4db689e691
This commit contains a complete redesign and rewrite of the database
package that approaches things in a vastly different manner than the
previous version. This is the first part of several stages that will be
needed to ultimately make use of this new package.
A quick summary of the changes is as follows:
- The previous database could only contain blocks on the main chain and
reorgs required deleting the blocks from the database. This made it
impossible to store orphans and could make external RPC calls for
information about blocks during the middle of a reorg fail.
- The previous database interface forced a high level of coin-specific
intelligence such as spend tracking into each backend driver.
- The aforementioned point led to making it difficult to implement new
backend drivers due to the need to repeat a lot of non-trivial logic
which is better handled at a higher layer, such as the blockchain
package.
- The old database stored all blocks in leveldb. This made it extremely
inefficient to do things such as lookup headers and individual
transactions since the entire block had to be loaded from leveldb (which
entails it doing data copies) to get access.
In order to address all of these concerns, and others not mentioned, the
database interface has been redesigned as follows:
- Two main categories of functionality are provided: block storage and
metadata storage
- All block storage and metadata storage are done via read-only and
read-write MVCC transactions with both manual and managed modes
- Support for multiple concurrent readers and a single writer
- Readers use a snapshot and therefore are not blocked by the writer
- Some key properties of the block storage and retrieval API:
- It is generic and does NOT contain additional coin logic such spend
tracking and block linking
- Provides access to the raw serialized bytes so deserialization is not
forced for callers that don't need it
- Support for fetching headers via independent functions which allows
implementations to provide significant optimizations
- Ability to efficiently retrieve arbitrary regions of blocks
(transactions, scripts, etc)
- A rich metadata storage API is provided:
- Key/value with arbitrary data
- Support for buckets and nested buckets
- Bucket iteration through a couple of different mechanisms
- Cursors for efficient and direct key seeking
- Supports registration of backend database implementations
- Comprehensive test coverage
- Provides strong documentation with example usage
This commit also contains an implementation of the previously discussed
interface named ffldb (flat file plus leveldb metadata backend). Here
is a quick overview:
- Highly optimized for read performance with consistent write performance
regardless of database size
- All blocks are stored in flat files on the file system
- Bulk block region fetching is optimized to perform linear reads which
improves performance on spindle disks
- Anti-corruption mechanisms:
- Flat files contain full block checksums to quickly an easily detect
database corruption without needing to do expensive merkle root
calculations
- Metadata checksums
- Open reconciliation
- Extensive test coverage:
- Comprehensive blackbox interface testing
- Whitebox testing which uses intimate knowledge to exercise uncommon
failure paths such as deleting files out from under the database
- Corruption tests (replacing random data in the files)
In addition, this commit also contains a new tool under the new database
directory named dbtool which provides a few basic commands for testing the
database. It is designed around commands, so it could be useful to expand
on in the future.
|
||
|---|---|---|
| addrmgr | ||
| blockchain | ||
| chaincfg | ||
| cmd | ||
| database | ||
| database2 | ||
| dcrec | ||
| dcrjson | ||
| docs | ||
| limits | ||
| peer | ||
| release | ||
| txscript | ||
| wire | ||
| .gitignore | ||
| .travis.yml | ||
| blocklogger.go | ||
| blockmanager.go | ||
| chainindexer.go | ||
| CHANGES | ||
| config.go | ||
| cpuminer.go | ||
| dcrd.go | ||
| deps.txt | ||
| discovery.go | ||
| doc.go | ||
| goclean.sh | ||
| LICENSE | ||
| log.go | ||
| mempool.go | ||
| mempoolerror.go | ||
| mining_test.go | ||
| mining.go | ||
| miningerror.go | ||
| mrunoncemap_test.go | ||
| mrunoncemap.go | ||
| params.go | ||
| policy_test.go | ||
| policy.go | ||
| README.md | ||
| rpcserver.go | ||
| rpcserverhelp_test.go | ||
| rpcserverhelp.go | ||
| rpcwebsocket.go | ||
| sample-dcrd.conf | ||
| server.go | ||
| service_windows.go | ||
| signal.go | ||
| signalsigterm.go | ||
| upgrade.go | ||
| upnp.go | ||
| version.go | ||
dcrd
[
]
(https://travis-ci.org/decred/dcrd) ![ISC License]
(http://img.shields.io/badge/license-ISC-blue.svg)
dcrd is a Decred full node implementation written in Go (golang).
This project is currently under active development and is in a Beta state. It is extremely stable and has been in production use for over 6 months as of May 2014, however there are still a couple of major features we want to add before we come out of beta.
It properly downloads, validates, and serves the block chain using the exact rules (including bugs) for block acceptance as Bitcoin Core. We have taken great care to avoid dcrd causing a fork to the block chain. It passes all of the 'official' block acceptance tests (https://github.com/TheBlueMatt/test-scripts) as well as all of the JSON test data in the Bitcoin Core code.
It also relays newly mined blocks, maintains a transaction pool, and relays individual transactions that have not yet made it into a block. It ensures all transactions admitted to the pool follow the rules required by the block chain and also includes the same checks which filter transactions based on miner requirements ("standard" transactions) as Bitcoin Core.
One key difference between dcrd and Bitcoin Core is that dcrd does NOT include wallet functionality and this was a very intentional design decision. See the blog entry here for more details. This means you can't actually make or receive payments directly with dcrd. That functionality is provided by the dcrwallet and btcgui projects which are both under active development.
Requirements
Go 1.3 or newer.
Installation
Windows - MSI Available
https://github.com/decred/dcrd/releases
Linux/BSD/MacOSX/POSIX - Build from Source
-
Install Go according to the installation instructions here: http://golang.org/doc/install
-
Ensure Go was installed properly and is a supported version:
$ go version
$ go env GOROOT GOPATH
NOTE: The GOROOT and GOPATH above must not be the same path. It is
recommended that GOPATH is set to a directory in your home directory such as
~/goprojects to avoid write permission issues.
- Run the following command to obtain dcrd, all dependencies, and install it:
$ go get -u github.com/decred/dcrd/...
- dcrd (and utilities) will now be installed in either
$GOROOT/binor$GOPATH/bindepending on your configuration. If you did not already add the bin directory to your system path during Go installation, we recommend you do so now.
Updating
Windows
Install a newer MSI
Linux/BSD/MacOSX/POSIX - Build from Source
- Run the following command to update dcrd, all dependencies, and install it:
$ go get -u -v github.com/decred/dcrd/...
Getting Started
dcrd has several configuration options avilable to tweak how it runs, but all of the basic operations described in the intro section work with zero configuration.
Windows (Installed from MSI)
Launch dcrd from your Start menu.
Linux/BSD/POSIX/Source
$ ./dcrd
IRC
- irc.freenode.net
- channel #decred
- webchat
Issue Tracker
The integrated github issue tracker is used for this project.
Documentation
The documentation is a work-in-progress. It is located in the docs folder.
License
dcrd is licensed under the copyfree ISC License.