Dot import -> named import

Changed modulename_ to short module names
Also removed Unreader, replaced with PrefixdReader in select locations

common/bit_array.go

@@ -0,0 +1,250 @@
+package common
+
+import (
+	"fmt"
+	"math/rand"
+	"strings"
+	"sync"
+)
+
+type BitArray struct {
+	mtx   sync.Mutex
+	Bits  uint     // NOTE: persisted via reflect, must be exported
+	Elems []uint64 // NOTE: persisted via reflect, must be exported
+}
+
+func NewBitArray(bits uint) BitArray {
+	return BitArray{
+		Bits:  bits,
+		Elems: make([]uint64, (bits+63)/64),
+	}
+}
+
+func (bA BitArray) Size() uint {
+	return bA.Bits
+}
+
+func (bA BitArray) IsZero() bool {
+	return bA.Bits == 0
+}
+
+// NOTE: behavior is undefined if i >= bA.Bits
+func (bA BitArray) GetIndex(i uint) bool {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	return bA.getIndex(i)
+}
+
+func (bA BitArray) getIndex(i uint) bool {
+	if i >= bA.Bits {
+		return false
+	}
+	return bA.Elems[i/64]&(uint64(1)<<(i%64)) > 0
+}
+
+// NOTE: behavior is undefined if i >= bA.Bits
+func (bA BitArray) SetIndex(i uint, v bool) bool {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	return bA.setIndex(i, v)
+}
+
+func (bA BitArray) setIndex(i uint, v bool) bool {
+
+	if i >= bA.Bits {
+		return false
+	}
+	if v {
+		bA.Elems[i/64] |= (uint64(1) << (i % 64))
+	} else {
+		bA.Elems[i/64] &= ^(uint64(1) << (i % 64))
+	}
+	return true
+}
+
+func (bA BitArray) Copy() BitArray {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+	return bA.copy()
+}
+
+func (bA BitArray) copy() BitArray {
+	c := make([]uint64, len(bA.Elems))
+	copy(c, bA.Elems)
+	return BitArray{
+		Bits:  bA.Bits,
+		Elems: c,
+	}
+}
+
+func (bA BitArray) copyBits(bits uint) BitArray {
+	c := make([]uint64, (bits+63)/64)
+	copy(c, bA.Elems)
+	return BitArray{
+		Bits:  bits,
+		Elems: c,
+	}
+}
+
+// Returns a BitArray of larger bits size.
+func (bA BitArray) Or(o BitArray) BitArray {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	c := bA.copyBits(MaxUint(bA.Bits, o.Bits))
+	for i := 0; i < len(c.Elems); i++ {
+		c.Elems[i] |= o.Elems[i]
+	}
+	return c
+}
+
+// Returns a BitArray of smaller bit size.
+func (bA BitArray) And(o BitArray) BitArray {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	return bA.and(o)
+}
+
+func (bA BitArray) and(o BitArray) BitArray {
+	c := bA.copyBits(MinUint(bA.Bits, o.Bits))
+	for i := 0; i < len(c.Elems); i++ {
+		c.Elems[i] &= o.Elems[i]
+	}
+	return c
+}
+
+func (bA BitArray) Not() BitArray {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	c := bA.copy()
+	for i := 0; i < len(c.Elems); i++ {
+		c.Elems[i] = ^c.Elems[i]
+	}
+	return c
+}
+
+func (bA BitArray) Sub(o BitArray) BitArray {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	if bA.Bits > o.Bits {
+		c := bA.copy()
+		for i := 0; i < len(o.Elems)-1; i++ {
+			c.Elems[i] &= ^c.Elems[i]
+		}
+		i := uint(len(o.Elems) - 1)
+		if i >= 0 {
+			for idx := i * 64; idx < o.Bits; idx++ {
+				c.setIndex(idx, c.getIndex(idx) && !o.GetIndex(idx))
+			}
+		}
+		return c
+	} else {
+		return bA.and(o.Not())
+	}
+}
+
+func (bA BitArray) IsFull() bool {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	if bA.Bits == 0 {
+		return false
+	}
+
+	// Check all elements except the last
+	for _, elem := range bA.Elems[:len(bA.Elems)-1] {
+		if (^elem) != 0 {
+			return false
+		}
+	}
+
+	// Check that the last element has (lastElemBits) 1's
+	lastElemBits := (bA.Bits+63)%64 + 1
+	lastElem := bA.Elems[len(bA.Elems)-1]
+	return (lastElem+1)&((uint64(1)<<lastElemBits)-1) == 0
+}
+
+func (bA BitArray) PickRandom() (uint, bool) {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	length := len(bA.Elems)
+	if length == 0 {
+		return 0, false
+	}
+	randElemStart := rand.Intn(length)
+	for i := 0; i < length; i++ {
+		elemIdx := ((i + randElemStart) % length)
+		if elemIdx < length-1 {
+			if bA.Elems[elemIdx] > 0 {
+				randBitStart := rand.Intn(64)
+				for j := 0; j < 64; j++ {
+					bitIdx := ((j + randBitStart) % 64)
+					if (bA.Elems[elemIdx] & (uint64(1) << uint(bitIdx))) > 0 {
+						return 64*uint(elemIdx) + uint(bitIdx), true
+					}
+				}
+				panic("should not happen")
+			}
+		} else {
+			// Special case for last elem, to ignore straggler bits
+			elemBits := int(bA.Bits) % 64
+			if elemBits == 0 {
+				elemBits = 64
+			}
+			randBitStart := rand.Intn(elemBits)
+			for j := 0; j < elemBits; j++ {
+				bitIdx := ((j + randBitStart) % elemBits)
+				if (bA.Elems[elemIdx] & (uint64(1) << uint(bitIdx))) > 0 {
+					return 64*uint(elemIdx) + uint(bitIdx), true
+				}
+			}
+		}
+	}
+	return 0, false
+}
+
+func (bA BitArray) String() string {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+
+	return bA.stringIndented("")
+}
+
+func (bA BitArray) StringIndented(indent string) string {
+	bA.mtx.Lock()
+	defer bA.mtx.Unlock()
+	return bA.StringIndented(indent)
+}
+
+func (bA BitArray) stringIndented(indent string) string {
+
+	lines := []string{}
+	bits := ""
+	for i := uint(0); i < bA.Bits; i++ {
+		if bA.getIndex(i) {
+			bits += "X"
+		} else {
+			bits += "_"
+		}
+		if i%100 == 99 {
+			lines = append(lines, bits)
+			bits = ""
+		}
+		if i%10 == 9 {
+			bits += " "
+		}
+		if i%50 == 49 {
+			bits += " "
+		}
+	}
+	if len(bits) > 0 {
+		lines = append(lines, bits)
+	}
+	return fmt.Sprintf("BA{%v:%v}", bA.Bits, strings.Join(lines, indent))
+}