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RE: BlockTrades Steem wallet is operational again
Okay. I hope they do it quickly and release some information concerning what actually happened that kept the blockchain down for some days. Really scary!
I believe a new function called approximate_square_root was used from a library commonly used by steem (the library is called "fc"). It was assumed that this function can only return positive values (like a true square root function). But apparently under some input conditions, it could return a negative number. This negative number in turn managed to trigger a protective check in the code that prevents bad math from happening by stopping block processing.
At first, you might wonder why a "protective check" stops blockchain processing, but it's a good idea to have these checks. These checks prevent generating bad state data or other unintended consequences that could result in money transactions being processed incorrectly.
Thanks for this explanation.
Thats great to know! Can you show us which line of code do this? Just wondering.
Looking at the public steem repo, I think the "quick fix" was here: https://github.com/steemit/steem/commit/587574f7aefd030ac440df853e00263a4d92c610
But there's active commits going on now, so if I had to guess, I would guess they are looking at creating a more elegant solution. But that's pure speculation on my part as I haven't reviewed any of those changes yet.