blob: 6ebda7832b6f59b2887956b3858d3fda8015b684 [file] [log] [blame]
package tilesource
import (
// GetTileStreamNow is a utility function that reads tiles in the given
// interval and sends them on the returned channel.
// The first tile is sent immediately.
// Should the call to read a new tile fail it will send that last
// successfully read tile. Thus it guarantees to send a tile in the provided
// interval, assuming at least one tile could be read.
// The metricsTag allows for us to monitor how long individual tile streams
// take, in the unlikely event there are multiple failures of the tile in a row.
func GetTileStreamNow(ts TileSource, interval time.Duration, metricsTag string) <-chan tiling.ComplexTile {
retCh := make(chan tiling.ComplexTile)
lastTileStreamed := metrics2.NewLiveness("last_tile_streamed", map[string]string{
"source": metricsTag,
go func() {
var lastTile tiling.ComplexTile = nil
readOneTile := func() {
tile := ts.GetTile()
if lastTile != tile {
lastTile = tile
retCh <- tile
} else {
sklog.Debugf("Tile hasn't changed for tile stream")
for range time.Tick(interval) {
return retCh