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56 lines
1.3 KiB
56 lines
1.3 KiB
/*!
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* lib/bitcoind-rpc/headers.js
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* Copyright © 2019 – Katana Cryptographic Ltd. All Rights Reserved.
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*/
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'use strict'
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const LRU = require('lru-cache')
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const errors = require('../errors')
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const { createRpcClient } = require('./rpc-client')
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/**
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* A singleton providing information about block headers
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*/
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class Headers {
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/**
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* Constructor
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*/
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constructor() {
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// Cache
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this.headers = LRU({
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// Maximum number of headers to store in cache
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max: 2016,
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// Function used to compute length of item
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length: (n, key) => 1,
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// Maximum age for items in the cache. Items do not expire
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maxAge: Infinity
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})
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// Initialize the rpc client
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this.rpcClient = createRpcClient()
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}
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/**
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* Get the block header for a given hash
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* @param {string} hash - block hash
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* @returns {Promise}
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*/
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async getHeader(hash) {
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if (this.headers.has(hash))
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return this.headers.get(hash)
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try {
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const header = await this.rpcClient.getblockheader({ blockhash: hash, verbose: true })
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const fmtHeader = JSON.stringify(header, null, 2)
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this.headers.set(hash, fmtHeader)
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return fmtHeader
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} catch(e) {
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return Promise.reject(errors.generic.GEN)
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}
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}
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}
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module.exports = new Headers()
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