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73 lines
2.1 KiB
73 lines
2.1 KiB
import { FirebaseUnit } from "../FirebaseUnit"
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import { Singleton, Inject } from "@extollo/di"
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import { Unit, Logging } from "@extollo/lib"
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import { Blockchain } from "../Blockchain"
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import { ExposureResource, ExposureResourceItem } from "../../rtdb/ExposureResource"
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/**
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* Exposure Unit
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* ---------------------------------------
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* This unit listens for exposure notifications created on the realtime database.
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* When new ones come through, it validates them, and pushes them onto this
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* server's blockchain.
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*/
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@Singleton()
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export class Exposure extends Unit {
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/** True if currently processing transactions. */
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private processing: boolean = false
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@Inject()
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protected readonly firebase!: FirebaseUnit
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@Inject()
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protected readonly blockchain!: Blockchain
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@Inject()
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protected readonly logging!: Logging
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/** Claim the right to process transactions. Returns true if the right was granted. */
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claim() {
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if ( !this.processing ) {
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this.processing = true
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return true
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}
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return false
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}
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/** Release the right to claim transactions. */
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release() {
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this.processing = false
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}
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/**
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* Subscribe to the transactions reference and wait for new transactions to be added.
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*/
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public async up() {
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this.firebase.ref('exposure').on('child_added', async (snapshot) => {
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this.logging.debug('Received child_added event for exposures reference.')
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if ( !this.claim() ) return
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await this.firebase.trylock('block')
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const exposure: ExposureResourceItem = snapshot.val()
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// Push the exposure transactions onto the chain
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await this.blockchain.submitExposures(exposure)
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if ( snapshot.key )
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await (<ExposureResource> this.make(ExposureResource)).ref().child(snapshot.key).remove()
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this.release()
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await this.firebase.unlock('block')
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})
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}
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/**
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* Release listeners and resources before shutdown.
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*/
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public async down() {
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// Release all subscriptions before shutdown
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this.firebase.ref("transaction").off()
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}
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}
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