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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: "sha256"}],
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["file_uses", {keyPath: "sha256"}],
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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(initialization_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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await new Promise(resolve => store.transaction.oncomplete = resolve);
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save_items(db, initialization_data);
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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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/*
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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(db, data)
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{
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const files = data.files;
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const resources =
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Object.values(data.resources || []).map(entities.get_newest);
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const mappings =
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Object.values(data.mappings || []).map(entities.get_newest);
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resources.concat(mappings).forEach(i => save_item(i, data.files, db));
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}
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/* helper function of save_item() */
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async function get_file_uses(transaction, file_uses_sha256, file_ref)
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{
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let uses = file_uses_sha256[file_ref.sha256];
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if (uses === undefined) {
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uses = await idb_get(transaction, "file_uses", file_ref.sha256);
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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 = {sha256: file_ref.sha256, uses: 0, new: true, initial: 0};
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file_uses_sha256[file_ref.sha256] = uses;
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}
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return uses;
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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 their sha256 sums.
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*/
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async function save_item(item, files_sha256, db)
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{
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const store_name = {resource: "resources", mapping: "mappings"}[item.type];
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const transaction =
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db.transaction([store_name, "files", "file_uses"], "readwrite");
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let resolve, reject;
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const result = new Promise((...cbs) => [resolve, reject] = cbs);
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transaction.oncomplete = resolve;
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transaction.onerror = reject;
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const uses_sha256 = {};
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for (const file_ref of entities.get_files(item))
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(await get_file_uses(transaction, uses_sha256, file_ref)).uses++;
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const old_item = await idb_get(transaction, store_name, item.identifier);
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if (old_item !== undefined) {
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for (const file_ref of entities.get_files(old_item))
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(await get_file_uses(transaction, uses_sha256, file_ref)).uses--;
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}
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for (const uses of Object.values(uses_sha256)) {
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if (uses.uses < 0)
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console.error("internal error: uses < 0 for file " + uses.sha256);
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const [is_new, initial_uses] = [uses.new, uses.initial];
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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(transaction, "file_uses", uses.sha256);
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idb_del(transaction, "files", uses.sha256);
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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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const file = files_sha256[uses.sha256];
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if (file === undefined)
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throw "file not present: " + uses.sha256;
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idb_put(transaction, "files", {sha256: uses.sha256, contents: file});
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idb_put(transaction, "file_uses", uses);
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}
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idb_put(transaction, store_name, item);
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return result;
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}
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const haketilodb = {
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get: get_db,
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save_item: save_item
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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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