[wip] do not use cached metadata for doc_count and seq

Author: jcoglan

packages/node_modules/pouchdb-adapter-indexeddb/src/bulkDocs.js

@@ -24,9 +24,9 @@ import { DOC_STORE, META_LOCAL_STORE, idbError } from './util';
 import { rewrite, sanitise } from './rewrite';
 const sanitisedAttachmentKey = sanitise('_attachments');
 
-export default function (api, req, opts, metadata, dbOpts, idbChanges, callback) {
+export default function (api, req, opts, connectionInfo, dbOpts, idbChanges, callback) {
 
-  let txn;
+  let metadata = {};
 
   // TODO: I would prefer to get rid of these globals
   let error;
@@ -49,7 +49,7 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
 
   // Reads the original doc from the store if available
   // As in allDocs with keys option using multiple get calls is the fastest way
-  function fetchExistingDocs(txn, docs) {
+  function fetchExistingDocs(txn, metadata, docs) {
     let fetched = 0;
     const oldDocs = {};
 
@@ -58,7 +58,7 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
         oldDocs[e.target.result.id] = e.target.result;
       }
       if (++fetched === docs.length) {
-        processDocs(txn, docs, oldDocs);
+        processDocs(txn, metadata, docs, oldDocs);
       }
     }
 
@@ -76,7 +76,7 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
       });
   }
 
-  function processDocs(txn, docs, oldDocs) {
+  function processDocs(txn, metadata, docs, oldDocs) {
 
     docs.forEach(function (doc, i) {
       let newDoc;
@@ -116,7 +116,7 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
       } else {
         oldDocs[newDoc.id] = newDoc;
         lastWriteIndex = i;
-        write(txn, newDoc, i);
+        write(txn, metadata, newDoc, i);
       }
     });
   }
@@ -182,7 +182,7 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
     return doc;
   }
 
-  function write(txn, doc, i) {
+  function write(txn, metadata, doc, i) {
 
     // We copy the data from the winning revision into the root
     // of the document so that it can be indexed
@@ -287,7 +287,7 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
           rev: '0-0'
         };
       };
-      updateSeq(i);
+      updateSeq(txn, metadata, i);
       return;
     }
 
@@ -298,11 +298,11 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
         id: doc.id,
         rev: writtenRev
       };
-      updateSeq(i);
+      updateSeq(txn, metadata, i);
     };
   }
 
-  function updateSeq(i) {
+  function updateSeq(txn, metadata, i) {
     if (i === lastWriteIndex) {
       txn.objectStore(META_LOCAL_STORE).put(metadata);
     }
@@ -320,12 +320,12 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
       } catch (e) {
         return Promise.reject(createError(BAD_ARG, 'Attachment is not a valid base64 string'));
       }
-      if (metadata.idb_attachment_format === 'binary') {
+      if (connectionInfo.idb_attachment_format === 'binary') {
         attachment.data = binStringToBlobOrBuffer(binData, attachment.content_type);
       }
     } else {
       binData = attachment.data;
-      if (metadata.idb_attachment_format === 'base64') {
+      if (connectionInfo.idb_attachment_format === 'base64') {
         // TODO could run these in parallel, if we cared
         return new Promise(resolve => {
           blufferToBase64(attachment.data, function (b64) {
@@ -395,13 +395,11 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
     // We _could_ check doc ids here, and skip opening DOC_STORE if all docs are local.
     // This may marginally slow things down for local docs.  It seems pragmatic to keep
     // the code simple and optimise for calls to bulkDocs() which include non-local docs.
-    api._openTransactionSafely([DOC_STORE, META_LOCAL_STORE], 'readwrite', function (err, _txn) {
+    api._openTransactionSafely([DOC_STORE, META_LOCAL_STORE], 'readwrite', function (err, txn) {
       if (err) {
         return callback(err);
       }
 
-      txn = _txn;
-
       txn.onabort = function () {
         callback(error || createError(UNKNOWN_ERROR, 'transaction was aborted'));
       };
@@ -412,8 +410,11 @@ export default function (api, req, opts, metadata, dbOpts, idbChanges, callback)
         callback(null, results);
       };
 
-      // We would like to use promises here, but idb sucks
-      fetchExistingDocs(txn, docs);
+      const metaStore = txn.objectStore(META_LOCAL_STORE);
+      metaStore.get(META_LOCAL_STORE).onsuccess = function (e) {
+        const metadata = e.target.result;
+        fetchExistingDocs(txn, metadata, docs);
+      };
     });
   }).catch(function (err) {
     callback(err);

packages/node_modules/pouchdb-adapter-indexeddb/src/index.js

@@ -34,14 +34,29 @@ function IndexeddbPouch(dbOpts, callback) {
   }
 
   const api = this;
-  let metadata = {};
+
+  // When the database is opened, we cache the "static" metadata fields i.e.
+  // those that do not change when docs are updated. These are needed for some
+  // async operations (e.g. preprocessing attachments) that cannot be performed
+  // in the middle of a transaction due to the nature of the IndexedDB API, so
+  // they need to know these settings without having to read from the object
+  // store. "Dynamic" values like `doc_count` and `seq` must always be read
+  // from the object store so that they are not stale.
+  const CACHED_INFO_KEYS = ['db_uuid', 'idb_attachment_format'];
+  const connectionInfo = {};
+
+  function updateConnectionInfo(metadata) {
+    for (const key of CACHED_INFO_KEYS) {
+      connectionInfo[key] = metadata[key];
+    }
+  }
 
   // Wrapper that gives you an active DB handle. You probably want $t.
   const $ = function (fun) {
     return function () {
       const args = Array.prototype.slice.call(arguments);
       setup(openDatabases, api, dbOpts).then(function (res) {
-        metadata = res.metadata;
+        updateConnectionInfo(res.metadata);
         args.unshift(res.idb);
         fun.apply(api, args);
       }).catch(function (err) {
@@ -60,9 +75,8 @@ function IndexeddbPouch(dbOpts, callback) {
       const args = Array.prototype.slice.call(arguments);
 
       return setup(openDatabases, api, dbOpts).then(function (res) {
-        metadata = res.metadata;
+        updateConnectionInfo(res.metadata);
         args.unshift(res.idb);
-
         return fun.apply(api, args);
       });
     };
@@ -78,7 +92,7 @@ function IndexeddbPouch(dbOpts, callback) {
       const args = Array.prototype.slice.call(arguments);
       const txn = {};
       setup(openDatabases, api, dbOpts).then(function (res) {
-        metadata = res.metadata;
+        updateConnectionInfo(res.metadata);
         txn.txn = res.idb.transaction(stores, mode);
       }).catch(function (err) {
         console.error('Failed to establish transaction safely');
@@ -97,29 +111,44 @@ function IndexeddbPouch(dbOpts, callback) {
     }, stores, mode)(callback);
   };
 
+  api._getMetadata = $t(function (txn, cb) {
+    const metaStore = txn.txn.objectStore(META_LOCAL_STORE);
+    metaStore.get(META_LOCAL_STORE).onsuccess = function (e) {
+      cb(null, e.target.result);
+    };
+  }, [META_LOCAL_STORE]);
+
   api._remote = false;
   api.type = function () { return ADAPTER_NAME; };
 
-  api._id = $(function (_, cb) {
-    cb(null, metadata.db_uuid);
-  });
+  api._id = function (cb) {
+    api._getMetadata(function (err, metadata) {
+      cb(null, metadata.db_uuid);
+    });
+  };
 
-  api._info = $(function (_, cb) {
-    return info(metadata, cb);
-  });
+  api._info = function (cb) {
+    api._getMetadata(function (err, metadata) {
+      return info(metadata, cb);
+    });
+  };
 
   api._get = $t(get, [DOC_STORE]);
   api._getLocal = $t(function (txn, id, callback) {
     return getLocal(txn, id, api, callback);
   }, [META_LOCAL_STORE]);
 
   api._bulkDocs = $(function (_, req, opts, callback) {
-    bulkDocs(api, req, opts, metadata, dbOpts, idbChanges, callback);
+    bulkDocs(api, req, opts, connectionInfo, dbOpts, idbChanges, callback);
   });
 
   api._allDocs = $t(function (txn, opts, cb) {
-    allDocs(txn, metadata, opts, cb);
-  }, [DOC_STORE]);
+    const metaStore = txn.txn.objectStore(META_LOCAL_STORE);
+    metaStore.get(META_LOCAL_STORE).onsuccess = function (e) {
+      const metadata = e.target.result;
+      allDocs(txn, metadata, opts, cb);
+    };
+  }, [DOC_STORE, META_LOCAL_STORE]);
 
   api._getAttachment = getAttachment;
 

packages/node_modules/pouchdb-adapter-indexeddb/src/setup.js

@@ -115,7 +115,9 @@ function upgradePouchDbSchema(dbName, db, tx, pouchdbVersion) {
 }
 
 function openDatabase(openDatabases, api, opts, resolve, reject) {
-  const openReq = indexedDB.open(opts.name, createIdbVersion());
+  const openReq = opts.versionChangedWhileOpen ?
+    indexedDB.open(opts.name) :
+    indexedDB.open(opts.name, createIdbVersion());
 
   openReq.onupgradeneeded = function (e) {
     if (e.oldVersion > 0 && e.oldVersion < versionMultiplier) {
@@ -183,15 +185,23 @@ function openDatabase(openDatabases, api, opts, resolve, reject) {
       idb.close();
     };
 
+    // In IndexedDB you can only change the version, and thus the schema, when you are opening the database.
+    // versionChangedWhileOpen means that something else outside of our control has likely updated the version.
+    // One way this could happen is if you open multiple tabs, as the version number changes each time the database is opened.
+    // If we suspect this we close the db and tag it, so that next time it's accessed it reopens the DB with the current version
+    // as opposed to upping the version again
+    // This avoids infinite loops of version updates if you have multiple tabs open
     idb.onversionchange = function () {
       console.log('Database was made stale, closing handle');
-      delete openDatabases[opts.name];
+      openDatabases[opts.name].versionChangedWhileOpen = true;
       idb.close();
     };
 
     idb.onclose = function () {
       console.log('Database was made stale, closing handle');
-      delete openDatabases[opts.name];
+      if (opts.name in openDatabases) {
+        openDatabases[opts.name].versionChangedWhileOpen = true;
+      }
     };
 
     let metadata = {id: META_LOCAL_STORE};
@@ -247,7 +257,10 @@ function openDatabase(openDatabases, api, opts, resolve, reject) {
 }
 
 export default function (openDatabases, api, opts) {
-  if (!openDatabases[opts.name]) {
+  if (!openDatabases[opts.name] || openDatabases[opts.name].versionChangedWhileOpen) {
+    opts.versionChangedWhileOpen = openDatabases[opts.name] &&
+                          openDatabases[opts.name].versionChangedWhileOpen;
+
     openDatabases[opts.name] = new Promise(function (resolve, reject) {
       openDatabase(openDatabases, api, opts, resolve, reject);
     });