def handle_save_request(self, ws):
"""Save serialized version of report deltas to the cloud."""
@tornado.gen.coroutine
def progress(percent):
progress_msg = ForwardMsg()
progress_msg.upload_report_progress = percent
yield ws.write_message(progress_msg.SerializeToString(),
binary=True)
# Indicate that the save is starting.
try:
yield progress(0)
url = yield self._save_final_report(progress)
# Indicate that the save is done.
progress_msg = ForwardMsg()
progress_msg.report_uploaded = url
yield ws.write_message(progress_msg.SerializeToString(),
binary=True)
except Exception as e:
# Horrible hack to show something if something breaks.
err_msg = '%s: %s' % (type(e).__name__, str(e)
or 'No further details.')
progress_msg = ForwardMsg()
progress_msg.report_uploaded = err_msg
yield ws.write_message(progress_msg.SerializeToString(),
binary=True)
raise e
def populate_hash_if_needed(msg: ForwardMsg) -> str:
"""Computes and assigns the unique hash for a ForwardMsg.
If the ForwardMsg already has a hash, this is a no-op.
Parameters
----------
msg : ForwardMsg
Returns
-------
string
The message's hash, returned here for convenience. (The hash
will also be assigned to the ForwardMsg; callers do not need
to do this.)
"""
if msg.hash == "":
# Move the message's metadata aside. It's not part of the
# hash calculation.
metadata = msg.metadata
msg.ClearField("metadata")
# MD5 is good enough for what we need, which is uniqueness.
hasher = hashlib.md5()
hasher.update(msg.SerializeToString())
msg.hash = hasher.hexdigest()
# Restore metadata.
msg.metadata.CopyFrom(metadata)
return msg.hash
def serialize_forward_msg(msg: ForwardMsg) -> bytes:
"""Serialize a ForwardMsg to send to a client.
If the message is too large, it will be converted to an exception message
instead.
"""
populate_hash_if_needed(msg)
msg_str = msg.SerializeToString()
if len(msg_str) > get_max_message_size_bytes():
import streamlit.elements.exception as exception
# Overwrite the offending ForwardMsg.delta with an error to display.
# This assumes that the size limit wasn't exceeded due to metadata.
exception.marshall(msg.delta.new_element.exception,
MessageSizeError(msg_str))
msg_str = msg.SerializeToString()
return msg_str
def serialize_forward_msg(msg: ForwardMsg) -> bytes:
"""Serialize a ForwardMsg to send to a client.
If the message is too large, it will be converted to an exception message
instead.
"""
populate_hash_if_needed(msg)
msg_str = msg.SerializeToString()
if len(msg_str) > MESSAGE_SIZE_LIMIT:
import streamlit.elements.exception as exception
error = RuntimeError(
f"Data of size {len(msg_str)/1e6:.1f}MB exceeds write limit of {MESSAGE_SIZE_LIMIT/1e6}MB"
)
# Overwrite the offending ForwardMsg.delta with an error to display.
# This assumes that the size limit wasn't exceeded due to metadata.
exception.marshall(msg.delta.new_element.exception, error)
msg_str = msg.SerializeToString()
return msg_str
def progress(percent):
progress_msg = ForwardMsg()
progress_msg.upload_report_progress = percent
yield ws.write_message(progress_msg.SerializeToString(),
binary=True)
