Introduce asynchronous fetching of HiPS tiles

.rtd-environment.yml

@@ -12,6 +12,7 @@ dependencies:
     - reproject
     - matplotlib
     - tqdm
+    - aiohttp
     # There's a problem with Sphinx 1.6 with astropy-helpers
     # For now, we pin the Sphinx version to something that works
     - sphinx==1.5.6

.travis.yml

@@ -27,7 +27,7 @@ env:
         - MAIN_CMD='python setup.py'
         - SETUP_CMD='test'
         - EVENT_TYPE='pull_request push'
-        - CONDA_DEPENDENCIES='healpy scikit-image Pillow reproject matplotlib tqdm'
+        - CONDA_DEPENDENCIES='healpy scikit-image Pillow reproject matplotlib tqdm aiohttp'
         - PIP_DEPENDENCIES=''
         - CONDA_CHANNELS='conda-forge astropy-ci-extras astropy'
         - SETUP_XVFB=True

docs/installation.rst

@@ -80,5 +80,6 @@ In addition, the following packages are needed for optional functionality:
 
 * `Matplotlib`_ 2.0 or later. Used for plotting in examples.
 * `tqdm`_. Used for showing progress bar either on terminal or in Jupyter notebook.
+* `aiohttp`_. Used for fetching HiPS tiles.
 
 We have some info at :ref:`py3` on why we don't support legacy Python (Python 2).

docs/references.txt

@@ -6,4 +6,5 @@
 .. _HiPS paper: https://www.aanda.org/articles/aa/pdf/2015/06/aa26075-15.pdf
 .. _HiPS IVOA recommendation: http://www.ivoa.net/documents/HiPS/
 .. _HiPS at CDS: http://aladin.u-strasbg.fr/hips/
-.. _tqdm: https://pypi.python.org/pypi/tqdm
+.. _tqdm: https://pypi.python.org/pypi/tqdm
+.. _aiohttp: http://aiohttp.readthedocs.io/en/stable/

hips/draw/paint.py

@@ -1,10 +1,10 @@
 # Licensed under a 3-clause BSD style license - see LICENSE.rst
 import time
 import numpy as np
-from typing import List, Tuple, Union, Dict, Any, Iterator
+from typing import List, Tuple, Union, Dict, Any
 from astropy.wcs.utils import proj_plane_pixel_scales
 from skimage.transform import ProjectiveTransform, warp
-from ..tiles import HipsSurveyProperties, HipsTile, HipsTileMeta
+from ..tiles import HipsSurveyProperties, HipsTile, HipsTileMeta, fetch_tiles
 from ..tiles.tile import compute_image_shape
 from ..utils import WCSGeometry, healpix_pixels_in_sky_image, hips_order_for_pixel_resolution
 
@@ -36,6 +36,9 @@ class HipsPainter:
         Use the precise drawing algorithm
     progress_bar : bool
         Show a progress bar for tile fetching and drawing
+    fetch_opts : dict
+        Keyword arguments for fetching HiPS tiles. To see the
+        list of passable arguments, refer to `~fetch_tiles`
 
     Examples
     --------
@@ -59,12 +62,13 @@ class HipsPainter:
     """
 
     def __init__(self, geometry: Union[dict, WCSGeometry], hips_survey: Union[str, HipsSurveyProperties],
-                 tile_format: str, precise: bool = False, progress_bar: bool = True) -> None:
+                 tile_format: str, precise: bool = False, progress_bar: bool = True, fetch_opts : dict = None) -> None:
         self.geometry = WCSGeometry.make(geometry)
         self.hips_survey = HipsSurveyProperties.make(hips_survey)
         self.tile_format = tile_format
         self.precise = precise
         self.progress_bar = progress_bar
+        self.fetch_opts = fetch_opts
         self._tiles = None
         self.float_image = None
         self._stats: Dict[str, Any] = {}
@@ -109,30 +113,22 @@ def projection(self, tile: HipsTile) -> ProjectiveTransform:
         pt.estimate(src, dst)
         return pt
 
-    def _fetch_tiles(self) -> Iterator[HipsTile]:
-        """Generator function to fetch HiPS tiles from a remote URL."""
-        if self.progress_bar:
-            from tqdm import tqdm
-            tile_indices = tqdm(self.tile_indices, desc='Fetching tiles')
-        else:
-            tile_indices = self.tile_indices
-
-        for healpix_pixel_index in tile_indices:
+    @property
+    def tiles(self) -> List[HipsTile]:
+        """List of `~hips.HipsTile` (cached on multiple access)."""
+        tile_metas = []
+        for healpix_pixel_index in self.tile_indices:
             tile_meta = HipsTileMeta(
                 order=self.draw_hips_order,
                 ipix=healpix_pixel_index,
                 frame=self.hips_survey.astropy_frame,
                 file_format=self.tile_format,
             )
-            url = self.hips_survey.tile_url(tile_meta)
-            tile = HipsTile.fetch(tile_meta, url)
-            yield tile
+            tile_metas.append(tile_meta)
 
-    @property
-    def tiles(self) -> List[HipsTile]:
-        """List of `~hips.HipsTile` (cached on multiple access)."""
         if self._tiles is None:
-            self._tiles = list(self._fetch_tiles())
+            self._tiles = fetch_tiles(tile_metas=tile_metas, hips_survey=self.hips_survey,
+                                      progress_bar=self.progress_bar, **(self.fetch_opts or {}))
 
         return self._tiles
 
@@ -163,7 +159,6 @@ def run(self) -> np.ndarray:
             self._stats['consumed_memory'] += len(tile.raw_data)
 
 
-
     def make_tile_list(self):
         parent_tiles = self.tiles
 

hips/draw/tests/test_paint.py

@@ -20,7 +20,8 @@ def setup_class(cls):
             width=2000, height=1000, fov="3 deg",
             coordsys='icrs', projection='AIT',
         )
-        cls.painter = HipsPainter(cls.geometry, cls.hips_survey, 'fits')
+        fetch_opts = dict(fetch_package='urllib', timeout=30, n_parallel=10)
+        cls.painter = HipsPainter(cls.geometry, cls.hips_survey, 'fits', fetch_opts=fetch_opts)
 
     def test_draw_hips_order(self):
         assert self.painter.draw_hips_order == 7
@@ -43,7 +44,8 @@ def test_compute_matching_hips_order(self, pars):
             coordsys='icrs', projection='AIT',
         )
 
-        simple_tile_painter = HipsPainter(geometry, self.hips_survey, 'fits')
+        fetch_opts = dict(fetch_package='urllib', timeout=30, n_parallel=10)
+        simple_tile_painter = HipsPainter(geometry, self.hips_survey, 'fits', fetch_opts=fetch_opts)
         assert simple_tile_painter.draw_hips_order == pars['order']
 
     def test_run(self):

hips/draw/tests/test_ui.py

@@ -61,7 +61,9 @@ def test_make_sky_image(tmpdir, pars):
     hips_survey = HipsSurveyProperties.fetch(url=pars['url'])
     geometry = make_test_wcs_geometry()
 
-    result = make_sky_image(geometry=geometry, hips_survey=hips_survey, tile_format=pars['file_format'], precise=pars['precise'])
+    fetch_opts = dict(fetch_package='urllib', timeout=30, n_parallel=10)
+    result = make_sky_image(geometry=geometry, hips_survey=hips_survey, tile_format=pars['file_format'],
+                            precise=pars['precise'], fetch_opts=fetch_opts)
 
     assert result.image.shape == pars['shape']
     assert result.image.dtype == pars['dtype']

hips/draw/ui.py

@@ -15,7 +15,7 @@
 
 
 def make_sky_image(geometry: Union[dict, WCSGeometry], hips_survey: Union[str, 'HipsSurveyProperties'],
-                   tile_format: str, precise: bool = False, progress_bar: bool = True) -> 'HipsDrawResult':
+                   tile_format: str, precise: bool = False, progress_bar: bool = True, fetch_opts: dict = None) -> 'HipsDrawResult':
     """Make sky image: fetch tiles and draw.
 
     The example for this can be found on the :ref:`gs` page.
@@ -33,13 +33,16 @@ def make_sky_image(geometry: Union[dict, WCSGeometry], hips_survey: Union[str, '
         Use the precise drawing algorithm
     progress_bar : bool
         Show a progress bar for tile fetching and drawing
+    fetch_opts : dict
+        Keyword arguments for fetching HiPS tiles. To see the
+        list of passable arguments, refer to `~hips.fetch_tiles`
 
     Returns
     -------
     result : `~hips.HipsDrawResult`
         Result object
     """
-    painter = HipsPainter(geometry, hips_survey, tile_format, precise, progress_bar)
+    painter = HipsPainter(geometry, hips_survey, tile_format, precise, progress_bar, fetch_opts)
     painter.run()
     return HipsDrawResult.from_painter(painter)
 

hips/tiles/__init__.py

@@ -3,3 +3,4 @@
 from .tile import *
 from .survey import *
 from .allsky import *
+from .fetch import *

hips/tiles/fetch.py

@@ -0,0 +1,157 @@
+# Licensed under a 3-clause BSD style license - see LICENSE.rst
+import asyncio
+import urllib.request
+import concurrent.futures
+from typing import List
+from ..tiles import HipsSurveyProperties, HipsTile, HipsTileMeta
+
+__all__ = [
+    'fetch_tiles',
+]
+
+__doctest_skip__ = [
+    'fetch_tiles',
+]
+
+
+def fetch_tiles(tile_metas: List[HipsTileMeta], hips_survey: HipsSurveyProperties,
+                progress_bar: bool = True, n_parallel: int = 5,
+                timeout: float = 10, fetch_package: str = 'urllib') -> List[HipsTile]:
+    """Fetch a list of HiPS tiles.
+
+    This function fetches a list of HiPS tiles based
+    on their URLs, which are generated using ``hips_survey``
+    and ``tile_metas``.
+
+    The tiles are then fetched asynchronously using ``urllib`` or ``aiohttp``.
+
+    Parameters
+    ----------
+    tile_metas : list
+        Python list of `~hips.HipsTileMeta`
+    hips_survey : `~hips.HipsSurveyProperties`
+        HiPS survey properties
+    progress_bar : bool
+        Show a progress bar for tile fetching and drawing
+    n_parallel : int
+        Number of tile fetch web requests to make in parallel
+    timeout : float
+        Seconds to timeout for fetching a HiPS tile
+    fetch_package : {'urllib', 'aiohttp'}
+        Package to use for fetching HiPS tiles
+
+    Examples
+    --------
+    Define a list of tiles we want::
+
+        from hips import HipsSurveyProperties, HipsTileMeta
+        from hips import fetch_tiles
+        url = 'http://alasky.unistra.fr/DSS/DSS2Merged/properties'
+        hips_survey = HipsSurveyProperties.fetch(url)
+        tile_indices = [69623, 69627, 69628, 69629, 69630, 69631]
+        tile_metas = []
+        for healpix_pixel_index in tile_indices:
+            tile_meta = HipsTileMeta(
+               order=7,
+               ipix=healpix_pixel_index,
+               frame=hips_survey.astropy_frame,
+               file_format='fits',
+            )
+            tile_metas.append(tile_meta)
+
+    Fetch all tiles (in parallel)::
+
+        tiles = fetch_tiles(tile_metas, hips_survey)
+
+    Returns
+    -------
+    tiles : list
+        A Python list of `~hips.HipsTile`
+    """
+    if fetch_package == 'aiohttp':
+        fetch_fct = tiles_aiohttp
+    elif fetch_package == 'urllib':
+        fetch_fct = tiles_urllib
+    else:
+        raise ValueError(f'Invalid package name: {fetch_package}')
+
+    tiles = fetch_fct(tile_metas, hips_survey, progress_bar, n_parallel, timeout)
+
+    # Sort tiles to match the tile_meta list
+    # TODO: this doesn't seem like a great solution.
+    # Use OrderedDict instead?
+    out = []
+    for tile_meta in tile_metas:
+        for tile in tiles:
+            if tile.meta == tile_meta:
+                out.append(tile)
+                continue
+    return out
+
+
+def fetch_tile_urllib(url: str, meta: HipsTileMeta, timeout: float) -> HipsTile:
+    """Fetch a HiPS tile asynchronously."""
+    with urllib.request.urlopen(url, timeout=timeout) as conn:
+        raw_data = conn.read()
+        return HipsTile(meta, raw_data)
+
+
+def tiles_urllib(tile_metas: List[HipsTileMeta], hips_survey: HipsSurveyProperties,
+                 progress_bar: bool, n_parallel, timeout: float) -> List[HipsTile]:
+    """Generator function to fetch HiPS tiles from a remote URL."""
+    with concurrent.futures.ThreadPoolExecutor(max_workers=n_parallel) as executor:
+        futures = []
+        for meta in tile_metas:
+            url = hips_survey.tile_url(meta)
+            future = executor.submit(fetch_tile_urllib, url, meta, timeout)
+            futures.append(future)
+
+        futures = concurrent.futures.as_completed(futures)
+        if progress_bar:
+            from tqdm import tqdm
+            futures = tqdm(futures, total=len(tile_metas), desc='Fetching tiles')
+
+        tiles = []
+        for future in futures:
+            tiles.append(future.result())
+
+    return tiles
+
+
+async def fetch_tile_aiohttp(url: str, meta: HipsTileMeta, session, timeout: float) -> HipsTile:
+    """Fetch a HiPS tile asynchronously using aiohttp."""
+    async with session.get(url, timeout=timeout) as response:
+        raw_data = await response.read()
+        return HipsTile(meta, raw_data)
+
+
+async def fetch_all_tiles_aiohttp(tile_metas: List[HipsTileMeta], hips_survey: HipsSurveyProperties,
+                                  progress_bar: bool, n_parallel: int, timeout: float) -> List[HipsTile]:
+    """Generator function to fetch HiPS tiles from a remote URL using aiohttp."""
+    import aiohttp
+
+    connector = aiohttp.TCPConnector(limit=n_parallel)
+    async with aiohttp.ClientSession(connector=connector) as session:
+        futures = []
+        for meta in tile_metas:
+            url = hips_survey.tile_url(meta)
+            future = asyncio.ensure_future(fetch_tile_aiohttp(url, meta, session, timeout))
+            futures.append(future)
+
+        futures = asyncio.as_completed(futures)
+        if progress_bar:
+            from tqdm import tqdm
+            futures = tqdm(futures, total=len(tile_metas), desc='Fetching tiles')
+
+        tiles = []
+        for future in futures:
+            tiles.append(await future)
+
+    return tiles
+
+
+def tiles_aiohttp(tile_metas: List[HipsTileMeta], hips_survey: HipsSurveyProperties,
+                  progress_bar: bool, n_parallel: int, timeout: float) -> List[HipsTile]:
+    return asyncio.get_event_loop().run_until_complete(
+        fetch_all_tiles_aiohttp(tile_metas, hips_survey, progress_bar, n_parallel, timeout)
+    )

hips/tiles/tests/test_fetch.py

@@ -0,0 +1,55 @@
+# Licensed under a 3-clause BSD style license - see LICENSE.rst
+import pytest
+from astropy.tests.helper import remote_data
+from numpy.testing import assert_allclose
+from ..fetch import fetch_tiles
+from ..survey import HipsSurveyProperties
+from ..tile import HipsTileMeta
+
+TILE_FETCH_TEST_CASES = [
+    dict(
+        tile_indices=[69623, 69627, 69628, 69629, 69630, 69631],
+        tile_format='fits',
+        order=7,
+        url='http://alasky.unistra.fr/DSS/DSS2Merged/properties',
+        progress_bar=True,
+        data=[2101, 1945, 1828, 1871, 2079, 2336],
+        fetch_package='urllib',
+    ),
+    dict(
+        tile_indices=[69623, 69627, 69628, 69629, 69630, 69631],
+        tile_format='fits',
+        order=7,
+        url='http://alasky.unistra.fr/DSS/DSS2Merged/properties',
+        progress_bar=True,
+        data=[2101, 1945, 1828, 1871, 2079, 2336],
+        fetch_package='aiohttp',
+    ),
+]
+
+
+def make_tile_metas(hips_survey, pars):
+    for healpix_pixel_index in pars['tile_indices']:
+        yield HipsTileMeta(
+            order=pars['order'],
+            ipix=healpix_pixel_index,
+            frame=hips_survey.astropy_frame,
+            file_format=pars['tile_format'],
+        )
+
+
+@pytest.mark.parametrize('pars', TILE_FETCH_TEST_CASES)
+@remote_data
+def test_fetch_tiles(pars):
+    hips_survey = HipsSurveyProperties.fetch(pars['url'])
+
+    tile_metas = list(make_tile_metas(hips_survey, pars))
+
+    tiles = fetch_tiles(
+        tile_metas, hips_survey,
+        progress_bar=pars['progress_bar'],
+        fetch_package=pars['fetch_package'],
+    )
+
+    for idx, val in enumerate(pars['data']):
+        assert_allclose(tiles[idx].data[0][5], val)