Issue 6621

lib/ioIndexedDB.js

Index: lib/ioIndexedDB.js
diff --git a/lib/ioIndexedDB.js b/lib/ioIndexedDB.js
new file mode 100644
index 0000000000000000000000000000000000000000..d4ed7ffa009bd53006245a860854736e621b1974
--- /dev/null
+++ b/lib/ioIndexedDB.js
@@ -0,0 +1,300 @@
+/*
+ * This file is part of Adblock Plus <https://adblockplus.org/>,
+ * Copyright (C) 2006-present eyeo GmbH
+ *
+ * Adblock Plus is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * Adblock Plus is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+"use strict";
+
+
+// values from the DefaultConfig
+// https://github.com/localForage/localForage/blob/2cdbd74/src/localforage.js#L42-L51
+const localForageDbConfig = {
+  dbName: "localforage",
+  storeName: "keyvaluepairs",
+  version: 2
+};
+
+const dbConfig = {
+  dbName: "adblockplus",
+  storeName: "file",
+  keyPath: "fileName",
+  version: 1
+};
+
+let db = openDB(dbConfig);
+let migrationDone = migrateFiles();
+
+const keyPrefix = "file:";
+
+/**
+ * Handles migrating all files from localforage db
+ * used in the previous implementation by the localForage library
+ * to the new adblockplus db that we use as a replacement
+ * @return {Promise}
+ *    Promise to be resolved or rejected once the operation is completed
+ */
+function migrateFiles()
+{
+  return openDB(localForageDbConfig)
+    .then(localForageDb =>
+    {
+      return getAllFiles(localForageDb, localForageDbConfig.storeName)

[kzar, 2018/06/12 10:46:17]

Nit: I guess we can omit the curly braces and the `return` here, like you've
done elsewhere.

[piscoi.georgiana, 2018/06/14 13:41:26]

Done.

+        .then(files =>
+          db.then(dbInstance => files.map(file =>
+            Promise.all(saveFile(file, dbInstance, dbConfig.storeName)))))

[Sebastian Noack, 2018/06/13 00:55:12]

Please apologize if I'm wrong, but to me this seems like a bug: saveFile() 
returns a promise (not an array of promises). So why do we call Promise.all()
here? Did you mean to pass the result of files.map(...) to Promise.all()?

[piscoi.georgiana, 2018/06/14 13:41:27]

Spot on, thank you! I've fixed it.

+        .then(() =>
+          clearObjectStore(localForageDb, localForageDbConfig.storeName));
+    });
+}
+
+function getAllFiles(dbInstance, storeName)
+{
+  return new Promise((resolve, reject) =>
+  {
+    // edge doesn't currently support getAll method on IDBObjectStore interface
+    // so a cursor is used to iterate over all objects from the store
+    let transaction = dbInstance
+      .transaction([storeName], IDBTransaction.READ_ONLY);
+
+    let store = transaction.objectStore(storeName);
+    let cursorReq = store.openCursor();
+    let filesData = [];
+
+    transaction.oncomplete = event =>
+    {
+      resolve(filesData);
+    };
+
+    cursorReq.onsuccess = event =>
+    {
+      let cursor = event.currentTarget.result;
+      if (cursor)
+      {
+        let value = cursor.value;
+
+        filesData.push({
+          fileName: cursor.key,
+          content: value.content,
+          lastModified: value.lastModified
+        });
+        cursor.continue();
+      }
+    };
+
+    cursorReq.onerror = reject;
+  });
+}
+
+function clearObjectStore(dbInstance, storeName)
+{
+  return new Promise((resolve, reject) =>
+  {
+    let store = getObjectStore(dbInstance, storeName);
+    let req = store.clear();
+
+    req.onsuccess = resolve;
+    req.onerror = reject;
+  });
+}
+
+function fileToKey(fileName)
+{
+  return keyPrefix + fileName;
+}
+
+function formatFile(name, data)
+{
+  return {
+    fileName: fileToKey(name),
+    content: Array.from(data),
+    lastModified: Date.now()
+  };
+}
+
+function openDB({dbName, storeName, version, keyPath})
+{
+  return new Promise((resolve, reject) =>
+  {
+    let req = indexedDB.open(dbName, version);
+
+    req.onsuccess = event =>
+    {
+      return resolve(event.currentTarget.result);
+    };
+
+    req.onerror = reject;
+
+    req.onupgradeneeded = event =>
+    {
+      event
+      .currentTarget
+      .result
+      .createObjectStore(storeName,
+        {
+          keyPath,
+          autoIncrement: true
+        });
+    };
+  });
+}
+
+function getObjectStore(dbInstance, storeName)
+{
+  return dbInstance
+    .transaction([storeName], IDBTransaction.READ_WRITE)
+    .objectStore(storeName);
+}
+
+function getFile(fileName, dbInstance, storeName)
+{
+  return new Promise((resolve, reject) =>
+  {
+    let store = getObjectStore(dbInstance, storeName);
+    let req = store.get(fileToKey(fileName));
+
+    req.onsuccess = event =>
+    {
+      let result = event.currentTarget.result;
+
+      if (result)
+        resolve(result);
+      else
+        reject({type: "NoSuchFile"});
+    };
+    req.onerror = reject;
+  });
+}
+
+function saveFile(data, dbInstance, storeName)
+{
+  return new Promise((resolve, reject) =>
+  {
+    let store = getObjectStore(dbInstance, storeName);
+    let req = store.put(data);
+
+    req.onsuccess = resolve;
+    req.onerror = reject;
+  });
+}
+
+function deleteFile(fileName, dbInstance, storeName)
+{
+  return new Promise((resolve, reject) =>
+  {
+    let store = getObjectStore(dbInstance, storeName);
+    let req = store.delete(fileToKey(fileName));
+
+    req.onsuccess = resolve;
+    req.onerror = reject;
+  });
+}
+
+exports.IO =
+{
+  /**
+   * Writes text lines to a file.
+   * @param {string} fileName
+   *    Name of the file to be written
+   * @param {Iterable.<string>} data
+   *    An array-like or iterable object containing the lines (without line
+   *    endings)
+   * @return {Promise}
+   *    Promise to be resolved or rejected once the operation is completed
+   */
+  writeToFile(fileName, data)
+  {
+    return migrationDone
+      .then(() => db)
+      .then(dbInstance =>
+        saveFile(formatFile(fileName, data), dbInstance, dbConfig.storeName));
+  },
+
+  /**
+   * Reads text lines from a file.
+   * @param {string} fileName
+   *    Name of the file to be read
+   * @param {TextSink} listener
+   *    Function that will be called for each line in the file
+   * @return {Promise}
+   *    Promise to be resolved or rejected once the operation is completed
+   */
+  readFromFile(fileName, listener)
+  {
+    return migrationDone
+    .then(() => db)
+    .then(dbInstance => getFile(fileName, dbInstance, dbConfig.storeName))
+      .then(entry =>
+      {
+        for (let line of entry.content)
+          listener(line);
+      });
+  },
+
+  /**
+   * Retrieves file metadata.
+   * @param {string} fileName
+   *    Name of the file to be looked up
+   * @return {Promise.<StatData>}
+   *    Promise to be resolved with file metadata once the operation is
+   *    completed
+   */
+  statFile(fileName)
+  {
+    return migrationDone
+      .then(() => db)

[kzar, 2018/06/12 10:46:17]

Couldn't we do `db.then(dbInstance => ...` instead? (Same elsewhere.)

[piscoi.georgiana, 2018/06/14 13:41:27]

Yes, it looks better your way. Thank you!

+      .then(dbInstance => getFile(fileName, dbInstance, dbConfig.storeName))
+      .then(entry =>
+      {
+        return {
+          exists: true,
+          lastModified: entry.lastModified
+        };
+      })
+      .catch(error =>
+      {
+        if (error.type == "NoSuchFile")
+          return {exists: false};
+        throw error;
+      });
+  },
+
+  /**
+   * Renames a file.
+   * @param {string} fromFile
+   *    Name of the file to be renamed
+   * @param {string} newName
+   *    New file name, will be overwritten if exists
+   * @return {Promise}
+   *    Promise to be resolved or rejected once the operation is completed
+   */
+  renameFile(fromFile, newName)
+  {
+    return migrationDone
+      .then(() => db)
+      .then(dbInstance =>
+        getFile(fromFile, dbInstance, dbConfig.storeName)
+        .then(fileData =>
+          saveFile(
+            {
+              fileName: fileToKey(newName),
+              content: fileData.content,
+              lastModified: fileData.lastModified
+            },
+            dbInstance,
+            dbConfig.storeName))
+        .then(() => deleteFile(fromFile, dbInstance, dbConfig.storeName)));
+  }
+};
+