ceremonyclient/pebble/sstable/reader_virtual.go
Cassandra Heart 2e2a1e4789
v1.2.0 (#31)
2024-01-03 01:31:42 -06:00

214 lines
8.2 KiB
Go

// Copyright 2011 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
package sstable
import (
"context"
"github.com/cockroachdb/pebble/internal/base"
"github.com/cockroachdb/pebble/internal/keyspan"
"github.com/cockroachdb/pebble/internal/manifest"
)
// VirtualReader wraps Reader. Its purpose is to restrict functionality of the
// Reader which should be inaccessible to virtual sstables, and enforce bounds
// invariants associated with virtual sstables. All reads on virtual sstables
// should go through a VirtualReader.
//
// INVARIANT: Any iterators created through a virtual reader will guarantee that
// they don't expose keys outside the virtual sstable bounds.
type VirtualReader struct {
vState virtualState
reader *Reader
Properties CommonProperties
}
// Lightweight virtual sstable state which can be passed to sstable iterators.
type virtualState struct {
lower InternalKey
upper InternalKey
fileNum base.FileNum
Compare Compare
isForeign bool
}
func ceilDiv(a, b uint64) uint64 {
return (a + b - 1) / b
}
// MakeVirtualReader is used to contruct a reader which can read from virtual
// sstables.
func MakeVirtualReader(
reader *Reader, meta manifest.VirtualFileMeta, isForeign bool,
) VirtualReader {
if reader.fileNum != meta.FileBacking.DiskFileNum {
panic("pebble: invalid call to MakeVirtualReader")
}
vState := virtualState{
lower: meta.Smallest,
upper: meta.Largest,
fileNum: meta.FileNum,
Compare: reader.Compare,
isForeign: isForeign,
}
v := VirtualReader{
vState: vState,
reader: reader,
}
v.Properties.RawKeySize = ceilDiv(reader.Properties.RawKeySize*meta.Size, meta.FileBacking.Size)
v.Properties.RawValueSize = ceilDiv(reader.Properties.RawValueSize*meta.Size, meta.FileBacking.Size)
v.Properties.NumEntries = ceilDiv(reader.Properties.NumEntries*meta.Size, meta.FileBacking.Size)
v.Properties.NumDeletions = ceilDiv(reader.Properties.NumDeletions*meta.Size, meta.FileBacking.Size)
v.Properties.NumRangeDeletions = ceilDiv(reader.Properties.NumRangeDeletions*meta.Size, meta.FileBacking.Size)
v.Properties.NumRangeKeyDels = ceilDiv(reader.Properties.NumRangeKeyDels*meta.Size, meta.FileBacking.Size)
// Note that we rely on NumRangeKeySets for correctness. If the sstable may
// contain range keys, then NumRangeKeySets must be > 0. ceilDiv works because
// meta.Size will not be 0 for virtual sstables.
v.Properties.NumRangeKeySets = ceilDiv(reader.Properties.NumRangeKeySets*meta.Size, meta.FileBacking.Size)
v.Properties.ValueBlocksSize = ceilDiv(reader.Properties.ValueBlocksSize*meta.Size, meta.FileBacking.Size)
v.Properties.NumSizedDeletions = ceilDiv(reader.Properties.NumSizedDeletions*meta.Size, meta.FileBacking.Size)
v.Properties.RawPointTombstoneKeySize = ceilDiv(reader.Properties.RawPointTombstoneKeySize*meta.Size, meta.FileBacking.Size)
v.Properties.RawPointTombstoneValueSize = ceilDiv(reader.Properties.RawPointTombstoneValueSize*meta.Size, meta.FileBacking.Size)
return v
}
// NewCompactionIter is the compaction iterator function for virtual readers.
func (v *VirtualReader) NewCompactionIter(
bytesIterated *uint64,
categoryAndQoS CategoryAndQoS,
statsCollector *CategoryStatsCollector,
rp ReaderProvider,
bufferPool *BufferPool,
) (Iterator, error) {
return v.reader.newCompactionIter(
bytesIterated, categoryAndQoS, statsCollector, rp, &v.vState, bufferPool)
}
// NewIterWithBlockPropertyFiltersAndContextEtc wraps
// Reader.NewIterWithBlockPropertyFiltersAndContext. We assume that the passed
// in [lower, upper) bounds will have at least some overlap with the virtual
// sstable bounds. No overlap is not currently supported in the iterator.
func (v *VirtualReader) NewIterWithBlockPropertyFiltersAndContextEtc(
ctx context.Context,
lower, upper []byte,
filterer *BlockPropertiesFilterer,
hideObsoletePoints, useFilterBlock bool,
stats *base.InternalIteratorStats,
categoryAndQoS CategoryAndQoS,
statsCollector *CategoryStatsCollector,
rp ReaderProvider,
) (Iterator, error) {
return v.reader.newIterWithBlockPropertyFiltersAndContext(
ctx, lower, upper, filterer, hideObsoletePoints, useFilterBlock, stats,
categoryAndQoS, statsCollector, rp, &v.vState)
}
// ValidateBlockChecksumsOnBacking will call ValidateBlockChecksumsOnBacking on the underlying reader.
// Note that block checksum validation is NOT restricted to virtual sstable bounds.
func (v *VirtualReader) ValidateBlockChecksumsOnBacking() error {
return v.reader.ValidateBlockChecksums()
}
// NewRawRangeDelIter wraps Reader.NewRawRangeDelIter.
func (v *VirtualReader) NewRawRangeDelIter() (keyspan.FragmentIterator, error) {
iter, err := v.reader.NewRawRangeDelIter()
if err != nil {
return nil, err
}
if iter == nil {
return nil, nil
}
// Truncation of spans isn't allowed at a user key that also contains points
// in the same virtual sstable, as it would lead to covered points getting
// uncovered. Set panicOnUpperTruncate to true if the file's upper bound
// is not an exclusive sentinel.
//
// As an example, if an sstable contains a rangedel a-c and point keys at
// a.SET.2 and b.SET.3, the file bounds [a#2,SET-b#RANGEDELSENTINEL] are
// allowed (as they exclude b.SET.3), or [a#2,SET-c#RANGEDELSENTINEL] (as it
// includes both point keys), but not [a#2,SET-b#3,SET] (as it would truncate
// the rangedel at b and lead to the point being uncovered).
return keyspan.Truncate(
v.reader.Compare, iter, v.vState.lower.UserKey, v.vState.upper.UserKey,
&v.vState.lower, &v.vState.upper, !v.vState.upper.IsExclusiveSentinel(), /* panicOnUpperTruncate */
), nil
}
// NewRawRangeKeyIter wraps Reader.NewRawRangeKeyIter.
func (v *VirtualReader) NewRawRangeKeyIter() (keyspan.FragmentIterator, error) {
iter, err := v.reader.NewRawRangeKeyIter()
if err != nil {
return nil, err
}
if iter == nil {
return nil, nil
}
// Truncation of spans isn't allowed at a user key that also contains points
// in the same virtual sstable, as it would lead to covered points getting
// uncovered. Set panicOnUpperTruncate to true if the file's upper bound
// is not an exclusive sentinel.
//
// As an example, if an sstable contains a range key a-c and point keys at
// a.SET.2 and b.SET.3, the file bounds [a#2,SET-b#RANGEKEYSENTINEL] are
// allowed (as they exclude b.SET.3), or [a#2,SET-c#RANGEKEYSENTINEL] (as it
// includes both point keys), but not [a#2,SET-b#3,SET] (as it would truncate
// the range key at b and lead to the point being uncovered).
return keyspan.Truncate(
v.reader.Compare, iter, v.vState.lower.UserKey, v.vState.upper.UserKey,
&v.vState.lower, &v.vState.upper, !v.vState.upper.IsExclusiveSentinel(), /* panicOnUpperTruncate */
), nil
}
// Constrain bounds will narrow the start, end bounds if they do not fit within
// the virtual sstable. The function will return if the new end key is
// inclusive.
func (v *virtualState) constrainBounds(
start, end []byte, endInclusive bool,
) (lastKeyInclusive bool, first []byte, last []byte) {
first = start
if start == nil || v.Compare(start, v.lower.UserKey) < 0 {
first = v.lower.UserKey
}
// Note that we assume that start, end has some overlap with the virtual
// sstable bounds.
last = v.upper.UserKey
lastKeyInclusive = !v.upper.IsExclusiveSentinel()
if end != nil {
cmp := v.Compare(end, v.upper.UserKey)
switch {
case cmp == 0:
lastKeyInclusive = !v.upper.IsExclusiveSentinel() && endInclusive
last = v.upper.UserKey
case cmp > 0:
lastKeyInclusive = !v.upper.IsExclusiveSentinel()
last = v.upper.UserKey
default:
lastKeyInclusive = endInclusive
last = end
}
}
// TODO(bananabrick): What if someone passes in bounds completely outside of
// virtual sstable bounds?
return lastKeyInclusive, first, last
}
// EstimateDiskUsage just calls VirtualReader.reader.EstimateDiskUsage after
// enforcing the virtual sstable bounds.
func (v *VirtualReader) EstimateDiskUsage(start, end []byte) (uint64, error) {
_, f, l := v.vState.constrainBounds(start, end, true /* endInclusive */)
return v.reader.EstimateDiskUsage(f, l)
}
// CommonProperties implements the CommonReader interface.
func (v *VirtualReader) CommonProperties() *CommonProperties {
return &v.Properties
}