+ }
+
+ async fn scan_keys(&self, keyspace: Keyspace) -> Result<HashSet<String>> {
+ let space_key = Self::get_space_key(&keyspace);
+ Ok(self
+ .states
+ .get(&space_key)
+ .map(|space_state| {
+ space_state
+ .value()
+ .iter()
+ .map(|e| format!("{}/{}", space_key, e.0))
+ .collect::<HashSet<String>>()
+ })
+ .unwrap_or_default())
+ }
+
+ async fn put(&self, keyspace: Keyspace, key: String, value: Vec<u8>) -> Result<()> {
+ let space_key = Self::get_space_key(&keyspace);
+ if !self.states.contains_key(&space_key) {
+ self.states.insert(space_key.clone(), BTreeMap::default());
+ }
+ self.states
+ .get_mut(&space_key)
+ .unwrap()
+ .value_mut()
+ .insert(key.clone(), value.clone());
+
+ // Notify subscribers
+ let full_key = format!("{}/{}", space_key, key);
+ if let Some(res) = self.subscribers.reserve(&full_key) {
+ let event = WatchEvent::Put(full_key, value);
+ res.complete(&event);
+ }
+
+ Ok(())
+ }
+
+ async fn apply_txn(&self, ops: Vec<(Operation, Keyspace, String)>) -> Result<()> {
+ let mut locks = vec![];
+ for (_, keyspace, key) in ops.iter() {
+ locks.push(self.lock(keyspace.clone(), key).await?);
+ }
+
+ for (op, keyspace, key) in ops.into_iter() {
+ match op {
+ Operation::Delete => {
+ self.delete(keyspace, &key).await?;
+ }
+ Operation::Put(value) => {
+ self.put(keyspace, key, value).await?;
+ }
+ };
+ }
+
+ Ok(())
+ }
+
+ async fn mv(
+ &self,
+ from_keyspace: Keyspace,
+ to_keyspace: Keyspace,
+ key: &str,
+ ) -> Result<()> {
+ let from_space_key = Self::get_space_key(&from_keyspace);
+
+ if let Some(from_space_state) = self.states.get(&from_space_key) {
+ if let Some(state) = from_space_state.value().get(key) {
+ let ops = vec![
+ (Operation::Delete, from_keyspace, key.to_owned()),
+ (Operation::Put(state.clone()), to_keyspace, key.to_owned()),
+ ];
+ self.apply_txn(ops).await
+ } else {
+ // TODO should this return an error?
+ warn!(
+ "Cannot move value at {}/{}, does not exist",
+ from_space_key, key
+ );
+ Ok(())
+ }
+ } else {
+ // TODO should this return an error?
+ warn!(
+ "Cannot move value at {}/{}, does not exist",
+ from_space_key, key
+ );
+ Ok(())
+ }
+ }
+
+ async fn lock(&self, keyspace: Keyspace, key: &str) -> Result<Box<dyn Lock>> {
+ let flat_key = Self::get_flat_key(&keyspace, key);
+ if let Some(lock) = self.locks.get_mut(&flat_key) {
+ Ok(Box::new(lock.value().clone().lock_owned().await))
+ } else {
+ let new_lock = Arc::new(Mutex::new(()));
+ self.locks.insert(flat_key, new_lock.clone());
+ Ok(Box::new(new_lock.lock_owned().await))
+ }
+ }
Review Comment:
Hmm, I think this might allow multiple locks.
Can we use the entry API here?
```rust
let new_lock = Arc::new(Mutex::new(()));
let lock = self.locks.entry(&flat_key).or_insert_with(|| Arc::new(Mutex::new(())));
Ok(Box::new(lock.value().clone().lock_owned().await))
```
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