/// <summary>
/// Remove unused snapshots.
/// A snapshot is considered unused if it has not been accessed for at least
/// (MDHeartbeatPeriod + MDOldSnapshotHeartbeatMargin) minutes.
/// However, the last MDMinNumberOfSnapshotsToKeep snapshots will be kept regardless
/// of the access time.
/// </summary>
public void Purge(ILogger logger)
{
var allSnapshotPaths = _storage.GetInstalledAndInstallingSnapshots();
var threshold = DateTime.UtcNow - _heartbeatPeriod - _oldHeartbeatAgeMargin;
var pathSortedByAccessTime = allSnapshotPaths
.Select(path => Tuple.Create(path, GetSnapshotAccessTimeUtc(path, logger)))
.OrderBy(entry => entry.Item2)
.ToArray();
for (var i = 0; i < pathSortedByAccessTime.Length - _minNumberOfSnapshotsToKeep; ++i)
{
var creationTime = pathSortedByAccessTime[i].Item2;
if (creationTime > threshold)
{
break;
}
var pathToRemove = pathSortedByAccessTime[i].Item1;
try
{
var message = string.Format(PowerShellWorkerStrings.RemovingDependenciesFolder, pathToRemove);
logger.Log(isUserOnlyLog: false, LogLevel.Trace, message);
_storage.RemoveSnapshot(pathToRemove);
}
catch (IOException e)
{
var message = string.Format(PowerShellWorkerStrings.FailedToRemoveDependenciesFolder, pathToRemove, e.Message);
logger.Log(isUserOnlyLog: false, LogLevel.Warning, message, e);
}
}
}
private bool IsAnyInstallationStartedRecently()
{
var threshold = DateTime.UtcNow - MinBackgroundUpgradePeriod;
return(_storage
.GetInstalledAndInstallingSnapshots()
.Select(path => _storage.GetSnapshotCreationTimeUtc(path))
.Any(creationTime => creationTime > threshold));
}