Journal: Second attempt at journal mode fallback #5723

Some filesystems, vms or other limitations make using the WAL journal
mode impossible. We are notified of this problem through an sqlite
IOERR for SHMMAP. In that case We want to attempt to fall back to the
DELETE journal mode.

diff --git a/src/libsync/syncjournaldb.cpp b/src/libsync/syncjournaldb.cpp
index f4d3510dd3440298f318915e4d94617a24a7027c..d963b8667451011a49e33a34d131a945d0adc3f7 100644 (file)
--- a/src/libsync/syncjournaldb.cpp
+++ b/src/libsync/syncjournaldb.cpp
@@ -35,11 +35,34 @@ namespace OCC {
 
 Q_LOGGING_CATEGORY(lcDb, "sync.database", QtInfoMsg)
 
+static QString defaultJournalMode(const QString &dbPath)
+{
+#ifdef Q_OS_WIN
+    // See #2693: Some exFAT file systems seem unable to cope with the
+    // WAL journaling mode. They work fine with DELETE.
+    QString fileSystem = FileSystem::fileSystemForPath(dbPath);
+    qCInfo(lcDb) << "Detected filesystem" << fileSystem << "for" << dbPath;
+    if (fileSystem.contains("FAT")) {
+        qCInfo(lcDb) << "Filesystem contains FAT - using DELETE journal mode";
+        return "DELETE";
+    }
+#else
+    Q_UNUSED(dbPath)
+#endif
+    return "WAL";
+}
+
 SyncJournalDb::SyncJournalDb(const QString &dbFilePath, QObject *parent)
     : QObject(parent)
     , _dbFile(dbFilePath)
     , _transaction(0)
 {
+    // Allow forcing the journal mode for debugging
+    static QString envJournalMode = QString::fromLocal8Bit(qgetenv("OWNCLOUD_SQLITE_JOURNAL_MODE"));
+    _journalMode = envJournalMode;
+    if (_journalMode.isEmpty()) {
+        _journalMode = defaultJournalMode(_dbFile);
+    }
 }
 
 QString SyncJournalDb::makeDbName(const QString &localPath,
@@ -215,23 +238,6 @@ bool SyncJournalDb::sqlFail(const QString &log, const SqlQuery &query)
     return false;
 }
 
-static QString defaultJournalMode(const QString &dbPath)
-{
-#ifdef Q_OS_WIN
-    // See #2693: Some exFAT file systems seem unable to cope with the
-    // WAL journaling mode. They work fine with DELETE.
-    QString fileSystem = FileSystem::fileSystemForPath(dbPath);
-    qCInfo(lcDb) << "Detected filesystem" << fileSystem << "for" << dbPath;
-    if (fileSystem.contains("FAT")) {
-        qCInfo(lcDb) << "Filesystem contains FAT - using DELETE journal mode";
-        return "DELETE";
-    }
-#else
-    Q_UNUSED(dbPath)
-#endif
-    return "WAL";
-}
-
 bool SyncJournalDb::checkConnect()
 {
     if (_db.isOpen()) {
@@ -264,13 +270,7 @@ bool SyncJournalDb::checkConnect()
         qCInfo(lcDb) << "sqlite3 version" << pragma1.stringValue(0);
     }
 
-    // Allow forcing the journal mode for debugging
-    static QString env_journal_mode = QString::fromLocal8Bit(qgetenv("OWNCLOUD_SQLITE_JOURNAL_MODE"));
-    QString journal_mode = env_journal_mode;
-    if (journal_mode.isEmpty()) {
-        journal_mode = defaultJournalMode(_dbFile);
-    }
-    pragma1.prepare(QString("PRAGMA journal_mode=%1;").arg(journal_mode));
+    pragma1.prepare(QString("PRAGMA journal_mode=%1;").arg(_journalMode));
     if (!pragma1.exec()) {
         return sqlFail("Set PRAGMA journal_mode", pragma1);
     } else {
@@ -323,26 +323,22 @@ bool SyncJournalDb::checkConnect()
                         ");");
 
     if (!createQuery.exec()) {
-        bool fail = true;
-
         // In certain situations the io error can be avoided by switching
         // to the DELETE journal mode, see #5723
-        if (createQuery.errorId() == SQLITE_IOERR) {
-            qCWarning(lcDb) << "IO error on table creation, attempting with DELETE journal mode";
-
-            pragma1.prepare(QString("PRAGMA journal_mode=DELETE;"));
-            if (!pragma1.exec()) {
-                return sqlFail("Set PRAGMA journal_mode", pragma1);
-            }
-            pragma1.next();
-            qCInfo(lcDb) << "sqlite3 journal_mode=" << pragma1.stringValue(0);
-
-            if (createQuery.exec()) {
-                fail = false;
-            }
+        if (_journalMode != "DELETE"
+            && createQuery.errorId() == SQLITE_IOERR
+            && sqlite3_extended_errcode(_db.sqliteDb()) == SQLITE_IOERR_SHMMAP) {
+            qCWarning(lcDb) << "IO error SHMMAP on table creation, attempting with DELETE journal mode";
+
+            _journalMode = "DELETE";
+            createQuery.finish();
+            pragma1.finish();
+            commitTransaction();
+            _db.close();
+            return checkConnect();
         }
-        if (fail)
-            return sqlFail("Create table metadata", createQuery);
+
+        return sqlFail("Create table metadata", createQuery);
     }
 
     createQuery.prepare("CREATE TABLE IF NOT EXISTS downloadinfo("

diff --git a/src/libsync/syncjournaldb.h b/src/libsync/syncjournaldb.h
index 931588dfa66e13ef2244bceee63f000744db8ea5..da8054109b6df6ef1bef5c1030adf24543d7172c 100644 (file)
--- a/src/libsync/syncjournaldb.h
+++ b/src/libsync/syncjournaldb.h
@@ -256,6 +256,13 @@ private:
      * that would write the etag and would void the purpose of avoidReadFromDbOnNextSync
      */
     QList<QString> _avoidReadFromDbOnNextSyncFilter;
+
+    /** The journal mode to use for the db.
+     *
+     * Typically WAL initially, but may be set to other modes via environment
+     * variable, for specific filesystems, or when WAL fails in a particular way.
+     */
+    QString _journalMode;
 };
 
 bool OWNCLOUDSYNC_EXPORT