The FILE_XFER class encapsulates a single transfer session to a particular data server. If the file has previously partially transferred, FILE_XFER resumes at the appropriate point.
The PERS_FILE_XFER class encapsulates a persistent file transfer, which may involve a sequence of FILE_XFERs, possibly to different data servers.
When a file is involved in a persistent file transfer,
the state is saved in the client state file
in the following XML element
(included in the
When there is a transient failure, the core client
increments num_retries and calculates a new next_request_time
based on randomized exponential backoff, given by
The client classifies the transfer as a permanent failure if the
current time becomes much later than this (default is two weeks).
??? later than what?
In this event, the file will be deleted and the failure reported
to the scheduling server.
??? in what form?
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<persistent_file_xfer>
<num_retries>2</num_retries>
<first_request_time>1030665600</first_request_time>
<next_request_time>1030665725</next_request_time>
</persistent_file_xfer>
next_request_time = current_time+max(MIN_DELAY,min(MAX_DELAY,exp(rand(0,1)*num_retries)))
Where MIN_DELAY is 1 minute and MAX_DELAY is 4 hours.