// Add the specified timestamp to the cache as covering the range of
// keys from start to end. If end is nil, the range covers the start
// key only. txnID is nil for no transaction. readOnly specifies
// whether the command adding this timestamp was read-only or not.
func (tc *TimestampCache) Add(start, end roachpb.Key, timestamp roachpb.Timestamp, txnID []byte, readOnly bool) {
// This gives us a memory-efficient end key if end is empty.
if len(end) == 0 {
end = start.Next()
start = end[:len(start)]
}
if tc.latest.Less(timestamp) {
tc.latest = timestamp
}
// Only add to the cache if the timestamp is more recent than the
// low water mark.
if tc.lowWater.Less(timestamp) {
// Check existing, overlapping entries. Remove superseded
// entries or return without adding this entry if necessary.
key := tc.cache.NewKey(start, end)
for _, o := range tc.cache.GetOverlaps(start, end) {
ce := o.Value.(cacheEntry)
if ce.readOnly != readOnly {
continue
}
if o.Key.Contains(key) && !ce.timestamp.Less(timestamp) {
return // don't add this key; there's already a cache entry with >= timestamp.
} else if key.Contains(o.Key) && !timestamp.Less(ce.timestamp) {
tc.cache.Del(o.Key) // delete existing key; this cache entry supersedes.
}
}
ce := cacheEntry{timestamp: timestamp, txnID: txnID, readOnly: readOnly}
tc.cache.Add(key, ce)
}
}
// getCachedRangeDescriptorLocked is a helper function to retrieve the
// descriptor of the range which contains the given key, if present in the
// cache. It is assumed that the caller holds a read lock on rdc.rangeCacheMu.
func (rdc *rangeDescriptorCache) getCachedRangeDescriptorLocked(key roachpb.Key, inclusive bool) (
rangeCacheKey, *roachpb.RangeDescriptor) {
// The cache is indexed using the end-key of the range, but the
// end-key is non-inclusive by default.
var metaKey roachpb.Key
if !inclusive {
metaKey = keys.RangeMetaKey(key.Next())
} else {
metaKey = keys.RangeMetaKey(key)
}
k, v, ok := rdc.rangeCache.Ceil(rangeCacheKey(metaKey))
if !ok {
return nil, nil
}
metaEndKey := k.(rangeCacheKey)
rd := v.(*roachpb.RangeDescriptor)
// Check that key actually belongs to the range.
if !rd.ContainsKey(key) {
// The key is the EndKey and we're inclusive, so just return the range descriptor.
if inclusive && key.Equal(rd.EndKey) {
return metaEndKey, rd
}
return nil, nil
}
// The key is the StartKey, but we're inclusive and thus need to return the
// previous range descriptor, but it is not in the cache yet.
if inclusive && key.Equal(rd.StartKey) {
return nil, nil
}
return metaEndKey, rd
}
// addKeyRange adds the specified key range to the interval cache,
// taking care not to add this range if existing entries already
// completely cover the range.
func (tm *txnMetadata) addKeyRange(start, end roachpb.Key) {
// This gives us a memory-efficient end key if end is empty.
// The most common case for keys in the intents interval map
// is for single keys. However, the interval cache requires
// a non-empty interval, so we create two key slices which
// share the same underlying byte array.
if len(end) == 0 {
end = start.Next()
start = end[:len(start)]
}
key := tm.keys.MakeKey(start, end)
for _, o := range tm.keys.GetOverlaps(key.Start, key.End) {
if o.Key.Contains(key) {
return
} else if key.Contains(*o.Key) {
tm.keys.Del(o.Key)
}
}
// Since no existing key range fully covered this range, add it now. The
// strange assignment to pkey makes sure we delay the heap allocation until
// we know it is necessary.
alloc := struct {
key cache.IntervalKey
entry cache.Entry
}{key: key}
alloc.entry.Key = &alloc.key
tm.keys.AddEntry(&alloc.entry)
}
// addKeyRange adds the specified key range to the range group,
// taking care not to add this range if existing entries already
// completely cover the range.
func addKeyRange(keys interval.RangeGroup, start, end roachpb.Key) {
// This gives us a memory-efficient end key if end is empty.
// The most common case for keys in the intents interval map
// is for single keys. However, the range group requires
// a non-empty interval, so we create two key slices which
// share the same underlying byte array.
if len(end) == 0 {
end = start.Next()
start = end[:len(start)]
}
keyR := interval.Range{
Start: interval.Comparable(start),
End: interval.Comparable(end),
}
keys.Add(keyR)
}
// GetMax returns the maximum read and write timestamps which overlap
// the interval spanning from start to end. Cached timestamps matching
// the specified txnID are not considered. If no part of the specified
// range is overlapped by timestamps in the cache, the low water
// timestamp is returned for both read and write timestamps.
//
// The txn ID prevents restarts with a pattern like: read("a"),
// write("a"). The read adds a timestamp for "a". Then the write (for
// the same transaction) would get that as the max timestamp and be
// forced to increment it. This allows timestamps from the same txn
// to be ignored.
func (tc *TimestampCache) GetMax(start, end roachpb.Key, txnID []byte) (roachpb.Timestamp, roachpb.Timestamp) {
if len(end) == 0 {
end = start.Next()
}
maxR := tc.lowWater
maxW := tc.lowWater
for _, o := range tc.cache.GetOverlaps(start, end) {
ce := o.Value.(*cacheValue)
if ce.txnID == nil || txnID == nil || !roachpb.TxnIDEqual(txnID, ce.txnID) {
if ce.readOnly && maxR.Less(ce.timestamp) {
maxR = ce.timestamp
} else if !ce.readOnly && maxW.Less(ce.timestamp) {
maxW = ce.timestamp
}
}
}
return maxR, maxW
}
func (tc *TimestampCache) getMax(start, end roachpb.Key, txnID *uuid.UUID, readOnly bool) roachpb.Timestamp {
if len(end) == 0 {
end = start.Next()
}
max := tc.lowWater
cache := tc.wCache
if readOnly {
cache = tc.rCache
}
for _, o := range cache.GetOverlaps(start, end) {
ce := o.Value.(*cacheValue)
if ce.txnID == nil || txnID == nil || !roachpb.TxnIDEqual(txnID, ce.txnID) {
if max.Less(ce.timestamp) {
max = ce.timestamp
}
}
}
return max
}
// MetaScanBounds returns the range [start,end) within which the desired meta
// record can be found by means of an engine scan. The given key must be a
// valid RangeMetaKey as defined by validateRangeMetaKey.
func MetaScanBounds(key roachpb.Key) (roachpb.Key, roachpb.Key, error) {
if err := validateRangeMetaKey(key); err != nil {
return nil, nil, err
}
if key.Equal(Meta2KeyMax) {
return nil, nil, NewInvalidRangeMetaKeyError("Meta2KeyMax can't be used as the key of scan", key)
}
if key.Equal(roachpb.KeyMin) {
// Special case KeyMin: find the first entry in meta1.
return Meta1Prefix, Meta1Prefix.PrefixEnd(), nil
}
if key.Equal(Meta1KeyMax) {
// Special case Meta1KeyMax: this is the last key in Meta1, we don't want
// to start at Next().
return key, Meta1Prefix.PrefixEnd(), nil
}
// Otherwise find the first entry greater than the given key in the same meta prefix.
return key.Next(), roachpb.Key(key[:len(Meta1Prefix)]).PrefixEnd(), nil
}
func (tc *timestampCache) getMax(start, end roachpb.Key, txnID *uuid.UUID, readTSCache bool) (hlc.Timestamp, bool) {
if len(end) == 0 {
end = start.Next()
}
var ok bool
max := tc.lowWater
cache := tc.wCache
if readTSCache {
cache = tc.rCache
}
for _, o := range cache.GetOverlaps(start, end) {
ce := o.Value.(*cacheValue)
if ce.txnID == nil || txnID == nil || !roachpb.TxnIDEqual(txnID, ce.txnID) {
if max.Less(ce.timestamp) {
ok = true
max = ce.timestamp
}
}
}
return max, ok
}
// addKeyRange adds the specified key range to the interval cache,
// taking care not to add this range if existing entries already
// completely cover the range.
func (tm *txnMetadata) addKeyRange(start, end roachpb.Key) {
// This gives us a memory-efficient end key if end is empty.
// The most common case for keys in the intents interval map
// is for single keys. However, the interval cache requires
// a non-empty interval, so we create two key slices which
// share the same underlying byte array.
if len(end) == 0 {
end = start.Next()
start = end[:len(start)]
}
key := tm.keys.NewKey(start, end)
for _, o := range tm.keys.GetOverlaps(start, end) {
if o.Key.Contains(key) {
return
} else if key.Contains(o.Key) {
tm.keys.Del(o.Key)
}
}
// Since no existing key range fully covered this range, add it now.
tm.keys.Add(key, nil)
}
// MetaReverseScanBounds returns the range [start,end) within which the desired
// meta record can be found by means of a reverse engine scan. The given key
// must be a valid RangeMetaKey as defined by validateRangeMetaKey.
func MetaReverseScanBounds(key roachpb.Key) (roachpb.Key, roachpb.Key, error) {
if err := validateRangeMetaKey(key); err != nil {
return nil, nil, err
}
if key.Equal(roachpb.KeyMin) || key.Equal(Meta1Prefix) {
return nil, nil, NewInvalidRangeMetaKeyError("KeyMin and Meta1Prefix can't be used as the key of reverse scan", key)
}
if key.Equal(Meta2Prefix) {
// Special case Meta2Prefix: this is the first key in Meta2, and the scan
// interval covers all of Meta1.
return Meta1Prefix, key.Next(), nil
}
// Otherwise find the first entry greater than the given key and find the last entry
// in the same prefix. For MVCCReverseScan the endKey is exclusive, if we want to find
// the range descriptor the given key specified,we need to set the key.Next() as the
// MVCCReverseScan`s endKey. For example:
// If we have ranges [a,f) and [f,z), then we'll have corresponding meta records
// at f and z. If you're looking for the meta record for key f, then you want the
// second record (exclusive in MVCCReverseScan), hence key.Next() below.
return key[:len(Meta1Prefix)], key.Next(), nil
}
// Add the specified timestamp to the cache as covering the range of
// keys from start to end. If end is nil, the range covers the start
// key only. txnID is nil for no transaction. readTSCache specifies
// whether the command adding this timestamp should update the read
// timestamp; false to update the write timestamp cache.
func (tc *TimestampCache) Add(start, end roachpb.Key, timestamp roachpb.Timestamp, txnID *uuid.UUID, readTSCache bool) {
// This gives us a memory-efficient end key if end is empty.
if len(end) == 0 {
end = start.Next()
start = end[:len(start)]
}
if tc.latest.Less(timestamp) {
tc.latest = timestamp
}
// Only add to the cache if the timestamp is more recent than the
// low water mark.
if tc.lowWater.Less(timestamp) {
cache := tc.wCache
if readTSCache {
cache = tc.rCache
}
addRange := func(r interval.Range) {
value := cacheValue{timestamp: timestamp, txnID: txnID}
key := cache.MakeKey(r.Start, r.End)
entry := makeCacheEntry(key, value)
cache.AddEntry(entry)
}
r := interval.Range{
Start: interval.Comparable(start),
End: interval.Comparable(end),
}
// Check existing, overlapping entries and truncate/split/remove if
// superseded and in the past. If existing entries are in the future,
// subtract from the range/ranges that need to be added to cache.
for _, o := range cache.GetOverlaps(r.Start, r.End) {
cv := o.Value.(*cacheValue)
sCmp := r.Start.Compare(o.Key.Start)
eCmp := r.End.Compare(o.Key.End)
if !timestamp.Less(cv.timestamp) {
// The existing interval has a timestamp less than or equal to the new interval.
// Compare interval ranges to determine how to modify existing interval.
switch {
case sCmp == 0 && eCmp == 0:
// New and old are equal; replace old with new and avoid the need to insert new.
//
// New: ------------
// Old: ------------
//
// New: ------------
*cv = cacheValue{timestamp: timestamp, txnID: txnID}
cache.MoveToEnd(o.Entry)
return
case sCmp <= 0 && eCmp >= 0:
// New contains or is equal to old; delete old.
//
// New: ------------ ------------ ------------
// Old: -------- or ---------- or ----------
//
// Old:
cache.DelEntry(o.Entry)
case sCmp > 0 && eCmp < 0:
// Old contains new; split up old into two.
//
// New: ----
// Old: ------------
//
// Old: ---- ----
oldEnd := o.Key.End
o.Key.End = r.Start
key := cache.MakeKey(r.End, oldEnd)
entry := makeCacheEntry(key, *cv)
cache.AddEntryAfter(entry, o.Entry)
case eCmp >= 0:
// Left partial overlap; truncate old end.
//
// New: -------- --------
// Old: -------- or ------------
//
// Old: ---- ----
o.Key.End = r.Start
case sCmp <= 0:
// Right partial overlap; truncate old start.
//
// New: -------- --------
// Old: -------- or ------------
//
// Old: ---- ----
o.Key.Start = r.End
default:
panic(fmt.Sprintf("no overlap between %v and %v", o.Key.Range, r))
}
} else {
// The existing interval has a timestamp greater than the new interval.
// Compare interval ranges to determine how to modify new interval before
// adding it to the timestamp cache.
switch {
case sCmp >= 0 && eCmp <= 0:
// Old contains or is equal to new; no need to add.
//
// Old: ----------- ----------- ----------- -----------
// New: ----- or ----------- or -------- or --------
//
// New:
return
case sCmp < 0 && eCmp > 0:
// New contains old; split up old into two. We can add the left piece
// immediately because it is guaranteed to be before the rest of the
// overlaps.
//
// Old: ------
// New: ------------
//
// New: --- ---
lr := interval.Range{Start: r.Start, End: o.Key.Start}
addRange(lr)
r.Start = o.Key.End
case eCmp > 0:
// Left partial overlap; truncate new start.
//
// Old: -------- --------
// New: -------- or ------------
//
// New: ---- ----
r.Start = o.Key.End
case sCmp < 0:
// Right partial overlap; truncate new end.
//
// Old: -------- --------
// New: -------- or ------------
//
// New: ---- ----
r.End = o.Key.Start
default:
panic(fmt.Sprintf("no overlap between %v and %v", o.Key.Range, r))
}
}
}
addRange(r)
}
}
// fetch retrieves spans from the kv
func (f *kvFetcher) fetch() error {
batchSize := f.getBatchSize()
b := &client.Batch{}
b.Header.MaxScanResults = batchSize
var resumeKey roachpb.Key
if len(f.kvs) > 0 {
resumeKey = f.kvs[len(f.kvs)-1].Key
// To resume forward scans we will set the (inclusive) scan start to the Next of the last
// received key. To resume reverse scans we will set the (exclusive) scan end to the last
// received key.
if !f.reverse {
resumeKey = resumeKey.Next()
}
}
atEnd := true
if !f.reverse {
for i := 0; i < len(f.spans); i++ {
start := f.spans[i].Start
if resumeKey != nil {
if resumeKey.Compare(f.spans[i].End) >= 0 {
// We are resuming from a key after this span.
continue
}
if resumeKey.Compare(start) > 0 {
// We are resuming from a key inside this span.
// In this case we should technically reduce the max count for the span; but
// since this count is only an optimization it's not incorrect to retrieve more
// keys for the span.
start = resumeKey
}
}
atEnd = false
b.Scan(start, f.spans[i].End, f.spans[i].Count)
}
} else {
for i := len(f.spans) - 1; i >= 0; i-- {
end := f.spans[i].End
if resumeKey != nil {
if resumeKey.Compare(f.spans[i].Start) <= 0 {
// We are resuming from a key before this span.
continue
}
if resumeKey.Compare(end) < 0 {
// We are resuming from a key inside this span.
// In this case we should technically reduce the max count for the span; but
// since this count is only an optimization it's not incorrect to retrieve more
// keys for the span.
end = resumeKey
}
}
atEnd = false
b.ReverseScan(f.spans[i].Start, end, f.spans[i].Count)
}
}
if atEnd {
// The last scan happened to finish just at the end of the last span.
f.kvs = nil
f.fetchEnd = true
return nil
}
if err := f.txn.Run(b); err != nil {
return err
}
if f.kvs == nil {
numResults := 0
for _, result := range b.Results {
numResults += len(result.Rows)
}
f.kvs = make([]client.KeyValue, 0, numResults)
} else {
f.kvs = f.kvs[:0]
}
for _, result := range b.Results {
f.kvs = append(f.kvs, result.Rows...)
}
f.batchIdx++
f.totalFetched += int64(len(f.kvs))
f.kvIndex = 0
if int64(len(f.kvs)) < batchSize {
f.fetchEnd = true
}
// TODO(radu): We should fetch the next chunk in the background instead of waiting for the next
// call to fetch(). We can use a pool of workers to issue the KV ops which will also limit the
// total number of fetches that happen in parallel (and thus the amount of resources we use).
return nil
}
