mirror of
https://github.com/fluencelabs/redis
synced 2025-03-18 16:40:50 +00:00
Geo: sync faster decoding from krtm that synched from Ardb.
Instead of successive divisions in iteration the new code uses bitwise magic to interleave / deinterleave two 32bit values into a 64bit one. All tests still passing and is measurably faster, so worth it.
This commit is contained in:
antirez
parent
d308cadc8a
commit
4160bf0448
141
deps/geohash-int/geohash.c
vendored
141
deps/geohash-int/geohash.c
vendored
@ -44,6 +44,71 @@
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* -----------------
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*/
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/* Interleave lower bits of x and y, so the bits of x
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* are in the even positions and bits from y in the odd;
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* x and y must initially be less than 2**32 (65536).
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* From: https://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN
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*/
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static inline uint64_t interleave64(uint32_t xlo, uint32_t ylo) {
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static const uint64_t B[] = {0x5555555555555555, 0x3333333333333333,
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0x0F0F0F0F0F0F0F0F, 0x00FF00FF00FF00FF,
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0x0000FFFF0000FFFF};
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static const unsigned int S[] = {1, 2, 4, 8, 16};
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uint64_t x = xlo;
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uint64_t y = ylo;
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x = (x | (x << S[4])) & B[4];
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y = (y | (y << S[4])) & B[4];
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x = (x | (x << S[3])) & B[3];
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y = (y | (y << S[3])) & B[3];
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x = (x | (x << S[2])) & B[2];
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y = (y | (y << S[2])) & B[2];
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x = (x | (x << S[1])) & B[1];
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y = (y | (y << S[1])) & B[1];
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x = (x | (x << S[0])) & B[0];
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y = (y | (y << S[0])) & B[0];
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return x | (y << 1);
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}
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/* reverse the interleave process
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* derived from http://stackoverflow.com/questions/4909263
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*/
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static inline uint64_t deinterleave64(uint64_t interleaved) {
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static const uint64_t B[] = {0x5555555555555555, 0x3333333333333333,
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0x0F0F0F0F0F0F0F0F, 0x00FF00FF00FF00FF,
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0x0000FFFF0000FFFF, 0x00000000FFFFFFFF};
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static const unsigned int S[] = {0, 1, 2, 4, 8, 16};
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uint64_t x = interleaved;
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uint64_t y = interleaved >> 1;
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x = (x | (x >> S[0])) & B[0];
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y = (y | (y >> S[0])) & B[0];
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x = (x | (x >> S[1])) & B[1];
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y = (y | (y >> S[1])) & B[1];
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x = (x | (x >> S[2])) & B[2];
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y = (y | (y >> S[2])) & B[2];
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x = (x | (x >> S[3])) & B[3];
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y = (y | (y >> S[3])) & B[3];
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x = (x | (x >> S[4])) & B[4];
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y = (y | (y >> S[4])) & B[4];
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x = (x | (x >> S[5])) & B[5];
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y = (y | (y >> S[5])) & B[5];
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return x | (y << 32);
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}
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void geohashGetCoordRange(GeoHashRange *long_range, GeoHashRange *lat_range) {
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/* These are constraints from EPSG:900913 / EPSG:3785 / OSGEO:41001 */
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/* We can't geocode at the north/south pole. */
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@ -56,8 +121,6 @@ void geohashGetCoordRange(GeoHashRange *long_range, GeoHashRange *lat_range) {
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int geohashEncode(GeoHashRange *long_range, GeoHashRange *lat_range,
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double longitude, double latitude, uint8_t step,
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GeoHashBits *hash) {
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uint8_t i;
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if (NULL == hash || step > 32 || step == 0 || RANGEPISZERO(lat_range) ||
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RANGEPISZERO(long_range)) {
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return 0;
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@ -71,29 +134,15 @@ int geohashEncode(GeoHashRange *long_range, GeoHashRange *lat_range,
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return 0;
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}
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for (i = 0; i < step; i++) {
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uint8_t lat_bit, long_bit;
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double lat_offset =
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(latitude - lat_range->min) / (lat_range->max - lat_range->min);
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double long_offset =
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(longitude - long_range->min) / (long_range->max - long_range->min);
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if (lat_range->max - latitude >= latitude - lat_range->min) {
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lat_bit = 0;
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lat_range->max = (lat_range->max + lat_range->min) / 2;
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} else {
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lat_bit = 1;
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lat_range->min = (lat_range->max + lat_range->min) / 2;
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}
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if (long_range->max - longitude >= longitude - long_range->min) {
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long_bit = 0;
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long_range->max = (long_range->max + long_range->min) / 2;
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} else {
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long_bit = 1;
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long_range->min = (long_range->max + long_range->min) / 2;
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}
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hash->bits <<= 1;
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hash->bits += long_bit;
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hash->bits <<= 1;
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hash->bits += lat_bit;
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}
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/* convert to fixed point based on the step size */
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lat_offset *= (1 << step);
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long_offset *= (1 << step);
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hash->bits = interleave64(lat_offset, long_offset);
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return 1;
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}
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@ -108,45 +157,35 @@ int geohashEncodeWGS84(double longitude, double latitude, uint8_t step,
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return geohashEncodeType(longitude, latitude, step, hash);
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}
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static inline uint8_t get_bit(uint64_t bits, uint8_t pos) {
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return (bits >> pos) & 0x01;
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}
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int geohashDecode(const GeoHashRange long_range, const GeoHashRange lat_range,
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const GeoHashBits hash, GeoHashArea *area) {
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uint8_t i;
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if (HASHISZERO(hash) || NULL == area || RANGEISZERO(lat_range) ||
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RANGEISZERO(long_range)) {
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return 0;
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}
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area->hash = hash;
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area->longitude.min = long_range.min;
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area->longitude.max = long_range.max;
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area->latitude.min = lat_range.min;
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area->latitude.max = lat_range.max;
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uint8_t step = hash.step;
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uint64_t hash_sep = deinterleave64(hash.bits); /* hash = [LAT][LONG] */
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for (i = 0; i < hash.step; i++) {
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uint8_t lat_bit, long_bit;
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double lat_scale = lat_range.max - lat_range.min;
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double long_scale = long_range.max - long_range.min;
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long_bit = get_bit(hash.bits, (hash.step - i) * 2 - 1);
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lat_bit = get_bit(hash.bits, (hash.step - i) * 2 - 2);
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uint32_t ilato = hash_sep; /* get lat part of deinterleaved hash */
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uint32_t ilono = hash_sep >> 32; /* shift over to get long part of hash */
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if (lat_bit == 0) {
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area->latitude.max = (area->latitude.max + area->latitude.min) / 2;
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} else {
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area->latitude.min = (area->latitude.max + area->latitude.min) / 2;
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}
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/* divide by 2**step.
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* Then, for 0-1 coordinate, multiply times scale and add
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to the min to get the absolute coordinate. */
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area->latitude.min =
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lat_range.min + (ilato * 1.0 / (1ull << step)) * lat_scale;
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area->latitude.max =
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lat_range.min + ((ilato + 1) * 1.0 / (1ull << step)) * lat_scale;
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area->longitude.min =
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long_range.min + (ilono * 1.0 / (1ull << step)) * long_scale;
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area->longitude.max =
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long_range.min + ((ilono + 1) * 1.0 / (1ull << step)) * long_scale;
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if (long_bit == 0) {
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area->longitude.max =
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(area->longitude.max + area->longitude.min) / 2;
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} else {
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area->longitude.min =
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(area->longitude.max + area->longitude.min) / 2;
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}
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}
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return 1;
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}
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@ -164,7 +164,7 @@ double extractDistanceOrReply(redisClient *c, robj **argv,
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* than "5.2144992818115 meters away." We provide 4 digits after the dot
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* so that the returned value is decently accurate even when the unit is
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* the kilometer. */
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inline void addReplyDoubleDistance(redisClient *c, double d) {
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void addReplyDoubleDistance(redisClient *c, double d) {
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char dbuf[128];
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int dlen = snprintf(dbuf, sizeof(dbuf), "%.4f", d);
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addReplyBulkCBuffer(c, dbuf, dlen);
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