BitcoinTalk

auto backing up of wallet.dat

203
Satoshi-only
BitcoinTalk
#3
From:
satoshi
Subject:
Re: auto backing up of wallet.dat
Date:
I started posting in the other topic but I'll repeat here, this thread seems more specific to the topic.

The main backup improvement will be a pre-generated pool of keys and a rescan at load to scrape missed transactions from the block history.  Then a backup will last forward for a long time.

I was starting to post the same idea you said nelisky.

How about a json-rpc command that locks the wallet, flushes it, copies wallet.dat to a location you specified, then unlocks it?  That would be a smaller project than the pooled keys, so maybe it could be done first.

What's the simplest portable way to copy a file?  Is there something in Boost?

What should it be named?  maybe:
backupwallet <destination>

BitcoinTalk
#6
From:
satoshi
Subject:
Re: auto backing up of wallet.dat
Date:
If you read it into memory and write it out, it could fail in tight memory situations.

I'm looking for something like copyfile(const char* from, const char* to) or copyfile(path from, path to), preferably something in Boost if it has it.  If you find it for me, it's more likely I'll get to implementing it.

Quote from: nelisky on August 26, 2010, 01:21:57 AM
As for the file copy, why add to the boost dependency? I for one would love to get a core lib with very little deps.
We require Boost for JSON and a dozen things replacing dependencies on wxWidgets.  Boost is good, portable stuff, we should not shy away from it.
BitcoinTalk
#9
From:
satoshi
Subject:
Re: auto backing up of wallet.dat
Date:
I doubt there's an mmap(2) on Windows.  I'd rather call an existing file copy function than make and test my own.

Quote from: nelisky on August 27, 2010, 01:21:09 AM
But if you are already using features from boost::filesystem you can use copy_file from that. I just think that, if not already required for something else, it's a tad overkill.
Thanks.  I thought it would be in there somewhere.

We already use boost::filesystem in a dozen places.  It's not a new added dependency.  It gives us a lot of portable stuff that we would otherwise have to have a #ifdef for each OS and test everywhere.
BitcoinTalk
#11
From:
satoshi
Subject:
Re: auto backing up of wallet.dat
Date:
Sorry, I've been so busy lately I've been skimming messages and I still can't keep up.

We want to avoid Windows API calls whenever possible.  They usually take about 6-8 parameters and a lot of testing to get right, it takes a page of code to do something simple.

I usually shy away from iostreams.  Seems like I too often hit limitations.  They kind of botched the C++ streams standard in the 90's, which is too bad, streams can be very powerful and useful when done right.  Using it in rpc.cpp may still turn out to be a mistake.

Bottom line is I'd rather call an existing file copy function than make and test my own.
BitcoinTalk
#12
From:
satoshi
Subject:
Re: auto backing up of wallet.dat
Date:
rpc backupwallet <destination> is in SVN rev 147.