187 lines
3.3 KiB
Go
187 lines
3.3 KiB
Go
package expire
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import (
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"database/sql"
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"fmt"
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_ "github.com/mattn/go-sqlite3"
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"imposm3/element"
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"io"
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"math"
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"sort"
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"sync"
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)
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var mercBbox = [4]float64{
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-20037508.342789244,
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-20037508.342789244,
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20037508.342789244,
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20037508.342789244,
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}
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var mercRes [20]float64
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func init() {
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res := 2 * 20037508.342789244 / 256
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for i, _ := range mercRes {
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mercRes[i] = res
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res /= 2
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}
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}
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func mercTileCoord(x, y float64, zoom uint32) (uint32, uint32) {
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res := mercRes[zoom]
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x = x - mercBbox[0]
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y = mercBbox[3] - y
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tileX := uint32(math.Floor(x / (res * 256)))
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tileY := uint32(math.Floor(y / (res * 256)))
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return tileX, tileY
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}
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type Tiles struct {
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tiles map[tileKey]bool
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zoom uint32
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mu *sync.Mutex
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}
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type tileKey struct {
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x uint32
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y uint32
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}
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type tile struct {
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x uint32
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y uint32
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z uint32
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d uint32
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}
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func NewTiles(zoom uint32) *Tiles {
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return &Tiles{make(map[tileKey]bool), zoom, &sync.Mutex{}}
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}
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func (tc *Tiles) addCoord(x, y float64) {
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tileX, tileY := mercTileCoord(x, y, tc.zoom)
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tc.mu.Lock()
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defer tc.mu.Unlock()
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tc.tiles[tileKey{tileX, tileY}] = true
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}
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func (tc *Tiles) SortedTiles() []tile {
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tiles := make([]tile, len(tc.tiles))
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i := 0
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for tileKey, _ := range tc.tiles {
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tiles[i] = tile{
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tileKey.x,
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tileKey.y,
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tc.zoom,
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hilbert(tileKey.x, tileKey.y, tc.zoom),
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}
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i++
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}
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sort.Sort(byHilbert(tiles))
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return tiles
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}
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func (tc *Tiles) ExpireFromNodes(nodes []element.Node) {
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for _, nd := range nodes {
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tc.addCoord(nd.Long, nd.Lat)
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}
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}
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type byHilbert []tile
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func (h byHilbert) Len() int { return len(h) }
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func (h byHilbert) Swap(i, j int) { h[i], h[j] = h[j], h[i] }
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func (h byHilbert) Less(i, j int) bool { return h[i].d < h[j].d }
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// Hilbert returns the distance of tile x, y in a hilbert curve of
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// level z, where z=0 is 1x1, z=1 is 2x2, etc.
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func hilbert(x, y, z uint32) uint32 {
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n := uint32(2 << (z - 1))
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var rx, ry, d, s uint32
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for s = n / 2; s > 0; s /= 2 {
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if (x & s) > 0 {
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rx = 1
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} else {
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rx = 0
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}
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if (y & s) > 0 {
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ry = 1
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} else {
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ry = 0
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}
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d += s * s * ((3 * rx) ^ ry)
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x, y = rot(s, x, y, rx, ry)
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}
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return d
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}
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//rotate/flip a quadrant appropriately
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func rot(n, x, y, rx, ry uint32) (uint32, uint32) {
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if ry == 0 {
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if rx == 1 {
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x = n - 1 - x
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y = n - 1 - y
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}
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//Swap x and y
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return y, x
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}
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return x, y
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}
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func WriteTileExpireList(tiles []tile, writer io.Writer) error {
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for _, tile := range tiles {
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_, err := fmt.Fprintf(writer, "%d/%d/%d\n", tile.z, tile.x, tile.y)
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if err != nil {
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return err
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}
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}
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return nil
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}
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func WriteTileExpireDb(tiles []tile, dbfile string) error {
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db, err := sql.Open("sqlite3", dbfile)
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if err != nil {
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return err
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}
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defer db.Close()
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tx, err := db.Begin()
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if err != nil {
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return err
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}
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stmts := []string{
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`create table if not exists tiles (
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x integer,
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y integer,
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z integer,
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time datetime,
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primary key (x, y, z)
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)`,
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}
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for _, stmt := range stmts {
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_, err := tx.Exec(stmt)
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if err != nil {
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return err
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}
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}
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stmt, err := tx.Prepare(`insert or replace into tiles (x, y, z, time) values (?, ?, ?, DATETIME('now'))`)
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if err != nil {
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return err
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}
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defer stmt.Close()
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for _, tile := range tiles {
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_, err := stmt.Exec(tile.x, tile.y, tile.z)
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if err != nil {
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return err
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}
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}
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return tx.Commit()
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}
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