dcrdata

dcrdata

dcrdata is an original Decred block explorer, with packages and apps for data collection, presentation, and storage. The backend and middleware are written in Go. On the front end, Webpack enables the use of modern javascript features, as well as SCSS for styling.

• dcrdata
  • Repository Overview
  • Requirements
  • Docker Support
  • Building
    • Preparation
    • Package the Static Web Assets
    • Building dcrdata with Go 1.11
    • Building dcrdata with Go 1.10
    • Setting build version flags
    • Runtime Resources
  • Updating
  • Upgrading Instructions
    • From v3.x or later
    • From v2.x or earlier
  • Getting Started
    • Configuring PostgreSQL (IMPORTANT! Seriously, read this.)
    • Creating the dcrdata Configuration File
    • Using Environment Variables for Configuration
    • Indexing the Blockchain
    • Starting dcrdata
    • Hiding the PostgreSQL db Configuration settings.
    • Running the Web Interface During Synchronization
  • System Hardware Requirements
    • "lite" Mode (SQLite only)
    • "full" Mode (SQLite and PostgreSQL)
  • dcrdata Daemon
    • Block Explorer
  • APIs
    • Insight API (EXPERIMENTAL)
    • dcrdata API
      • Endpoint List
  • Important Note About Mempool
  • Command Line Utilities
    • rebuilddb
    • rebuilddb2
    • scanblocks
  • Front End Development
    • CSS Guidelines
    • HTML
    • Javascript
    • Web Performance
  • Helper Packages
  • Internal-use Packages
  • Plans
  • Contributing
  • License

Repository Overview

../dcrdata              The dcrdata daemon.
├── api                 Package blockdata implements dcrdata's own HTTP API.
│   ├── insight         Package insight implements the Insight API.
│   └── types           Package types includes the exported structures used by
|                         the dcrdata and Insight APIs.
├── blockdata           Package blockdata is the primary data collection and
|                         storage hub, and chain monitor.
├── cmd
│   ├── rebuilddb       rebuilddb utility, for SQLite backend. Not required.
│   ├── rebuilddb2      rebuilddb2 utility, for PostgreSQL backend. Not required.
│   └── scanblocks      scanblocks utility. Not required.
├── db
│   ├── agendadb        Package agendadb is a basic PoS voting agenda database.
│   ├── dbtypes         Package dbtypes with common data types.
│   ├── dcrpg           Package dcrpg providing PostgreSQL backend.
│   └── dcrsqlite       Package dcrsqlite providing SQLite backend.
├── dev                 Shell scripts for maintenance and deployment.
├── explorer            Package explorer, powering the block explorer.
├── mempool             Package mempool for monitoring mempool for transactions,
|                         data collection, and storage.
├── middleware          Package middleware provides HTTP router middleware.
├── notification        Package notification manages dcrd notifications, and
|                         synchronous data collection by a queue of collectors.
├── public              Public resources for block explorer (css, js, etc.).
├── rpcutils            Package rpcutils contains helper types and functions for
|                         interacting with a chain server via RPC.
├── semver              Package semver.
├── stakedb             Package stakedb, for tracking tickets.
├── testutil            Package testutil provides some testing helper functions.
├── txhelpers           Package txhelpers provides many functions and types for
|                         processing blocks, transactions, voting, etc.
├── version             Package version describes the dcrdata version.
└── views               HTML templates for block explorer.

Requirements

• Go 1.11.x. Instructions are also provided for 1.10, but only Go 1.11 is officially supported.
• Node.js 10.x or 11.x. Node.js is only used as a build tool, and is not used at runtime.
• Running dcrd synchronized to the current best block on the network. On startup, dcrdata will verify that the dcrd version is compatible. Compatibility depends on the version of dcrdata:
  • For dcrdata v3.0.x, use dcrd v1.3.0. Earlier dcrd versions should not be used since testnet2 support was removed from dcrdata v3.0.0. Further, dcrd v1.4.0 has incompatible RPC reorg event notifications.
  • For dcrdata v3.1.x or later (including master), use dcrd v1.4.x or build from master.
• (For "full" mode) PostgreSQL 10.5+. Version 11.x is supported and recommended for improved performance with a number of tasks.

Docker Support

Dockerfiles are provided for convenience, but not actively supported. See the Docker documentation for more information. The supported build instructions are described below.

Building

The dcrdata build process comprises two general steps:

1. Bundle the static web page assets with Webpack (via the npm tool).
2. Build the dcrdata executable from the Go source files.

These steps are described in detail in the following sections.

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

Preparation

• Install Go

• Verify Go installation:

  go env GOROOT GOPATH
  

• Ensure $GOPATH/bin is on your $PATH.

• Clone the dcrdata repository. It is conventional to put it under GOPATH, but this is no longer necessary with go module.

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

• Install a C compiler. The sqlite driver uses cgo, which requires a C compiler (e.g. gcc) to compile the sources. On Windows this is easily handled with MSYS2 (download and install MinGW-w64 gcc packages).

• Install Node.js, which is required to lint and package the static web assets.

Note that none of the above is required at runtime.

Package the Static Web Assets

Webpack, a JavaScript module bundler, is used to compile and package the static assets in the public folder. Node.js' npm tool is used to install the required Node.js dependencies and build the bundled JavaScript distribution for deployment.

First, install the build dependencies:

npm install # creates node_modules folder

Then, for production, build the webpack bundle:

npm run build # creates public/dist folder

Alternatively, for development, npm can be made to watch for and integrate JavaScript source changes:

npm run watch

See Front End Development for more information.

Building dcrdata with Go 1.11

Go 1.11 introduced modules, a new dependency management approach, that obviates the need for third party tooling such as dep.

Usage is simple and nothing is required except Go 1.11. If building in a folder under GOPATH, it is necessary to explicitly build with modules enabled:

GO111MODULE=on go build

If building outside of GOPATH, modules are automatically enabled, and go build is sufficient.

The go tool will process the source code and automatically download dependencies. If the dependencies are configured correctly, there will be no modifications to the go.mod and go.sum files.

Beware: For the v3 dcrdata module, the executable generated by go build may be named "v3" instead of "dcrdata". The situation is analogous for v4. This is a known issue in Go 1.11 that will be resolved in Go 1.12.

As a reward for reading this far, you may use the build.sh script to mostly automate the build steps.

Building dcrdata with Go 1.10

Module-enabled builds with Go 1.10 require the vgo command. Follow the same procedures as if you were using Go 1.11, but replacing go with vgo.

NOTE: The dep tool is no longer supported. If you must use Go 1.10, install and use vgo. If possible, upgrade to Go 1.11 or using the Docker container build instructions.

Setting build version flags

By default, the version string will be postfixed with "-pre+dev". For example, dcrdata version 3.1.0-pre+dev (Go version go1.11). However, it may be desirable to set the "pre" and "dev" values to different strings, such as "beta" or the actual commit hash. To set these values, build with the -ldflags switch as follows:

GO111MODULE=on go build -ldflags \
    "-X github.com/decred/dcrdata/v4/version.appPreRelease=beta \
     -X github.com/decred/dcrdata/v4/version.appBuild=`git rev-parse --short HEAD`"

This produces a string like dcrdata version 3.1.0-beta+86cc62a (Go version go1.11).

Runtime Resources

The config file, logs, and data files are stored in the application data folder, which may be specified via the -A/--appdata and -b/--datadir settings. However, the location of the config file may also be set with -C/--configfile. The default paths for your system are shown in the --help description. If encountering errors involving file system paths, check the permissions on these folders to ensure that the user running dcrdata is able to access these paths.

The "public" and "views" folders must be in the same folder as the dcrdata executable. Set read-only permissions as appropriate.

Updating

Update the repository (assuming you have master checked out in GOPATH):

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

Look carefully for errors with git pull, and reset locally modified files if necessary.

Next, build dcrdata and bundle the web assets:

GO111MODULE=on go build
npm install
npm run build # or npm run watch

Upgrading Instructions

From v3.x or later

No special actions are required. Simply start the new dcrdata and automatic database schema upgrades and table data patches will begin.

From v2.x or earlier

The database scheme change from dcrdata v2.x to v3.x does not permit an automatic migration. The tables must be rebuilt from scratch:

1. Drop the old dcrdata database, and create a new empty dcrdata database.

   -- Drop the old database.
   DROP DATABASE dcrdata;
   
   -- Create a new database with the same "pguser" set in the dcrdata.conf.
   CREATE DATABASE dcrdata OWNER dcrdata;
   

2. Delete the dcrdata data folder (i.e. corresponding to the datadir setting). By default, datadir is in {appdata}/data:

   • Linux: ~/.dcrdata/data
   • Mac: ~/Library/Application Support/Dcrdata/data
   • Windows: C:\Users\<your-username>\AppData\Local\Dcrdata\data (%localappdata%\Dcrdata\data)

3. With dcrd synchronized to the network's best block, start dcrdata to begin the initial block data sync.

Getting Started

Configuring PostgreSQL (IMPORTANT! Seriously, read this.)

If you intend to run dcrdata in "full" mode (i.e. with the --pg switch), which uses a PostgreSQL database backend, it is crucial that you configure your PostgreSQL server for your hardware and the dcrdata workload.

Read postgresql-tuning.conf carefully for details on how to make the necessary changes to your system. A helpful online tool for determining good settings for your system is called PGTune. DO NOT simply use this file in place of your existing postgresql.conf. DO NOT simply copy and paste these settings into the existing postgresql.conf. It is necessary to edit the existing postgresql.conf, reviewing all the settings to ensure the same configuration parameters are not set in two different places in the file (postgres will not complain).

On Linux, you may wish to use a unix domain socket instead of a TCP connection. The path to the socket depends on the system, but it is commonly /var/run/postgresql. Just set this path in pghost.

Creating the dcrdata Configuration File

Begin with the sample configuration file. With the default appdata directory for the current user on Linux:

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

Then edit dcrdata.conf with your dcrd RPC settings. See the output of dcrdata --help for a list of all options and their default values.

Using Environment Variables for Configuration

There may be times when a config file is inconvenient, or you cannot use command line arguments. Almost all configuration items are available to set via environment variables. See the config.go file and the config struct for a complete list of which settings may be set via environment variables. Each setting uses the env struct field tag to specify the name of the environment variable (i.e. env:"DCRDATA_USE_TESTNET").

Setting precedence:

1. Command line flags
2. Config file settings
3. Environment variables
4. Defaults defined in config.go

In general, boolean-typed variables will contain USE, ENABLE, or DISABLE in the name.

List of recognized environment variables:

Description	Name
Path to application home directory	DCRDATA_APPDATA_DIR
Path to configuration file	DCRDATA_CONFIG_FILE
Directory to store data	DCRDATA_DATA_DIR
Directory to log output	DCRDATA_LOG_DIR
Folder for file outputs	DCRDATA_OUT_FOLDER
Use the test network (default mainnet)	DCRDATA_USE_TESTNET
Use the simulation test network (default mainnet)	DCRDATA_USE_SIMNET
Logging level {trace, debug, info, warn, error, critical}	DCRDATA_LOG_LEVEL
Easy way to set debuglevel to error	DCRDATA_QUIET
Start HTTP profiler.	DCRDATA_ENABLE_HTTP_PROFILER
URL path prefix for the HTTP profiler.	DCRDATA_HTTP_PROFILER_PREFIX
File for CPU profiling.	DCRDATA_CPU_PROFILER_FILE
Run with gops diagnostics agent listening. See github.com/google/gops for more information.	DCRDATA_USE_GOPS
Protocol for API (http or https)	DCRDATA_ENABLE_HTTPS
Listen address for API	DCRDATA_LISTEN_URL
Use the RealIP to get the client's real IP from the X-Forwarded-For or X-Real-IP headers, in that order.	DCRDATA_USE_REAL_IP
Set CacheControl in the HTTP response header	DCRDATA_MAX_CACHE_AGE
Monitor mempool for new transactions, and report ticket fee info when new tickets are added.	DCRDATA_ENABLE_MEMPOOL_MONITOR
The minimum time in seconds between mempool reports, regardless of number of new tickets seen.	DCRDATA_MEMPOOL_MIN_INTERVAL
The maximum time in seconds between mempool reports (within a couple seconds), regardless of number of new tickets seen.	DCRDATA_MEMPOOL_MAX_INTERVAL
The number minimum number of new tickets that must be seen to trigger a new mempool report.	DCRDATA_MP_TRIGGER_TICKETS
Dump to file the fees of all the tickets in mempool.	DCRDATA_ENABLE_DUMP_ALL_MP_TIX
SQLite DB file name (default is dcrdata.sqlt.db)	DCRDATA_SQLITE_DB_FILE_NAME
Agendas DB file name (default is agendas.db)	DCRDATA_AGENDAS_DB_FILE_NAME
Proposals DB file name (default is proposals.db)	DCRDATA_PROPOSALS_DB_FILE_NAME
Run in "Full Mode" mode, enables postgresql support	DCRDATA_ENABLE_FULL_MODE
PostgreSQL DB name.	DCRDATA_PG_DB_NAME
PostgreSQL DB user	DCRDATA_POSTGRES_USER
PostgreSQL DB password.	DCRDATA_POSTGRES_PASS
port or UNIX socket (e.g. /run/postgresql).	DCRDATA_POSTGRES_HOST_URL
Disable automatic dev fund balance query on new blocks.	DCRDATA_DISABLE_DEV_PREFETCH
Sync to the best block and exit. Do not start the explorer or API.	DCRDATA_ENABLE_SYNC_N_QUIT
(experimental) Import side chain blocks from dcrd via the getchaintips RPC.	DCRDATA_IMPORT_SIDE_CHAINS
Daemon RPC user name	DCRDATA_DCRD_USER
Daemon RPC password	DCRDATA_DCRD_PASS
Hostname/IP and port of dcrd RPC server	DCRDATA_DCRD_URL
File containing the dcrd certificate file	DCRDATA_DCRD_CERT
Disable TLS for the daemon RPC client	DCRDATA_DCRD_DISABLE_TLS

Indexing the Blockchain

If dcrdata has not previously been run with the PostgreSQL database backend, it is necessary to perform a bulk import of blockchain data and generate table indexes. This will be done automatically by dcrdata on a fresh startup.

Alternatively (but not recommended), the PostgreSQL tables may also be generated with the rebuilddb2 command line tool:

• Create the dcrdata user and database in PostgreSQL (tables will be created automatically).
• Set your PostgreSQL credentials and host in both ./cmd/rebuilddb2/rebuilddb2.conf, and dcrdata.conf in the location specified by the appdata flag.
• Run ./rebuilddb2 to bulk import data and index the tables.
• In case of irrecoverable errors, such as detected schema changes without an upgrade path, the tables and their indexes may be dropped with rebuilddb2 -D.

Note that dcrdata requires that dcrd is running with some optional indexes enabled. By default, these indexes are not turned on when dcrd is installed. To enable them, set the following in dcrd.conf:

txindex=1
addrindex=1

If these parameters are not set, dcrdata will be unable to retrieve transaction details and perform address searches, and will exit with an error mentioning these indexes.

Starting dcrdata

Launch the dcrdata daemon and allow the databases to process new blocks. In "lite" mode (without --pg), only a SQLite DB is populated, which usually requires 30-60 minutes. In "full" mode (with --pg), concurrent synchronization of both SQLite and PostgreSQL databases is performed, requiring from 3-12 hours. See System Hardware Requirements for more information.

On subsequent launches, only blocks new to dcrdata are processed.

./dcrdata    # don't forget to configure dcrdata.conf in the appdata folder!

Unlike dcrdata.conf, which must be placed in the appdata folder or explicitly set with -C, the "public" and "views" folders must be in the same folder as the dcrdata executable.

Hiding the PostgreSQL db Configuration settings.

By default postgres configuration settings are logged on system start up. --hidepgconfig flag blocks the logging on dcrdata start up.

Running the Web Interface During Synchronization

By default, on dcrdata startup, a syncing status page is the only page available until sync is completed.

However, most of the explorer pages can be made available via the sync-status-limit setting, which indicates a threshold on the number of blocks yet to sync, below which the entire explorer will be made available. When set with a value on the range [2,5000], all dcrdata pages will be active on startup if the number of remaining blocks to process are less than the specified value.

For example, if sync-status-limit is set to 1000, all dcrdata pages will be active when fewer than 1000 blocks remain to be processed, otherwise only the sync status page will be accessible until synchronization is complete.

If sync-status-limit is not set (the default), only the sync status page will be available.

sync-status-limit=1000

It is recommended that you avoid setting sync-status-limit as a value larger than 1000 especially if your machine struggles handling dcrdata normal load. Setting a larger value might worsen your situation especially when you try to load processor intensive pages like ticketpool.

System Hardware Requirements

The time required to sync in "full" mode varies greatly with system hardware and software configuration. The most important factor is the storage medium on the database machine. An SSD (preferably NVMe, not SATA) is strongly recommended if you value your time and system performance.

"lite" Mode (SQLite only)

Minimum:

• 1 CPU core
• 2 GB RAM
• HDD with 4GB free space

"full" Mode (SQLite and PostgreSQL)

These specifications assume dcrdata and postgres are running on the same machine.

Minimum:

• 1 CPU core
• 4 GB RAM
• HDD with 60GB free space

Recommend:

• 2+ CPU cores
• 7+ GB RAM
• SSD (NVMe preferred) with 60 GB free space

If PostgreSQL is running on a separate machine, the minimum "lite" mode requirements may be applied to the dcrdata machine, while the recommended "full" mode requirements should be applied to the PostgreSQL host.

dcrdata Daemon

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

1. Block explorer (web interface).
2. Blockchain monitoring and data collection.
3. Mempool monitoring and reporting.
4. Database backend interfaces.
5. RESTful JSON API (custom and Insight) over HTTP(S).

Block Explorer

After dcrdata syncs with the blockchain server via RPC, by default it will begin listening for HTTP connections on http://127.0.0.1:7777/. This means it starts a web server listening on IPv4 localhost, port 7777. Both the interface and port are configurable. The block explorer and the JSON APIs are both provided by the server on this port.

Note that while dcrdata can be started with HTTPS support, it is recommended to employ a reverse proxy such as Nginx ("engine x"). See sample-nginx.conf for an example Nginx configuration.

To save time and tens of gigabytes of disk storage space, dcrdata runs by default in a reduced functionality ("lite") mode that does not require PostgreSQL. To enable the PostgreSQL backend (and the expanded functionality), dcrdata may be started with the --pg switch. See --help or sample-dcrdata.conf for additional PostgreSQL configuration settings.

APIs

The dcrdata block explorer is exposed by two APIs: a Decred implementation of the Insight API (EXPERIMENTAL), and its own JSON HTTP API. The Insight API uses the path prefix /insight/api. The dcrdata API uses the path prefix /api. File downloads are served from the /download path.

Insight API (EXPERIMENTAL)

The Insight API is accessible via HTTP via REST or WebSocket.

See the Insight API documentation for further details.

dcrdata API

The dcrdata API is a REST API accessible via HTTP. To call the dcrdata API, use the /api path prefix.

Endpoint List

Best block	Path	Type
Summary	/block/best	types.BlockDataBasic
Stake info	/block/best/pos	types.StakeInfoExtended
Header	/block/best/header	dcrjson.GetBlockHeaderVerboseResult
Hash	/block/best/hash	string
Height	/block/best/height	int
Size	/block/best/size	int32
Subsidy	/block/best/subsidy	types.BlockSubsidies
Transactions	/block/best/tx	types.BlockTransactions
Transactions Count	/block/best/tx/count	types.BlockTransactionCounts
Verbose block result	/block/best/verbose	dcrjson.GetBlockVerboseResult

Block X (block index)	Path	Type
Summary	/block/X	types.BlockDataBasic
Stake info	/block/X/pos	types.StakeInfoExtended
Header	/block/X/header	dcrjson.GetBlockHeaderVerboseResult
Hash	/block/X/hash	string
Size	/block/X/size	int32
Subsidy	/block/best/subsidy	types.BlockSubsidies
Transactions	/block/X/tx	types.BlockTransactions
Transactions Count	/block/X/tx/count	types.BlockTransactionCounts
Verbose block result	/block/X/verbose	dcrjson.GetBlockVerboseResult

Block H (block hash)	Path	Type
Summary	/block/hash/H	types.BlockDataBasic
Stake info	/block/hash/H/pos	types.StakeInfoExtended
Header	/block/hash/H/header	dcrjson.GetBlockHeaderVerboseResult
Height	/block/hash/H/height	int
Size	/block/hash/H/size	int32
Subsidy	/block/best/subsidy	types.BlockSubsidies
Transactions	/block/hash/H/tx	types.BlockTransactions
Transactions count	/block/hash/H/tx/count	types.BlockTransactionCounts
Verbose block result	/block/hash/H/verbose	dcrjson.GetBlockVerboseResult

Block range (X < Y)	Path	Type
Summary array for blocks on [X,Y]	/block/range/X/Y	[]types.BlockDataBasic
Summary array with block index step S	/block/range/X/Y/S	[]types.BlockDataBasic
Size (bytes) array	/block/range/X/Y/size	[]int32
Size array with step S	/block/range/X/Y/S/size	[]int32

Transaction T (transaction id)	Path	Type
Transaction details	/tx/T	types.Tx
Transaction details w/o block info	/tx/trimmed/T	types.TrimmedTx
Inputs	/tx/T/in	[]types.TxIn
Details for input at index X	/tx/T/in/X	types.TxIn
Outputs	/tx/T/out	[]types.TxOut
Details for output at index X	/tx/T/out/X	types.TxOut
Vote info (ssgen transactions only)	/tx/T/vinfo	types.VoteInfo
Serialized bytes of the transaction	/tx/hex/T	string
Same as /tx/trimmed/T	/tx/decoded/T	types.TrimmedTx

Transactions (batch)	Path	Type
Transaction details (POST body is JSON of types.Txns)	/txs	[]types.Tx
Transaction details w/o block info	/txs/trimmed	[]types.TrimmedTx

Address A	Path	Type
Summary of last 10 transactions	/address/A	types.Address
Number and value of spent and unspent outputs	/address/A/totals	types.AddressTotals
Verbose transaction result for last 10 transactions	/address/A/raw	types.AddressTxRaw
Summary of last N transactions	/address/A/count/N	types.Address
Verbose transaction result for last N transactions	/address/A/count/N/raw	types.AddressTxRaw
Summary of last N transactions, skipping M	/address/A/count/N/skip/M	types.Address
Verbose transaction result for last N transactions, skipping M	/address/A/count/N/skip/M/raw	types.AddressTxRaw
Transaction inputs and outputs as a CSV formatted file.	/download/address/io/A	CSV file

Stake Difficulty (Ticket Price)	Path	Type
Current sdiff and estimates	/stake/diff	types.StakeDiff
Sdiff for block X	/stake/diff/b/X	[]float64
Sdiff for block range [X,Y] (X <= Y)	/stake/diff/r/X/Y	[]float64
Current sdiff separately	/stake/diff/current	dcrjson.GetStakeDifficultyResult
Estimates separately	/stake/diff/estimates	dcrjson.EstimateStakeDiffResult

Ticket Pool	Path	Type
Current pool info (size, total value, and average price)	/stake/pool	types.TicketPoolInfo
Current ticket pool, in a JSON object with a "tickets" key holding an array of ticket hashes	/stake/pool/full	[]string
Pool info for block X	/stake/pool/b/X	types.TicketPoolInfo
Full ticket pool at block height or hash H	/stake/pool/b/H/full	[]string
Pool info for block range [X,Y] (X <= Y)	/stake/pool/r/X/Y?arrays=[true|false]*	[]apitypes.TicketPoolInfo

The full ticket pool endpoints accept the URL query ?sort=[true\|false] for requesting the tickets array in lexicographical order. If a sorted list or list with deterministic order is not required, using sort=false will reduce server load and latency. However, be aware that the ticket order will be random, and will change each time the tickets are requested.

^*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.

Votes and Agendas Info	Path	Type
The current agenda and its status	/stake/vote/info	dcrjson.GetVoteInfoResult
All agendas high level details	/agendas	[]types.AgendasInfo

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

Exchanges	Path	Type
Exchange data summary	/exchanges	exchanges.ExchangeBotState
List of available currency codes	/exchanges/codes	[]string

Exchange monitoring is off by default. Server must be started with --exchange-monitor to enable exchange data. The server will set a default currency code. To use a different code, pass URL parameter ?code=[code]. For example, /exchanges?code=EUR.

Other	Path	Type
Status	/status	types.Status
Coin Supply	/supply	types.CoinSupply
Endpoint list (always indented)	/list	[]string

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.

Important Note 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 exactly 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.

rebuilddb2

rebuilddb2 is a CLI app used for maintenance of dcrdata's dcrpg database (a.k.a. DB v2) that uses PostgreSQL to store a nearly complete record of the Decred blockchain data. This functionality is included in the startup of the dcrdata daemon, but may be called alone with rebuilddb. See the README.md for rebuilddb2 for important usage information.

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.

Front End Development

Make sure you have a recent version of node and npm installed. You may want to use the node version manager (nvm) for managing your node download and installation.

From the dcrdata root directory, run the following command to install the node modules.

npm install

This will create and install into a directory named node_modules.

You'll also want to run npm install after merging changes from upstream. It is run for you when you use the build script (./dev/build.sh).

For development, there's a webpack script that watches for file changes and automatically bundles. To use it, run the following command in a separate terminal and leave it running while you work. You'll only use this command if you are editing javascript files.

npm run watch

For production, bundle assets via:

npm run build

Both the watch and build scripts create a single output file at /public/js/dist/app.bundle.js. You will need to at least build if changes have been made. watch essentially runs build after file changes, but also performs some additional checks.

CSS Guidelines

Webpack compiles SCSS to CSS while bundling. The watch script described above also watches for changes in these files and performs linting to ensure syntax compliance.

Before you write any CSS, see if you can achieve your goal by using existing classes available in Bootstrap 4. This helps prevent our stylesheets from getting bloated and makes it easier for things to work well across a wide range browsers & devices. Please take the time to Read the docs

Note there is a dark mode, so make sure things look good with the dark background as well.

HTML

The core functionality of dcrdata is server-side rendered in Go and designed to work well with javascript disabled. For users with javascript enabled, Turbolinks creates a persistent single page application that handles all HTML rendering.

.tmpl files are cached by the backend, and can be reloaded via running killall -USR1 v4 from the command line.

Javascript

To encourage code that is idiomatic to Turbolinks based execution environment, javascript based enhancements should use Stimulus controllers with corresponding actions and targets. Keeping things tightly scoped with controllers and modules helps to localize complexity and maintain a clean application lifecycle. When using events handlers, bind and unbind them in the connect and disconnect function of controllers which executes when they get removed from the DOM.

Web Performance

The core functionality of dcrdata should perform well in low power device / high latency scenarios (eg. a cheap smart phone with poor reception). This means that heavy assets should be lazy loaded when they are actually needed. Simple tasks like checking a transaction or address should have a very fast initial page load.

Helper Packages

package dbtypes defines the data types used by the DB backends to model the block, transaction, and related blockchain data structures. Functions for converting from standard Decred data types (e.g. wire.MsgBlock) are also provided.

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

package stakedb defines the StakeDatabase and ChainMonitor types for efficiently tracking live tickets, with the primary purpose of computing ticket pool value quickly. It uses the database.DB type from github.com/decred/dcrd/database with an ffldb storage backend from github.com/decred/dcrd/database/ffldb. It also makes use of the stake.Node type from github.com/decred/dcrd/blockchain/stake. The ChainMonitor type handles connecting new blocks and chain reorganization in response to notifications from dcrd.

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

Internal-use Packages

Some packages are currently designed only for internal use by other dcrdata packages, but 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 and its Collect() and CollectHash() methods that are called by the chain monitor when a new block is detected.
• The BlockDataSaver interface required by chainMonitor for storage of collected data.

dcrpg defines:

• The ChainDB type, which is the primary exported type from dcrpg, providing an interface for a PostgreSQL database.
• A large set of lower-level functions to perform a range of queries given a *sql.DB instance and various parameters.
• The internal package contains the raw SQL statements.

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 DataSourceLite 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.

package mempool defines a mempoolMonitor type that can monitor a node's mempool using the OnTxAccepted notification handler to send newly received transaction hashes via a designated channel. Ticket purchases (SSTx) are triggers for mempool data collection, which is handled by the MempoolDataCollector class, and data storage, which is handled by any number of objects implementing the MempoolDataSaver interface.

Plans

See the GitHub issue tracker and the project milestones.

Contributing

Yes, please! See CONTRIBUTING.md for details, but here's the gist of it:

1. Fork the repo.
2. Create a branch for your work (git checkout -b cool-stuff).
3. Code something great.
4. Commit and push to your repo.
5. Create a pull request.

DO NOT merge from master to your feature branch; rebase.

Note that all dcrdata.org community and team members are expected to adhere to the code of conduct, described in the CODE_OF_CONDUCT file.

Also, come chat with us on Slack at the #drcdata channel!

License

This project is licensed under the ISC License. See the LICENSE file for details.