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dcrd v1.6.0-rc2
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pre-release3 years ago

dcrd v1.6.0-rc2

This release of dcrd introduces a large number of updates. Some of the key highlights are:

  • A new consensus vote agenda which allows the stakeholders to decide whether or not to activate support for a decentralized treasury
  • Aggregate fee transaction selection in block templates (Child Pays For Parent)
  • Improved peer discovery via HTTPS seeding with filtering capabilities
  • Major performance enhancements for signature validation and other cryptographic operations
  • Approximately 15% less overall resident memory usage
  • Proactive signature cache eviction
  • Improved support for single-party Schnorr signatures
  • Ticket exhaustion prevention
  • Various updates to the RPC server such as:
    • A new method to retrieve the current treasury balance
    • A new method to query treasury spend transaction vote details
  • Infrastructure improvements
  • Quality assurance changes

For those unfamiliar with the voting process in Decred, all code needed in order to support a decentralized treasury is already included in this release, however it will remain dormant until the stakeholders vote to activate it.

For reference, the decentralized treasury work was originally proposed and approved for initial implementation via the following Politeia proposal:

The following Decred Change Proposal (DCP) describes the proposed changes in detail and provides a full technical specification:

It is important for everyone to upgrade their software to this latest release even if you don't intend to vote in favor of the agenda.

Downgrade Warning

The database format in v1.6.0 is not compatible with previous versions of the software. This only affects downgrades as users upgrading from previous versions will see a one time database migration.

Once this migration has been completed, it will no longer be possible to downgrade to a previous version of the software without having to delete the database and redownload the chain.

The database migration typically takes about 5 to 10 minutes on HDDs and 2 to 4 minutes on SSDs.

Notable Changes

Decentralized Treasury Vote

A new vote with the id treasury is now available as of this release. After upgrading, stakeholders may set their preferences through their wallet or Voting Service Provider's (VSP) website.

The primary goal of this change is to fully decentralize treasury spending so that it is controlled by the stakeholders via ticket voting.

See the initial Politeia proposal for more details.

Aggregate Fee Block Template Transaction Selection (Child Pays For Parent)

The transactions that are selected for inclusion in block templates that Proof-of-Work miners solve now prioritize the overall fees of the entire transaction ancestor graph.

This is beneficial for both miners and end users as it:

  • Helps maximize miner profit by ensuring that unconfirmed transaction chains with higher aggregate fees are given priority over others with lower aggregate fees
  • Provides a mechanism for users to increase the priority of an unconfirmed transaction by spending its outputs with another transaction that pays higher fees

This is commonly referred to as Child Pays For Parent (CPFP) as the spending ("child") transaction is able to increase the priority of the spent ("parent") transaction.

HTTPS Seeding

The initial bootstrap process that contacts seeders to discover other nodes to connect to now uses a REST-based API over HTTPS.

This change will be imperceptible for most users, with the exception that it accelerates the process of finding suitable candidate nodes that support desired services, particularly in the case of recently-introduced services that have not yet achieved widespread adoption on the network.

The following are some key benefits of HTTPS seeders over the previous DNS-based seeders:

  • Support for non-standard ports
  • Advertisement of supported service
  • Better scalability both in terms of network load and new features
  • Native support for TLS-secured communication channels
  • Native support for proxies which allows the use of anonymous overlay networks
    such as Tor and I2P
  • No need for a large DNSSEC dependency surface
  • Uses better audited infrastructure
  • More secure
  • Increases flexibility

Signature Validation And Other Crypto Operation Optimizations

The underlying crypto code has been reworked to significantly improve its execution speed and reduce the number of memory allocations. While this has more benefits than enumerated here, probably the most important ones for most stakeholders are:

  • Improved vote times since blocks and transactions propagate more quickly throughout the network
  • The initial sync process is around 15% faster

Proactive Signature Cache Eviction

Signature cache entries that are nearly guaranteed to no longer be useful are now immediately and proactively evicted resulting in overall faster validation during steady state operation due to fewer cache misses.

The primary purpose of the cache is to avoid double checking signatures that are already known to be valid.

Orphan Transaction Relay Policy Refinement

Transactions that spend outputs which are not known to nodes relaying them, known as orphan transactions, now have the same size restrictions applied to them as standard non-orphan transactions.

This ensures that transactions chains are not artificially hindered from relaying regardless of the order they are received.

In order to keep memory usage of the now potentially larger orphan transactions under control, more intelligent orphan eviction has been implemented and the maximum number of allowed orphans before random eviction occurs has been lowered.

These changes, in conjunction with other related changes, mean that nodes are better about orphan transaction management and thus missing ancestors will typically either be broadcast or mined fairly quickly resulting in fewer overall orphans and smaller actual run-time orphan pools.

Ticket Exhaustion Prevention

Mining templates that would lead to the chain becoming unrecoverable due to inevitable ticket exhaustion will no longer be generated.

This is primarily aimed at the testing networks, but it could also theoretically affect the main network in some far future if the demand for tickets were to ever dry up for some unforeseen reason.

New Initial State Protocol Messages (getinitstate/initstate)

This release introduces a pair of peer-to-peer protocol messages named getinitstate and initstate which support querying one or more pieces of information that are useful to acquire when a node first connects in a consolidated fashion.

Some examples of the aforementioned information are the mining state as of the current tip block and, with the introduction of the decentralized treasury, any outstanding treasury spend transactions that are being voted on.

Mining State Protocol Messages Deprecated (getminings/minings)

Due to the addition of the previously-described initial state peer-to-peer protocol messages, the getminings and minings protocol messages are now deprecated. Use the new getinitstate and initstate messages with the headblocks and headblockvotes state types instead.

RPC Server Changes

The RPC server version as of this release is 6.1.2.

New Treasury Balance Query RPC (gettreasurybalance)

A new RPC named gettreasurybalance is now available to query the current balance of the decentralized treasury. Please note that this requires the decentralized treasury vote to pass and become active, so it will return an appropriate error indicating the decentralized treasury is inactive until that time.

See the gettreasurybalance JSON-RPC API Documentation for API details.

New Treasury Spend Vote Query RPC (gettreasuryspendvotes)

A new RPC named gettreasuryspendvotes is now available to query vote information about one or more treasury spend transactions. Please note that this requires the decentralized treasury vote to pass and become active to produce a meaningful result since treasury spend transactions are invalid until that time.

See the gettreasuryspendvotes JSON-RPC API Documentation for API details.

New Force Mining Template Regeneration RPC (regentemplate)

A new RPC named regentemplate is now available which can be used to force the current background block template to be regenerated.

See the regentemplate JSON-RPC API Documentation for API details.

New Unspent Transaction Output Set Query RPC (gettxoutsetinfo)

A new RPC named gettxoutsetinfo is now available which can be used to retrieve statistics about the current global set of unspent transaction outputs (UTXOs).

See the gettxoutsetinfo JSON-RPC API Documentation for API details.

Updates to Peer Information Query RPC (getpeerinfo)

The results of the getpeerinfo RPC are now sorted by the id field.

See the getpeerinfo JSON-RPC API Documentation for API details.

Enforced Results Limit on Transaction Search RPC (searchrawtransactions)

The maximum number of transactions returned by a single request to the searchrawtransactions RPC is now limited to 10,000 transactions. This far exceeds the number of results for all typical cases; however, for the rare cases where it does not, the caller can make use of the skip parameter in subsequent requests to access additional data if they require access to more results.

See the searchrawtransactions JSON-RPC API Documentation for API details.

New Index Status Fields on Info Query RPC (getinfo)

The results of the getinfo RPC now include txindex and addrindex fields that specify whether or not the respective indexes are active.

See the getinfo JSON-RPC API Documentation for API details.

Version 1 Block Filters Deprecated

Support for version 1 block filters is deprecated and is scheduled to be removed in the next release. Use version 2 block filters with their associated block header commitment and inclusion proof instead.

Changelog

This release consists of 614 commits from 17 contributors which total to 525 files changed, 62548 additional lines of code, and 26153 deleted lines of code.

All commits since the last release may be viewed on GitHub here.

Protocol and network:

Transaction relay (memory pool):

Mining:

RPC:

dcrd command-line flags and configuration:

gencerts utility changes:

dcrctl utility changes:

Documentation:

Developer-related package and module changes:

Developer-related module management:

Testing and Quality Assurance:

Misc:

Code Contributors (alphabetical order):

  • Brian Stafford
  • Dave Collins
  • David Hill
  • degeri
  • Donald Adu-Poku
  • Jamie Holdstock
  • Joe Gruffins
  • Josh Rickmar
  • Julian Yap
  • Marco Peereboom
  • Matheus Degiovani
  • Matt Hawkins
  • Ryan Riley
  • Ryan Staudt
  • Wisdom Arerosuoghene
  • Youssef Boukenken
  • zhizhongzhiwai
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