/// <summary>
/// Start monitoring the resources.
/// </summary>
/// <param name="resourcesToMonitor">The resources to be monitored.</param>
/// <param name="callbackAction">Handler to call when any of the resources is uptdated</param>
/// <returns><c>true</c> if the operation succeeded; <c>false</c> otherwise.</returns>
public bool TryStartMonitoring(IEnumerable <IResource> resourcesToMonitor, ResourceUpdatedHandler callbackAction)
{
if (!Code.ValidateArgument(resourcesToMonitor, nameof(resourcesToMonitor), TaggingUtilities.ReserveTag(0x238208c9 /* tag_9669j */)) ||
!Code.ValidateArgument(callbackAction, nameof(callbackAction), TaggingUtilities.ReserveTag(0x238208ca /* tag_9669k */)))
{
return(false);
}
IList <IResource> resources = resourcesToMonitor.ToList();
ResourceMonitoringData monitoringData = new ResourceMonitoringData(callbackAction, resources);
if (!TryPerformInitialLoad(resources, monitoringData))
{
return(false);
}
if (!m_resourceMonitoringData.TryAdd(callbackAction, monitoringData))
{
return(false);
}
foreach (IResource resource in resources)
{
if (!resource.IsStatic)
{
m_monitoredResources.TryAdd(resource, true);
}
}
StartExclusiveAction();
return(true);
}
/// <summary>
/// Perfroms initial load of the resources which are not yet known to the monitor
/// </summary>
/// <param name="resources">A list of resources</param>
/// <param name="monitoringData">Monitoring data for this initial load</param>
private bool TryPerformInitialLoad(IEnumerable <IResource> resources, ResourceMonitoringData monitoringData)
{
List <IResource> resourcesNotYetSeen = new List <IResource>();
foreach (IResource resource in resources)
{
if (!m_resourceDetails.TryGetValue(resource, out IResourceDetails details))
{
// it is not terrible if we add here a resource that we have actually already loaded
// but we would want to reduce the number of such occasions to minimum
resourcesNotYetSeen.Add(resource);
}
}
CheckResourcesForUpdates(resourcesNotYetSeen, monitoringData);
foreach (IResource resource in resourcesNotYetSeen)
{
if (!m_resourceDetails.TryGetValue(resource, out IResourceDetails details))
{
return(false);
}
}
return(true);
}
/// <summary>
/// Call all of the handlers who are initerested in any of the updated resources
/// or just the specified handler if it should be called
/// </summary>
/// <param name="updatedResources">Resources that were updated since the last check</param>
/// <param name="singleMonitoringData">Single handler to be called if not null</param>
private void NotifyHandlers(HashSet <IResource> updatedResources, ResourceMonitoringData singleMonitoringData)
{
ICollection <ResourceMonitoringData> monitoringCollection = m_resourceMonitoringData.Values;
if (singleMonitoringData != null)
{
monitoringCollection = new List <ResourceMonitoringData> {
singleMonitoringData
};
}
foreach (ResourceMonitoringData monitoringInstance in monitoringCollection)
{
monitoringInstance.CallHandlerIfNecessary(m_resourceDetails, updatedResources);
}
}
/// <summary>
/// Check resources for updates
/// </summary>
/// <param name="resources">A list of resources to be checked</param>
/// <param name="singleMonitoringData">Signle instance of ResourceMonitoringData to use if present (use class-wide dict instead)</param>
private void CheckResourcesForUpdates(IEnumerable <IResource> resources, ResourceMonitoringData singleMonitoringData)
{
HashSet <IResource> updatedResources = new HashSet <IResource>();
foreach (IResource resource in resources)
{
IResourceDetails newDetails = GetFileDetails(resource);
if (newDetails == null)
{
ULSLogging.LogTraceTag(0x238208cc /* tag_9669m */, Categories.ConfigurationDataSet, Levels.Warning, "Failed to load resource details for '{0}'", resource.Name);
continue;
}
bool updated;
if (m_resourceDetails.TryGetValue(resource, out IResourceDetails currentDetails) && currentDetails != null)
{
updated = !string.Equals(currentDetails.SHA256Hash, newDetails.SHA256Hash, StringComparison.Ordinal);
}
else
{
// it is the first time we load this resource
updated = true;
}
if (updated)
{
// No explicit synchronization was added here for the following reason:
// the worst thing that can happed is two parallel threads consider the same resource
// updated and both call the ResourceMonitoringData.CallHandlerIfNecessary
// That method on its own ensures in-order execution of handlers
m_resourceDetails.AddOrUpdate(resource, newDetails, (res, oldDetails) => newDetails);
updatedResources.Add(resource);
}
}
NotifyHandlers(updatedResources, singleMonitoringData);
}
