public async Task <Result <AbsolutePath> > BackupAsync(OperationContext context, AbsolutePath instancePath, string?name = null)
{
int numCopiedFiles = 0;
AbsolutePath?backupPath = null;
return(await context.PerformOperationAsync(_tracer, async() =>
{
var backupTime = _clock.UtcNow.ToString("yyyyMMdd_HHmmss", CultureInfo.InvariantCulture);
var backupName = backupTime;
if (!string.IsNullOrEmpty(name))
{
backupName += $"-{name}";
}
backupPath = _backupPath / backupName;
// Unlikely, but it is possible for GC to start running and think that it should purge this directory,
// this avoids the scenario.
using var _ = await _locks.AcquireAsync(backupPath);
if (_fileSystem.DirectoryExists(backupPath))
{
_fileSystem.DeleteDirectory(backupPath, DeleteOptions.All);
}
_fileSystem.CreateDirectory(backupPath);
// See: https://github.com/facebook/rocksdb/wiki/rocksdb-basics#database-debug-logs
_fileSystem.EnumerateFiles(instancePath, "*LOG*", false,
fileInfo =>
{
var fileName = fileInfo.FullPath.FileName;
var targetFilePath = backupPath / fileName;
// Do not use Async here: since EnumerateFiles takes an Action, making this async means we'll
// need to make the action async as well, which is equivalent to an async void function. That
// leads to race conditions.
#pragma warning disable AsyncFixer02 // Long running or blocking operations under an async method
_fileSystem.CopyFile(fileInfo.FullPath, targetFilePath, replaceExisting: true);
#pragma warning restore AsyncFixer02 // Long running or blocking operations under an async method
++numCopiedFiles;
});
if (numCopiedFiles == 0)
{
_fileSystem.DeleteDirectory(backupPath, DeleteOptions.All);
}
return new Result <AbsolutePath>(backupPath);
}, extraEndMessage : _ => $"From=[{instancePath}] To=[{backupPath?.ToString() ?? "Unknown"}] NumCopiedFiles=[{numCopiedFiles}]"));