38 lines
990 B
JavaScript
38 lines
990 B
JavaScript
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import lndService from 'ln-service'
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import lnd from '../lnd'
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const cache = new Map()
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const expiresIn = 1000 * 30 // 30 seconds in milliseconds
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async function fetchBlockHeight () {
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let blockHeight = 0
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try {
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const height = await lndService.getHeight({ lnd })
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blockHeight = height.current_block_height
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} catch (err) {
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console.error('fetchBlockHeight', err)
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}
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cache.set('block', { height: blockHeight, createdAt: Date.now() })
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return blockHeight
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}
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async function getBlockHeight () {
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if (cache.has('block')) {
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const { height, createdAt } = cache.get('block')
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const expired = createdAt + expiresIn < Date.now()
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if (expired) fetchBlockHeight().catch(console.error) // update cache
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return height // serve stale block height (this on the SSR critical path)
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} else {
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fetchBlockHeight().catch(console.error)
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}
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return 0
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}
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export default {
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Query: {
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blockHeight: async (parent, opts, ctx) => {
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return await getBlockHeight()
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}
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}
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}
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