Version bits with timeout and delay

en · official · sha256:1956e0f8dd219961680ee88af672264798d0d3b99ef26df11b0d19ff8d53232b

With each block and soft fork, we associate a deployment state. The possible states are: # '''DEFINED''' is the first state that each soft fork starts out as. The genesis block is by definition in this state for each deployment. # '''STARTED''' for blocks past the starttime. # '''LOCKED_IN''' for one retarget period after the first retarget period with STARTED blocks of which at least threshold have the associated bit set in nVersion. # '''ACTIVE''' for all blocks after the LOCKED_IN retarget period. # '''FAILED''' for one retarget period past the timeout time, if LOCKED_IN was not reached.

Referencing norms: Bip9Activation, Bip9Activation/ActivateAfterLockedInPeriod, Bip9Activation/Active, Bip9Activation/Defined, Bip9Activation/FailAtTimeout, Bip9Activation/FailBeforeStart, Bip9Activation/Failed, Bip9Activation/LockInAtNinetyFivePercent, Bip9Activation/LockedIn, Bip9Activation/Start, Bip9Activation/Started, Bip9ActivationState, Bip9ActivationStep, Bip9ActivationTransition, Bip9State, Deployment, attempted_transition, bip9_current_locked_in_period_elapsed, bip9_current_period_boundary, bip9_period_boundary, current_state, entered_state, initial_state, left_state, one_locked_in_retarget_period_elapsed, procedure_instance, state_before, valid_transition

en · official · sha256:31c540c27079f3efbf0add3344f0cc63754745bac4779f40f665ac50321103b6

All blocks within a retarget period have the same state. This means that if floor(block1.height / 2016) = floor(block2.height / 2016), they are guaranteed to have the same state for every deployment. if ((block.height % 2016) != 0) { return GetStateForBlock(block.parent); } Otherwise, the next state depends on the previous state: switch (GetStateForBlock(GetAncestorAtHeight(block, block.height - 2016))) { We remain in the initial state until either we pass the start time or the timeout. GetMedianTimePast in the code below refers to the median nTime of a block and its 10 predecessors. The expression GetMedianTimePast(block.parent) is referred to as MTP in the diagram above, and is treated as a monotonic clock defined by the chain. case DEFINED: if (GetMedianTimePast(block.parent) >= timeout) { return FAILED; } if (GetMedianTimePast(block.parent) >= starttime) { return STARTED; } return DEFINED; After a period in the STARTED state, if we're past the timeout, we switch to FAILED. If not, we tally the bits set, and transition to LOCKED_IN if a sufficient number of blocks in the past period set the deployment bit in their version numbers. The threshold is ≥1916 blocks (95% of 2016), or ≥1512 for testnet (75% of 2016).

Referencing norms: BIP9ThresholdIsNinetyFivePercentOf2016, Bip9Activation, Bip9Activation/ActivateAfterLockedInPeriod, Bip9Activation/Active, Bip9Activation/Defined, Bip9Activation/FailAtTimeout, Bip9Activation/FailBeforeStart, Bip9Activation/Failed, Bip9Activation/LockInAtNinetyFivePercent, Bip9Activation/LockedIn, Bip9Activation/Start, Bip9Activation/Started, Bip9ActivationState, Bip9ActivationStep, Bip9ActivationTransition, Deployment, attempted_transition, bip9_current_period_boundary, bip9_current_period_start_time_reached, bip9_current_period_threshold_met, bip9_current_period_timeout_reached, bip9_mainnet_threshold_met, bip9_period_boundary, current_state, deployment_start_time_reached, deployment_timeout_reached, entered_state, initial_state, left_state, procedure_instance, signals_in_2016_block_period, state_before, valid_transition