openCom-Companion/sbapp/mapview/downloader.py

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# coding=utf-8
__all__ = ["Downloader"]
import logging
import traceback
from concurrent.futures import ThreadPoolExecutor, TimeoutError, as_completed
from os import environ, makedirs
from os.path import exists, join
from random import choice
from time import time
import requests
from kivy.clock import Clock
from kivy.logger import LOG_LEVELS, Logger
from mapview.constants import CACHE_DIR
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# if "MAPVIEW_DEBUG_DOWNLOADER" in environ:
# Logger.setLevel(LOG_LEVELS['debug'])
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# Logger.setLevel(LOG_LEVELS['error'])
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# user agent is needed because since may 2019 OSM gives me a 429 or 403 server error
# I tried it with a simpler one (just Mozilla/5.0) this also gets rejected
USER_AGENT = 'Kivy-garden.mapview'
class Downloader:
_instance = None
MAX_WORKERS = 5
CAP_TIME = 0.064 # 15 FPS
@staticmethod
def instance(cache_dir=None):
if Downloader._instance is None:
if not cache_dir:
cache_dir = CACHE_DIR
Downloader._instance = Downloader(cache_dir=cache_dir)
return Downloader._instance
def __init__(self, max_workers=None, cap_time=None, **kwargs):
self.cache_dir = kwargs.get('cache_dir', CACHE_DIR)
if max_workers is None:
max_workers = Downloader.MAX_WORKERS
if cap_time is None:
cap_time = Downloader.CAP_TIME
self.is_paused = False
self.cap_time = cap_time
self.executor = ThreadPoolExecutor(max_workers=max_workers)
self._futures = []
Clock.schedule_interval(self._check_executor, 1 / 60.0)
if not exists(self.cache_dir):
makedirs(self.cache_dir)
def submit(self, f, *args, **kwargs):
future = self.executor.submit(f, *args, **kwargs)
self._futures.append(future)
def download_tile(self, tile):
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# Logger.debug(
# "Downloader: queue(tile) zoom={} x={} y={}".format(
# tile.zoom, tile.tile_x, tile.tile_y
# )
# )
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future = self.executor.submit(self._load_tile, tile)
self._futures.append(future)
def download(self, url, callback, **kwargs):
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# Logger.debug("Downloader: queue(url) {}".format(url))
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future = self.executor.submit(self._download_url, url, callback, kwargs)
self._futures.append(future)
def _download_url(self, url, callback, kwargs):
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# Logger.debug("Downloader: download(url) {}".format(url))
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response = requests.get(url, **kwargs)
response.raise_for_status()
return callback, (url, response)
def _load_tile(self, tile):
if tile.state == "done":
return
cache_fn = tile.cache_fn
if exists(cache_fn):
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# Logger.debug("Downloader: use cache {}".format(cache_fn))
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return tile.set_source, (cache_fn,)
tile_y = tile.map_source.get_row_count(tile.zoom) - tile.tile_y - 1
uri = tile.map_source.url.format(
z=tile.zoom, x=tile.tile_x, y=tile_y, s=choice(tile.map_source.subdomains)
)
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# Logger.debug("Downloader: download(tile) {}".format(uri))
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response = requests.get(uri, headers={'User-agent': USER_AGENT}, timeout=5)
try:
response.raise_for_status()
data = response.content
with open(cache_fn, "wb") as fd:
fd.write(data)
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# Logger.debug("Downloaded {} bytes: {}".format(len(data), uri))
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return tile.set_source, (cache_fn,)
except Exception as e:
print("Downloader error: {!r}".format(e))
def _check_executor(self, dt):
start = time()
try:
for future in as_completed(self._futures[:], 0):
self._futures.remove(future)
try:
result = future.result()
except Exception:
traceback.print_exc()
# make an error tile?
continue
if result is None:
continue
callback, args = result
callback(*args)
# capped executor in time, in order to prevent too much
# slowiness.
# seems to works quite great with big zoom-in/out
if time() - start > self.cap_time:
break
except TimeoutError:
pass