mito2/
wal.rs

1// Copyright 2023 Greptime Team
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15//! Write ahead log of the engine.
16
17pub mod encoder;
18pub(crate) mod entry_distributor;
19pub(crate) mod entry_reader;
20pub(crate) mod raw_entry_reader;
21
22use std::collections::HashMap;
23use std::mem;
24use std::sync::Arc;
25
26use api::v1::WalEntry;
27use common_error::ext::BoxedError;
28use common_telemetry::debug;
29use encoder::WalEntryEncoder;
30use entry_reader::NoopEntryReader;
31use futures::future::BoxFuture;
32use futures::stream::BoxStream;
33use snafu::ResultExt;
34use store_api::logstore::entry::Entry;
35use store_api::logstore::provider::Provider;
36use store_api::logstore::{AppendBatchResponse, LogStore, WalIndex};
37use store_api::storage::RegionId;
38
39use crate::error::{BuildEntrySnafu, DeleteWalSnafu, Result, WaitWalDurableSnafu, WriteWalSnafu};
40use crate::wal::entry_reader::{LogStoreEntryReader, WalEntryReader};
41use crate::wal::raw_entry_reader::{LogStoreRawEntryReader, RegionRawEntryReader};
42
43/// WAL entry id.
44pub type EntryId = store_api::logstore::entry::Id;
45/// A stream that yields tuple of WAL entry id and corresponding entry.
46pub type WalEntryStream<'a> = BoxStream<'a, Result<(EntryId, WalEntry)>>;
47
48/// Waits until the WAL of one region is durable through an entry id.
49///
50/// A flush calls it before it records an entry id as flushed in the manifest:
51/// a log store that acknowledges an append before its entries are durable
52/// hands out entry ids that a crash can lose, and a manifest watermark that
53/// names such an id would skip the entries assigned again after a restart.
54#[derive(Clone)]
55pub(crate) struct DurabilityBarrier(
56    Arc<dyn Fn(EntryId) -> BoxFuture<'static, Result<()>> + Send + Sync>,
57);
58
59impl DurabilityBarrier {
60    /// Returns once the region is durable through `entry_id`.
61    pub(crate) async fn wait(&self, entry_id: EntryId) -> Result<()> {
62        (self.0)(entry_id).await
63    }
64
65    /// A barrier that never waits, for tests without a log store.
66    #[cfg(test)]
67    pub(crate) fn noop() -> Self {
68        Self(Arc::new(|_| Box::pin(async { Ok(()) })))
69    }
70}
71
72impl std::fmt::Debug for DurabilityBarrier {
73    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
74        f.write_str("DurabilityBarrier")
75    }
76}
77
78/// Write ahead log.
79///
80/// All regions in the engine shares the same WAL instance.
81#[derive(Debug)]
82pub struct Wal<S> {
83    /// The underlying log store.
84    store: Arc<S>,
85}
86
87impl<S> Wal<S> {
88    /// Creates a new [Wal] from the log store.
89    pub fn new(store: Arc<S>) -> Self {
90        Self { store }
91    }
92
93    pub fn store(&self) -> &Arc<S> {
94        &self.store
95    }
96}
97
98impl<S> Clone for Wal<S> {
99    fn clone(&self) -> Self {
100        Self {
101            store: Arc::clone(&self.store),
102        }
103    }
104}
105
106impl<S: LogStore> Wal<S> {
107    /// Returns a writer to write to the WAL.
108    pub fn writer(&self) -> WalWriter<S> {
109        WalWriter {
110            store: self.store.clone(),
111            entries: Vec::new(),
112            providers: HashMap::new(),
113            encoder: WalEntryEncoder::new(),
114        }
115    }
116
117    /// Returns a [OnRegionOpened] function.
118    pub(crate) fn on_region_opened(
119        &self,
120    ) -> impl FnOnce(RegionId, EntryId, &Provider) -> BoxFuture<Result<()>> {
121        let store = self.store.clone();
122        move |region_id, last_entry_id, provider| -> BoxFuture<'_, Result<()>> {
123            if let Provider::Noop = provider {
124                debug!("Skip obsolete for region: {}", region_id);
125                return Box::pin(async move { Ok(()) });
126            }
127            Box::pin(async move {
128                store
129                    .obsolete(provider, region_id, last_entry_id)
130                    .await
131                    .map_err(BoxedError::new)
132                    .context(DeleteWalSnafu { region_id })
133            })
134        }
135    }
136
137    /// Returns the [DurabilityBarrier] of the region written through `provider`.
138    pub(crate) fn durability_barrier(
139        &self,
140        region_id: RegionId,
141        provider: &Provider,
142    ) -> DurabilityBarrier {
143        let store = self.store.clone();
144        let provider = provider.clone();
145        DurabilityBarrier(Arc::new(move |entry_id| {
146            let store = store.clone();
147            let provider = provider.clone();
148            Box::pin(async move {
149                if let Provider::Noop = provider {
150                    return Ok(());
151                }
152                store
153                    .wait_durable(&provider, entry_id)
154                    .await
155                    .map_err(BoxedError::new)
156                    .context(WaitWalDurableSnafu { region_id })
157            })
158        }))
159    }
160
161    /// Returns a [WalEntryReader]
162    pub(crate) fn wal_entry_reader(
163        &self,
164        provider: &Provider,
165        region_id: RegionId,
166        location_id: Option<u64>,
167    ) -> Box<dyn WalEntryReader> {
168        match provider {
169            Provider::RaftEngine(_) => Box::new(LogStoreEntryReader::new(
170                LogStoreRawEntryReader::new(self.store.clone()),
171            )),
172            // Entries of many regions share one namespace, so the reader filters by region.
173            Provider::Kafka(_) | Provider::ObjectStore(_) => {
174                let reader = if let Some(location_id) = location_id {
175                    LogStoreRawEntryReader::new(self.store.clone())
176                        .with_wal_index(WalIndex::new(region_id, location_id))
177                } else {
178                    LogStoreRawEntryReader::new(self.store.clone())
179                };
180
181                Box::new(LogStoreEntryReader::new(RegionRawEntryReader::new(
182                    reader, region_id,
183                )))
184            }
185            Provider::Noop => Box::new(NoopEntryReader),
186        }
187    }
188
189    /// Scan entries of specific region starting from `start_id` (inclusive).
190    /// Currently only used in tests.
191    pub fn scan<'a>(
192        &'a self,
193        region_id: RegionId,
194        start_id: EntryId,
195        provider: &'a Provider,
196    ) -> Result<WalEntryStream<'a>> {
197        let mut reader = self.wal_entry_reader(provider, region_id, None);
198        reader.read(provider, start_id)
199    }
200
201    /// Mark entries whose ids `<= last_id` as deleted.
202    pub async fn obsolete(
203        &self,
204        region_id: RegionId,
205        last_id: EntryId,
206        provider: &Provider,
207    ) -> Result<()> {
208        if let Provider::Noop = provider {
209            return Ok(());
210        }
211        self.store
212            .obsolete(provider, region_id, last_id)
213            .await
214            .map_err(BoxedError::new)
215            .context(DeleteWalSnafu { region_id })
216    }
217
218    /// Deletes all WAL entries in the namespace represented by `provider`.
219    pub async fn delete_namespace(&self, region_id: RegionId, provider: &Provider) -> Result<()> {
220        if let Provider::Noop = provider {
221            return Ok(());
222        }
223        self.store
224            .delete_namespace(provider)
225            .await
226            .map_err(BoxedError::new)
227            .context(DeleteWalSnafu { region_id })
228    }
229
230    /// Marks all WAL entries of a region as obsolete and removes its dedicated namespace when
231    /// supported by the backend.
232    pub async fn obsolete_all(&self, region_id: RegionId, provider: &Provider) -> Result<()> {
233        self.store
234            .obsolete_all(provider, region_id)
235            .await
236            .map_err(BoxedError::new)
237            .context(DeleteWalSnafu { region_id })
238    }
239}
240
241/// WAL batch writer.
242pub struct WalWriter<S: LogStore> {
243    /// Log store of the WAL.
244    store: Arc<S>,
245    /// Entries to write.
246    entries: Vec<Entry>,
247    /// Providers of regions being written into.
248    providers: HashMap<RegionId, Provider>,
249    /// Cached-size single-pass encoder, reused across entries in this batch.
250    encoder: WalEntryEncoder,
251}
252
253impl<S: LogStore> WalWriter<S> {
254    /// Add a wal entry for specific region to the writer's buffer.
255    pub fn add_entry(
256        &mut self,
257        region_id: RegionId,
258        entry_id: EntryId,
259        wal_entry: &WalEntry,
260        provider: &Provider,
261    ) -> Result<()> {
262        // Gets or inserts with a newly built provider.
263        let provider = self
264            .providers
265            .entry(region_id)
266            .or_insert_with(|| provider.clone());
267
268        let data = self.encoder.encode_to_vec(wal_entry);
269        let entry = self
270            .store
271            .entry(data, entry_id, region_id, provider)
272            .map_err(BoxedError::new)
273            .context(BuildEntrySnafu { region_id })?;
274
275        self.entries.push(entry);
276
277        Ok(())
278    }
279
280    /// Write all buffered entries to the WAL.
281    pub async fn write_to_wal(&mut self) -> Result<AppendBatchResponse> {
282        // TODO(yingwen): metrics.
283
284        let entries = mem::take(&mut self.entries);
285        self.store
286            .append_batch(entries)
287            .await
288            .map_err(BoxedError::new)
289            .context(WriteWalSnafu)
290    }
291}
292
293#[cfg(test)]
294mod tests {
295    use api::v1::helper::{tag_column_schema, time_index_column_schema};
296    use api::v1::{
297        ArrowIpc, BulkWalEntry, ColumnDataType, Mutation, OpType, Row, Rows, Value, bulk_wal_entry,
298        value,
299    };
300    use common_recordbatch::DfRecordBatch;
301    use common_test_util::flight::encode_to_flight_data;
302    use common_test_util::temp_dir::{TempDir, create_temp_dir};
303    use datatypes::arrow;
304    use datatypes::arrow::array::{ArrayRef, TimestampMillisecondArray};
305    use datatypes::arrow::datatypes::Field;
306    use datatypes::arrow_array::StringArray;
307    use futures::TryStreamExt;
308    use log_store::raft_engine::log_store::RaftEngineLogStore;
309    use log_store::test_util::log_store_util;
310    use store_api::storage::SequenceNumber;
311
312    use super::*;
313
314    struct WalEnv {
315        _wal_dir: TempDir,
316        log_store: Option<Arc<RaftEngineLogStore>>,
317    }
318
319    impl WalEnv {
320        async fn new() -> WalEnv {
321            let wal_dir = create_temp_dir("");
322            let log_store =
323                log_store_util::create_tmp_local_file_log_store(wal_dir.path().to_str().unwrap())
324                    .await;
325            WalEnv {
326                _wal_dir: wal_dir,
327                log_store: Some(Arc::new(log_store)),
328            }
329        }
330
331        fn new_wal(&self) -> Wal<RaftEngineLogStore> {
332            let log_store = self.log_store.clone().unwrap();
333            Wal::new(log_store)
334        }
335    }
336
337    /// Create a new mutation from rows.
338    ///
339    /// The row format is (string, i64).
340    fn new_mutation(op_type: OpType, sequence: SequenceNumber, rows: &[(&str, i64)]) -> Mutation {
341        let rows = rows
342            .iter()
343            .map(|(str_col, int_col)| {
344                let values = vec![
345                    Value {
346                        value_data: Some(value::ValueData::StringValue(str_col.to_string())),
347                    },
348                    Value {
349                        value_data: Some(value::ValueData::TimestampMillisecondValue(*int_col)),
350                    },
351                ];
352                Row { values }
353            })
354            .collect();
355        let schema = vec![
356            tag_column_schema("tag", ColumnDataType::String),
357            time_index_column_schema("ts", ColumnDataType::TimestampMillisecond),
358        ];
359
360        Mutation {
361            op_type: op_type as i32,
362            sequence,
363            rows: Some(Rows { schema, rows }),
364            write_hint: None,
365        }
366    }
367
368    #[tokio::test]
369    async fn test_write_wal() {
370        let env = WalEnv::new().await;
371        let wal = env.new_wal();
372
373        let entry = WalEntry {
374            mutations: vec![
375                new_mutation(OpType::Put, 1, &[("k1", 1), ("k2", 2)]),
376                new_mutation(OpType::Put, 2, &[("k3", 3), ("k4", 4)]),
377            ],
378            bulk_entries: vec![],
379        };
380        let mut writer = wal.writer();
381        // Region 1 entry 1.
382        let region_id = RegionId::new(1, 1);
383        writer
384            .add_entry(
385                region_id,
386                1,
387                &entry,
388                &Provider::raft_engine_provider(region_id.as_u64()),
389            )
390            .unwrap();
391        // Region 2 entry 1.
392        let region_id = RegionId::new(1, 2);
393        writer
394            .add_entry(
395                region_id,
396                1,
397                &entry,
398                &Provider::raft_engine_provider(region_id.as_u64()),
399            )
400            .unwrap();
401        // Region 1 entry 2.
402        let region_id = RegionId::new(1, 2);
403        writer
404            .add_entry(
405                region_id,
406                2,
407                &entry,
408                &Provider::raft_engine_provider(region_id.as_u64()),
409            )
410            .unwrap();
411
412        // Test writing multiple region to wal.
413        writer.write_to_wal().await.unwrap();
414    }
415
416    fn build_record_batch(rows: &[(&str, i64)]) -> DfRecordBatch {
417        let schema = Arc::new(arrow::datatypes::Schema::new(vec![
418            Field::new("tag", arrow::datatypes::DataType::Utf8, false),
419            Field::new(
420                "ts",
421                arrow::datatypes::DataType::Timestamp(
422                    arrow::datatypes::TimeUnit::Millisecond,
423                    None,
424                ),
425                false,
426            ),
427        ]));
428
429        let tag = Arc::new(StringArray::from_iter_values(
430            rows.iter().map(|r| r.0.to_string()),
431        )) as ArrayRef;
432        let ts = Arc::new(TimestampMillisecondArray::from_iter_values(
433            rows.iter().map(|r| r.1),
434        )) as ArrayRef;
435        DfRecordBatch::try_new(schema, vec![tag, ts]).unwrap()
436    }
437
438    fn build_bulk_wal_entry(sequence_number: SequenceNumber, rows: &[(&str, i64)]) -> BulkWalEntry {
439        let rb = build_record_batch(rows);
440        let (schema, rb) = encode_to_flight_data(rb);
441        let max_ts = rows.iter().map(|r| r.1).max().unwrap();
442        let min_ts = rows.iter().map(|r| r.1).min().unwrap();
443        BulkWalEntry {
444            sequence: sequence_number,
445            max_ts,
446            min_ts,
447            timestamp_index: 1,
448            body: Some(bulk_wal_entry::Body::ArrowIpc(ArrowIpc {
449                schema: schema.data_header,
450                data_header: rb.data_header,
451                payload: rb.data_body,
452            })),
453        }
454    }
455
456    fn sample_entries() -> Vec<WalEntry> {
457        vec![
458            WalEntry {
459                mutations: vec![
460                    new_mutation(OpType::Put, 1, &[("k1", 1), ("k2", 2)]),
461                    new_mutation(OpType::Put, 2, &[("k3", 3), ("k4", 4)]),
462                ],
463                bulk_entries: vec![],
464            },
465            WalEntry {
466                mutations: vec![new_mutation(OpType::Put, 3, &[("k1", 1), ("k2", 2)])],
467                bulk_entries: vec![],
468            },
469            WalEntry {
470                mutations: vec![
471                    new_mutation(OpType::Put, 4, &[("k1", 1), ("k2", 2)]),
472                    new_mutation(OpType::Put, 5, &[("k3", 3), ("k4", 4)]),
473                ],
474                bulk_entries: vec![],
475            },
476            WalEntry {
477                mutations: vec![new_mutation(OpType::Put, 6, &[("k1", 1), ("k2", 2)])],
478                bulk_entries: vec![build_bulk_wal_entry(7, &[("k1", 8), ("k2", 9)])],
479            },
480        ]
481    }
482
483    fn check_entries(
484        expect: &[WalEntry],
485        expect_start_id: EntryId,
486        actual: &[(EntryId, WalEntry)],
487    ) {
488        for (idx, (expect_entry, (actual_id, actual_entry))) in
489            expect.iter().zip(actual.iter()).enumerate()
490        {
491            let expect_id_entry = (expect_start_id + idx as u64, expect_entry);
492            assert_eq!(expect_id_entry, (*actual_id, actual_entry));
493        }
494        assert_eq!(expect.len(), actual.len());
495    }
496
497    #[tokio::test]
498    async fn test_scan_wal() {
499        let env = WalEnv::new().await;
500        let wal = env.new_wal();
501
502        let entries = sample_entries();
503        let (id1, id2) = (RegionId::new(1, 1), RegionId::new(1, 2));
504        let ns1 = Provider::raft_engine_provider(id1.as_u64());
505        let ns2 = Provider::raft_engine_provider(id2.as_u64());
506        let mut writer = wal.writer();
507        writer.add_entry(id1, 1, &entries[0], &ns1).unwrap();
508        // Insert one entry into region2. Scan should not return this entry.
509        writer.add_entry(id2, 1, &entries[0], &ns2).unwrap();
510        writer.add_entry(id1, 2, &entries[1], &ns1).unwrap();
511        writer.add_entry(id1, 3, &entries[2], &ns1).unwrap();
512        writer.add_entry(id1, 4, &entries[3], &ns1).unwrap();
513
514        writer.write_to_wal().await.unwrap();
515
516        // Scan all contents region1
517        let stream = wal.scan(id1, 1, &ns1).unwrap();
518        let actual: Vec<_> = stream.try_collect().await.unwrap();
519        check_entries(&entries, 1, &actual);
520
521        // Scan parts of contents
522        let stream = wal.scan(id1, 2, &ns1).unwrap();
523        let actual: Vec<_> = stream.try_collect().await.unwrap();
524        check_entries(&entries[1..], 2, &actual);
525
526        // Scan out of range
527        let stream = wal.scan(id1, 5, &ns1).unwrap();
528        let actual: Vec<_> = stream.try_collect().await.unwrap();
529        assert!(actual.is_empty());
530    }
531
532    #[tokio::test]
533    async fn test_obsolete_wal() {
534        let env = WalEnv::new().await;
535        let wal = env.new_wal();
536
537        let entries = sample_entries();
538        let mut writer = wal.writer();
539        let region_id = RegionId::new(1, 1);
540        let ns = Provider::raft_engine_provider(region_id.as_u64());
541        writer.add_entry(region_id, 1, &entries[0], &ns).unwrap();
542        writer.add_entry(region_id, 2, &entries[1], &ns).unwrap();
543        writer.add_entry(region_id, 3, &entries[2], &ns).unwrap();
544
545        writer.write_to_wal().await.unwrap();
546
547        // Delete 1, 2.
548        wal.obsolete(region_id, 2, &ns).await.unwrap();
549
550        // Put 4.
551        let mut writer = wal.writer();
552        writer.add_entry(region_id, 4, &entries[3], &ns).unwrap();
553        writer.write_to_wal().await.unwrap();
554
555        // Scan all
556        let stream = wal.scan(region_id, 1, &ns).unwrap();
557        let actual: Vec<_> = stream.try_collect().await.unwrap();
558        check_entries(&entries[2..], 3, &actual);
559    }
560}
mito2/wal.rs

mito2/
wal.rs
