* This is safer than DB_TXN_NOSYNC, and does not appear to impact
performance.
* Applying this to the dbenv is necessary to avoid many fdatasync(2)
calls on db 5.x
* We carefully and thoroughly flush databases upon shutdown and
other important events already.
The best log rotation method formerly available was to configure
logrotate with the copytruncate option. As described in the logrotate
documentation, "there is a very small time slice between copying the
file and truncating it, so some logging data might be lost".
By sending SIGHUP to the server process, one can now reopen the debug
log file without losing any data.
Acquire an exclusive, advisory lock before sending output to debug.log
and release it when we're done. This should avoid output from multiple
threads being interspersed in the log file.
We can't use CRITICAL_SECTION machinery for this because the debug log
is written during startup and shutdown when that machinery is not
available.
(Thanks to Gavin for pointing out the CRITICAL_SECTION problems based
on his earlier work in this area)
Create a maximum-10MB signature verification result cache.
This should almost double the number of transactions that
can be processed on a given CPU, because before this change
ECDSA signatures were verified when transactions were added
to the memory pool and then again when they appeared in
a block.
Loop over all inputs doing inexpensive validity checks first,
and then loop over them a second time doing expensive signature
checks. This helps prevent possible CPU exhaustion attacks
where an attacker tries to make a victim waste time checking
signatures for invalid transactions.
Remove orphan transactions from memory once
all of their parent transactions are received
and they're still not valid.
Thanks to Sergio Demian Lerner for suggesting this fix.
Old log message:
storing orphan tx df2244f6bc
New log message:
storing orphan tx df2244f6bc (mapsz 51)
Also, trim a few trailing whitespace in main.cpp.
Immediately issue a "getblocks", instead of a "getdata" (which will
trigger the relevant "inv" to be sent anyway), and only do so when
the previous set of invs led us into a known and attached part of
the block tree.
As noticed by sipa (Pieter Wuille), this can happen when CBigNum::setint64() is
called with an integer value of INT64_MIN (-2^63).
When compiled with -ftrapv, the program would crash. Otherwise, it would
execute an undefined operation (although in practice, usually the correct one).
One of the test cases currently aborts when using gcc's flag -ftrapv, due to
negating an INT64_MIN int64 variable, which is an undefined operation.
This will be fixed in a subsequent commit.
CBigNum::setint64() does 'n <<= 8', where n is of type "long long".
This leads to shifting onto and past the sign bit, which is undefined
behavior in C++11 and can cause problems in the future.
This prevents an undefined operation in main.cpp, when shifting the hash value
left by 32 bits.
Shifting a signed int left into the sign bit is undefined in C++11.
Jeff Garzik