Merge #7800: [0.12] Update release notes
e10c044 [0.12] Update release notes (BtcDrak)This commit is contained in:
Wladimir J. van der Laan
commit
e3341aa94e
@ -35,7 +35,108 @@ earlier.
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Notable changes
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===============
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The p2p alert system is off by default. To turn on, use `-alert` with startup configuration.
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First version bits BIP9 softfork deployment
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-------------------------------------------
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This release includes a soft fork deployment to enforce [BIP68][],
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[BIP112][] and [BIP113][] using the [BIP9][] deployment mechanism.
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The deployment sets the block version number to 0x20000001 between
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midnight 1st May 2016 and midnight 1st May 2017 to signal readiness for
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deployment. The version number consists of 0x20000000 to indicate version
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bits together with setting bit 0 to indicate support for this combined
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deployment, shown as "csv" in the `getblockchaininfo` RPC call.
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For more information about the soft forking change, please see
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<https://github.com/bitcoin/bitcoin/pull/7648>
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This specific backport pull-request can be viewed at
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<https://github.com/bitcoin/bitcoin/pull/7543>
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[BIP9]: https://github.com/bitcoin/bips/blob/master/bip-0009.mediawiki
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[BIP68]: https://github.com/bitcoin/bips/blob/master/bip-0068.mediawiki
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[BIP112]: https://github.com/bitcoin/bips/blob/master/bip-0112.mediawiki
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BIP68 soft fork to enforce sequence locks for relative locktime
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---------------------------------------------------------------
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[BIP68][] introduces relative lock-time consensus-enforced semantics of
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the sequence number field to enable a signed transaction input to remain
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invalid for a defined period of time after confirmation of its corresponding
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outpoint.
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For more information about the implementation, see
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<https://github.com/bitcoin/bitcoin/pull/7184>
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BIP112 soft fork to enforce OP_CHECKSEQUENCEVERIFY
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--------------------------------------------------
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[BIP112][] redefines the existing OP_NOP3 as OP_CHECKSEQUENCEVERIFY (CSV)
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for a new opcode in the Bitcoin scripting system that in combination with
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[BIP68][] allows execution pathways of a script to be restricted based
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on the age of the output being spent.
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For more information about the implementation, see
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<https://github.com/bitcoin/bitcoin/pull/7524>
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BIP113 locktime enforcement soft fork
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-------------------------------------
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Bitcoin Core 0.11.2 previously introduced mempool-only locktime
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enforcement using GetMedianTimePast(). This release seeks to
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consensus enforce the rule.
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Bitcoin transactions currently may specify a locktime indicating when
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they may be added to a valid block. Current consensus rules require
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that blocks have a block header time greater than the locktime specified
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in any transaction in that block.
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Miners get to choose what time they use for their header time, with the
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consensus rule being that no node will accept a block whose time is more
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than two hours in the future. This creates a incentive for miners to
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set their header times to future values in order to include locktimed
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transactions which weren't supposed to be included for up to two more
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hours.
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The consensus rules also specify that valid blocks may have a header
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time greater than that of the median of the 11 previous blocks. This
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GetMedianTimePast() time has a key feature we generally associate with
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time: it can't go backwards.
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[BIP113][] specifies a soft fork enforced in this release that
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weakens this perverse incentive for individual miners to use a future
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time by requiring that valid blocks have a computed GetMedianTimePast()
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greater than the locktime specified in any transaction in that block.
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Mempool inclusion rules currently require transactions to be valid for
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immediate inclusion in a block in order to be accepted into the mempool.
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This release begins applying the BIP113 rule to received transactions,
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so transaction whose time is greater than the GetMedianTimePast() will
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no longer be accepted into the mempool.
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**Implication for miners:** you will begin rejecting transactions that
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would not be valid under BIP113, which will prevent you from producing
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invalid blocks when BIP113 is enforced on the network. Any
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transactions which are valid under the current rules but not yet valid
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under the BIP113 rules will either be mined by other miners or delayed
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until they are valid under BIP113. Note, however, that time-based
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locktime transactions are more or less unseen on the network currently.
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**Implication for users:** GetMedianTimePast() always trails behind the
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current time, so a transaction locktime set to the present time will be
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rejected by nodes running this release until the median time moves
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forward. To compensate, subtract one hour (3,600 seconds) from your
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locktimes to allow those transactions to be included in mempools at
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approximately the expected time.
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For more information about the implementation, see
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<https://github.com/bitcoin/bitcoin/pull/6566>
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Miscellaneous
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-------------
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The p2p alert system is off by default. To turn on, use `-alert` with
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startup configuration.
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0.12.1 Change log
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=================
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