feat: introduce the Noop WAL provider for datanode

config/config.md

@@ -474,7 +474,7 @@
 | `meta_client.metadata_cache_ttl` | String | `10m` | TTL of the metadata cache. |
 | `meta_client.metadata_cache_tti` | String | `5m` | -- |
 | `wal` | -- | -- | The WAL options. |
-| `wal.provider` | String | `raft_engine` | The provider of the WAL.<br/>- `raft_engine`: the wal is stored in the local file system by raft-engine.<br/>- `kafka`: it's remote wal that data is stored in Kafka. |
+| `wal.provider` | String | `raft_engine` | The provider of the WAL.<br/>- `raft_engine`: the wal is stored in the local file system by raft-engine.<br/>- `kafka`: it's remote wal that data is stored in Kafka.<br/>- `noop`: it's a no-op WAL provider that does not store any WAL data.<br/>**Notes: any unflushed data will be lost when the datanode is shutdown.** |
 | `wal.dir` | String | Unset | The directory to store the WAL files.<br/>**It's only used when the provider is `raft_engine`**. |
 | `wal.file_size` | String | `128MB` | The size of the WAL segment file.<br/>**It's only used when the provider is `raft_engine`**. |
 | `wal.purge_threshold` | String | `1GB` | The threshold of the WAL size to trigger a purge.<br/>**It's only used when the provider is `raft_engine`**. |

config/datanode.example.toml

@@ -118,6 +118,7 @@ metadata_cache_tti = "5m"
 ## The provider of the WAL.
 ## - `raft_engine`: the wal is stored in the local file system by raft-engine.
 ## - `kafka`: it's remote wal that data is stored in Kafka.
+## - `noop`: it's a no-op WAL provider that does not store any WAL data.<br/>**Notes: any unflushed data will be lost when the datanode is shutdown.**
 provider = "raft_engine"
 
 ## The directory to store the WAL files.

src/cmd/src/error.rs

@@ -316,6 +316,13 @@ pub enum Error {
         location: Location,
         source: standalone::error::Error,
     },
+
+    #[snafu(display("Invalid WAL provider"))]
+    InvalidWalProvider {
+        #[snafu(implicit)]
+        location: Location,
+        source: common_wal::error::Error,
+    },
 }
 
 pub type Result<T> = std::result::Result<T, Error>;
@@ -373,6 +380,7 @@ impl ErrorExt for Error {
             }
             Error::MetaClientInit { source, .. } => source.status_code(),
             Error::SchemaNotFound { .. } => StatusCode::DatabaseNotFound,
+            Error::InvalidWalProvider { .. } => StatusCode::InvalidArguments,
         }
     }
 

src/cmd/src/standalone.rs

@@ -476,7 +476,11 @@ impl StartCommand {
                 .step(10)
                 .build(),
         );
-        let kafka_options = opts.wal.clone().into();
+        let kafka_options = opts
+            .wal
+            .clone()
+            .try_into()
+            .context(error::InvalidWalProviderSnafu)?;
         let wal_options_allocator = build_wal_options_allocator(&kafka_options, kv_backend.clone())
             .await
             .context(error::BuildWalOptionsAllocatorSnafu)?;

src/common/wal/src/config.rs

@@ -25,6 +25,7 @@ use crate::config::kafka::common::{
 };
 use crate::config::kafka::{DatanodeKafkaConfig, MetasrvKafkaConfig};
 use crate::config::raft_engine::RaftEngineConfig;
+use crate::error::{Error, UnsupportedWalProviderSnafu};
 
 /// Wal configurations for metasrv.
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq, Default)]
@@ -43,6 +44,7 @@ pub enum MetasrvWalConfig {
 pub enum DatanodeWalConfig {
     RaftEngine(RaftEngineConfig),
     Kafka(DatanodeKafkaConfig),
+    Noop,
 }
 
 impl Default for DatanodeWalConfig {
@@ -51,11 +53,13 @@ impl Default for DatanodeWalConfig {
     }
 }
 
-impl From<DatanodeWalConfig> for MetasrvWalConfig {
-    fn from(config: DatanodeWalConfig) -> Self {
+impl TryFrom<DatanodeWalConfig> for MetasrvWalConfig {
+    type Error = Error;
+
+    fn try_from(config: DatanodeWalConfig) -> Result<Self, Self::Error> {
         match config {
-            DatanodeWalConfig::RaftEngine(_) => Self::RaftEngine,
-            DatanodeWalConfig::Kafka(config) => Self::Kafka(MetasrvKafkaConfig {
+            DatanodeWalConfig::RaftEngine(_) => Ok(Self::RaftEngine),
+            DatanodeWalConfig::Kafka(config) => Ok(Self::Kafka(MetasrvKafkaConfig {
                 connection: config.connection,
                 kafka_topic: config.kafka_topic,
                 auto_create_topics: config.auto_create_topics,
@@ -67,7 +71,11 @@ impl From<DatanodeWalConfig> for MetasrvWalConfig {
                 flush_trigger_size: DEFAULT_FLUSH_TRIGGER_SIZE,
                 // This field won't be used in standalone mode
                 checkpoint_trigger_size: DEFAULT_CHECKPOINT_TRIGGER_SIZE,
-            }),
+            })),
+            DatanodeWalConfig::Noop => UnsupportedWalProviderSnafu {
+                provider: "noop".to_string(),
+            }
+            .fail(),
         }
     }
 }

src/common/wal/src/error.rs

@@ -92,6 +92,13 @@ pub enum Error {
         #[snafu(implicit)]
         location: Location,
     },
+
+    #[snafu(display("Unsupported WAL provider: {}", provider))]
+    UnsupportedWalProvider {
+        provider: String,
+        #[snafu(implicit)]
+        location: Location,
+    },
 }
 
 pub type Result<T> = std::result::Result<T, Error>;

src/datanode/src/datanode.rs

@@ -34,6 +34,7 @@ use common_wal::config::raft_engine::RaftEngineConfig;
 use file_engine::engine::FileRegionEngine;
 use log_store::kafka::log_store::KafkaLogStore;
 use log_store::kafka::{GlobalIndexCollector, default_index_file};
+use log_store::noop::log_store::NoopLogStore;
 use log_store::raft_engine::log_store::RaftEngineLogStore;
 use meta_client::MetaClientRef;
 use metric_engine::engine::MetricEngine;
@@ -561,6 +562,27 @@ impl DatanodeBuilder {
                     self.extension_range_provider_factory.take(),
                 );
 
+                builder.try_build().await.context(BuildMitoEngineSnafu)?
+            }
+            DatanodeWalConfig::Noop => {
+                let log_store = Arc::new(NoopLogStore);
+
+                let builder = MitoEngineBuilder::new(
+                    &opts.storage.data_home,
+                    config,
+                    log_store,
+                    object_store_manager,
+                    schema_metadata_manager,
+                    file_ref_manager,
+                    partition_expr_fetcher.clone(),
+                    plugins,
+                );
+
+                #[cfg(feature = "enterprise")]
+                let builder = builder.with_extension_range_provider_factory(
+                    self.extension_range_provider_factory.take(),
+                );
+
                 builder.try_build().await.context(BuildMitoEngineSnafu)?
             }
         };

src/log-store/src/lib.rs

@@ -18,5 +18,6 @@
 pub mod error;
 pub mod kafka;
 pub mod metrics;
+pub mod noop;
 pub mod raft_engine;
 pub mod test_util;

src/log-store/src/noop.rs

@@ -0,0 +1,15 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed 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.
+
+pub mod log_store;

src/log-store/src/noop/log_store.rs

@@ -0,0 +1,116 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed 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 std::collections::HashMap;
+
+use futures::stream;
+use store_api::logstore::entry::{Entry, NaiveEntry};
+use store_api::logstore::provider::Provider;
+use store_api::logstore::{AppendBatchResponse, EntryId, LogStore, SendableEntryStream, WalIndex};
+use store_api::storage::RegionId;
+
+use crate::error::{Error, Result};
+
+#[derive(Debug, Clone, Copy)]
+pub struct NoopLogStore;
+
+#[async_trait::async_trait]
+impl LogStore for NoopLogStore {
+    type Error = Error;
+
+    async fn stop(&self) -> Result<()> {
+        Ok(())
+    }
+
+    async fn append_batch(&self, entries: Vec<Entry>) -> Result<AppendBatchResponse> {
+        let last_entry_ids = entries
+            .iter()
+            .map(|entry| (entry.region_id(), 0))
+            .collect::<HashMap<RegionId, EntryId>>();
+        Ok(AppendBatchResponse { last_entry_ids })
+    }
+
+    async fn read(
+        &self,
+        _provider: &Provider,
+        _entry_id: EntryId,
+        _index: Option<WalIndex>,
+    ) -> Result<SendableEntryStream<'static, Entry, Self::Error>> {
+        Ok(Box::pin(stream::empty()))
+    }
+
+    async fn create_namespace(&self, _ns: &Provider) -> Result<()> {
+        Ok(())
+    }
+
+    async fn delete_namespace(&self, _ns: &Provider) -> Result<()> {
+        Ok(())
+    }
+
+    async fn list_namespaces(&self) -> Result<Vec<Provider>> {
+        Ok(vec![])
+    }
+
+    fn entry(
+        &self,
+        data: Vec<u8>,
+        entry_id: EntryId,
+        region_id: RegionId,
+        provider: &Provider,
+    ) -> Result<Entry> {
+        Ok(Entry::Naive(NaiveEntry {
+            provider: provider.clone(),
+            region_id,
+            entry_id,
+            data,
+        }))
+    }
+
+    async fn obsolete(
+        &self,
+        _provider: &Provider,
+        _region_id: RegionId,
+        _entry_id: EntryId,
+    ) -> Result<()> {
+        Ok(())
+    }
+
+    fn latest_entry_id(&self, _provider: &Provider) -> Result<EntryId> {
+        Ok(0)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn test_append_batch() {
+        let log_store = NoopLogStore;
+        let entries = vec![Entry::Naive(NaiveEntry {
+            provider: Provider::noop_provider(),
+            region_id: RegionId::new(1, 1),
+            entry_id: 1,
+            data: vec![1],
+        })];
+
+        let last_entry_ids = log_store
+            .append_batch(entries)
+            .await
+            .unwrap()
+            .last_entry_ids;
+        assert_eq!(last_entry_ids.len(), 1);
+        assert_eq!(last_entry_ids[&(RegionId::new(1, 1))], 0);
+    }
+}

src/mito2/src/region/opener.rs

@@ -25,6 +25,7 @@ use common_wal::options::WalOptions;
 use futures::StreamExt;
 use futures::future::BoxFuture;
 use log_store::kafka::log_store::KafkaLogStore;
+use log_store::noop::log_store::NoopLogStore;
 use log_store::raft_engine::log_store::RaftEngineLogStore;
 use object_store::manager::ObjectStoreManagerRef;
 use object_store::util::{join_dir, normalize_dir};
@@ -367,7 +368,8 @@ impl RegionOpener {
         match wal_options {
             WalOptions::RaftEngine => {
                 ensure!(
-                    TypeId::of::<RaftEngineLogStore>() == TypeId::of::<S>(),
+                    TypeId::of::<RaftEngineLogStore>() == TypeId::of::<S>()
+                        || TypeId::of::<NoopLogStore>() == TypeId::of::<S>(),
                     error::IncompatibleWalProviderChangeSnafu {
                         global: "`kafka`",
                         region: "`raft_engine`",
@@ -377,7 +379,8 @@ impl RegionOpener {
             }
             WalOptions::Kafka(options) => {
                 ensure!(
-                    TypeId::of::<KafkaLogStore>() == TypeId::of::<S>(),
+                    TypeId::of::<KafkaLogStore>() == TypeId::of::<S>()
+                        || TypeId::of::<NoopLogStore>() == TypeId::of::<S>(),
                     error::IncompatibleWalProviderChangeSnafu {
                         global: "`raft_engine`",
                         region: "`kafka`",

tests-integration/src/standalone.rs

@@ -202,7 +202,7 @@ impl GreptimeDbStandaloneBuilder {
                 .step(10)
                 .build(),
         );
-        let kafka_options = opts.wal.clone().into();
+        let kafka_options = opts.wal.clone().try_into().unwrap();
         let wal_options_allocator = build_wal_options_allocator(&kafka_options, kv_backend.clone())
             .await
             .unwrap();

tests-integration/src/tests.rs

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 mod instance_kafka_wal_test;
+mod instance_noop_wal_test;
 mod instance_test;
 mod promql_test;
 mod reconcile_table;