/// <summary>
/// Add a value and version to the list, returning the prior value of the variable.
/// </summary>
/// <param name="version">for the value to add</param>
/// <param name="value">to add</param>
/// <param name="timestamp">the time associated with the version</param>
/// <returns>prior value</returns>
public object AddValue(
int version,
T value,
long timestamp)
{
if (ExecutionPathDebugLog.IsDebugEnabled && Log.IsDebugEnabled) {
Log.Debug(
".addValue Thread " +
Thread.CurrentThread.ManagedThreadId +
" for '" +
Name +
"' adding version " +
version +
" at value " +
value);
}
// push to prior if not already used
if (_currentAndPriorValue.PriorVersion.Version == -1) {
_currentAndPriorValue = new CurrentValue<T>(
new VersionedValue<T>(version, value, timestamp),
_currentAndPriorValue.CurrentVersion);
return _currentAndPriorValue.PriorVersion.Value;
}
// add to list
var priorVersion = _currentAndPriorValue.PriorVersion;
_olderVersions.Add(priorVersion);
// check watermarks
if (_olderVersions.Count >= _highWatermark) {
var expireBefore = timestamp - _millisecondLifetimeOldVersions;
while (_olderVersions.Count > 0) {
var oldestVersion = _olderVersions[0];
if (oldestVersion.Timestamp <= expireBefore) {
_olderVersions.RemoveAt(0);
}
else {
break;
}
}
}
_currentAndPriorValue = new CurrentValue<T>(
new VersionedValue<T>(version, value, timestamp),
_currentAndPriorValue.CurrentVersion);
return _currentAndPriorValue.PriorVersion.Value;
}
/// <summary>Ctor.</summary>
/// <param name="name">variable name</param>
/// <param name="initialVersion">first version number</param>
/// <param name="initialValue">first value</param>
/// <param name="timestamp">timestamp of first version</param>
/// <param name="millisecondLifetimeOldVersions">
/// number of milliseconds after which older versions get expired and removed
/// </param>
/// <param name="readLock">for coordinating Update to old versions</param>
/// <param name="highWatermark">
/// when the number of old versions reached high watermark, the list inspects size on every write
/// </param>
/// <param name="errorWhenNotFound">
/// true if an exception should be throw if the requested version cannot be found,
/// or false if the engine should log a warning
/// </param>
public VersionedValueList(
string name,
int initialVersion,
T initialValue,
long timestamp,
long millisecondLifetimeOldVersions,
ILockable readLock,
int highWatermark,
bool errorWhenNotFound)
{
Name = name;
_readLock = readLock;
_highWatermark = highWatermark;
_olderVersions = new List<VersionedValue<T>>();
_errorWhenNotFound = errorWhenNotFound;
_millisecondLifetimeOldVersions = millisecondLifetimeOldVersions;
_currentAndPriorValue = new CurrentValue<T>(
new VersionedValue<T>(initialVersion, initialValue, timestamp),
new VersionedValue<T>(-1, null, timestamp));
}