Line data Source code
1 : // Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
2 : // of this source code is governed by a BSD-style license that can be found in
3 : // the LICENSE file.
4 :
5 : package pebble
6 :
7 : import (
8 : "context"
9 : "fmt"
10 : "sync/atomic"
11 : "time"
12 :
13 : "github.com/cockroachdb/errors"
14 : "github.com/cockroachdb/pebble/internal/base"
15 : "github.com/cockroachdb/pebble/internal/invariants"
16 : "github.com/cockroachdb/pebble/internal/keyspan"
17 : "github.com/cockroachdb/pebble/internal/keyspan/keyspanimpl"
18 : "github.com/cockroachdb/pebble/internal/manifest"
19 : )
20 :
21 : // flushable defines the interface for immutable memtables.
22 : type flushable interface {
23 : newIter(o *IterOptions) internalIterator
24 : newFlushIter(o *IterOptions) internalIterator
25 : newRangeDelIter(o *IterOptions) keyspan.FragmentIterator
26 : newRangeKeyIter(o *IterOptions) keyspan.FragmentIterator
27 : containsRangeKeys() bool
28 : // inuseBytes returns the number of inuse bytes by the flushable.
29 : inuseBytes() uint64
30 : // totalBytes returns the total number of bytes allocated by the flushable.
31 : totalBytes() uint64
32 : // readyForFlush returns true when the flushable is ready for flushing. See
33 : // memTable.readyForFlush for one implementation which needs to check whether
34 : // there are any outstanding write references.
35 : readyForFlush() bool
36 : // computePossibleOverlaps determines whether the flushable's keys overlap
37 : // with the bounds of any of the provided bounded items. If an item overlaps
38 : // or might overlap but it's not possible to determine overlap cheaply,
39 : // computePossibleOverlaps invokes the provided function with the object
40 : // that might overlap. computePossibleOverlaps must not perform any I/O and
41 : // implementations should invoke the provided function for items that would
42 : // require I/O to determine overlap.
43 : computePossibleOverlaps(overlaps func(bounded) shouldContinue, bounded ...bounded)
44 : }
45 :
46 : type shouldContinue bool
47 :
48 : const (
49 : continueIteration shouldContinue = true
50 : stopIteration = false
51 : )
52 :
53 : type bounded interface {
54 : UserKeyBounds() base.UserKeyBounds
55 : }
56 :
57 : var _ bounded = (*fileMetadata)(nil)
58 : var _ bounded = KeyRange{}
59 :
60 1 : func sliceAsBounded[B bounded](s []B) []bounded {
61 1 : ret := make([]bounded, len(s))
62 1 : for i := 0; i < len(s); i++ {
63 1 : ret[i] = s[i]
64 1 : }
65 1 : return ret
66 : }
67 :
68 : // flushableEntry wraps a flushable and adds additional metadata and
69 : // functionality that is common to all flushables.
70 : type flushableEntry struct {
71 : flushable
72 : // Channel which is closed when the flushable has been flushed.
73 : flushed chan struct{}
74 : // flushForced indicates whether a flush was forced on this memtable (either
75 : // manual, or due to ingestion). Protected by DB.mu.
76 : flushForced bool
77 : // delayedFlushForcedAt indicates whether a timer has been set to force a
78 : // flush on this memtable at some point in the future. Protected by DB.mu.
79 : // Holds the timestamp of when the flush will be issued.
80 : delayedFlushForcedAt time.Time
81 : // logNum corresponds to the WAL that contains the records present in the
82 : // receiver.
83 : logNum base.DiskFileNum
84 : // logSize is the size in bytes of the associated WAL. Protected by DB.mu.
85 : logSize uint64
86 : // The current logSeqNum at the time the memtable was created. This is
87 : // guaranteed to be less than or equal to any seqnum stored in the memtable.
88 : logSeqNum base.SeqNum
89 : // readerRefs tracks the read references on the flushable. The two sources of
90 : // reader references are DB.mu.mem.queue and readState.memtables. The memory
91 : // reserved by the flushable in the cache is released when the reader refs
92 : // drop to zero. If the flushable is referencing sstables, then the file
93 : // refount is also decreased once the reader refs drops to 0. If the
94 : // flushable is a memTable, when the reader refs drops to zero, the writer
95 : // refs will already be zero because the memtable will have been flushed and
96 : // that only occurs once the writer refs drops to zero.
97 : readerRefs atomic.Int32
98 : // Closure to invoke to release memory accounting.
99 : releaseMemAccounting func()
100 : // unrefFiles, if not nil, should be invoked to decrease the ref count of
101 : // files which are backing the flushable.
102 : unrefFiles func() []*fileBacking
103 : // deleteFnLocked should be called if the caller is holding DB.mu.
104 : deleteFnLocked func(obsolete []*fileBacking)
105 : // deleteFn should be called if the caller is not holding DB.mu.
106 : deleteFn func(obsolete []*fileBacking)
107 : }
108 :
109 1 : func (e *flushableEntry) readerRef() {
110 1 : switch v := e.readerRefs.Add(1); {
111 0 : case v <= 1:
112 0 : panic(fmt.Sprintf("pebble: inconsistent reference count: %d", v))
113 : }
114 : }
115 :
116 : // db.mu must not be held when this is called.
117 1 : func (e *flushableEntry) readerUnref(deleteFiles bool) {
118 1 : e.readerUnrefHelper(deleteFiles, e.deleteFn)
119 1 : }
120 :
121 : // db.mu must be held when this is called.
122 1 : func (e *flushableEntry) readerUnrefLocked(deleteFiles bool) {
123 1 : e.readerUnrefHelper(deleteFiles, e.deleteFnLocked)
124 1 : }
125 :
126 : func (e *flushableEntry) readerUnrefHelper(
127 : deleteFiles bool, deleteFn func(obsolete []*fileBacking),
128 1 : ) {
129 1 : switch v := e.readerRefs.Add(-1); {
130 0 : case v < 0:
131 0 : panic(fmt.Sprintf("pebble: inconsistent reference count: %d", v))
132 1 : case v == 0:
133 1 : if e.releaseMemAccounting == nil {
134 0 : panic("pebble: memtable reservation already released")
135 : }
136 1 : e.releaseMemAccounting()
137 1 : e.releaseMemAccounting = nil
138 1 : if e.unrefFiles != nil {
139 1 : obsolete := e.unrefFiles()
140 1 : e.unrefFiles = nil
141 1 : if deleteFiles {
142 1 : deleteFn(obsolete)
143 1 : }
144 : }
145 : }
146 : }
147 :
148 : type flushableList []*flushableEntry
149 :
150 : // ingestedFlushable is the implementation of the flushable interface for the
151 : // ingesting sstables which are added to the flushable list.
152 : type ingestedFlushable struct {
153 : // files are non-overlapping and ordered (according to their bounds).
154 : files []physicalMeta
155 : comparer *Comparer
156 : newIters tableNewIters
157 : newRangeKeyIters keyspanimpl.TableNewSpanIter
158 :
159 : // Since the level slice is immutable, we construct and set it once. It
160 : // should be safe to read from slice in future reads.
161 : slice manifest.LevelSlice
162 : // hasRangeKeys is set on ingestedFlushable construction.
163 : hasRangeKeys bool
164 : // exciseSpan is populated if an excise operation should be performed during
165 : // flush.
166 : exciseSpan KeyRange
167 : }
168 :
169 : func newIngestedFlushable(
170 : files []*fileMetadata,
171 : comparer *Comparer,
172 : newIters tableNewIters,
173 : newRangeKeyIters keyspanimpl.TableNewSpanIter,
174 : exciseSpan KeyRange,
175 1 : ) *ingestedFlushable {
176 1 : if invariants.Enabled {
177 1 : for i := 1; i < len(files); i++ {
178 1 : prev := files[i-1].UserKeyBounds()
179 1 : this := files[i].UserKeyBounds()
180 1 : if prev.End.IsUpperBoundFor(comparer.Compare, this.Start) {
181 0 : panic(errors.AssertionFailedf("ingested flushable files overlap: %s %s", prev, this))
182 : }
183 : }
184 : }
185 1 : var physicalFiles []physicalMeta
186 1 : var hasRangeKeys bool
187 1 : for _, f := range files {
188 1 : if f.HasRangeKeys {
189 1 : hasRangeKeys = true
190 1 : }
191 1 : physicalFiles = append(physicalFiles, f.PhysicalMeta())
192 : }
193 :
194 1 : ret := &ingestedFlushable{
195 1 : files: physicalFiles,
196 1 : comparer: comparer,
197 1 : newIters: newIters,
198 1 : newRangeKeyIters: newRangeKeyIters,
199 1 : // slice is immutable and can be set once and used many times.
200 1 : slice: manifest.NewLevelSliceKeySorted(comparer.Compare, files),
201 1 : hasRangeKeys: hasRangeKeys,
202 1 : exciseSpan: exciseSpan,
203 1 : }
204 1 :
205 1 : return ret
206 : }
207 :
208 : // TODO(sumeer): ingestedFlushable iters also need to plumb context for
209 : // tracing.
210 :
211 : // newIter is part of the flushable interface.
212 1 : func (s *ingestedFlushable) newIter(o *IterOptions) internalIterator {
213 1 : var opts IterOptions
214 1 : if o != nil {
215 1 : opts = *o
216 1 : }
217 : // TODO(bananabrick): The manifest.Level in newLevelIter is only used for
218 : // logging. Update the manifest.Level encoding to account for levels which
219 : // aren't truly levels in the lsm. Right now, the encoding only supports
220 : // L0 sublevels, and the rest of the levels in the lsm.
221 1 : return newLevelIter(
222 1 : context.Background(), opts, s.comparer, s.newIters, s.slice.Iter(), manifest.Level(0),
223 1 : internalIterOpts{},
224 1 : )
225 : }
226 :
227 : // newFlushIter is part of the flushable interface.
228 0 : func (s *ingestedFlushable) newFlushIter(*IterOptions) internalIterator {
229 0 : // newFlushIter is only used for writing memtables to disk as sstables.
230 0 : // Since ingested sstables are already present on disk, they don't need to
231 0 : // make use of a flush iter.
232 0 : panic("pebble: not implemented")
233 : }
234 :
235 : func (s *ingestedFlushable) constructRangeDelIter(
236 : file *manifest.FileMetadata, _ keyspan.SpanIterOptions,
237 1 : ) (keyspan.FragmentIterator, error) {
238 1 : iters, err := s.newIters(context.Background(), file, nil, internalIterOpts{}, iterRangeDeletions)
239 1 : if err != nil {
240 0 : return nil, err
241 0 : }
242 1 : return iters.RangeDeletion(), nil
243 : }
244 :
245 : // newRangeDelIter is part of the flushable interface.
246 : // TODO(bananabrick): Using a level iter instead of a keyspan level iter to
247 : // surface range deletes is more efficient.
248 : //
249 : // TODO(sumeer): *IterOptions are being ignored, so the index block load for
250 : // the point iterator in constructRangeDeIter is not tracked.
251 1 : func (s *ingestedFlushable) newRangeDelIter(_ *IterOptions) keyspan.FragmentIterator {
252 1 : return keyspanimpl.NewLevelIter(
253 1 : keyspan.SpanIterOptions{}, s.comparer.Compare,
254 1 : s.constructRangeDelIter, s.slice.Iter(), manifest.Level(0),
255 1 : manifest.KeyTypePoint,
256 1 : )
257 1 : }
258 :
259 : // newRangeKeyIter is part of the flushable interface.
260 1 : func (s *ingestedFlushable) newRangeKeyIter(o *IterOptions) keyspan.FragmentIterator {
261 1 : if !s.containsRangeKeys() {
262 1 : return nil
263 1 : }
264 :
265 1 : return keyspanimpl.NewLevelIter(
266 1 : keyspan.SpanIterOptions{}, s.comparer.Compare, s.newRangeKeyIters,
267 1 : s.slice.Iter(), manifest.Level(0), manifest.KeyTypeRange,
268 1 : )
269 : }
270 :
271 : // containsRangeKeys is part of the flushable interface.
272 1 : func (s *ingestedFlushable) containsRangeKeys() bool {
273 1 : return s.hasRangeKeys
274 1 : }
275 :
276 : // inuseBytes is part of the flushable interface.
277 0 : func (s *ingestedFlushable) inuseBytes() uint64 {
278 0 : // inuseBytes is only used when memtables are flushed to disk as sstables.
279 0 : panic("pebble: not implemented")
280 : }
281 :
282 : // totalBytes is part of the flushable interface.
283 1 : func (s *ingestedFlushable) totalBytes() uint64 {
284 1 : // We don't allocate additional bytes for the ingestedFlushable.
285 1 : return 0
286 1 : }
287 :
288 : // readyForFlush is part of the flushable interface.
289 1 : func (s *ingestedFlushable) readyForFlush() bool {
290 1 : // ingestedFlushable should always be ready to flush. However, note that
291 1 : // memtables before the ingested sstables in the memtable queue must be
292 1 : // flushed before an ingestedFlushable can be flushed. This is because the
293 1 : // ingested sstables need an updated view of the Version to
294 1 : // determine where to place the files in the lsm.
295 1 : return true
296 1 : }
297 :
298 : // computePossibleOverlaps is part of the flushable interface.
299 : func (s *ingestedFlushable) computePossibleOverlaps(
300 : fn func(bounded) shouldContinue, bounded ...bounded,
301 1 : ) {
302 1 : for _, b := range bounded {
303 1 : if s.anyFileOverlaps(b.UserKeyBounds()) {
304 1 : // Some file overlaps in key boundaries. The file doesn't necessarily
305 1 : // contain any keys within the key range, but we would need to perform I/O
306 1 : // to know for sure. The flushable interface dictates that we're not
307 1 : // permitted to perform I/O here, so err towards assuming overlap.
308 1 : if !fn(b) {
309 1 : return
310 1 : }
311 : }
312 : }
313 : }
314 :
315 : // anyFileBoundsOverlap returns true if there is at least a file in s.files with
316 : // bounds that overlap the given bounds.
317 1 : func (s *ingestedFlushable) anyFileOverlaps(bounds base.UserKeyBounds) bool {
318 1 : // Note that s.files are non-overlapping and sorted.
319 1 : for _, f := range s.files {
320 1 : fileBounds := f.UserKeyBounds()
321 1 : if !fileBounds.End.IsUpperBoundFor(s.comparer.Compare, bounds.Start) {
322 1 : // The file ends before the bounds start. Go to the next file.
323 1 : continue
324 : }
325 1 : if !bounds.End.IsUpperBoundFor(s.comparer.Compare, fileBounds.Start) {
326 1 : // The file starts after the bounds end. There is no overlap, and
327 1 : // further files will not overlap either (the files are sorted).
328 1 : return false
329 1 : }
330 : // There is overlap. Note that UserKeyBounds.Overlaps() performs exactly the
331 : // checks above.
332 1 : return true
333 : }
334 1 : return false
335 : }
336 :
337 : // computePossibleOverlapsGenericImpl is an implementation of the flushable
338 : // interface's computePossibleOverlaps function for flushable implementations
339 : // with only in-memory state that do not have special requirements and should
340 : // read through the ordinary flushable iterators.
341 : //
342 : // This function must only be used with implementations that are infallible (eg,
343 : // memtable iterators) and will panic if an error is encountered.
344 : func computePossibleOverlapsGenericImpl[F flushable](
345 : f F, cmp Compare, fn func(bounded) shouldContinue, bounded []bounded,
346 1 : ) {
347 1 : iter := f.newIter(nil)
348 1 : rangeDelIter := f.newRangeDelIter(nil)
349 1 : rangeKeyIter := f.newRangeKeyIter(nil)
350 1 : for _, b := range bounded {
351 1 : overlap, err := determineOverlapAllIters(cmp, b.UserKeyBounds(), iter, rangeDelIter, rangeKeyIter)
352 1 : if invariants.Enabled && err != nil {
353 0 : panic(errors.AssertionFailedf("expected iterator to be infallible: %v", err))
354 : }
355 1 : if overlap {
356 1 : if !fn(b) {
357 1 : break
358 : }
359 : }
360 : }
361 :
362 1 : if iter != nil {
363 1 : if err := iter.Close(); err != nil {
364 0 : // This implementation must be used in circumstances where
365 0 : // reading through the iterator is infallible.
366 0 : panic(err)
367 : }
368 : }
369 1 : if rangeDelIter != nil {
370 1 : rangeDelIter.Close()
371 1 : }
372 1 : if rangeKeyIter != nil {
373 1 : rangeKeyIter.Close()
374 1 : }
375 : }
376 :
377 : // determineOverlapAllIters checks for overlap in a point iterator, range
378 : // deletion iterator and range key iterator.
379 : func determineOverlapAllIters(
380 : cmp base.Compare,
381 : bounds base.UserKeyBounds,
382 : pointIter base.InternalIterator,
383 : rangeDelIter, rangeKeyIter keyspan.FragmentIterator,
384 1 : ) (bool, error) {
385 1 : if pointIter != nil {
386 1 : if pointOverlap, err := determineOverlapPointIterator(cmp, bounds, pointIter); pointOverlap || err != nil {
387 1 : return pointOverlap, err
388 1 : }
389 : }
390 1 : if rangeDelIter != nil {
391 1 : if rangeDelOverlap, err := determineOverlapKeyspanIterator(cmp, bounds, rangeDelIter); rangeDelOverlap || err != nil {
392 1 : return rangeDelOverlap, err
393 1 : }
394 : }
395 1 : if rangeKeyIter != nil {
396 1 : return determineOverlapKeyspanIterator(cmp, bounds, rangeKeyIter)
397 1 : }
398 1 : return false, nil
399 : }
400 :
401 : func determineOverlapPointIterator(
402 : cmp base.Compare, bounds base.UserKeyBounds, iter internalIterator,
403 1 : ) (bool, error) {
404 1 : kv := iter.SeekGE(bounds.Start, base.SeekGEFlagsNone)
405 1 : if kv == nil {
406 1 : return false, iter.Error()
407 1 : }
408 1 : return bounds.End.IsUpperBoundForInternalKey(cmp, kv.K), nil
409 : }
410 :
411 : func determineOverlapKeyspanIterator(
412 : cmp base.Compare, bounds base.UserKeyBounds, iter keyspan.FragmentIterator,
413 1 : ) (bool, error) {
414 1 : // NB: The spans surfaced by the fragment iterator are non-overlapping.
415 1 : span, err := iter.SeekGE(bounds.Start)
416 1 : if err != nil {
417 0 : return false, err
418 0 : }
419 1 : for ; span != nil; span, err = iter.Next() {
420 1 : if !bounds.End.IsUpperBoundFor(cmp, span.Start) {
421 1 : // The span starts after our bounds.
422 1 : return false, nil
423 1 : }
424 1 : if !span.Empty() {
425 1 : return true, nil
426 1 : }
427 : }
428 1 : return false, err
429 : }
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