// 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.RKey, 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.RKey
if !inclusive {
metaKey = meta(key.Next())
} else {
metaKey = meta(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
}
// 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.rangeCache.
func (rdc *rangeDescriptorCache) getCachedRangeDescriptorLocked(key roachpb.RKey, inclusive bool) (rangeCacheKey, *roachpb.RangeDescriptor, error) {
// The cache is indexed using the end-key of the range, but the
// end-key is non-inclusive by default.
var metaKey roachpb.RKey
var err error
if !inclusive {
metaKey, err = meta(key.Next())
} else {
metaKey, err = meta(key)
}
if err != nil {
return nil, nil, err
}
k, v, ok := rdc.rangeCache.cache.Ceil(rangeCacheKey(metaKey))
if !ok {
return nil, nil, nil
}
metaEndKey := k.(rangeCacheKey)
rd := v.(*roachpb.RangeDescriptor)
// Return nil if the key does not belong to the range.
if (!inclusive && !rd.ContainsKey(key)) || (inclusive && !rd.ContainsExclusiveEndKey(key)) {
return nil, nil, nil
}
return metaEndKey, rd, nil
}
func (db *testDescriptorDB) getDescriptors(key roachpb.RKey, considerIntents bool, useReverseScan bool) ([]roachpb.RangeDescriptor, []roachpb.RangeDescriptor, *roachpb.Error) {
rs := make([]roachpb.RangeDescriptor, 0, 1)
preRs := make([]roachpb.RangeDescriptor, 0, 2)
for i := 0; i < 3; i++ {
var endKey roachpb.RKey
if useReverseScan {
endKey = key
} else {
endKey = key.Next()
}
v := db.data.Ceil(testDescriptorNode{
&roachpb.RangeDescriptor{
EndKey: endKey,
},
})
if v == nil {
break
}
desc := *(v.(testDescriptorNode).RangeDescriptor)
if i == 0 {
rs = append(rs, desc)
if considerIntents {
desc.RangeID++
rs = append(rs, desc)
break
} else if db.disablePrefetch {
break
}
} else {
preRs = append(preRs, desc)
}
// Break to keep from skidding off the end of the available ranges.
if desc.EndKey.Equal(roachpb.RKeyMax) {
break
}
if useReverseScan {
key = desc.StartKey
} else {
key = desc.EndKey
}
}
return rs, preRs, nil
}
// 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.
// TODO(tschottdorf): a lot of casting going on inside.
func MetaScanBounds(key roachpb.RKey) (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.RKeyMin) {
// 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 Meta1KeyMax, Meta1Prefix.PrefixEnd(), nil
}
// Otherwise find the first entry greater than the given key in the same meta prefix.
return key.Next().AsRawKey(), key[:len(Meta1Prefix)].PrefixEnd().AsRawKey(), 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.RKey) (roachpb.Key, roachpb.Key, error) {
if err := validateRangeMetaKey(key); err != nil {
return nil, nil, err
}
if key.Equal(roachpb.RKeyMin) || 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().AsRawKey(), 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)].AsRawKey(), key.Next().AsRawKey(), nil
}