ceph/src/rocksdb/utilities/spatialdb/utils.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under the BSD-style license found in the
   3 //  LICENSE file in the root directory of this source tree. An additional grant
   4 //  of patent rights can be found in the PATENTS file in the same directory.
   5
   6 #pragma once
   7 #include <string>
   8 #include <algorithm>
   9
  10 #include "rocksdb/utilities/spatial_db.h"
  11
  12 namespace rocksdb {
  13 namespace spatial {
  14
  15 // indexing idea from http://msdn.microsoft.com/en-us/library/bb259689.aspx
  16 inline uint64_t GetTileFromCoord(double x, double start, double end,
  17                                  uint32_t tile_bits) {
  18   if (x < start) {
  19     return 0;
  20   }
  21   uint64_t tiles = 1ull << tile_bits;
  22   uint64_t r = static_cast<uint64_t>(((x - start) / (end - start)) * tiles);
  23   return std::min(r, tiles - 1);
  24 }
  25
  26 inline uint64_t GetQuadKeyFromTile(uint64_t tile_x, uint64_t tile_y,
  27                                    uint32_t tile_bits) {
  28   uint64_t quad_key = 0;
  29   for (uint32_t i = 0; i < tile_bits; ++i) {
  30     uint64_t mask = (1ull << i);
  31     quad_key |= (tile_x & mask) << i;
  32     quad_key |= (tile_y & mask) << (i + 1);
  33   }
  34   return quad_key;
  35 }
  36
  37 inline BoundingBox<uint64_t> GetTileBoundingBox(
  38     const SpatialIndexOptions& spatial_index, BoundingBox<double> bbox) {
  39   return BoundingBox<uint64_t>(
  40       GetTileFromCoord(bbox.min_x, spatial_index.bbox.min_x,
  41                        spatial_index.bbox.max_x, spatial_index.tile_bits),
  42       GetTileFromCoord(bbox.min_y, spatial_index.bbox.min_y,
  43                        spatial_index.bbox.max_y, spatial_index.tile_bits),
  44       GetTileFromCoord(bbox.max_x, spatial_index.bbox.min_x,
  45                        spatial_index.bbox.max_x, spatial_index.tile_bits),
  46       GetTileFromCoord(bbox.max_y, spatial_index.bbox.min_y,
  47                        spatial_index.bbox.max_y, spatial_index.tile_bits));
  48 }
  49
  50 // big endian can be compared using memcpy
  51 inline void PutFixed64BigEndian(std::string* dst, uint64_t value) {
  52   char buf[sizeof(value)];
  53   buf[0] = (value >> 56) & 0xff;
  54   buf[1] = (value >> 48) & 0xff;
  55   buf[2] = (value >> 40) & 0xff;
  56   buf[3] = (value >> 32) & 0xff;
  57   buf[4] = (value >> 24) & 0xff;
  58   buf[5] = (value >> 16) & 0xff;
  59   buf[6] = (value >> 8) & 0xff;
  60   buf[7] = value & 0xff;
  61   dst->append(buf, sizeof(buf));
  62 }
  63
  64 // big endian can be compared using memcpy
  65 inline bool GetFixed64BigEndian(const Slice& input, uint64_t* value) {
  66   if (input.size() < sizeof(uint64_t)) {
  67     return false;
  68   }
  69   auto ptr = input.data();
  70   *value = (static_cast<uint64_t>(static_cast<unsigned char>(ptr[0])) << 56) |
  71            (static_cast<uint64_t>(static_cast<unsigned char>(ptr[1])) << 48) |
  72            (static_cast<uint64_t>(static_cast<unsigned char>(ptr[2])) << 40) |
  73            (static_cast<uint64_t>(static_cast<unsigned char>(ptr[3])) << 32) |
  74            (static_cast<uint64_t>(static_cast<unsigned char>(ptr[4])) << 24) |
  75            (static_cast<uint64_t>(static_cast<unsigned char>(ptr[5])) << 16) |
  76            (static_cast<uint64_t>(static_cast<unsigned char>(ptr[6])) << 8) |
  77            static_cast<uint64_t>(static_cast<unsigned char>(ptr[7]));
  78   return true;
  79 }
  80
  81 inline void PutDouble(std::string* dst, double d) {
  82   dst->append(reinterpret_cast<char*>(&d), sizeof(double));
  83 }
  84
  85 inline bool GetDouble(Slice* input, double* d) {
  86   if (input->size() < sizeof(double)) {
  87     return false;
  88   }
  89   memcpy(d, input->data(), sizeof(double));
  90   input->remove_prefix(sizeof(double));
  91   return true;
  92 }
  93
  94 }  // namespace spatial
  95 }  // namespace rocksdb