forked from LBRYCommunity/lbry-sdk
190 lines
8.5 KiB
Python
190 lines
8.5 KiB
Python
from random import choice
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import logging
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from twisted.internet import defer, task
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from twisted.internet.error import ConnectingCancelledError
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import treq
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from lbrynet.core.utils import DeferredDict
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from lbrynet.core.Error import DownloadCanceledError
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log = logging.getLogger(__name__)
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class HTTPBlobDownloader:
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'''
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A downloader that is able to get blobs from HTTP mirrors.
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Note that when a blob gets downloaded from a mirror or from a peer, BlobManager will mark it as completed
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and cause any other type of downloader to progress to the next missing blob. Also, BlobFile is naturally able
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to cancel other writers when a writer finishes first. That's why there is no call to cancel/resume/stop between
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different types of downloaders.
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'''
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def __init__(self, blob_manager, blob_hashes=None, servers=None, client=None, sd_hashes=None, retry=True,
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clock=None):
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if not clock:
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from twisted.internet import reactor
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self.clock = reactor
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else:
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self.clock = clock
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self.blob_manager = blob_manager
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self.servers = servers or []
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self.client = client or treq
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self.blob_hashes = blob_hashes or []
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self.missing_blob_hashes = []
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self.downloaded_blob_hashes = []
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self.sd_hashes = sd_hashes or []
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self.head_blob_hashes = []
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self.max_failures = 3
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self.semaphore = defer.DeferredSemaphore(2)
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self.deferreds = []
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self.writers = []
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self.retry = retry
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self.looping_call = task.LoopingCall(self._download_lc)
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self.looping_call.clock = self.clock
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self.finished_deferred = defer.Deferred()
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self.finished_deferred.addErrback(lambda err: err.trap(defer.CancelledError))
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self.short_delay = 30
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self.long_delay = 600
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self.delay = self.short_delay
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self.last_missing = 10000000
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self.lc_deferred = None
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@defer.inlineCallbacks
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def start(self):
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if not self.looping_call.running:
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self.lc_deferred = self.looping_call.start(self.short_delay, now=True)
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self.lc_deferred.addErrback(lambda err: err.trap(defer.CancelledError))
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yield self.finished_deferred
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def stop(self):
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for d in reversed(self.deferreds):
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d.cancel()
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while self.writers:
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writer = self.writers.pop()
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writer.close(DownloadCanceledError())
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self.blob_hashes = []
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if self.looping_call.running:
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self.looping_call.stop()
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if self.lc_deferred and not self.lc_deferred.called:
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self.lc_deferred.cancel()
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if not self.finished_deferred.called:
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self.finished_deferred.cancel()
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@defer.inlineCallbacks
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def _download_lc(self):
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delay = yield self._download_and_get_retry_delay()
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log.debug("delay: %s, missing: %i, downloaded from mirror: %i", delay, len(self.missing_blob_hashes),
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len(self.downloaded_blob_hashes))
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while self.missing_blob_hashes:
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self.blob_hashes.append(self.missing_blob_hashes.pop())
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if not delay:
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if self.looping_call.running:
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self.looping_call.stop()
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if not self.finished_deferred.called:
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log.debug("mirror finished")
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self.finished_deferred.callback(None)
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elif delay and delay != self.delay:
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if delay == self.long_delay:
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log.debug("mirror not making progress, trying less frequently")
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elif delay == self.short_delay:
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log.debug("queueing retry of %i blobs", len(self.missing_blob_hashes))
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if self.looping_call.running:
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self.looping_call.stop()
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self.delay = delay
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self.looping_call = task.LoopingCall(self._download_lc)
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self.looping_call.clock = self.clock
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self.lc_deferred = self.looping_call.start(self.delay, now=False)
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self.lc_deferred.addErrback(lambda err: err.trap(defer.CancelledError))
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yield self.finished_deferred
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@defer.inlineCallbacks
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def _download_and_get_retry_delay(self):
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if self.blob_hashes and self.servers:
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if self.sd_hashes:
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log.debug("trying to download stream from mirror (sd %s)", self.sd_hashes[0][:8])
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else:
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log.debug("trying to download %i blobs from mirror", len(self.blob_hashes))
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blobs = yield DeferredDict(
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{blob_hash: self.blob_manager.get_blob(blob_hash) for blob_hash in self.blob_hashes}
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)
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self.deferreds = [self.download_blob(blobs[blob_hash]) for blob_hash in self.blob_hashes]
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yield defer.DeferredList(self.deferreds)
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if self.retry and self.missing_blob_hashes:
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if not self.downloaded_blob_hashes:
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defer.returnValue(self.long_delay)
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if len(self.missing_blob_hashes) < self.last_missing:
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self.last_missing = len(self.missing_blob_hashes)
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defer.returnValue(self.short_delay)
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if self.retry and self.last_missing and len(self.missing_blob_hashes) == self.last_missing:
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defer.returnValue(self.long_delay)
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defer.returnValue(None)
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@defer.inlineCallbacks
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def _download_blob(self, blob):
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for _ in range(self.max_failures):
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writer, finished_deferred = blob.open_for_writing('mirror')
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self.writers.append(writer)
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try:
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downloaded = yield self._write_blob(writer, blob)
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if downloaded:
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yield finished_deferred # yield for verification errors, so we log them
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if blob.verified:
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log.info('Mirror completed download for %s', blob.blob_hash)
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should_announce = blob.blob_hash in self.sd_hashes or blob.blob_hash in self.head_blob_hashes
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yield self.blob_manager.blob_completed(blob, should_announce=should_announce)
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self.downloaded_blob_hashes.append(blob.blob_hash)
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break
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except (IOError, Exception, defer.CancelledError, ConnectingCancelledError) as e:
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if isinstance(
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e, (DownloadCanceledError, defer.CancelledError, ConnectingCancelledError)
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) or 'closed file' in str(e):
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# some other downloader finished first or it was simply cancelled
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log.info("Mirror download cancelled: %s", blob.blob_hash)
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break
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else:
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log.exception('Mirror failed downloading')
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finally:
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finished_deferred.addBoth(lambda _: None) # suppress echoed errors
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if 'mirror' in blob.writers:
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writer.close()
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self.writers.remove(writer)
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def download_blob(self, blob):
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if not blob.verified:
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d = self.semaphore.run(self._download_blob, blob)
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d.addErrback(lambda err: err.trap(defer.TimeoutError, defer.CancelledError))
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return d
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return defer.succeed(None)
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@defer.inlineCallbacks
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def _write_blob(self, writer, blob):
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response = yield self.client.get(url_for(choice(self.servers), blob.blob_hash))
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if response.code != 200:
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log.debug('Missing a blob: %s', blob.blob_hash)
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if blob.blob_hash in self.blob_hashes:
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self.blob_hashes.remove(blob.blob_hash)
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if blob.blob_hash not in self.missing_blob_hashes:
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self.missing_blob_hashes.append(blob.blob_hash)
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defer.returnValue(False)
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log.debug('Download started: %s', blob.blob_hash)
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blob.set_length(response.length)
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yield self.client.collect(response, writer.write)
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defer.returnValue(True)
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@defer.inlineCallbacks
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def download_stream(self, stream_hash, sd_hash):
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stream_crypt_blobs = yield self.blob_manager.storage.get_blobs_for_stream(stream_hash)
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self.blob_hashes.extend([
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b.blob_hash for b in stream_crypt_blobs
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if b.blob_hash and b.blob_hash not in self.blob_hashes
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])
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if sd_hash not in self.sd_hashes:
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self.sd_hashes.append(sd_hash)
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head_blob_hash = stream_crypt_blobs[0].blob_hash
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if head_blob_hash not in self.head_blob_hashes:
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self.head_blob_hashes.append(head_blob_hash)
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yield self.start()
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def url_for(server, blob_hash=''):
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return 'http://{}/{}'.format(server, blob_hash)
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