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SEBWIN-301, SEBWIN-322: Improved service feature configuration with retry mechanism.

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This commit is contained in:
dbuechel 2019-08-28 09:54:52 +02:00
parent 18e6b366a5
commit d54d7c17dc
1 changed files with 64 additions and 33 deletions
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97
SafeExamBrowser.Lockdown/FeatureConfigurations/ServiceConfigurations/ServiceConfiguration.cs
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@ -18,7 +18,9 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
[Serializable] [Serializable]
internal abstract class ServiceConfiguration : FeatureConfiguration internal abstract class ServiceConfiguration : FeatureConfiguration
{ {
private static readonly TimeSpan TEN_SECONDS = TimeSpan.FromSeconds(10); private static readonly TimeSpan FIVE_SECONDS = TimeSpan.FromSeconds(5);
private const int MAX_ATTEMPTS = 5;
private IList<ServiceDataItem> originalItems; private IList<ServiceDataItem> originalItems;
protected abstract IEnumerable<ServiceConfigurationItem> Items { get; } protected abstract IEnumerable<ServiceConfigurationItem> Items { get; }
@ -34,7 +36,7 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
foreach (var item in Items) foreach (var item in Items)
{ {
success &= TrySet(new ServiceDataItem { Name = item.Name, Status = item.Disabled }); success &= TrySetWithRetry(new ServiceDataItem { Name = item.Name, Status = item.Disabled });
} }
if (success) if (success)
@ -55,7 +57,7 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
foreach (var item in Items) foreach (var item in Items)
{ {
success &= TrySet(new ServiceDataItem { Name = item.Name, Status = item.Enabled }); success &= TrySetWithRetry(new ServiceDataItem { Name = item.Name, Status = item.Enabled });
} }
if (success) if (success)
@ -114,7 +116,7 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
{ {
foreach (var item in new List<ServiceDataItem>(originalItems)) foreach (var item in new List<ServiceDataItem>(originalItems))
{ {
if (TrySet(item)) if (TrySetWithRetry(item))
{ {
originalItems.Remove(item); originalItems.Remove(item);
} }
@ -153,38 +155,56 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
return item; return item;
} }
private bool TrySetWithRetry(ServiceDataItem item)
{
var success = false;
if (IsAvailable(item))
{
for (var attempt = 1; attempt <= MAX_ATTEMPTS && !success; attempt++)
{
logger.Debug($"Attempt {attempt}/{MAX_ATTEMPTS} to set service {item}...");
success = TrySet(item);
}
if (!success)
{
logger.Error($"All attempts to set service {item} have failed!");
}
}
else
{
logger.Warn($"Cannot set service {item} as it does not exist!");
}
return success;
}
private bool TrySet(ServiceDataItem item) private bool TrySet(ServiceDataItem item)
{ {
var success = false; var success = false;
try try
{ {
if (IsAvailable(item)) using (var service = new ServiceController(item.Name))
{ {
using (var service = new ServiceController(item.Name)) if (item.Status == ServiceStatus.Running)
{ {
if (item.Status == ServiceStatus.Running) success = TryStart(service);
{ }
success = TryStart(service); else if (item.Status == ServiceStatus.Stopped)
} {
else if (item.Status == ServiceStatus.Stopped) success = TryStop(service);
{ }
success = TryStop(service);
} if (success)
{
if (success) logger.Debug($"Successfully set service {item}.");
{ }
logger.Debug($"Successfully set service {item}."); else
} {
else logger.Warn($"Could not set service {item}! Current status: {service.Status}.");
{
logger.Warn($"Could not set service {item}! Current status: {service.Status}.");
}
} }
}
else
{
logger.Warn($"Cannot set service {item} as it does not exist!");
} }
} }
catch (Exception e) catch (Exception e)
@ -197,11 +217,11 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
private bool TryStart(ServiceController service) private bool TryStart(ServiceController service)
{ {
var success = true; var success = false;
if (service.Status == ServiceControllerStatus.PausePending) if (service.Status == ServiceControllerStatus.PausePending)
{ {
service.WaitForStatus(ServiceControllerStatus.Paused, TEN_SECONDS); service.WaitForStatus(ServiceControllerStatus.Paused, FIVE_SECONDS);
service.Refresh(); service.Refresh();
} }
@ -219,7 +239,7 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
if (service.Status == ServiceControllerStatus.StartPending || service.Status == ServiceControllerStatus.ContinuePending) if (service.Status == ServiceControllerStatus.StartPending || service.Status == ServiceControllerStatus.ContinuePending)
{ {
service.WaitForStatus(ServiceControllerStatus.Running, TEN_SECONDS); service.WaitForStatus(ServiceControllerStatus.Running, FIVE_SECONDS);
service.Refresh(); service.Refresh();
} }
@ -243,7 +263,7 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
if (service.Status == ServiceControllerStatus.StartPending || service.Status == ServiceControllerStatus.ContinuePending) if (service.Status == ServiceControllerStatus.StartPending || service.Status == ServiceControllerStatus.ContinuePending)
{ {
service.WaitForStatus(ServiceControllerStatus.Running, TEN_SECONDS); service.WaitForStatus(ServiceControllerStatus.Running, FIVE_SECONDS);
service.Refresh(); service.Refresh();
} }
@ -255,7 +275,7 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
if (service.Status == ServiceControllerStatus.StopPending) if (service.Status == ServiceControllerStatus.StopPending)
{ {
service.WaitForStatus(ServiceControllerStatus.Stopped, TEN_SECONDS); service.WaitForStatus(ServiceControllerStatus.Stopped, FIVE_SECONDS);
service.Refresh(); service.Refresh();
} }
@ -269,7 +289,18 @@ namespace SafeExamBrowser.Lockdown.FeatureConfigurations.ServiceConfigurations
private bool IsAvailable(ServiceDataItem item) private bool IsAvailable(ServiceDataItem item)
{ {
return ServiceController.GetServices().Any(s => s.ServiceName == item.Name); var available = false;
try
{
available = ServiceController.GetServices().Any(s => s.ServiceName == item.Name);
}
catch (Exception e)
{
logger.Error($"Failed to check whether service '{item.Name}' is available!", e);
}
return available;
} }
private ServiceStatus ToStatus(ServiceControllerStatus status) private ServiceStatus ToStatus(ServiceControllerStatus status)