Several backup tasks have been cleaned up / simplified because they no longer need to manage the ‘raw’ structure of the backup. The addition of IBackupFile and its finish() method simplified the log and range writer tasks. Updated BlobStoreEndpoint to support now-required bucket creation and bucket listing prefix/delimiter options for finding common prefixes. Added KeyBackedSet<T> type. Moved JSONDoc to its own header. Added platform::findFilesRecursively().
Still to do: update command line tool to use new IBackupContainer interface, fix bugs in Restore startup.
backtrace() gives a list of return addresses, which means that addr2line will
print out the line after the caller. GetStackTrace returns the list of caller
addresses, so the addr2line results should be accurate. The flow profiler was
also changed to use the new backtracing code, so flow profiles will now be
accurate as well. Unfortunately, the abseil code doesn't work on MacOS, so we
still fall back to backtrace() in this case.
For the stack unwinder to work, we must disable -fomit-frame-pointer. This can
result in a small performance penalty, as it effectively reduces the number of
general purpose registers available by one. (I'm also curious if this has
anything to do with the overly frequent "<value optimized out>" messages from
gdb.) If this shows up as a problem, we can make release builds still have
-fomit-frame-pointer, and fall back to backtrace when it's enabled then as
well.
A.J. Beamon