Method CheckpointThread

libraries/lib-project-file-io/DBConnection.cpp:493–585

}

void DBConnection::CheckpointThread(sqlite3 *db, const FilePath &fileName)
{
   int rc = SQLITE_OK;
   bool giveUp = false;

   while (true)
   {
      {
         // Wait for work or the stop signal
         std::unique_lock<std::mutex> lock(mCheckpointMutex);
         mCheckpointCondition.wait(lock,
                                   [&]
                                   {
                                      return mCheckpointPending || mCheckpointStop;
                                   });

         // Requested to stop, so bail
         if (mCheckpointStop)
         {
            break;
         }

         // Capture the number of pages that need checkpointing and reset
         mCheckpointActive = true;
         mCheckpointPending = false;
      }

      // And kick off the checkpoint. This may not checkpoint ALL frames
      // in the WAL.  They'll be gotten the next time around.
      using namespace std::chrono;
      do {
         rc = giveUp ? SQLITE_OK :
            sqlite3_wal_checkpoint_v2(
               db, nullptr, SQLITE_CHECKPOINT_PASSIVE, nullptr, nullptr);
      }
      // Contentions for an exclusive lock on the database are possible,
      // even while the main thread is merely drawing the tracks, which
      // may perform reads
      while (rc == SQLITE_BUSY && (std::this_thread::sleep_for(1ms), true));

      // Reset
      mCheckpointActive = false;

      if (rc != SQLITE_OK)
      {
         ADD_EXCEPTION_CONTEXT("sqlite3.rc", std::to_string(rc));
         ADD_EXCEPTION_CONTEXT("sqlite3.context", "DBConnection::CheckpointThread");

         wxLogMessage("Failed to perform checkpoint on %s\n"
                      "\tErrCode: %d\n"
                      "\tErrMsg: %s",
                      fileName,
                      sqlite3_errcode(db),
                      sqlite3_errmsg(db));

         // Can't checkpoint -- maybe the device has too little space
         wxFileNameWrapper fName{ fileName };
         auto path = FileNames::AbbreviatePath(fName);