dcrdata

README

dcrdata

The dcrdata repository is a collection of golang packages and apps for Decred data collection, storage, and presentation.

Repository overview

../dcrdata              The dcrdata daemon.
├── blockdata           Package blockdata.
├── cmd
│   ├── rebuilddb       rebuilddb utility.
│   └── scanblocks      scanblocks utility.
├── dcrdataapi          Package dcrdataapi for golang API clients.
├── dcrsqlite           Package dcrsqlite providing SQLite backend.
├── public              Public resources for web UI (css, js, etc.).
├── rpcutils            Package rpcutils.
├── semver              Package semver.
├── txhelpers           Package txhelpers.
└── views               HTML temlates for web UI.

dcrdata daemon

The root of the repository is the main package for the dcrdata app, which has several components including:

1. Block chain monitoring and data collection.
2. Data storage in durable database.
3. RESTful JSON API over HTTP(S).
4. Web interface.

JSON REST API

The API serves JSON data over HTTP(S). After dcrdata syncs with the blockchain server, by default it will begin listening on http://0.0.0.0:7777/. This means it starts a web server listening on all network interfaces on port 7777. All API endpoints are currently prefixed with /api (e.g. http://localhost:7777/api/stake), but this may be configurable in the future.

Endpoint List

Best block
Summary	/block/best
Stake info	/block/best/pos
Header	/block/best/header

Block X (block index)
Summary	/block/X
Stake info	/block/X/pos
Header	/block/X/header

Block range (X < Y)
Summary array	/block/range/X/Y

Stake Difficulty
Current sdiff and estimates	/stake/diff
Current sdiff separately	/stake/diff/current
Estimates separately	/stake/diff/estimates

Ticket Pool
Current pool info (size, total value, and average price)	/stake/pool
Pool info for block X	/stake/pool/b/X
Pool info for block range [X,Y] (X <= Y)	/stake/pool/r/X/Y?arrays=[true|false] *

^*For the pool info block range endpoint that accepts the arrays url query, a value of true will put all pool values and pool sizes into separate arrays, rather than having a single array of pool info JSON objects. This may make parsing more efficient for the client.

Mempool
Ticket fee rate summary	/mempool/sstx
Ticket fee rate list (all)	/mempool/sstx/fees
Ticket fee rate list (N highest)	/mempool/sstx/fees/N
Detailed ticket list (fee, hash, size, age, etc.)	/mempool/sstx/details
Detailed ticket list (N highest fee rates)	/mempool/sstx/details/N

Other
Status	/status
Endpoint list (always indented)	/list
Directory	/directory

All JSON endpoints accept the URL query indent=[true|false]. For example, /stake/diff?indent=true. By default, indentation is off. The characters to use for indentation may be specified with the indentjson string configuration option.

Web Interface

In addition to the API that is accessible via paths beginning with /api, an HTML interface is served on the root path (/).

Important Node About Mempool

Although there is mempool data collection and serving, it is very important to keep in mind that the mempool in your node (dcrd) is not likely to be the same as other nodes' mempool. Also, your mempool is cleared out when you shutdown dcrd. So, if you have recently (e.g. after the start of the current ticket price window) started dcrd, your mempool will be missing transactions that other nodes have.

Command Line Utilities

rebuilddb

rebuilddb is a CLI app that performs a full blockchain scan that fills past block data into a SQLite database. This functionality is included in the startup of the dcrdata daemon, but may be called alone with rebuilddb.

scanblocks

scanblocks is a CLI app to scan the blockchain and save data into a JSON file. More details are in its own README. The repository also includes a shell script, jsonarray2csv.sh, to convert the result into a comma-separated value (CSV) file.

Helper packages

package dcrdataapi defines the data types, with json tags, used by the JSON API. This facilitates authoring of robust golang clients of the API.

package rpcutils includes helper functions for interacting with a dcrrpcclient.Client.

package txhelpers includes helper functions for working with the common types dcrutil.Tx, dcrutil.Block, chainhash.Hash, and others.

Internal-use packages

Packages blockdata and dcrsqlite are currenly designed only for internal use by other dcrdata packages, but they may be of general value in the future.

blockdata defines:

• The chainMonitor type and its BlockConnectedHandler() method that handles block-connected notifications and triggers data collection and storage.
• The BlockData type and methods for converting to API types.
• The blockDataCollector type its Collect() method that is called by the chain monitor when a new block is detected.
• The BlockDataSaver interface required by chainMonitor for storage of collected data.

dcrsqlite defines:

• A sql.DB wrapper type (DB) with the necessary SQLite queries for storage and retrieval of block and stake data.
• The wiredDB type, intended to satisfy the APIDataSource interface used by the dcrdata app's API. The block header is not stored in the DB, so a RPC client is used by wiredDB to get it on demand. wiredDB also includes methods to resync the database file.

Plans

The GitHub issue tracker for dcrdata lists planned improvements. A few important ones:

• More database backend options, perhaps PostgreSQL and/or mongodb.
• Chain reorg handling.
• test cases.

Requirements

• Go 1.7 or newer.
• Running dcrd (>=0.6.1) synchronized to the current best block on the network.

Installation

Build from Source

The following instructions assume a Unix-like shell (e.g. bash).

• Install Go

• Verify Go installation:

    go env GOROOT GOPATH
  

• Ensure $GOPATH/bin is on your $PATH

• Install glide

    go get -u -v github.com/Masterminds/glide
  

• Clone dcrdata repo

    git clone https://github.com/dcrdata/dcrdata $GOPATH/src/github.com/dcrdata/dcrdata
  

• Glide install, and build executable

    cd $GOPATH/src/github.com/dcrdata/dcrdata
    glide install
    go build # or go install $(glide nv)
  

The sqlite driver uses cgo, which requires gcc to compile the C sources. On Windows this is easily handles with MSYS2 (download and install MinGW-w64 gcc packages).

If you receive other build errors, it may be due to "vendor" directories left by glide builds of dependencies such as dcrwallet. You may safely delete vendor folders.

Updating

First, update the repository (assuming you have master checked out):

cd $GOPATH/src/github.com/dcrdata/dcrdata
git pull origin master

Look carefully for errors with git pull, and revert changed files if necessary. Then follow the install instructions starting at "Glide install...".

Getting Started

Create configuration file.

cp ./sample-dcrdata.conf ./dcrdata.conf

Then edit dcrdata.conf with your dcrd RPC settings.

Finally, launch the daemon and allow the databases to sync.

./dcrdata