Beispiel #1
0
class TestMetaGridLevelMetaTiles(object):
    def __init__(self):
        self.meta_grid = MetaGrid(TileGrid(), meta_size=(2, 2))

    def test_full_grid_0(self):
        bbox = (-20037508.34, -20037508.34, 20037508.34, 20037508.34)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 0)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox(bbox, abbox)

        eq_(len(meta_tiles), 1)
        eq_(meta_tiles[0], (0, 0, 0))

    def test_full_grid_2(self):
        bbox = (-20037508.34, -20037508.34, 20037508.34, 20037508.34)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 2)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox(bbox, abbox)

        eq_(tile_grid, (2, 2))
        eq_(len(meta_tiles), 4)
        eq_(meta_tiles[0], (0, 2, 2))
        eq_(meta_tiles[1], (2, 2, 2))
        eq_(meta_tiles[2], (0, 0, 2))
        eq_(meta_tiles[3], (2, 0, 2))
Beispiel #2
0
class TestMetaGridLevelMetaTilesGeodetic(object):
    def __init__(self):
        self.meta_grid = MetaGrid(TileGrid(is_geodetic=True), meta_size=(2, 2))

    def test_full_grid_2(self):
        bbox = (-180.0, -90.0, 180.0, 90)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 2)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox(bbox, abbox)

        eq_(tile_grid, (2, 1))
        eq_(len(meta_tiles), 2)
        eq_(meta_tiles[0], (0, 0, 2))
        eq_(meta_tiles[1], (2, 0, 2))

    def test_partial_grid_3(self):
        bbox = (0.0, 5.0, 45, 40)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 3)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox((0.0, 0.0, 90.0, 90.0), abbox)

        eq_(tile_grid, (1, 1))
        eq_(len(meta_tiles), 1)
        eq_(meta_tiles[0], (4, 2, 3))
Beispiel #3
0
class TestMetaGridLevelMetaTilesGeodetic(object):
    def __init__(self):
        self.meta_grid = MetaGrid(TileGrid(is_geodetic=True), meta_size=(2, 2))

    def test_full_grid_2(self):
        bbox = (-180.0, -90.0, 180.0, 90)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 2)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox(bbox, abbox)

        eq_(tile_grid, (2, 1))
        eq_(len(meta_tiles), 2)
        eq_(meta_tiles[0], (0, 0, 2))
        eq_(meta_tiles[1], (2, 0, 2))

    def test_partial_grid_3(self):
        bbox = (0.0, 5.0, 45, 40)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 3)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox((0.0, 0.0, 90.0, 90.0), abbox)

        eq_(tile_grid, (1, 1))
        eq_(len(meta_tiles), 1)
        eq_(meta_tiles[0], (4, 2, 3))
Beispiel #4
0
class TestMetaGridLevelMetaTiles(object):
    def __init__(self):
        self.meta_grid = MetaGrid(TileGrid(), meta_size=(2, 2))

    def test_full_grid_0(self):
        bbox = (-20037508.34, -20037508.34, 20037508.34, 20037508.34)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 0)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox(bbox, abbox)

        eq_(len(meta_tiles), 1)
        eq_(meta_tiles[0], (0, 0, 0))

    def test_full_grid_2(self):
        bbox = (-20037508.34, -20037508.34, 20037508.34, 20037508.34)
        abbox, tile_grid, meta_tiles = \
            self.meta_grid.get_affected_level_tiles(bbox, 2)
        meta_tiles = list(meta_tiles)
        assert_almost_equal_bbox(bbox, abbox)

        eq_(tile_grid, (2, 2))
        eq_(len(meta_tiles), 4)
        eq_(meta_tiles[0], (0, 2, 2))
        eq_(meta_tiles[1], (2, 2, 2))
        eq_(meta_tiles[2], (0, 0, 2))
        eq_(meta_tiles[3], (2, 0, 2))
Beispiel #5
0
class TileWalker(object):
    def __init__(self, task, worker_pool, handle_stale=False, handle_uncached=False,
                 work_on_metatiles=True, skip_geoms_for_last_levels=0, progress_logger=None,
                 seed_progress=None):
        self.tile_mgr = task.tile_manager
        self.task = task
        self.worker_pool = worker_pool
        self.handle_stale = handle_stale
        self.handle_uncached = handle_uncached
        self.work_on_metatiles = work_on_metatiles
        self.skip_geoms_for_last_levels = skip_geoms_for_last_levels
        self.progress_logger = progress_logger

        num_seed_levels = len(task.levels)
        self.report_till_level = task.levels[int(num_seed_levels * 0.8)]
        meta_size = self.tile_mgr.meta_grid.meta_size if self.tile_mgr.meta_grid else (1, 1)
        self.tiles_per_metatile = meta_size[0] * meta_size[1]
        self.grid = MetaGrid(self.tile_mgr.grid, meta_size=meta_size, meta_buffer=0)
        self.count = 0
        self.seed_progress = seed_progress or SeedProgress()

    def walk(self):
        assert self.handle_stale or self.handle_uncached
        bbox = self.task.coverage.extent.bbox_for(self.tile_mgr.grid.srs)
        if self.seed_progress.already_processed():
            # nothing to seed
            self.seed_progress.step_forward()
        else:
            try:
                self._walk(bbox, self.task.levels)
            except StopProcess:
                pass
        self.report_progress(self.task.levels[0], self.task.coverage.bbox)

    def _walk(self, cur_bbox, levels, all_subtiles=False):
        """
        :param cur_bbox: the bbox to seed in this call
        :param levels: list of levels to seed
        :param all_subtiles: seed all subtiles and do not check for
                             intersections with bbox/geom
        """
        current_level, levels = levels[0], levels[1:]
        bbox_, tiles, subtiles = self.grid.get_affected_level_tiles(cur_bbox, current_level)
        total_subtiles = tiles[0] * tiles[1]

        if len(levels) < self.skip_geoms_for_last_levels:
            # do not filter in last levels
            all_subtiles = True
        subtiles = self._filter_subtiles(subtiles, all_subtiles)

        if current_level <= self.report_till_level:
            self.report_progress(current_level, cur_bbox)

        if not self.seed_progress.running():
            self.report_progress(current_level, cur_bbox)
            self.tile_mgr.cleanup()
            raise StopProcess()

        for i, (subtile, sub_bbox, intersection) in enumerate(subtiles):
            if subtile is None: # no intersection
                self.seed_progress.step_forward(total_subtiles)
                continue
            if levels: # recurse to next level
                sub_bbox = limit_sub_bbox(cur_bbox, sub_bbox)
                if intersection == CONTAINS:
                    all_subtiles = True
                else:
                    all_subtiles = False

                with self.seed_progress.step_down(i, total_subtiles):
                    if self.seed_progress.already_processed():
                        self.seed_progress.step_forward()
                    else:
                        self._walk(sub_bbox, levels,
                            all_subtiles=all_subtiles)

            if not self.work_on_metatiles:
                # collect actual tiles
                handle_tiles = self.grid.tile_list(subtile)
            else:
                handle_tiles = [subtile]

            if self.handle_uncached:
                handle_tiles = [t for t in handle_tiles if
                                    t is not None and
                                    not self.tile_mgr.is_cached(t)]
            elif self.handle_stale:
                handle_tiles = [t for t in handle_tiles if
                                    t is not None and
                                    self.tile_mgr.is_stale(t)]
            if handle_tiles:
                self.count += 1
                self.worker_pool.process(handle_tiles, self.seed_progress)

            if not levels:
                self.seed_progress.step_forward(total_subtiles)

        if len(levels) >= 4:
            # call cleanup to close open caches
            # for connection based caches
            self.tile_mgr.cleanup()

    def report_progress(self, level, bbox):
        if self.progress_logger:
            self.progress_logger.log_progress(self.seed_progress, level, bbox,
                self.count * self.tiles_per_metatile)

    def _filter_subtiles(self, subtiles, all_subtiles):
        """
        Return an iterator with all sub tiles.
        Yields (None, None, None) for non-intersecting tiles,
        otherwise (subtile, subtile_bbox, intersection).
        """
        for subtile in subtiles:
            if subtile is None:
                yield None, None, None
            else:
                sub_bbox = self.grid.meta_tile(subtile).bbox
                if all_subtiles:
                    intersection = CONTAINS
                else:
                    intersection = self.task.intersects(sub_bbox)
                if intersection:
                    yield subtile, sub_bbox, intersection
                else:
                    yield None, None, None
Beispiel #6
0
class TileWalker(object):
    def __init__(self,
                 task,
                 worker_pool,
                 handle_stale=False,
                 handle_uncached=False,
                 work_on_metatiles=True,
                 skip_geoms_for_last_levels=0,
                 progress_logger=None):
        self.tile_mgr = task.tile_manager
        self.task = task
        self.worker_pool = worker_pool
        self.handle_stale = handle_stale
        self.handle_uncached = handle_uncached
        self.work_on_metatiles = work_on_metatiles
        self.skip_geoms_for_last_levels = skip_geoms_for_last_levels
        self.progress_logger = progress_logger

        num_seed_levels = len(task.levels)
        self.report_till_level = task.levels[int(num_seed_levels * 0.8)]
        meta_size = self.tile_mgr.meta_grid.meta_size if self.tile_mgr.meta_grid else (
            1, 1)
        self.tiles_per_metatile = meta_size[0] * meta_size[1]
        self.grid = MetaGrid(self.tile_mgr.grid,
                             meta_size=meta_size,
                             meta_buffer=0)
        self.progress = 0.0
        self.eta = ETA()
        self.count = 0

    def walk(self):
        assert self.handle_stale or self.handle_uncached
        bbox = self.task.coverage.extent.bbox_for(self.tile_mgr.grid.srs)
        self._walk(bbox, self.task.levels)
        self.report_progress(self.task.levels[0], self.task.coverage.bbox)

    def _walk(self,
              cur_bbox,
              levels,
              progess_str='',
              progress=1.0,
              all_subtiles=False):
        """
        :param cur_bbox: the bbox to seed in this call
        :param levels: list of levels to seed
        :param all_subtiles: seed all subtiles and do not check for
                             intersections with bbox/geom
        """
        current_level, levels = levels[0], levels[1:]
        bbox_, tiles, subtiles = self.grid.get_affected_level_tiles(
            cur_bbox, current_level)
        total_subtiles = tiles[0] * tiles[1]

        if len(levels) < self.skip_geoms_for_last_levels:
            # do not filter in last levels
            all_subtiles = True
        subtiles = self._filter_subtiles(subtiles, all_subtiles)

        if current_level <= self.report_till_level:
            self.report_progress(current_level, cur_bbox)

        progress = progress / total_subtiles
        for i, (subtile, sub_bbox, intersection) in enumerate(subtiles):
            if subtile is None:  # no intersection
                self.progress += progress
                continue
            if levels:  # recurse to next level
                sub_bbox = limit_sub_bbox(cur_bbox, sub_bbox)
                cur_progess_str = progess_str + status_symbol(
                    i, total_subtiles)
                if intersection == CONTAINS:
                    all_subtiles = True
                else:
                    all_subtiles = False
                self._walk(sub_bbox,
                           levels,
                           cur_progess_str,
                           all_subtiles=all_subtiles,
                           progress=progress)

            if not self.work_on_metatiles:
                # collect actual tiles
                handle_tiles = self.grid.tile_list(subtile)
            else:
                handle_tiles = [subtile]

            if self.handle_uncached:
                handle_tiles = [
                    t for t in handle_tiles
                    if t is not None and not self.tile_mgr.is_cached(t)
                ]
            elif self.handle_stale:
                handle_tiles = [
                    t for t in handle_tiles
                    if t is not None and self.tile_mgr.is_stale(t)
                ]
            if handle_tiles:
                self.count += 1
                self.worker_pool.process(
                    handle_tiles, (progess_str, self.progress, self.eta))

            if not levels:
                self.progress += progress

        if len(levels) >= 4:
            # call cleanup to close open caches
            # for connection based caches
            self.tile_mgr.cleanup()
        self.eta.update(self.progress)

    def report_progress(self, level, bbox):
        if self.progress_logger:
            self.progress_logger.log_progress(
                self.progress, level, bbox,
                self.count * self.tiles_per_metatile, self.eta)

    def _filter_subtiles(self, subtiles, all_subtiles):
        """
        Return an iterator with all sub tiles.
        Yields (None, None, None) for non-intersecting tiles,
        otherwise (subtile, subtile_bbox, intersection).
        """
        for subtile in subtiles:
            if subtile is None:
                yield None, None, None
            else:
                sub_bbox = self.grid.meta_tile(subtile).bbox
                if all_subtiles:
                    intersection = CONTAINS
                else:
                    intersection = self.task.intersects(sub_bbox)
                if intersection:
                    yield subtile, sub_bbox, intersection
                else:
                    yield None, None, None
Beispiel #7
0
class TileWalker(object):
    """
    TileWalker traverses through all tiles in a tile grid and calls worker_pool.process
    for each (meta) tile. It traverses the tile grid (pyramid) depth-first.
    Intersection with coverages are checked before handling subtiles in the next level,
    allowing to determine if all subtiles should be seeded or skipped.
    """
    def __init__(self,
                 task,
                 worker_pool,
                 handle_stale=False,
                 handle_uncached=False,
                 work_on_metatiles=True,
                 skip_geoms_for_last_levels=0,
                 progress_logger=None,
                 seed_progress=None):
        self.tile_mgr = task.tile_manager
        self.task = task
        self.worker_pool = worker_pool
        self.handle_stale = handle_stale
        self.handle_uncached = handle_uncached
        self.work_on_metatiles = work_on_metatiles
        self.skip_geoms_for_last_levels = skip_geoms_for_last_levels
        self.progress_logger = progress_logger

        num_seed_levels = len(task.levels)
        if num_seed_levels >= 4:
            self.report_till_level = task.levels[num_seed_levels - 2]
        else:
            self.report_till_level = task.levels[num_seed_levels - 1]
        meta_size = self.tile_mgr.meta_grid.meta_size if self.tile_mgr.meta_grid else (
            1, 1)
        self.tiles_per_metatile = meta_size[0] * meta_size[1]
        self.grid = MetaGrid(self.tile_mgr.grid,
                             meta_size=meta_size,
                             meta_buffer=0)
        self.count = 0
        self.seed_progress = seed_progress or SeedProgress()

        # It is possible that we 'walk' through the same tile multiple times
        # when seeding irregular tile grids[0]. limit_sub_bbox prevents that we
        # recurse into the same area multiple times, but it is still possible
        # that a tile is processed multiple times. Locking prevents that a tile
        # is seeded multiple times, but it is possible that we count the same tile
        # multiple times (in dry-mode, or while the tile is in the process queue).

        # Tile counts can be off by 280% with sqrt2 grids.
        # We keep a small cache of already processed tiles to skip most duplicates.
        # A simple cache of 64 tile coordinates for each level already brings the
        # difference down to ~8%, which is good enough and faster than a more
        # sophisticated FIFO cache with O(1) lookup, or even caching all tiles.

        # [0] irregular tile grids: where one tile does not have exactly 4 subtiles
        # Typically when you use res_factor, or a custom res list.
        self.seeded_tiles = {l: deque(maxlen=64) for l in task.levels}

    def walk(self):
        assert self.handle_stale or self.handle_uncached
        bbox = self.task.coverage.extent.bbox_for(self.tile_mgr.grid.srs)
        if self.seed_progress.already_processed():
            # nothing to seed
            self.seed_progress.step_forward()
        else:
            try:
                self._walk(bbox, self.task.levels)
            except StopProcess:
                pass
        self.report_progress(self.task.levels[0], self.task.coverage.bbox)

    def _walk(self, cur_bbox, levels, current_level=0, all_subtiles=False):
        """
        :param cur_bbox: the bbox to seed in this call
        :param levels: list of levels to seed
        :param all_subtiles: seed all subtiles and do not check for
                             intersections with bbox/geom
        """
        bbox_, tiles, subtiles = self.grid.get_affected_level_tiles(
            cur_bbox, current_level)
        total_subtiles = tiles[0] * tiles[1]
        if len(levels) < self.skip_geoms_for_last_levels:
            # do not filter in last levels
            all_subtiles = True
        subtiles = self._filter_subtiles(subtiles, all_subtiles)

        if current_level in levels and current_level <= self.report_till_level:
            self.report_progress(current_level, cur_bbox)

        if not self.seed_progress.running():
            if current_level in levels:
                self.report_progress(current_level, cur_bbox)
            self.tile_mgr.cleanup()
            raise StopProcess()

        process = False
        if current_level in levels:
            levels = levels[1:]
            process = True

        for i, (subtile, sub_bbox, intersection) in enumerate(subtiles):
            if subtile is None:  # no intersection
                self.seed_progress.step_forward(total_subtiles)
                continue
            if levels:  # recurse to next level
                sub_bbox = limit_sub_bbox(cur_bbox, sub_bbox)
                if intersection == CONTAINS:
                    all_subtiles = True
                else:
                    all_subtiles = False

                with self.seed_progress.step_down(i, total_subtiles):
                    if self.seed_progress.already_processed():
                        self.seed_progress.step_forward()
                    else:
                        self._walk(sub_bbox,
                                   levels,
                                   current_level=current_level + 1,
                                   all_subtiles=all_subtiles)

            if not process:
                continue

            # check if subtile was already processed. see comment in __init__
            if subtile in self.seeded_tiles[current_level]:
                if not levels:
                    self.seed_progress.step_forward(total_subtiles)
                continue
            self.seeded_tiles[current_level].appendleft(subtile)

            if not self.work_on_metatiles:
                # collect actual tiles
                handle_tiles = self.grid.tile_list(subtile)
            else:
                handle_tiles = [subtile]

            if self.handle_uncached:
                handle_tiles = [
                    t for t in handle_tiles
                    if t is not None and not self.tile_mgr.is_cached(t)
                ]
            elif self.handle_stale:
                handle_tiles = [
                    t for t in handle_tiles
                    if t is not None and self.tile_mgr.is_stale(t)
                ]
            if handle_tiles:
                self.count += 1
                self.worker_pool.process(handle_tiles, self.seed_progress)

            if not levels:
                self.seed_progress.step_forward(total_subtiles)

        if len(levels) >= 4:
            # call cleanup to close open caches
            # for connection based caches
            self.tile_mgr.cleanup()

    def report_progress(self, level, bbox):
        if self.progress_logger:
            self.progress_logger.log_progress(
                self.seed_progress, level, bbox,
                self.count * self.tiles_per_metatile)

    def _filter_subtiles(self, subtiles, all_subtiles):
        """
        Return an iterator with all sub tiles.
        Yields (None, None, None) for non-intersecting tiles,
        otherwise (subtile, subtile_bbox, intersection).
        """
        for subtile in subtiles:
            if subtile is None:
                yield None, None, None
            else:
                sub_bbox = self.grid.meta_tile(subtile).bbox
                if all_subtiles:
                    intersection = CONTAINS
                else:
                    intersection = self.task.intersects(sub_bbox)
                if intersection:
                    yield subtile, sub_bbox, intersection
                else:
                    yield None, None, None
Beispiel #8
0
class TileWalker(object):
    """
    TileWalker traverses through all tiles in a tile grid and calls worker_pool.process
    for each (meta) tile. It traverses the tile grid (pyramid) depth-first.
    Intersection with coverages are checked before handling subtiles in the next level,
    allowing to determine if all subtiles should be seeded or skipped.
    """
    def __init__(self, task, worker_pool, handle_stale=False, handle_uncached=False,
                 work_on_metatiles=True, skip_geoms_for_last_levels=0, progress_logger=None,
                 seed_progress=None):
        self.tile_mgr = task.tile_manager
        self.task = task
        self.worker_pool = worker_pool
        self.handle_stale = handle_stale
        self.handle_uncached = handle_uncached
        self.work_on_metatiles = work_on_metatiles
        self.skip_geoms_for_last_levels = skip_geoms_for_last_levels
        self.progress_logger = progress_logger

        num_seed_levels = len(task.levels)
        if num_seed_levels >= 4:
            self.report_till_level = task.levels[num_seed_levels-2]
        else:
            self.report_till_level = task.levels[num_seed_levels-1]
        meta_size = self.tile_mgr.meta_grid.meta_size if self.tile_mgr.meta_grid else (1, 1)
        self.tiles_per_metatile = meta_size[0] * meta_size[1]
        self.grid = MetaGrid(self.tile_mgr.grid, meta_size=meta_size, meta_buffer=0)
        self.count = 0
        self.seed_progress = seed_progress or SeedProgress()

        # It is possible that we 'walk' through the same tile multiple times
        # when seeding irregular tile grids[0]. limit_sub_bbox prevents that we
        # recurse into the same area multiple times, but it is still possible
        # that a tile is processed multiple times. Locking prevents that a tile
        # is seeded multiple times, but it is possible that we count the same tile
        # multiple times (in dry-mode, or while the tile is in the process queue).

        # Tile counts can be off by 280% with sqrt2 grids.
        # We keep a small cache of already processed tiles to skip most duplicates.
        # A simple cache of 64 tile coordinates for each level already brings the
        # difference down to ~8%, which is good enough and faster than a more
        # sophisticated FIFO cache with O(1) lookup, or even caching all tiles.

        # [0] irregular tile grids: where one tile does not have exactly 4 subtiles
        # Typically when you use res_factor, or a custom res list.
        self.seeded_tiles = {l: deque(maxlen=64) for l in task.levels}

    def walk(self):
        assert self.handle_stale or self.handle_uncached
        bbox = self.task.coverage.extent.bbox_for(self.tile_mgr.grid.srs)
        if self.seed_progress.already_processed():
            # nothing to seed
            self.seed_progress.step_forward()
        else:
            try:
                self._walk(bbox, self.task.levels)
            except StopProcess:
                pass
        self.report_progress(self.task.levels[0], self.task.coverage.bbox)

    def _walk(self, cur_bbox, levels, current_level=0, all_subtiles=False):
        """
        :param cur_bbox: the bbox to seed in this call
        :param levels: list of levels to seed
        :param all_subtiles: seed all subtiles and do not check for
                             intersections with bbox/geom
        """
        bbox_, tiles, subtiles = self.grid.get_affected_level_tiles(cur_bbox, current_level)
        total_subtiles = tiles[0] * tiles[1]
        if len(levels) < self.skip_geoms_for_last_levels:
            # do not filter in last levels
            all_subtiles = True
        subtiles = self._filter_subtiles(subtiles, all_subtiles)

        if current_level in levels and current_level <= self.report_till_level:
            self.report_progress(current_level, cur_bbox)

        if not self.seed_progress.running():
            if current_level in levels:
                self.report_progress(current_level, cur_bbox)
            self.tile_mgr.cleanup()
            raise StopProcess()

        process = False;
        if current_level in levels:
            levels = levels[1:]
            process = True

        for i, (subtile, sub_bbox, intersection) in enumerate(subtiles):
            if subtile is None: # no intersection
                self.seed_progress.step_forward(total_subtiles)
                continue
            if levels: # recurse to next level
                sub_bbox = limit_sub_bbox(cur_bbox, sub_bbox)
                if intersection == CONTAINS:
                    all_subtiles = True
                else:
                    all_subtiles = False

                with self.seed_progress.step_down(i, total_subtiles):
                    if self.seed_progress.already_processed():
                        self.seed_progress.step_forward()
                    else:
                        self._walk(sub_bbox, levels, current_level=current_level+1,
                            all_subtiles=all_subtiles)

            if not process:
                continue

            # check if subtile was already processed. see comment in __init__
            if subtile in self.seeded_tiles[current_level]:
                if not levels:
                    self.seed_progress.step_forward(total_subtiles)
                continue
            self.seeded_tiles[current_level].appendleft(subtile)

            if not self.work_on_metatiles:
                # collect actual tiles
                handle_tiles = self.grid.tile_list(subtile)
            else:
                handle_tiles = [subtile]

            if self.handle_uncached:
                handle_tiles = [t for t in handle_tiles if
                                    t is not None and
                                    not self.tile_mgr.is_cached(t)]
            elif self.handle_stale:
                handle_tiles = [t for t in handle_tiles if
                                    t is not None and
                                    self.tile_mgr.is_stale(t)]
            if handle_tiles:
                self.count += 1
                self.worker_pool.process(handle_tiles, self.seed_progress)

            if not levels:
                self.seed_progress.step_forward(total_subtiles)

        if len(levels) >= 4:
            # call cleanup to close open caches
            # for connection based caches
            self.tile_mgr.cleanup()

    def report_progress(self, level, bbox):
        if self.progress_logger:
            self.progress_logger.log_progress(self.seed_progress, level, bbox,
                self.count * self.tiles_per_metatile)

    def _filter_subtiles(self, subtiles, all_subtiles):
        """
        Return an iterator with all sub tiles.
        Yields (None, None, None) for non-intersecting tiles,
        otherwise (subtile, subtile_bbox, intersection).
        """
        for subtile in subtiles:
            if subtile is None:
                yield None, None, None
            else:
                sub_bbox = self.grid.meta_tile(subtile).bbox
                if all_subtiles:
                    intersection = CONTAINS
                else:
                    intersection = self.task.intersects(sub_bbox)
                if intersection:
                    yield subtile, sub_bbox, intersection
                else:
                    yield None, None, None