I thought I'd transplant Gavin's post to here, rather than derail the original thread.
What's the timeline for enabling relaying of OP_EVAL transactions and for a client that can generate OP_EVAL transactions?
Good question. The timeline for clients is less critical, as long as a majority of hashing power will properly interpret OP_EVAL clients that relay/generate those transactions can be rolled out anytime after Feb 1.What's the timeline for enabling relaying of OP_EVAL transactions and for a client that can generate OP_EVAL transactions?
So I'd suggest releasing a 0.5.something or 0.6 after the Jan 15 "are the big miners on board" evaluation that turns on OP_EVAL support Feb 1.
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Also, when will clients be patched to start rejecting blocks with the OP_NOP1 interpretation of OP_EVAL?
Same time.
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I presume that, if all goes well, then on the 1st of Feb 2012, blocks containing OP_EVAL will suddenly be interpreted in the new stricter fashion than when it was OP_NOP1. We know that GetTime() seems to return widely disparate results over the bitcoin network. Are we confident that problems are not going to arise because of the pseudorandomly timed nature of the change of interpretation of the opcode?
Another very good question. The timestamp in the block will be used to determine whether OP_NOP1s in the block are interpreted as no-ops or OP_EVAL when checking block validitity (wall-clock GMT time will be used to figure out if the node should relay/mine OP_EVAL transactions). I'll double-check my code, I think I did NOT code it that way.
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Majority hashpower support for OP_EVAL is required before changeover. It's conceivable that something might go wrong after OP_EVAL transactions are mainstream which might make miners revert to interpreting OP_EVAL as OP_NOP1. If OP_EVAL loses majority hashpower support then the bitcoin system keeps going but with considerable damage to reputation, prospects and some people's wallets.
Has there been any consideration of this possibility?
Has there been any consideration of this possibility?
That seems exceedingly unlikely; once the big mining pools switch, there is a very strong incentive for the smaller pools to switch, too.