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Index ¶
- func GenerateBits(bitmap []byte, start, length int64, g func() bool)
- func GenerateBitsUnrolled(bitmap []byte, start, length int64, g func() bool)
- func IsMultipleOf64(v int64) bool
- func LeastSignificantBitMask(index int64) uint64
- func VisitBitBlocks(bitmap []byte, offset, length int64, visitValid func(pos int64), ...)
- func VisitBitBlocksShort(bitmap []byte, offset, length int64, visitValid func(pos int64) error, ...) error
- func VisitSetBitRuns(bitmap []byte, bitmapOffset int64, length int64, visitFn VisitFn) error
- func VisitSetBitRunsNoErr(bitmap []byte, bitmapOffset int64, length int64, ...)
- func VisitTwoBitBlocks(leftBitmap, rightBitmap []byte, leftOffset, rightOffset int64, len int64, ...)
- type BinaryBitBlockCounter
- type BitBlockCount
- type BitBlockCounter
- type BitRun
- type BitRunReader
- type OptionalBitBlockCounter
- type SetBitRun
- type SetBitRunReader
- type VisitFn
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func GenerateBits ¶
GenerateBits writes sequential bits to a bitmap. Bits preceding the initial start offset are preserved, bits following the bitmap may get clobbered.
func GenerateBitsUnrolled ¶
GenerateBitsUnrolled is like GenerateBits but unrolls its main loop for higher performance.
See the benchmarks for evidence.
func IsMultipleOf64 ¶
IsMultipleOf64 returns whether v is a multiple of 64.
func LeastSignificantBitMask ¶
LeastSignificantBitMask returns a bit mask to return the least significant bits for a value starting from the bit index passed in. ie: if you want a mask for the 4 least significant bits, you call LeastSignificantBitMask(4)
func VisitBitBlocks ¶
func VisitBitBlocks(bitmap []byte, offset, length int64, visitValid func(pos int64), visitInvalid func())
VisitBitBlocks is a utility for easily iterating through the blocks of bits in a bitmap, calling the appropriate visitValid/visitInvalid function as we iterate through the bits. visitValid is called with the bitoffset of the valid bit. Don't use this inside a tight loop when performance is needed and instead prefer manually constructing these loops in that scenario.
func VisitBitBlocksShort ¶
func VisitBitBlocksShort(bitmap []byte, offset, length int64, visitValid func(pos int64) error, visitInvalid func() error) error
VisitBitBlocks is a utility for easily iterating through the blocks of bits in a bitmap, calling the appropriate visitValid/visitInvalid function as we iterate through the bits. visitValid is called with the bitoffset of the valid bit. Don't use this inside a tight loop when performance is needed and instead prefer manually constructing these loops in that scenario.
func VisitSetBitRuns ¶
VisitSetBitRuns is just a convenience function for calling NewSetBitRunReader and then VisitSetBitRuns
func VisitSetBitRunsNoErr ¶
Types ¶
type BinaryBitBlockCounter ¶
type BinaryBitBlockCounter struct {
// contains filtered or unexported fields
}
BinaryBitBlockCounter computes popcounts on the result of bitwise operations between two bitmaps, 64 bits at a time. A 64-bit word is loaded from each bitmap, then the popcount is computed on e.g. the bitwise-and of the two words
func NewBinaryBitBlockCounter ¶
func NewBinaryBitBlockCounter(left, right []byte, leftOffset, rightOffset int64, length int64) *BinaryBitBlockCounter
NewBinaryBitBlockCounter constructs a binary bit block counter for computing the popcounts on the results of operations between the passed in bitmaps, with their respective offsets.
func (*BinaryBitBlockCounter) NextAndNotWord ¶
func (b *BinaryBitBlockCounter) NextAndNotWord() BitBlockCount
NextAndNotWord is like NextAndWord but performs x &^ y on each run
func (*BinaryBitBlockCounter) NextAndWord ¶
func (b *BinaryBitBlockCounter) NextAndWord() BitBlockCount
NextAndWord returns the popcount of the bitwise-and of the next run of available bits, up to 64. The returned pair contains the size of the run and the number of true values. the last block will have a length less than 64 if the bitmap length is not a multiple of 64, and will return 0-length blocks in subsequent invocations
func (*BinaryBitBlockCounter) NextOrNotWord ¶
func (b *BinaryBitBlockCounter) NextOrNotWord() BitBlockCount
NextOrWord is like NextAndWord but performs x | ^y on each run
func (*BinaryBitBlockCounter) NextOrWord ¶
func (b *BinaryBitBlockCounter) NextOrWord() BitBlockCount
NextOrWord is like NextAndWord but performs x | y on each run
type BitBlockCount ¶
BitBlockCount is returned by the various bit block counter utilities in order to return a length of bits and the population count of that slice of bits.
func (BitBlockCount) AllSet ¶
func (b BitBlockCount) AllSet() bool
AllSet returns true if ALL the bits were 1 in this set, ie: Popcnt == Len
func (BitBlockCount) NoneSet ¶
func (b BitBlockCount) NoneSet() bool
NoneSet returns true if ALL the bits were 0 in this set, ie: Popcnt == 0
type BitBlockCounter ¶
type BitBlockCounter struct {
// contains filtered or unexported fields
}
BitBlockCounter is a utility for grabbing chunks of a bitmap at a time and efficiently counting the number of bits which are 1.
func NewBitBlockCounter ¶
func NewBitBlockCounter(bitmap []byte, startOffset, nbits int64) *BitBlockCounter
NewBitBlockCounter returns a BitBlockCounter for the passed bitmap starting at startOffset of length nbits.
func (*BitBlockCounter) NextFourWords ¶
func (b *BitBlockCounter) NextFourWords() BitBlockCount
NextFourWords returns the next run of available bits, usually 256. The returned pair contains the size of run and the number of true values. The last block will have a length less than 256 if the bitmap length is not a multiple of 256, and will return 0-length blocks in subsequent invocations.
func (*BitBlockCounter) NextWord ¶
func (b *BitBlockCounter) NextWord() BitBlockCount
NextWord returns the next run of available bits, usually 64. The returned pair contains the size of run and the number of true values. The last block will have a length less than 64 if the bitmap length is not a multiple of 64, and will return 0-length blocks in subsequent invocations.
type BitRun ¶
BitRun represents a run of bits with the same value of length Len with Set representing if the group of bits were 1 or 0.
type BitRunReader ¶
type BitRunReader interface {
NextRun() BitRun
}
BitRunReader is an interface that is usable by multiple callers to provide multiple types of bit run readers such as a reverse reader and so on.
It's a convenience interface for counting contiguous set/unset bits in a bitmap. In places where BitBlockCounter can be used, then it would be preferred to use that as it would be faster than using BitRunReader.
func NewBitRunReader ¶
func NewBitRunReader(bitmap []byte, offset int64, length int64) BitRunReader
NewBitRunReader returns a reader for the given bitmap, offset and length that grabs runs of the same value bit at a time for easy iteration.
type OptionalBitBlockCounter ¶
type OptionalBitBlockCounter struct {
// contains filtered or unexported fields
}
OptionalBitBlockCounter is a useful counter to iterate through a possibly nonexistent validity bitmap to allow us to write one code path for both the with-nulls and no-nulls cases without giving up a lot of performance.
func NewOptionalBitBlockCounter ¶
func NewOptionalBitBlockCounter(bitmap []byte, offset, length int64) *OptionalBitBlockCounter
NewOptionalBitBlockCounter constructs and returns a new bit block counter that can properly handle the case when a bitmap is null, if it is guaranteed that the the bitmap is not nil, then prefer NewBitBlockCounter here.
func (*OptionalBitBlockCounter) NextBlock ¶
func (obc *OptionalBitBlockCounter) NextBlock() BitBlockCount
NextBlock returns block count for next word when the bitmap is available otherwise return a block with length up to INT16_MAX when there is no validity bitmap (so all the referenced values are not null).
func (*OptionalBitBlockCounter) NextWord ¶
func (obc *OptionalBitBlockCounter) NextWord() BitBlockCount
NextWord is like NextBlock, but returns a word-sized block even when there is no validity bitmap
type SetBitRun ¶
SetBitRun describes a run of contiguous set bits in a bitmap with Pos being the starting position of the run and Length being the number of bits.
type SetBitRunReader ¶
type SetBitRunReader interface {
// NextRun will return the next run of contiguous set bits in the bitmap
NextRun() SetBitRun
// Reset allows re-using the reader by providing a new bitmap, offset and length. The arguments
// match the New function for the reader being used.
Reset([]byte, int64, int64)
// VisitSetBitRuns calls visitFn for each set in a loop starting from the current position
// it's roughly equivalent to simply looping, calling NextRun and calling visitFn on the run
// for each run.
VisitSetBitRuns(visitFn VisitFn) error
}
SetBitRunReader is an interface for reading groups of contiguous set bits from a bitmap. The interface allows us to create different reader implementations that share the same interface easily such as a reverse set reader.
func NewReverseSetBitRunReader ¶
func NewReverseSetBitRunReader(validBits []byte, startOffset, numValues int64) SetBitRunReader
NewReverseSetBitRunReader returns a SetBitRunReader like NewSetBitRunReader, except it will return runs starting from the end of the bitmap until it reaches startOffset rather than starting at startOffset and reading from there. The SetBitRuns will still operate the same, so Pos will still be the position of the "left-most" bit of the run or the "start" of the run. It just returns runs starting from the end instead of starting from the beginning.
func NewSetBitRunReader ¶
func NewSetBitRunReader(validBits []byte, startOffset, numValues int64) SetBitRunReader
NewSetBitRunReader returns a SetBitRunReader for the bitmap starting at startOffset which will read numvalues bits.
Source Files