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.
├── 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.
├── dcrdataapi          Package dcrdataapi for golang API clients.
├── 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 1.9.x or 1.10.x.
• Running dcrd (>=1.3.0) synchronized to the current best block on the network. This is a strict requirement as testnet2 support is removed from dcrdata v3.0.0.
• (Optional) PostgreSQL 9.6+, if running in "full" mode. v10.x is recommended for improved dump/restore formats and utilities.

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 dep, the dependency management tool. The current released binary of dep is recommended, but the latest may be installed from git via:

  go get -u -v github.com/golang/dep/cmd/dep
  

• Clone the dcrdata repository. It must be cloned into the following directory.

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

• Fetch dependencies, and build the dcrdata executable.

  cd $GOPATH/src/github.com/decred/dcrdata
  dep ensure -vendor-only
  # build dcrdata executable in workspace:
  go build
  

To build with the git commit hash appended to the version, set it as follows:

go build -ldflags "-X github.com/decred/dcrdata/version.CommitHash=`git describe --abbrev=8 --long | awk -F "-" '{print $(NF-1)"-"$NF}'`"

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

Tip: If you receive other build errors, it may be due to "vendor" directories left by dep builds of dependencies such as dcrwallet. You may safely delete vendor folders and run dep ensure -vendor-only again.

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 be set with -C/--configfile. 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

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

cd $GOPATH/src/github.com/decred/dcrdata
git pull origin master
dep ensure -vendor-only
go build

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

Updating dependencies

dep ensure -vendor-only fetches project dependencies, without making changes in manifest files Gopkg.toml and Gopkg.lock.

Call dep ensure to update project dependencies when introduce new imports.

For guides and reference materials about dep, see the documentation.

The following FAQ explains the difference between Gopkg.toml and Gopkg.lock files.

Upgrading Instructions

Only necessary while upgrading from v2.x or below. 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;

-- grant all permissions to user dcrdata
GRANT ALL PRIVILEGES ON DATABASE dcrdata to 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 import.

Getting Started

Configuring PostgreSQL (IMPORTANT)

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 or copy and paste these settings into the existing postgresql.conf. It is necessary to edit postgresql.conf, reviewing all the settings to ensure the same configuration parameters are not set in two different places in the file.

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 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.

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.

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. See JSON REST API for details.

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.

Insight API (EXPERIMENTAL)

The Insight API is accessible via HTTP at the /insight/api URL path prefix, and via WebSocket at the /insight/socket.io URL path prefix.

The following endpoints are not implemented: status, sync, peer, email, and rates.

dcrdata API

dcrdata has its own JSON HTTP API in addition to the experimental Insight API implementation. dcrdata's API endpoints are prefixed with /api (e.g. http://localhost:7777/api/stake). The Insight API endpoints (not described in this section) are prefixed with /insight/api.

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/Mraw	types.AddressTxRaw

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.

Vote and Agenda Info	Path	Type
The current agenda and its status	/stake/vote/info	dcrjson.GetVoteInfoResult

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

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.

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 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

Packages blockdata and dcrsqlite are currently designed only for internal use 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 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 the CONTRIBUTING.md file for details, but here's the gist of it:

1. Fork the repo.
2. Create a branch for your work (git branch -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.

Before committing any changes to the Gopkg.lock file, you must update dep to the latest version via:

go get -u github.com/golang/dep/cmd/dep

To update dep from the network, it is important to use the -u flag as shown above.

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!

License

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