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/**
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* This file is part of Haketilo.
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*
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* Function: Facilitate use of IndexedDB within Haketilo.
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*
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* Copyright (C) 2021 Wojtek Kosior <koszko@koszko.org>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* As additional permission under GNU GPL version 3 section 7, you
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* may distribute forms of that code without the copy of the GNU
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* GPL normally required by section 4, provided you include this
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* license notice and, in case of non-source distribution, a URL
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* through which recipients can access the Corresponding Source.
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* If you modify file(s) with this exception, you may extend this
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* exception to your version of the file(s), but you are not
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* obligated to do so. If you do not wish to do so, delete this
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* exception statement from your version.
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*
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* As a special exception to the GPL, any HTML file which merely
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* makes function calls to this code, and for that purpose
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* includes it by reference shall be deemed a separate work for
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* copyright law purposes. If you modify this code, you may extend
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* this exception to your version of the code, but you are not
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* obligated to do so. If you do not wish to do so, delete this
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* exception statement from your version.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*
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* I, Wojtek Kosior, thereby promise not to sue for violation of this file's
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* license. Although I request that you do not make use this code in a
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* proprietary program, I am not going to enforce this in court.
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*/
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/*
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* IMPORTS_START
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* IMPORT initial_data
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* IMPORT entities
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* IMPORTS_END
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*/
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/* Update when changes are made to database schema. Must have 3 elements */
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const db_version = [1, 0, 0];
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const nr_reductor = ([i, s], num) => [i - 1, s + num * 1024 ** i];
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const version_nr = ver => Array.reduce(ver.slice(0, 3), nr_reductor, [2, 0])[1];
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const stores = [
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["files", {keyPath: "hash_key"}],
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["file_uses", {keyPath: "hash_key"}],
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["resources", {keyPath: "identifier"}],
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["mappings", {keyPath: "identifier"}]
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];
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let db = null;
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/* Generate a Promise that resolves when an IndexedDB request succeeds. */
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async function wait_request(idb_request)
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{
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let resolve, reject;
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const waiter = new Promise((...cbs) => [resolve, reject] = cbs);
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[idb_request.onsuccess, idb_request.onerror] = [resolve, reject];
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return waiter;
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}
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/* asynchronous wrapper for IDBObjectStore's get() method. */
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async function idb_get(transaction, store_name, key)
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{
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const req = transaction.objectStore(store_name).get(key);
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return (await wait_request(req)).target.result;
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}
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/* asynchronous wrapper for IDBObjectStore's put() method. */
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async function idb_put(transaction, store_name, object)
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{
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return wait_request(transaction.objectStore(store_name).put(object));
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}
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/* asynchronous wrapper for IDBObjectStore's delete() method. */
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async function idb_del(transaction, store_name, key)
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{
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return wait_request(transaction.objectStore(store_name).delete(key));
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}
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/* Open haketilo database, asynchronously return an IDBDatabase object. */
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async function get_db(data=initial_data)
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{
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if (db)
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return db;
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let resolve, reject;
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const waiter = new Promise((...cbs) => [resolve, reject] = cbs);
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const request = indexedDB.open("haketilo", version_nr(db_version));
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request.onsuccess = resolve;
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request.onerror = ev => reject("db error: " + ev.target.errorCode);
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request.onupgradeneeded = resolve;
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const event = await waiter;
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const opened_db = event.target.result;
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if (event instanceof IDBVersionChangeEvent) {
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/*
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* When we move to a new database schema, we will add upgrade logic
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* here.
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*/
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if (event.oldVersion > 0)
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throw "bad db version: " + event.oldVersion;
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let store;
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for (const [store_name, key_mode] of stores)
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store = opened_db.createObjectStore(store_name, key_mode);
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const context = make_context(store.transaction, data.files);
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await _save_items(data.resources, data.mappings, context);
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}
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db = opened_db;
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return db;
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}
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/* Helper function used by start_items_transaction() and get_db(). */
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function make_context(transaction, files)
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{
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files = files || {};
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const context = {transaction, files, file_uses: {}};
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let resolve, reject;
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context.result = new Promise((...cbs) => [resolve, reject] = cbs);
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context.transaction.oncomplete = resolve;
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context.transaction.onerror = reject;
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return context;
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}
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/*
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* item_store_names should be an array with either string "mappings", string
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* "resources" or both. files should be a dict with values being contents of
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* files that are to be possibly saved in this transaction and keys of the form
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* `sha256-<file's-sha256-sum>`.
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*
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* Returned is a context object wrapping the transaction and handling the
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* counting of file references in IndexedDB.
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*/
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async function start_items_transaction(item_store_names, files)
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{
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const db = await haketilodb.get();
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const scope = [...item_store_names, "files", "file_uses"];
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return make_context(db.transaction(scope, "readwrite"), files);
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}
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async function incr_file_uses(context, file_ref, by=1)
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{
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const hash_key = file_ref.hash_key;
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let uses = context.file_uses[hash_key];
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if (uses === undefined) {
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uses = await idb_get(context.transaction, "file_uses", hash_key);
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if (uses)
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[uses.new, uses.initial] = [false, uses.uses];
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else
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uses = {hash_key, uses: 0, new: true, initial: 0};
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context.file_uses[hash_key] = uses;
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}
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uses.uses = uses.uses + by;
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}
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const decr_file_uses = (ctx, file_ref) => incr_file_uses(ctx, file_ref, -1);
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async function finalize_items_transaction(context)
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{
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for (const uses of Object.values(context.file_uses)) {
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if (uses.uses < 0)
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console.error("internal error: uses < 0 for file " + uses.hash_key);
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const is_new = uses.new;
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const initial_uses = uses.initial;
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const hash_key = uses.hash_key;
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delete uses.new;
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delete uses.initial;
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if (uses.uses < 1) {
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if (!is_new) {
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idb_del(context.transaction, "file_uses", hash_key);
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idb_del(context.transaction, "files", hash_key);
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}
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continue;
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}
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if (uses.uses === initial_uses)
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continue;
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idb_put(context.transaction, "file_uses", uses);
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if (initial_uses > 0)
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continue;
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const file = context.files[hash_key];
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if (file === undefined) {
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context.transaction.abort();
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throw "file not present: " + hash_key;
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}
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idb_put(context.transaction, "files", {hash_key, contents: file});
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}
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return context.result;
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}
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async function with_items_transaction(cb, item_store_names, files={})
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{
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const context = await start_items_transaction(item_store_names, files);
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await cb(context);
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await finalize_items_transaction(context);
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}
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/*
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* How a sample data argument to the function below might look like:
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*
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* data = {
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* resources: {
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* "resource1": {
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* "1": {
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* // some stuff
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* },
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* "1.1": {
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* // some stuff
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* }
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* },
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* "resource2": {
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* "0.4.3": {
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* // some stuff
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* }
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* },
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* },
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* mappings: {
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* "mapping1": {
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* "2": {
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* // some stuff
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* }
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* },
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* "mapping2": {
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* "0.1": {
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* // some stuff
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* }
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* },
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* },
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* files: {
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* "sha256-f9444510dc7403e41049deb133f6892aa6a63c05591b2b59e4ee5b234d7bbd99": "console.log(\"hello\");\n",
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* "sha256-b857cd521cc82fff30f0d316deba38b980d66db29a5388eb6004579cf743c6fd": "console.log(\"bye\");"
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* }
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* }
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*/
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async function save_items(transaction, data)
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{
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const items_store_names = ["resources", "mappings"];
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const context = start_items_transaction(items_store_names, data.files);
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return _save_items(data.resources, data.mappings, context);
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}
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async function _save_items(resources, mappings, context)
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{
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resources = Object.values(resources || {}).map(entities.get_newest);
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mappings = Object.values(mappings || {}).map(entities.get_newest);
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for (const item of resources.concat(mappings))
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await save_item(item, context);
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await finalize_items_transaction(context);
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}
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/*
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* Save given definition of a resource/mapping to IndexedDB. If the definition
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* (passed as `item`) references files that are not already present in
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* IndexedDB, those files should be present as values of the `files_sha256`
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* object with keys being of the form `sha256-<file's-sha256-sum>`.
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*
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* context should be one returned from start_items_transaction() and should be
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* later passed to finalize_items_transaction() so that files depended on are
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* added to IndexedDB and files that are no longer depended on after this
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* operation are removed from IndexedDB.
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*/
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async function save_item(item, context)
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{
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const store_name = {resource: "resources", mapping: "mappings"}[item.type];
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for (const file_ref of entities.get_files(item))
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await incr_file_uses(context, file_ref);
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await _remove_item(store_name, item.identifier, context, false);
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await idb_put(context.transaction, store_name, item);
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}
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/* Helper function used by remove_item() and save_item(). */
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async function _remove_item(store_name, identifier, context)
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{
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const item = await idb_get(context.transaction, store_name, identifier);
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if (item !== undefined) {
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for (const file_ref of entities.get_files(item))
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await decr_file_uses(context, file_ref);
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}
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}
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/*
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* Remove definition of a resource/mapping from IndexedDB.
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*
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* context should be one returned from start_items_transaction() and should be
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* later passed to finalize_items_transaction() so that files depended on are
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* added to IndexedDB and files that are no longer depended on after this
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* operation are removed from IndexedDB.
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*/
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async function remove_item(store_name, identifier, context)
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{
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await _remove_item(store_name, identifier, context);
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await idb_del(context.transaction, store_name, identifier);
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}
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const remove_resource =
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(identifier, ctx) => remove_item("resources", identifier, ctx);
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const remove_mapping =
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(identifier, ctx) => remove_item("mappings", identifier, ctx);
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const haketilodb = {
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get: get_db,
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save_items,
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save_item,
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remove_resource,
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remove_mapping,
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start_items_transaction,
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finalize_items_transaction
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};
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/*
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* EXPORTS_START
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* EXPORT haketilodb
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* EXPORT idb_get
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* EXPORT idb_put
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* EXPORT idb_del
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* EXPORTS_END
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*/
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