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This commit is contained in:
Doug Hoyte
2023-03-08 16:42:09 -05:00
parent 4ab168861c
commit d1a8383e64
3 changed files with 65 additions and 9 deletions
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56
js/xor.js
View File

@ -112,6 +112,62 @@ class XorView {
lastTimestampOut[0] = temp;
return encodeVarInt(timestamp + 1);
};
let appendBoundKey = (key, output) => {
output.push(...encodeTimestampOut(key.timestamp));
output.push(...encodeVarInt(key.id.length));
output.push(...key.id);
};
let appendMinimalBoundKey = (curr, prev) => {
output.push(...encodeTimestampOut(curr.timestamp));
if (curr.timestamp !== prev.timestamp) {
output.push(...encodeVarInt(0));
} else {
let sharedPrefixBytes = 0;
for (let i = 0; i < this.idSize; i++) {
if (curr.id[i] !== prev.id[i]) break;
sharedPrefixBytes++;
}
output.push(...encodeVarInt(sharedPrefixBytes + 1));
output.push(...curr.id.slice(0, sharedPrefixBytes + 1));
}
};
// Split our range
let numElems = upper - lower;
let buckets = 16;
if (numElems < buckets * 2) {
appendBoundKey(lowerKey);
appendBoundKey(upperKey);
output.push(...encodeVarInt(numElems + 8));
for (let it = lower; it < upper; ++it) output.push(...this.elems[it].id);
} else {
let elemsPerBucket = Math.floor(numElems / buckets);
let bucketsWithExtra = numElems % buckets;
let curr = lower;
for (let i = 0; i < buckets; i++) {
if (i == 0) appendBoundKey(lowerKey);
else appendMinimalBoundKey(this.elems[curr], this.elems[curr - 1]);
let ourXorSet = new Array(this.idSize).fill(0);
for (let bucketEnd = curr + elemsPerBucket + (i < bucketsWithExtra ? 1 : 0); curr != bucketEnd; curr++) {
for (let j = 0; j < this.idSize; j++) ourXorSet[j] ^= this.elems[curr][j];
}
if (i === buckets - 1) appendBoundKey(upperKey);
else appendMinimalBoundKey(this.elems[curr], this.elems[curr - 1]);
output.push(...encodeVarInt(0)); // mode = 0
output.push(...ourXorSet.id);
}
}
}
}

16
src/xor.h
View File

@ -157,13 +157,13 @@ struct XorView {
return encodeVarInt(timestamp + 1);
};
auto appendBoundKey = [&](uint64_t t, std::string k, std::string &output) {
auto appendBoundKey = [&](uint64_t t, std::string k) {
output += encodeTimestampOut(t);
output += encodeVarInt(k.size());
output += k;
};
auto appendMinimalBoundKey = [&](const XorElem &curr, const XorElem &prev, std::string &output) {
auto appendMinimalBoundKey = [&](const XorElem &curr, const XorElem &prev) {
output += encodeTimestampOut(curr.timestamp);
if (curr.timestamp != prev.timestamp) {
@ -188,8 +188,8 @@ struct XorView {
const uint64_t buckets = 16;
if (numElems < buckets * 2) {
appendBoundKey(lowerTimestamp, lowerKey, output);
appendBoundKey(upperTimestamp, upperKey, output);
appendBoundKey(lowerTimestamp, lowerKey);
appendBoundKey(upperTimestamp, upperKey);
output += encodeVarInt(numElems + 8);
for (auto it = lower; it < upper; ++it) output += it->getId(idSize);
@ -199,16 +199,16 @@ struct XorView {
auto curr = lower;
for (uint64_t i = 0; i < buckets; i++) {
if (i == 0) appendBoundKey(lowerTimestamp, lowerKey, output);
else appendMinimalBoundKey(*curr, *std::prev(curr), output);
if (i == 0) appendBoundKey(lowerTimestamp, lowerKey);
else appendMinimalBoundKey(*curr, *std::prev(curr));
XorElem ourXorSet;
for (auto bucketEnd = curr + elemsPerBucket + (i < bucketsWithExtra ? 1 : 0); curr != bucketEnd; curr++) {
ourXorSet ^= *curr;
}
if (i == buckets - 1) appendBoundKey(upperTimestamp, upperKey, output);
else appendMinimalBoundKey(*curr, *std::prev(curr), output);
if (i == buckets - 1) appendBoundKey(upperTimestamp, upperKey);
else appendMinimalBoundKey(*curr, *std::prev(curr));
output += encodeVarInt(0); // mode = 0
output += ourXorSet.getId(idSize);

2
test/xor.cpp
View File

@ -55,7 +55,7 @@ int main() {
x1.finalise();
x2.finalise();
std::string q = x1.initialQuery();
std::string q = x1.initial();
uint64_t round = 0;