Unless configured otherwise in named.conf, "rndc dumpdb" causes a cache
dump to be written to a file called "named_dump.db" in the working
directory of the given named instance. Repeatedly using this command
throughout different checks in the cacheclean system test causes cache
dumps for older checks to be overwritten, which hinders failure
diagnosis. Prevent this by moving each cache dump to a check-specific
location after running "rndc dumpdb".
Furthermore, during the "check flushtree clears adb correctly" check,
dump_cache() is called twice without renaming the resulting files.
Prevent the first cache dump from being overwritten by moving it to a
different file before calling "rndc dumpdb" for the second time.
Instead of checking current dnstap output file size and potentially
synchronously calling dns_dt_reopen() upon every call to dns_dt_send():
- call dns_dt_reopen() asynchronously by queuing an event to the task
specified at dnstap environment creation time,
- ensure no roll event is outstanding before checking dnstap output
file size and potentially queuing another roll event.
This causes dnstap output files to exceed their configured size limits,
but prevents any two threads from performing the roll simultaneously
(which causes crashes).
Instead of relying on the caller to set up task-exclusive mode, make
dns_dt_reopen() enforce task-exclusive mode itself, using the task
specified at dnstap environment creation time.
Implement a new variant of dns_dt_create() to enable a dnstap
environment structure to hold the task in the context of which
dns_dt_reopen() will be executed.
