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kevacoin/doc/litecoin-release-notes/release-notes-0.14.2.md

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Kevacoin Core version 0.14.2 is now available from:

https://download.kevacoin.org/kevacoin-0.14.2.0/

This is a new major version release, including new features, various bugfixes and performance improvements, as well as updated translations.

Please report bugs using the issue tracker at github:

https://github.com/kevacoin-project/kevacoin/issues

To receive security and update notifications, please subscribe to:

https://groups.google.com/forum/#!forum/kevacoin-dev

Compatibility

Kevacoin Core is extensively tested on multiple operating systems using the Linux kernel, macOS 10.8+, and Windows Vista and later.

Microsoft ended support for Windows XP on April 8th, 2014, No attempt is made to prevent installing or running the software on Windows XP, you can still do so at your own risk but be aware that there are known instabilities and issues. Please do not report issues about Windows XP to the issue tracker.

Kevacoin Core should also work on most other Unix-like systems but is not frequently tested on them.

Notable changes

New Multisig Address Prefix

Kevacoin Core now supports P2SH addresses beginning with M on mainnet and Q on testnet. P2SH addresses beginning with 3 on mainnet and m or n on testnet will continue to be valid. Old and new addresses can be used interchangeably.

miniupnp CVE-2017-8798

Bundled miniupnpc was updated to 2.0.20170509. This fixes an integer signedness error (present in MiniUPnPc v1.4.20101221 through v2.0) that allows remote attackers (within the LAN) to cause a denial of service or possibly have unspecified other impact.

This only affects users that have explicitly enabled UPnP through the GUI setting or through the -upnp option, as since the last UPnP vulnerability (in Kevacoin Core 0.10.4) it has been disabled by default.

If you use this option, it is recommended to upgrade to this version as soon as possible.

Reset Testnet

Testnet3 has been deprecated and replaced with Testnet4. The server port has been changed to 19335 however the RPC port remains the same (19332).

Testnet faucets can be located at:

Developers who require the new testnet blockchain paramaters can find them here.

Performance Improvements

Validation speed and network propagation performance have been greatly improved, leading to much shorter sync and initial block download times.

  • The script signature cache has been reimplemented as a "cuckoo cache", allowing for more signatures to be cached and faster lookups.
  • Assumed-valid blocks have been introduced which allows script validation to be skipped for ancestors of known-good blocks, without changing the security model. See below for more details.
  • In some cases, compact blocks are now relayed before being fully validated as per BIP152.
  • P2P networking has been refactored with a focus on concurrency and throughput. Network operations are no longer bottlenecked by validation. As a result, block fetching is several times faster than previous releases in many cases.
  • The UTXO cache now claims unused mempool memory. This speeds up initial block download as UTXO lookups are a major bottleneck there, and there is no use for the mempool at that stage.

Manual Pruning

Kevacoin Core has supported automatically pruning the blockchain since 0.13.2. Pruning the blockchain allows for significant storage space savings as the vast majority of the downloaded data can be discarded after processing so very little of it remains on the disk.

Manual block pruning can now be enabled by setting -prune=1. Once that is set, the RPC command pruneblockchain can be used to prune the blockchain up to the specified height or timestamp.

getinfo Deprecated

The getinfo RPC command has been deprecated. Each field in the RPC call has been moved to another command's output with that command also giving additional information that getinfo did not provide. The following table shows where each field has been moved to:

getinfo field Moved to
"version" getnetworkinfo()["version"]
"protocolversion" getnetworkinfo()["protocolversion"]
"walletversion" getwalletinfo()["walletversion"]
"balance" getwalletinfo()["balance"]
"blocks" getblockchaininfo()["blocks"]
"timeoffset" getnetworkinfo()["timeoffset"]
"connections" getnetworkinfo()["connections"]
"proxy" getnetworkinfo()["networks"][0]["proxy"]
"difficulty" getblockchaininfo()["difficulty"]
"testnet" getblockchaininfo()["chain"] == "test"
"keypoololdest" getwalletinfo()["keypoololdest"]
"keypoolsize" getwalletinfo()["keypoolsize"]
"unlocked_until" getwalletinfo()["unlocked_until"]
"paytxfee" getwalletinfo()["paytxfee"]
"relayfee" getnetworkinfo()["relayfee"]
"errors" getnetworkinfo()["warnings"]

ZMQ On Windows

Previously the ZeroMQ notification system was unavailable on Windows due to various issues with ZMQ. These have been fixed upstream and now ZMQ can be used on Windows. Please see this document for help with using ZMQ in general.

Nested RPC Commands in Debug Console

The ability to nest RPC commands has been added to the debug console. This allows users to have the output of a command become the input to another command without running the commands separately.

The nested RPC commands use bracket syntax (i.e. getwalletinfo()) and can be nested (i.e. getblock(getblockhash(1))). Simple queries can be done with square brackets where object values are accessed with either an array index or a non-quoted string (i.e. listunspent()[0][txid]). Both commas and spaces can be used to separate parameters in both the bracket syntax and normal RPC command syntax.

Network Activity Toggle

A RPC command and GUI toggle have been added to enable or disable all p2p network activity. The network status icon in the bottom right hand corner is now the GUI toggle. Clicking the icon will either enable or disable all p2p network activity. If network activity is disabled, the icon will be grayed out with an X on top of it.

Additionally the setnetworkactive RPC command has been added which does the same thing as the GUI icon. The command takes one boolean parameter, true enables networking and false disables it.

Out-of-sync Modal Info Layer

When Kevacoin Core is out-of-sync on startup, a semi-transparent information layer will be shown over top of the normal display. This layer contains details about the current sync progress and estimates the amount of time remaining to finish syncing. This layer can also be hidden and subsequently unhidden by clicking on the progress bar at the bottom of the window.

Support for JSON-RPC Named Arguments

Commands sent over the JSON-RPC interface and through the kevacoin-cli binary can now use named arguments. This follows the JSON-RPC specification for passing parameters by-name with an object.

kevacoin-cli has been updated to support this by parsing name=value arguments when the -named option is given.

Some examples:

src/kevacoin-cli -named help command="help"
src/kevacoin-cli -named getblockhash height=0
src/kevacoin-cli -named getblock blockhash=000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
src/kevacoin-cli -named sendtoaddress address="(snip)" amount="1.0" subtractfeefromamount=true

The order of arguments doesn't matter in this case. Named arguments are also useful to leave out arguments that should stay at their default value. The rarely-used arguments comment and comment_to to sendtoaddress, for example, can be left out. However, this is not yet implemented for many RPC calls, this is expected to land in a later release.

The RPC server remains fully backwards compatible with positional arguments.

Sensitive Data Is No Longer Stored In Debug Console History

The debug console maintains a history of previously entered commands that can be accessed by pressing the Up-arrow key so that users can easily reuse previously entered commands. Commands which have sensitive information such as passphrases and private keys will now have a (...) in place of the parameters when accessed through the history.

Retaining the Mempool Across Restarts

The mempool will be saved to the data directory prior to shutdown to a mempool.dat file. This file preserves the mempool so that when the node restarts the mempool can be filled with transactions without waiting for new transactions to be created. This will also preserve any changes made to a transaction through commands such as prioritisetransaction so that those changes will not be lost.

Final Alert

The Alert System was disabled and deprecated in Kevacoin Core 0.10.4 and removed in 0.13.2. The Alert System was retired with a maximum sequence final alert which causes any nodes supporting the Alert System to display a static hard-coded "Alert Key Compromised" message which also prevents any other alerts from overriding it. This final alert is hard-coded into this release so that all old nodes receive the final alert.

GUI Changes

  • After resetting the options by clicking the Reset Options button in the options dialog or with the -resetguioptions startup option, the user will be prompted to choose the data directory again. This is to ensure that custom data directories will be kept after the option reset which clears the custom data directory set via the choose datadir dialog.

  • Multiple peers can now be selected in the list of peers in the debug window. This allows for users to ban or disconnect multiple peers simultaneously instead of banning them one at a time.

  • An indicator has been added to the bottom right hand corner of the main window to indicate whether the wallet being used is a HD wallet. This icon will be grayed out with an X on top of it if the wallet is not a HD wallet.

Low-level RPC changes

  • importprunedfunds only accepts two required arguments. Some versions accept an optional third arg, which was always ignored. Make sure to never pass more than two arguments.

  • The first boolean argument to getaddednodeinfo has been removed. This is an incompatible change.

  • RPC command getmininginfo loses the "testnet" field in favor of the more generic "chain" (which has been present for years).

  • A new RPC command preciousblock has been added which marks a block as precious. A precious block will be treated as if it were received earlier than a competing block.

  • A new RPC command importmulti has been added which receives an array of JSON objects representing the intention of importing a public key, a private key, an address and script/p2sh

  • Use of getrawtransaction for retrieving confirmed transactions with unspent outputs has been deprecated. For now this will still work, but in the future it may change to only be able to retrieve information about transactions in the mempool or if txindex is enabled.

  • A new RPC command getmemoryinfo has been added which will return information about the memory usage of Kevacoin Core. This was added in conjunction with optimizations to memory management. See Pull #8753 for more information.

  • A new RPC command bumpfee has been added which allows replacing an unconfirmed wallet transaction that signaled RBF (see the -walletrbf startup option above) with a new transaction that pays a higher fee, and should be more likely to get confirmed quickly.

  • The first positional argument of createrawtransaction was renamed from transactions to inputs.

  • The argument of disconnectnode was renamed from node to address.

Client software using these calls with named arguments needs to be updated.

HTTP REST Changes

  • UTXO set query (GET /rest/getutxos/<checkmempool>/<txid>-<n>/<txid>-<n> /.../<txid>-<n>.<bin|hex|json>) responses were changed to return status code HTTP_BAD_REQUEST (400) instead of HTTP_INTERNAL_SERVER_ERROR (500) when requests contain invalid parameters.

Minimum Fee Rate Policies

Since the changes in 0.13 to automatically limit the size of the mempool and improve the performance of block creation in mining code it has not been important for relay nodes or miners to set -minrelaytxfee. With this release the following concepts that were tied to this option have been separated out:

  • calculation of threshold for a dust output. (effectively 3 * 1000 satoshis/kB)
  • minimum fee rate of a package of transactions to be included in a block created by the mining code. If miners wish to set this minimum they can use the new -blockmintxfee option. (defaults to 1000 satoshis/kB)

The -minrelaytxfee option continues to exist but is recommended to be left unset.

Fee Estimation Changes

  • Since 0.13.2 fee estimation for a confirmation target of 1 block has been disabled. The fee slider will no longer be able to choose a target of 1 block. This is only a minor behavior change as there was often insufficient data for this target anyway. estimatefee 1 will now always return -1 and estimatesmartfee 1 will start searching at a target of 2.

  • The default target for fee estimation is changed to 6 blocks in both the GUI (previously 25) and for RPC calls (previously 2).

Removal of Priority Estimation

  • Estimation of "priority" needed for a transaction to be included within a target number of blocks has been removed. The RPC calls are deprecated and will either return -1 or 1e24 appropriately. The format for fee_estimates.dat has also changed to no longer save these priority estimates. It will automatically be converted to the new format which is not readable by prior versions of the software.

  • Support for "priority" (coin age) transaction sorting for mining is considered deprecated in Core and will be removed in the next major version. This is not to be confused with the prioritisetransaction RPC which will remain supported by Core for adding fee deltas to transactions.

P2P connection management

  • Peers manually added through the -addnode option or addnode RPC now have their own limit of eight connections which does not compete with other inbound or outbound connection usage and is not subject to the limitation imposed by the -maxconnections option.

  • New connections to manually added peers are performed more quickly.

Introduction of assumed-valid blocks

  • A significant portion of the initial block download time is spent verifying scripts/signatures. Although the verification must pass to ensure the security of the system, no other result from this verification is needed: If the node knew the history of a given block were valid it could skip checking scripts for its ancestors.

  • A new configuration option 'assumevalid' is provided to express this knowledge to the software. Unlike the 'checkpoints' in the past this setting does not force the use of a particular chain: chains that are consistent with it are processed quicker, but other chains are still accepted if they'd otherwise be chosen as best. Also unlike 'checkpoints' the user can configure which block history is assumed true, this means that even outdated software can sync more quickly if the setting is updated by the user.

  • Because the validity of a chain history is a simple objective fact it is much easier to review this setting. As a result the software ships with a default value adjusted to match the current chain shortly before release. The use of this default value can be disabled by setting -assumevalid=0

Fundrawtransaction change address reuse

  • Before 0.14, fundrawtransaction was by default wallet stateless. In almost all cases fundrawtransaction does add a change-output to the outputs of the funded transaction. Before 0.14, the used keypool key was never marked as change-address key and directly returned to the keypool (leading to address reuse). Before 0.14, calling getnewaddress directly after fundrawtransaction did generate the same address as the change-output address.

  • Since 0.14, fundrawtransaction does reserve the change-output-key from the keypool by default (optional by setting reserveChangeKey, default = true)

  • Users should also consider using getrawchangeaddress() in conjunction with fundrawtransaction's changeAddress option.

Unused mempool memory used by coincache

  • Before 0.14, memory reserved for mempool (using the -maxmempool option) went unused during initial block download, or IBD. In 0.14, the UTXO DB cache (controlled with the -dbcache option) borrows memory from the mempool when there is extra memory available. This may result in an increase in memory usage during IBD for those previously relying on only the -dbcache option to limit memory during that time.

Mining

In previous versions, getblocktemplate required segwit support from downstream clients/miners once the feature activated on the network. In this version, it now supports non-segwit clients even after activation, by removing all segwit transactions from the returned block template. This allows non-segwit miners to continue functioning correctly even after segwit has activated.

Due to the limitations in previous versions, getblocktemplate also recommended non-segwit clients to not signal for the segwit version-bit. Since this is no longer an issue, getblocktemplate now always recommends signalling segwit for all miners. This is safe because ability to enforce the rule is the only required criteria for safe activation, not actually producing segwit-enabled blocks.

UTXO memory accounting

Memory usage for the UTXO cache is being calculated more accurately, so that the configured limit (-dbcache) will be respected when memory usage peaks during cache flushes. The memory accounting in prior releases is estimated to only account for half the actual peak utilization.

The default -dbcache has also been changed in this release to 450MiB. Users who currently set -dbcache to a high value (e.g. to keep the UTXO more fully cached in memory) should consider increasing this setting in order to achieve the same cache performance as prior releases. Users on low-memory systems (such as systems with 1GB or less) should consider specifying a lower value for this parameter.

Additional information relating to running on low-memory systems can be found here, originally written for Bitcoin but can also be used for Kevacoin: reducing-bitcoind-memory-usage.md.

Credits

Thanks to everyone who directly contributed to this release: