Issue 6775 - Work around filter data stored in IndexedDB getting lost on Microsoft Edge

lib/ioIndexedDB.js

 /*
  * 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
@@ skipping 139 matching lines @@
   };
 }
 
 function getObjectStore(dbInstance, storeName)
 {
   return dbInstance
     .transaction([storeName], IDBTransaction.READ_WRITE)
     .objectStore(storeName);
 }
 
-function reestablishConnection(dbInstance, retries)
+function reestablishConnection(dbInstance, retries = 10)
 {
   dbInstance.close();
-  retries = retries || 1;

[Sebastian Noack, 2018/08/31 18:07:05]

You can use default arguments. Also I would rather count down to zero than
counting up to n. That way you have the maximum number of retries configured in
a more structured way (rather than being hidden in the code), and as a
side-effect you can easily override it to test something during development.

  function reestablishConnection(dbInstance, retries=10)
  {
    ...
  }

[geo, 2018/09/04 16:12:08]

Done.

   db = openDB(dbConfig);
 
   return db.catch(err =>
   {
-    if (retries == 10)
+    if (!retries)
       throw err;
 
-    return reestablishConnection(dbInstance, ++retries);
+    return reestablishConnection(dbInstance, --retries);
   });
 }
 
 function getFile(fileName, dbInstance, storeName)
 {
   return getFromIndexedDB(fileToKey(fileName), dbInstance, storeName)
     .then(indexedDBResult =>
     {
       if (!indexedDBResult)
       {
         const {IndexedDBBackup} = require("./indexedDBBackup");

[Sebastian Noack, 2018/08/31 18:07:05]

Nit: Can this import be moved to the top of the module, or do we have a circular
dependency then?

[geo, 2018/09/04 16:12:08]

Yes, we end up with a circular dependency, as indexedDBBackup requires
filterStorage and filterStorage requires ioIndexedDB.

 
         return IndexedDBBackup.getBackupData()
           .then(backupData =>
             saveFile(
               {
                 fileName: fileToKey(fileName),
                 content: backupData.content,
                 lastModified: backupData.lastModified
               },
               dbInstance,
-              storeName)
-            .then(() => backupData));

[Sebastian Noack, 2018/08/31 18:07:05]

Nit: The indentation is a little off here:

  .then(backupData =>
    saveFile(
      ...
    )
  .then(...);

[geo, 2018/09/04 16:12:08]

I've changed a bit the indentation, hopefully it's more clear now.

+              storeName).then(() => backupData)
+          );
       }
       return indexedDBResult;
     });
 }
 
 function getFromIndexedDB(fileName, dbInstance, storeName)
 {
   return new Promise((resolve, reject) =>
   {
     let store = getObjectStore(dbInstance, storeName);
     let req = store.get(fileName);
 
     req.onsuccess = event => resolve(event.currentTarget.result);
     req.onerror = event => reject(event.target.error);
   })
   .catch(error =>
   {
     if (error.name == "UnknownError")
-      return reestablishConnection(dbInstance)
-        .then(() => Promise.resolve());
+      return reestablishConnection(dbInstance).then(() => undefined);
   });
 }
 
 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 = event => reject(event.target.error);
   })
   .catch(error =>
   {
     if (error.name == "UnknownError")
     {
-      return reestablishConnection(dbInstance)
-      .then(newDbInstance =>
-        saveFile(data, newDbInstance, storeName));

[Sebastian Noack, 2018/08/31 18:07:05]

Nit: For consistent with other code, can you indent this like that:

  return reestablishConnection(dbInstance).then(newDbInstance =>
    saveFile(data, newDbInstance, storeName)
  );

[geo, 2018/09/04 16:12:08]

Done.

+      return reestablishConnection(dbInstance).then(newDbInstance =>
+        saveFile(data, newDbInstance, storeName)
+      );
     }
   });
 }
 
 function deleteFile(fileName, dbInstance, storeName)
 {
   return new Promise((resolve, reject) =>
   {
     let store = getObjectStore(dbInstance, storeName);
     let req = store.delete(fileToKey(fileName));
@@ skipping 101 matching lines @@
                 fileName: fileToKey(newName),
                 content: fileData.content,
                 lastModified: fileData.lastModified
               },
               dbInstance,
               dbConfig.storeName))
           .then(() => deleteFile(fromFile, dbInstance, dbConfig.storeName))));
   }
 };