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import {randomUUID} from "node:crypto";
import EventEmitter from "node:events";
import {Delta} from "./delta";
import {Entity, EntityProperties} from "./entity";
import {ResolvedViewOne} from './last-write-wins';
import {RhizomeNode} from "./node";
import {DomainEntityID} from "./types";
const debug = Debug('rz:abstract-collection');
export abstract class Collection<View> {
rhizomeNode?: RhizomeNode;
name: string;
eventStream = new EventEmitter();
lossy?: View;
constructor(name: string) {
this.name = name;
}
abstract initializeView(): void;
abstract resolve(id: DomainEntityID): ResolvedViewOne | undefined;
rhizomeConnect(rhizomeNode: RhizomeNode) {
this.rhizomeNode = rhizomeNode;
this.initializeView();
// Listen for completed transactions, and emit updates to event stream
this.rhizomeNode.lossless.eventStream.on("updated", (id) => {
// TODO: Filter so we only get members of our collection
// TODO: Reslover / Delta Filter?
const res = this.resolve(id);
this.eventStream.emit("update", res);
});
rhizomeNode.httpServer.httpApi.serveCollection<View>(this);
debug(`[${this.rhizomeNode.config.peerId}]`, `Connected ${this.name} to rhizome`);
}
// This function is here instead of Entity so that it can:
// - read the current state in order to build its delta
// - include the collection name in the delta it produces
generateDeltas(
entityId: DomainEntityID,
newProperties: EntityProperties,
creator: string,
host: string,
): {
transactionDelta: Delta | undefined,
deltas: Delta[]
} {
const deltas: Delta[] = [];
let oldProperties: EntityProperties = {};
if (entityId) {
const entity = this.resolve(entityId);
Iif (entity) {
oldProperties = entity.properties;
}
}
// Generate a transaction ID
const transactionId = `transaction-${randomUUID()}`;
// Generate a delta for each changed property
Object.entries(newProperties).forEach(([key, value]) => {
// Disallow property named "id"
Iif (key === 'id') return;
if (oldProperties[key] !== value && host && creator) {
deltas.push(new Delta({
creator,
host,
pointers: [{
localContext: this.name,
target: entityId,
targetContext: key
}, {
localContext: key,
target: value
}]
}));
}
});
let transactionDelta: Delta | undefined;
if (deltas.length > 1) {
// We can generate a separate delta describing this transaction
transactionDelta = new Delta({
creator,
host,
pointers: [{
localContext: "_transaction",
target: transactionId,
targetContext: "size"
}, {
localContext: "size",
target: deltas.length
}]
});
// Also need to annotate the deltas with the transactionId
for (const delta of deltas) {
delta.pointers.unshift({
localContext: "_transaction",
target: transactionId,
targetContext: "deltas"
});
}
}
return {transactionDelta, deltas};
}
onCreate(cb: (entity: Entity) => void) {
// TODO: Trigger for changes received from peers
this.eventStream.on('create', (entity: Entity) => {
cb(entity);
});
}
onUpdate(cb: (entity: Entity) => void) {
// TODO: Trigger for changes received from peers
this.eventStream.on('update', (entity: Entity) => {
cb(entity);
});
}
getIds(): string[] {
Iif (!this.rhizomeNode) return [];
const set = this.rhizomeNode.lossless.referencedAs.get(this.name);
Iif (!set) return [];
return Array.from(set.values());
}
// THIS PUT SHOULD CORRESOND TO A PARTICULAR MATERIALIZED VIEW...
// How can we encode that?
// Well, we have a way to do that, we just need the same particular inputs.
// We take a resolver as an optional argument.
async put(
entityId: DomainEntityID | undefined,
properties: EntityProperties,
): Promise<ResolvedViewOne> {
Iif (!this.rhizomeNode) throw new Error('collection not connecte to rhizome');
// For convenience, we allow setting id via properties.id
Iif (!entityId && !!properties.id && typeof properties.id === 'string') {
entityId = properties.id;
}
// Generate an ID if none is provided
Iif (!entityId) {
entityId = randomUUID();
}
const {transactionDelta, deltas} = this.generateDeltas(
entityId,
properties,
this.rhizomeNode?.config.creator,
this.rhizomeNode?.config.peerId,
);
const ingested = new Promise<boolean>((resolve) => {
this.rhizomeNode!.lossless.eventStream.on("updated", (id: DomainEntityID) => {
if (id === entityId) resolve(true);
})
});
if (transactionDelta) {
deltas.unshift(transactionDelta);
}
deltas.forEach(async (delta: Delta) => {
// record this delta just as if we had received it from a peer
delta.receivedFrom = this.rhizomeNode!.myRequestAddr;
this.rhizomeNode!.deltaStream.deltasAccepted.push(delta);
// publish the delta to our subscribed peers
await this.rhizomeNode!.deltaStream.publishDelta(delta);
// ingest the delta as though we had received it from a peer
this.rhizomeNode!.lossless.ingestDelta(delta);
});
// Return updated view of this entity
// Let's wait for an event notifying us that the entity has been updated.
// This means all of our deltas have been applied.
await ingested;
const res = this.resolve(entityId);
Iif (!res) throw new Error("could not get what we just put!");
return res;
}
}
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