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https://github.com/matrix-org/synapse-s3-storage-provider.git
synced 2024-10-23 07:29:40 +00:00
Factor out generic streaming from s3 specific
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parent
1314baff14
commit
005f857917
1 changed files with 81 additions and 45 deletions
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@ -34,6 +34,9 @@ logger = logging.getLogger("synapse.s3")
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# The list of valid AWS storage class names
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_VALID_STORAGE_CLASSES = ('STANDARD', 'REDUCED_REDUNDANCY', 'STANDARD_IA')
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# Chunk size to use when reading from s3 connection in bytes
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READ_CHUNK_SIZE = 16 * 1024
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class S3StorageProviderBackend(StorageProvider):
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"""
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@ -97,14 +100,8 @@ class _S3DownloadThread(threading.Thread):
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deferred (Deferred[_S3Responder|None]): If file exists
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resolved with an _S3Responder instance, if it doesn't
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exist then resolves with None.
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Attributes:
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READ_CHUNK_SIZE (int): The chunk size in bytes used when downloading
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file.
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"""
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READ_CHUNK_SIZE = 16 * 1024
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def __init__(self, bucket, key, deferred):
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super(_S3DownloadThread, self).__init__(name="s3-download")
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self.bucket = bucket
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@ -125,28 +122,51 @@ class _S3DownloadThread(threading.Thread):
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reactor.callFromThread(self.deferred.errback, Failure())
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return
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# Triggered by responder when more data has been requested (or
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# stop_event has been triggered)
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wakeup_event = threading.Event()
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# Trigered by responder when we should abort the download.
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stop_event = threading.Event()
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producer = _S3Responder(wakeup_event, stop_event)
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producer = _S3Responder()
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reactor.callFromThread(self.deferred.callback, producer)
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_stream_to_producer(self.deferred, resp["Body"], timeout=90.)
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def _stream_to_producer(reactor, producer, body, status=None, timeout=None):
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"""Streams a file like object to the producer.
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Correctly handles producer being paused/resumed/stopped.
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Args:
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reactor
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producer (_S3Responder): Producer object to stream results to
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body (file like): The object to read from
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status (_ProducerStatus|None): Used to track whether we're currently
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paused or not. Used for testing
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timeout (float|None): Timeout in seconds to wait for consume to resume
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after being paused
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"""
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# Set when we should be producing, cleared when we are paused
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wakeup_event = producer.wakeup_event
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# Set if we should stop producing forever
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stop_event = producer.stop_event
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if not status:
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status = _ProducerStatus()
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try:
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body = resp["Body"]
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while not stop_event.is_set():
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# We wait for the producer to signal that the consumer wants
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# more data (or we should abort)
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wakeup_event.wait()
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if not wakeup_event.is_set():
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status.set_paused(True)
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ret = wakeup_event.wait(timeout)
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if not ret:
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raise Exception("Timed out waiting to resume")
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status.set_paused(False)
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# Check if we were woken up so that we abort the download
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if stop_event.is_set():
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return
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chunk = body.read(self.READ_CHUNK_SIZE)
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chunk = body.read(READ_CHUNK_SIZE)
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if not chunk:
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return
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@ -154,7 +174,6 @@ class _S3DownloadThread(threading.Thread):
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except Exception:
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reactor.callFromThread(producer._error, Failure())
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return
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finally:
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reactor.callFromThread(producer._finish)
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if body:
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@ -163,18 +182,13 @@ class _S3DownloadThread(threading.Thread):
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class _S3Responder(Responder):
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"""A Responder for S3. Created by _S3DownloadThread
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Args:
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wakeup_event (threading.Event): Used to signal to _S3DownloadThread
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that consumer is ready for more data (or that we've triggered
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stop_event).
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stop_event (threading.Event): Used to signal to _S3DownloadThread that
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it should stop producing. `wakeup_event` must also be set if
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`stop_event` is used.
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"""
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def __init__(self, wakeup_event, stop_event):
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self.wakeup_event = wakeup_event
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self.stop_event = stop_event
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def __init__(self):
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# Triggered by responder when more data has been requested (or
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# stop_event has been triggered)
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self.wakeup_event = threading.Event()
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# Trigered by responder when we should abort the download.
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self.stop_event = threading.Event()
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# The consumer we're registered to
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self.consumer = None
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@ -214,6 +228,7 @@ class _S3Responder(Responder):
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# The consumer wants no more data ever, signal _S3DownloadThread
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self.stop_event.set()
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self.wakeup_event.set()
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if not self.deferred.called:
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self.deferred.errback(Exception("Consumer ask to stop producing"))
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def _write(self, chunk):
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@ -242,3 +257,24 @@ class _S3Responder(Responder):
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if not self.deferred.called:
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self.deferred.callback(None)
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class _ProducerStatus(object):
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"""Used to track whether the s3 download thread is currently paused
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waiting for consumer to resume. Used for testing.
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"""
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def __init__(self):
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self.is_paused = threading.Event()
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self.is_paused.clear()
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def wait_until_paused(self, timeout=None):
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is_paused = self.is_paused.wait(timeout)
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if not is_paused:
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raise Exception("Timed out waiting")
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def set_paused(self, paused):
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if paused:
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self.is_paused.set()
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else:
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self.is_paused.clear()
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