stats: change FMSketch hash function from fnv to murmur

_vendor/src/github.com/spaolacci/murmur3/LICENSE

@@ -0,0 +1,24 @@
+Copyright 2013, Sébastien Paolacci.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright
+      notice, this list of conditions and the following disclaimer in the
+      documentation and/or other materials provided with the distribution.
+    * Neither the name of the library nor the
+      names of its contributors may be used to endorse or promote products
+      derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

_vendor/src/github.com/spaolacci/murmur3/murmur.go

@@ -0,0 +1,65 @@
+// Copyright 2013, Sébastien Paolacci. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+/*
+Native (and fast) implementation of Austin Appleby's MurmurHash3.
+
+Package murmur3 implements Austin Appleby's non-cryptographic MurmurHash3.
+
+ Reference implementation:
+    http://code.google.com/p/smhasher/wiki/MurmurHash3
+
+ History, characteristics and (legacy) perfs:
+    https://sites.google.com/site/murmurhash/
+    https://sites.google.com/site/murmurhash/statistics
+*/
+package murmur3
+
+type bmixer interface {
+	bmix(p []byte) (tail []byte)
+	Size() (n int)
+	reset()
+}
+
+type digest struct {
+	clen int      // Digested input cumulative length.
+	tail []byte   // 0 to Size()-1 bytes view of `buf'.
+	buf  [16]byte // Expected (but not required) to be Size() large.
+	bmixer
+}
+
+func (d *digest) BlockSize() int { return 1 }
+
+func (d *digest) Write(p []byte) (n int, err error) {
+	n = len(p)
+	d.clen += n
+
+	if len(d.tail) > 0 {
+		// Stick back pending bytes.
+		nfree := d.Size() - len(d.tail) // nfree ∈ [1, d.Size()-1].
+		if nfree < len(p) {
+			// One full block can be formed.
+			block := append(d.tail, p[:nfree]...)
+			p = p[nfree:]
+			_ = d.bmix(block) // No tail.
+		} else {
+			// Tail's buf is large enough to prevent reallocs.
+			p = append(d.tail, p...)
+		}
+	}
+
+	d.tail = d.bmix(p)
+
+	// Keep own copy of the 0 to Size()-1 pending bytes.
+	nn := copy(d.buf[:], d.tail)
+	d.tail = d.buf[:nn]
+
+	return n, nil
+}
+
+func (d *digest) Reset() {
+	d.clen = 0
+	d.tail = nil
+	d.bmixer.reset()
+}

_vendor/src/github.com/spaolacci/murmur3/murmur128.go

@@ -0,0 +1,189 @@
+package murmur3
+
+import (
+	//"encoding/binary"
+	"hash"
+	"unsafe"
+)
+
+const (
+	c1_128 = 0x87c37b91114253d5
+	c2_128 = 0x4cf5ad432745937f
+)
+
+// Make sure interfaces are correctly implemented.
+var (
+	_ hash.Hash = new(digest128)
+	_ Hash128   = new(digest128)
+	_ bmixer    = new(digest128)
+)
+
+// Hack: the standard api doesn't define any Hash128 interface.
+type Hash128 interface {
+	hash.Hash
+	Sum128() (uint64, uint64)
+}
+
+// digest128 represents a partial evaluation of a 128 bites hash.
+type digest128 struct {
+	digest
+	h1 uint64 // Unfinalized running hash part 1.
+	h2 uint64 // Unfinalized running hash part 2.
+}
+
+func New128() Hash128 {
+	d := new(digest128)
+	d.bmixer = d
+	d.Reset()
+	return d
+}
+
+func (d *digest128) Size() int { return 16 }
+
+func (d *digest128) reset() { d.h1, d.h2 = 0, 0 }
+
+func (d *digest128) Sum(b []byte) []byte {
+	h1, h2 := d.Sum128()
+	return append(b,
+		byte(h1>>56), byte(h1>>48), byte(h1>>40), byte(h1>>32),
+		byte(h1>>24), byte(h1>>16), byte(h1>>8), byte(h1),
+
+		byte(h2>>56), byte(h2>>48), byte(h2>>40), byte(h2>>32),
+		byte(h2>>24), byte(h2>>16), byte(h2>>8), byte(h2),
+	)
+}
+
+func (d *digest128) bmix(p []byte) (tail []byte) {
+	h1, h2 := d.h1, d.h2
+
+	nblocks := len(p) / 16
+	for i := 0; i < nblocks; i++ {
+		t := (*[2]uint64)(unsafe.Pointer(&p[i*16]))
+		k1, k2 := t[0], t[1]
+
+		k1 *= c1_128
+		k1 = (k1 << 31) | (k1 >> 33) // rotl64(k1, 31)
+		k1 *= c2_128
+		h1 ^= k1
+
+		h1 = (h1 << 27) | (h1 >> 37) // rotl64(h1, 27)
+		h1 += h2
+		h1 = h1*5 + 0x52dce729
+
+		k2 *= c2_128
+		k2 = (k2 << 33) | (k2 >> 31) // rotl64(k2, 33)
+		k2 *= c1_128
+		h2 ^= k2
+
+		h2 = (h2 << 31) | (h2 >> 33) // rotl64(h2, 31)
+		h2 += h1
+		h2 = h2*5 + 0x38495ab5
+	}
+	d.h1, d.h2 = h1, h2
+	return p[nblocks*d.Size():]
+}
+
+func (d *digest128) Sum128() (h1, h2 uint64) {
+
+	h1, h2 = d.h1, d.h2
+
+	var k1, k2 uint64
+	switch len(d.tail) & 15 {
+	case 15:
+		k2 ^= uint64(d.tail[14]) << 48
+		fallthrough
+	case 14:
+		k2 ^= uint64(d.tail[13]) << 40
+		fallthrough
+	case 13:
+		k2 ^= uint64(d.tail[12]) << 32
+		fallthrough
+	case 12:
+		k2 ^= uint64(d.tail[11]) << 24
+		fallthrough
+	case 11:
+		k2 ^= uint64(d.tail[10]) << 16
+		fallthrough
+	case 10:
+		k2 ^= uint64(d.tail[9]) << 8
+		fallthrough
+	case 9:
+		k2 ^= uint64(d.tail[8]) << 0
+
+		k2 *= c2_128
+		k2 = (k2 << 33) | (k2 >> 31) // rotl64(k2, 33)
+		k2 *= c1_128
+		h2 ^= k2
+
+		fallthrough
+
+	case 8:
+		k1 ^= uint64(d.tail[7]) << 56
+		fallthrough
+	case 7:
+		k1 ^= uint64(d.tail[6]) << 48
+		fallthrough
+	case 6:
+		k1 ^= uint64(d.tail[5]) << 40
+		fallthrough
+	case 5:
+		k1 ^= uint64(d.tail[4]) << 32
+		fallthrough
+	case 4:
+		k1 ^= uint64(d.tail[3]) << 24
+		fallthrough
+	case 3:
+		k1 ^= uint64(d.tail[2]) << 16
+		fallthrough
+	case 2:
+		k1 ^= uint64(d.tail[1]) << 8
+		fallthrough
+	case 1:
+		k1 ^= uint64(d.tail[0]) << 0
+		k1 *= c1_128
+		k1 = (k1 << 31) | (k1 >> 33) // rotl64(k1, 31)
+		k1 *= c2_128
+		h1 ^= k1
+	}
+
+	h1 ^= uint64(d.clen)
+	h2 ^= uint64(d.clen)
+
+	h1 += h2
+	h2 += h1
+
+	h1 = fmix64(h1)
+	h2 = fmix64(h2)
+
+	h1 += h2
+	h2 += h1
+
+	return h1, h2
+}
+
+func fmix64(k uint64) uint64 {
+	k ^= k >> 33
+	k *= 0xff51afd7ed558ccd
+	k ^= k >> 33
+	k *= 0xc4ceb9fe1a85ec53
+	k ^= k >> 33
+	return k
+}
+
+/*
+func rotl64(x uint64, r byte) uint64 {
+	return (x << r) | (x >> (64 - r))
+}
+*/
+
+// Sum128 returns the MurmurHash3 sum of data. It is equivalent to the
+// following sequence (without the extra burden and the extra allocation):
+//     hasher := New128()
+//     hasher.Write(data)
+//     return hasher.Sum128()
+func Sum128(data []byte) (h1 uint64, h2 uint64) {
+	d := &digest128{h1: 0, h2: 0}
+	d.tail = d.bmix(data)
+	d.clen = len(data)
+	return d.Sum128()
+}