@node Spool
@unnumbered Spool directory

Spool directory holds @ref{Encrypted, encrypted packets} received from
remote nodes and queued for sending to them. It has the following
example structure:

@verbatim
spool/tmp/
spool/2WHB...OABQ/rx.lock
spool/2WHB...OABQ/rx/5ZIB...UMKW.part
spool/2WHB...OABQ/tx.lock
spool/BYRR...CG6Q/rx.lock
spool/BYRR...CG6Q/rx/
spool/BYRR...CG6Q/tx.lock
spool/BYRR...CG6Q/tx/NSYY...ZUU6
spool/BYRR...CG6Q/tx/ZI5U...5RRQ
@end verbatim

Except for @code{tmp}, all other directories are Base32-encoded node
identifiers (@code{2WHB...OABQ}, @code{BYRR...CG6Q} in our example).
Each node subdirectory has @code{rx} (received, partly received and
currently unprocessed packets) and @code{tx} (for outbound packets)
directories.

Each @code{rx}/@code{tx} directory contains one file per encrypted
packet. Its filename is Base32 encoded BLAKE2b hash of the contents. So
it can be integrity checked at any time. @code{5ZIB...UMKW.part} is
partly received file from @code{2WHB...OABQ} node. @code{tx} directory
can not contain partly written files -- they are moved atomically from
@code{tmp}.

Only one process can work with @code{rx}/@code{tx} directories at once,
so there are corresponding lock files.