264 lines
8.1 KiB
TypeScript
264 lines
8.1 KiB
TypeScript
import z from "zod"
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import type { ZodObject } from "zod"
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import { EventEmitter } from "events"
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import { Database, eq } from "@/storage/db"
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import { Bus as ProjectBus } from "@/bus"
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import { BusEvent } from "@/bus/bus-event"
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import { EventSequenceTable, EventTable } from "./event.sql"
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import { EventID } from "./schema"
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import { Flag } from "@/flag/flag"
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export namespace SyncEvent {
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export type Definition = {
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type: string
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version: number
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aggregate: string
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schema: z.ZodObject
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// This is temporary and only exists for compatibility with bus
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// event definitions
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properties: z.ZodObject
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}
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export type Event<Def extends Definition = Definition> = {
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id: string
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seq: number
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aggregateID: string
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data: z.infer<Def["schema"]>
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}
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export type SerializedEvent<Def extends Definition = Definition> = Event<Def> & { type: string }
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type ProjectorFunc = (db: Database.TxOrDb, data: unknown) => void
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export const registry = new Map<string, Definition>()
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let projectors: Map<Definition, ProjectorFunc> | undefined
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const versions = new Map<string, number>()
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let frozen = false
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let convertEvent: (type: string, event: Event["data"]) => Promise<Record<string, unknown>> | Record<string, unknown>
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const Bus = new EventEmitter<{ event: [{ def: Definition; event: Event }] }>()
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export function reset() {
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frozen = false
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projectors = undefined
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convertEvent = (_, data) => data
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}
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export function init(input: { projectors: Array<[Definition, ProjectorFunc]>; convertEvent?: typeof convertEvent }) {
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projectors = new Map(input.projectors)
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// Install all the latest event defs to the bus. We only ever emit
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// latest versions from code, and keep around old versions for
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// replaying. Replaying does not go through the bus, and it
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// simplifies the bus to only use unversioned latest events
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for (let [type, version] of versions.entries()) {
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let def = registry.get(versionedType(type, version))!
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BusEvent.define(def.type, def.properties || def.schema)
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}
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// Freeze the system so it clearly errors if events are defined
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// after `init` which would cause bugs
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frozen = true
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convertEvent = input.convertEvent || ((_, data) => data)
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}
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export function versionedType<A extends string>(type: A): A
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export function versionedType<A extends string, B extends number>(type: A, version: B): `${A}/${B}`
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export function versionedType(type: string, version?: number) {
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return version ? `${type}.${version}` : type
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}
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export function define<
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Type extends string,
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Agg extends string,
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Schema extends ZodObject<Record<Agg, z.ZodType<string>>>,
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BusSchema extends ZodObject = Schema,
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>(input: { type: Type; version: number; aggregate: Agg; schema: Schema; busSchema?: BusSchema }) {
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if (frozen) {
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throw new Error("Error defining sync event: sync system has been frozen")
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}
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const def = {
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type: input.type,
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version: input.version,
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aggregate: input.aggregate,
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schema: input.schema,
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properties: input.busSchema ? input.busSchema : input.schema,
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}
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versions.set(def.type, Math.max(def.version, versions.get(def.type) || 0))
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registry.set(versionedType(def.type, def.version), def)
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return def
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}
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export function project<Def extends Definition>(
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def: Def,
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func: (db: Database.TxOrDb, data: Event<Def>["data"]) => void,
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): [Definition, ProjectorFunc] {
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return [def, func as ProjectorFunc]
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}
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function process<Def extends Definition>(def: Def, event: Event<Def>, options: { publish: boolean }) {
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if (projectors == null) {
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throw new Error("No projectors available. Call `SyncEvent.init` to install projectors")
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}
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const projector = projectors.get(def)
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if (!projector) {
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throw new Error(`Projector not found for event: ${def.type}`)
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}
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// idempotent: need to ignore any events already logged
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Database.transaction((tx) => {
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projector(tx, event.data)
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if (Flag.OPENCODE_EXPERIMENTAL_WORKSPACES) {
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tx.insert(EventSequenceTable)
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.values({
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aggregate_id: event.aggregateID,
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seq: event.seq,
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})
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.onConflictDoUpdate({
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target: EventSequenceTable.aggregate_id,
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set: { seq: event.seq },
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})
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.run()
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tx.insert(EventTable)
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.values({
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id: event.id,
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seq: event.seq,
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aggregate_id: event.aggregateID,
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type: versionedType(def.type, def.version),
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data: event.data as Record<string, unknown>,
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})
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.run()
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}
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Database.effect(() => {
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Bus.emit("event", {
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def,
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event,
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})
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if (options?.publish) {
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const result = convertEvent(def.type, event.data)
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if (result instanceof Promise) {
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result.then((data) => {
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ProjectBus.publish({ type: def.type, properties: def.schema }, data)
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})
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} else {
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ProjectBus.publish({ type: def.type, properties: def.schema }, result)
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}
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}
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})
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})
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}
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// TODO:
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//
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// * Support applying multiple events at one time. One transaction,
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// and it validets all the sequence ids
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// * when loading events from db, apply zod validation to ensure shape
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export function replay(event: SerializedEvent, options?: { republish: boolean }) {
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const def = registry.get(event.type)
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if (!def) {
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throw new Error(`Unknown event type: ${event.type}`)
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}
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const row = Database.use((db) =>
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db
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.select({ seq: EventSequenceTable.seq })
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.from(EventSequenceTable)
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.where(eq(EventSequenceTable.aggregate_id, event.aggregateID))
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.get(),
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)
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const latest = row?.seq ?? -1
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if (event.seq <= latest) {
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return
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}
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const expected = latest + 1
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if (event.seq !== expected) {
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throw new Error(`Sequence mismatch for aggregate "${event.aggregateID}": expected ${expected}, got ${event.seq}`)
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}
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process(def, event, { publish: !!options?.republish })
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}
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export function run<Def extends Definition>(def: Def, data: Event<Def>["data"]) {
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const agg = (data as Record<string, string>)[def.aggregate]
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// This should never happen: we've enforced it via typescript in
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// the definition
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if (agg == null) {
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throw new Error(`SyncEvent.run: "${def.aggregate}" required but not found: ${JSON.stringify(data)}`)
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}
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if (def.version !== versions.get(def.type)) {
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throw new Error(`SyncEvent.run: running old versions of events is not allowed: ${def.type}`)
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}
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// Note that this is an "immediate" transaction which is critical.
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// We need to make sure we can safely read and write with nothing
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// else changing the data from under us
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Database.transaction(
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(tx) => {
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const id = EventID.ascending()
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const row = tx
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.select({ seq: EventSequenceTable.seq })
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.from(EventSequenceTable)
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.where(eq(EventSequenceTable.aggregate_id, agg))
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.get()
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const seq = row?.seq != null ? row.seq + 1 : 0
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const event = { id, seq, aggregateID: agg, data }
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process(def, event, { publish: true })
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},
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{
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behavior: "immediate",
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},
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)
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}
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export function remove(aggregateID: string) {
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Database.transaction((tx) => {
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tx.delete(EventSequenceTable).where(eq(EventSequenceTable.aggregate_id, aggregateID)).run()
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tx.delete(EventTable).where(eq(EventTable.aggregate_id, aggregateID)).run()
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})
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}
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export function subscribeAll(handler: (event: { def: Definition; event: Event }) => void) {
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Bus.on("event", handler)
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return () => Bus.off("event", handler)
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}
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export function payloads() {
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return z
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.union(
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registry
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.entries()
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.map(([type, def]) => {
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return z
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.object({
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type: z.literal(type),
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aggregate: z.literal(def.aggregate),
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data: def.schema,
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})
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.meta({
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ref: "SyncEvent" + "." + def.type,
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})
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})
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.toArray() as any,
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)
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.meta({
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ref: "SyncEvent",
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})
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}
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}
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