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/*
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Maybe storage available as a service.
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This code is similar to the changefeed server, because 
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it provides a changefeed on a given persist storage, 
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and a way to see values.
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DEVELOPMENT:
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Change to the packages/backend directory and run node.
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TERMINAL 1: This sets up the environment and starts the server running:
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   require('@cocalc/backend/conat/persist').initServer()
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TERMINAL 2: In another node session, create a client:
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    user = {account_id:'00000000-0000-4000-8000-000000000000'}; storage = {path:'a.db'}; const {id, stream} = await require('@cocalc/backend/conat/persist').getAll({user, storage}); console.log({id}); for await(const x of stream) { console.log(x.data) }; console.log("DONE")
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// client also does this periodically to keep subscription alive:
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    await renew({user, id }) 
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TERMINAL 3:
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user = {account_id:'00000000-0000-4000-8000-000000000000'}; storage = {path:'a.db'}; const {set,get} = require('@cocalc/backend/conat/persist');  const { messageData } =require("@cocalc/conat/core/client"); 0;
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   await set({user, storage, messageData:messageData('hi')})
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   await get({user, storage,  seq:1})
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   await set({user, storage, key:'bella', messageData:messageData('hi', {headers:{x:10}})})
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   await get({user, storage,  key:'bella'})
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Also getAll using start_seq:
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   cf = const {id,  stream} = await require('@cocalc/backend/conat/persist').getAll({user, storage, start_seq:10}); for await(const x of stream) { console.log(x) };
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*/
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import { assertHasWritePermission } from "./auth";
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import { pstream, PersistentStream } from "./storage";
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import { join } from "path";
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import { syncFiles, ensureContainingDirectoryExists } from "./context";
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// this is per-server -- and "user" means where the resource is, usually
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// a given project.  E.g., 500 streams in a project, across many users.
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export const MAX_PER_USER = 500;
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export const MAX_GLOBAL = 10000;
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export const RESOURCE = "persistent storage";
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//import { getLogger } from "@cocalc/conat/client";
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//const logger = getLogger("persist:util");
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export const SERVICE = "persist";
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export type User = {
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  account_id?: string;
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  project_id?: string;
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  hub_id?: string;
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};
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export function persistSubject({ account_id, project_id }: User) {
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  if (account_id) {
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    return `${SERVICE}.account-${account_id}`;
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  } else if (project_id) {
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    return `${SERVICE}.project-${project_id}`;
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  } else {
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    return `${SERVICE}.hub`;
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  }
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}
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export async function getStream({
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  subject,
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  storage,
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}): Promise<PersistentStream> {
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  // this permsissions check should always work and use should
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  // never see an error here, since
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  // the same check runs on the client before the message is sent to the
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  // persist storage.  However a malicious user would hit this.
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  // IMPORTANT: must be here so error *code* also sent back.
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  assertHasWritePermission({
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    subject,
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    path: storage.path,
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  });
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  const path = join(syncFiles.local, storage.path);
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  await ensureContainingDirectoryExists(path);
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  return pstream({ ...storage, path });
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}
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