private static void PushException(ref LoggingFields a, Exception m)
{
if (m != null)
{
a.BeginStruct("Exception");
a.AddString("Type", m.GetType().Name);
a.AddString("Message", m.Message ?? string.Empty);
a.AddString("Source", m.Source ?? string.Empty);
a.AddInt32("HResult", m.HResult);
a.AddString("StackTrace", m.StackTrace ?? string.Empty);
PushException(ref a, m.InnerException);
a.EndStruct();
}
else
{
return;
}
}
/// <summary>
/// This method demonstrates the LoggingChannel and LoggingActivity APIs.
/// </summary>
/// <param name="channel">
/// The channel to use for the demonstration. This channel may have been
/// constructed using a Windows 8.1 constructor or a Windows 10 constructor.
/// The same APIs are supported in both cases, but the ETL events will be
/// formatted a bit differently depending on how the channel was constructed.
/// </param>
private void DemonstrateLogging(LoggingChannel channel)
{
// Whenever any ETW session changes the way it is listening to this
// channel, the LoggingEnable event is fired. For example, this might
// be called when a session begins listening, changes the level at
// which it is listening, or stops listening.
channel.LoggingEnabled += this.OnLoggingEnabled;
// Log simple string events
channel.LogMessage("Simple message"); // default level is Verbose
channel.LogMessage("Simple error", LoggingLevel.Error);
// Log simple string + integer events.
channel.LogValuePair("Simple message", 123); // default level is Verbose
channel.LogValuePair("Simple error", 456, LoggingLevel.Error);
// The channel.Name property returns the name that was used when the
// channel was constructed. When running in Windows 10 mode, the name
// is already set as the provider name, so no LoggingChannelName is
// automatically added to the event.
channel.LogMessage(channel.Name);
// The channel.Id property is new to Windows 10.
channel.LogMessage(channel.Id.ToString());
// If you want to avoid the overhead of collecting data when nobody is
// listening to your channel, check the Enabled property before logging.
if (channel.Enabled)
{
channel.LogMessage(this.CollectExpensiveData());
}
// The IsEnabled() method is exactly the same as the Enabled property,
// except that it is a new Windows 10 API.
if (channel.IsEnabled())
{
channel.LogMessage(this.CollectExpensiveData());
}
// If you want to only collect data if somebody is listening at a specific
// level, you need to check both Enabled and Level. Note that the value of
// the Level is unspecified when Enabled is false.
if (channel.Enabled && channel.Level <= LoggingLevel.Warning)
{
channel.LogMessage(this.CollectExpensiveData(), LoggingLevel.Warning);
}
// The IsEnabled(LoggingLevel) method is a bit nicer than checking both
// Enabled and Level, but it is only available on Windows 10 or later.
if (channel.IsEnabled(LoggingLevel.Warning))
{
channel.LogMessage(this.CollectExpensiveData(), LoggingLevel.Warning);
}
// You can also use IsEnabled to check for keywords.
if (channel.IsEnabled(LoggingLevel.Information, 0x10))
{
channel.LogMessage(this.CollectExpensiveData(), LoggingLevel.Information);
}
// Use LoggingFields with the LogEvent method to write complex events.
var fields = new LoggingFields();
fields.AddDouble("pi", 3.14159);
channel.LogEvent(
"ComplexEvent",
fields,
LoggingLevel.Verbose,
new LoggingOptions(0x10)); // Keywords = 0x10
// You can add any number of name-value pairs to a fields object, though
// you may encounter ETW limitations if you add too many. For example,
// ETW is limited to a maximum event size of 64KB, and the current
// TraceLogging decoder can handle no more than 128 fields.
// Performance optimization: You can reuse a LoggingFields object to
// avoid unnecessary allocations. Don't forget to call Clear()
// between uses, and don't try to share a LoggingFields object between
// threads.
fields.Clear();
fields.AddDateTime("Date", DateTimeOffset.Now);
channel.LogEvent("Now", fields);
fields.Clear();
// You can add a formatting hint to affect the way a value is decoded.
// Not all combinations are useful, and the hint may be ignored.
// For example, you can encode an MBCS string by writing a byte array
// with a String hint.
fields.AddUInt8Array(
"AnsiString",
new byte[] { 65, 66, 67, 49, 50, 51 }, // "ABC123"
LoggingFieldFormat.String);
// You can add "tag" bits to a field. These are user-defined bits that
// can be used to communicate with an event processing tool. For example,
// you might define a tag bit to indicate that a field contains private
// data that should not be displayed on-screen.
fields.AddString("Password", "12345", LoggingFieldFormat.Default, 0x10);
// You can add a "structure" to an event. A structure is a name for a
// group of fields. Structures can nest. Call BeginStruct to add a level
// of nesting, and call EndStruct after the last field of the structure.
fields.BeginStruct("Nested");
fields.AddInt16("Nested-1", 1);
fields.AddInt16("Nested-2", 2);
fields.BeginStruct("Nested-Nested");
fields.AddInt16("Nested-Nested-3", 3);
fields.EndStruct();
fields.AddInt16("Nested-4", 4);
fields.EndStruct();
// Advanced scenarios: you can use a LoggingOptions object to control
// detailed event settings such as keywords, opcodes, and activity Ids.
// These have their normal ETW semantics. You can also set event tags,
// which are bit values that can be used to communicate with the event
// processor.
channel.LogEvent(
"VeryComplexEvent",
fields,
LoggingLevel.Information,
new LoggingOptions {
Keywords = 0x123, Tags = 0x10
});
// Windows 10 introduces the ILoggingTarget interface. LoggingChannel
// implements this interface. This interface allows components to accept
// a logger as an parameter.
this.DoSomething(channel);
/*
* If a LoggingActivity is created using a LoggingActivity constructor,
* it will use Windows 8.1 semantics:
*
* - If an activity is destroyed (garbage-collected) without being closed
* and the associated LoggingChannel is still open, the activity will
* write a default Stop event.
* - The default Stop event (written by the destructor or by the Close()
* method) is encoded as a "simple" event.
*
* The 8.1 semantics are deprecated because the automatic generation of
* a Stop event at garbage-collection can be misleading. The Stop event
* is intended to mark the a precise point at which an activity is
* completed, while the garbage-collection of an abandoned activity is
* inherently imprecise and unpredictable.
*
* If a LoggingActivity is created using a StartActivity method, it will
* use Windows 10 semantics:
*
* - If an activity is destroyed (garbage-collected) without being closed,
* there will be no Stop event for the activity.
* - The default Stop event (written by the Close() method) is encoded as
* a TraceLogging event with name "ActivityClosed".
*/
// This activity is created with Windows 8.1 semantics.
using (var a1 = new LoggingActivity("Activity1", channel))
{
// The activity Start event is written by the LoggingActivity constructor.
// You would do your activity's work here.
// The activity Stop event is written when the activity is closed (disposed).
// The Windows 10 LoggingActivity adds new methods for writing events
// that are marked as associated with the activity.
a1.LogEvent("Activity event");
// LoggingActivity also implements the ILoggingTarget interface, so you can
// use either a channel or an activity as a logging target.
this.DoSomething(a1);
// The Windows 10 LoggingActivity adds new methods for creating nested activities.
// Note that nested activities are always created with Windows 10 semantics,
// even when nested under an activity that is using Windows 8.1 semantics.
using (var a2 = a1.StartActivity("Activity2"))
{
// Nested task occurs here.
// The Windows 10 LoggingActivity allows you to customize the Stop event.
a2.StopActivity("Activity 2 stop");
}
// Because a1 is using Windows 8.1 semantics, if we did not call Dispose(),
// it would attempt to write a Stop event when it is garbage collected.
// Writing Stop events during garbage collection is not useful, so be sure
// to properly stop, close, or dispose activities.
}
// The Windows 10 StartActivity method creates a new activity, optionally with
// specified fields and characteristics.
// This activity is created with Windows 10 semantics.
using (var a3 = channel.StartActivity("Activity3"))
{
// Because a3 is using Windows 10 semantics, if we did not call Dispose(),
// there would be no Stop event (not even when the activity is garbage
// collected). To get a Stop event, be sure to stop, close, or dispose the
// activity.
}
}
/// <summary>
/// This method demonstrates the LoggingChannel and LoggingActivity APIs.
/// </summary>
/// <param name="channel">
/// The channel to use for the demonstration. This channel may have been
/// constructed using a Windows 8.1 constructor or a Windows 10 constructor.
/// The same APIs are supported in both cases, but the ETL events will be
/// formatted a bit differently depending on how the channel was constructed.
/// </param>
private void DemonstrateLogging(LoggingChannel channel)
{
// Whenever any ETW session changes the way it is listening to this
// channel, the LoggingEnable event is fired. For example, this might
// be called when a session begins listening, changes the level at
// which it is listening, or stops listening.
channel.LoggingEnabled += this.OnLoggingEnabled;
// Log simple string events
channel.LogMessage("Simple message"); // default level is Verbose
channel.LogMessage("Simple error", LoggingLevel.Error);
// Log simple string + integer events.
channel.LogValuePair("Simple message", 123); // default level is Verbose
channel.LogValuePair("Simple error", 456, LoggingLevel.Error);
// The channel.Name property returns the name that was used when the
// channel was constructed. When running in Windows 10 mode, the name
// is already set as the provider name, so no LoggingChannelName is
// automatically added to the event.
channel.LogMessage(channel.Name);
// The channel.Id property is new to Windows 10.
channel.LogMessage(channel.Id.ToString());
// If you want to avoid the overhead of collecting data when nobody is
// listening to your channel, check the Enabled property before logging.
if (channel.Enabled)
{
channel.LogMessage(this.CollectExpensiveData());
}
// The IsEnabled() method is exactly the same as the Enabled property,
// except that it is a new Windows 10 API.
if (channel.IsEnabled())
{
channel.LogMessage(this.CollectExpensiveData());
}
// If you want to only collect data if somebody is listening at a specific
// level, you need to check both Enabled and Level. Note that the value of
// the Level is unspecified when Enabled is false.
if (channel.Enabled && channel.Level <= LoggingLevel.Warning)
{
channel.LogMessage(this.CollectExpensiveData(), LoggingLevel.Warning);
}
// The IsEnabled(LoggingLevel) method is a bit nicer than checking both
// Enabled and Level, but it is only available on Windows 10 or later.
if (channel.IsEnabled(LoggingLevel.Warning))
{
channel.LogMessage(this.CollectExpensiveData(), LoggingLevel.Warning);
}
// You can also use IsEnabled to check for keywords.
if (channel.IsEnabled(LoggingLevel.Information, 0x10))
{
channel.LogMessage(this.CollectExpensiveData(), LoggingLevel.Information);
}
// Use LoggingFields with the LogEvent method to write complex events.
var fields = new LoggingFields();
fields.AddDouble("pi", 3.14159);
channel.LogEvent(
"ComplexEvent",
fields,
LoggingLevel.Verbose,
new LoggingOptions(0x10)); // Keywords = 0x10
// You can add any number of name-value pairs to a fields object, though
// you may encounter ETW limitations if you add too many. For example,
// ETW is limited to a maximum event size of 64KB, and the current
// TraceLogging decoder can handle no more than 128 fields.
// Performance optimization: You can reuse a LoggingFields object to
// avoid unnecessary allocations. Don't forget to call Clear()
// between uses, and don't try to share a LoggingFields object between
// threads.
fields.Clear();
fields.AddDateTime("Date", DateTimeOffset.Now);
channel.LogEvent("Now", fields);
fields.Clear();
// You can add a formatting hint to affect the way a value is decoded.
// Not all combinations are useful, and the hint may be ignored.
// For example, you can encode an MBCS string by writing a byte array
// with a String hint.
fields.AddUInt8Array(
"AnsiString",
new byte[] { 65, 66, 67, 49, 50, 51 }, // "ABC123"
LoggingFieldFormat.String);
// You can add "tag" bits to a field. These are user-defined bits that
// can be used to communicate with an event processing tool. For example,
// you might define a tag bit to indicate that a field contains private
// data that should not be displayed on-screen.
fields.AddString("Password", "12345", LoggingFieldFormat.Default, 0x10);
// You can add a "structure" to an event. A structure is a name for a
// group of fields. Structures can nest. Call BeginStruct to add a level
// of nesting, and call EndStruct after the last field of the structure.
fields.BeginStruct("Nested");
fields.AddInt16("Nested-1", 1);
fields.AddInt16("Nested-2", 2);
fields.BeginStruct("Nested-Nested");
fields.AddInt16("Nested-Nested-3", 3);
fields.EndStruct();
fields.AddInt16("Nested-4", 4);
fields.EndStruct();
// Advanced scenarios: you can use a LoggingOptions object to control
// detailed event settings such as keywords, opcodes, and activity Ids.
// These have their normal ETW semantics. You can also set event tags,
// which are bit values that can be used to communicate with the event
// processor.
channel.LogEvent(
"VeryComplexEvent",
fields,
LoggingLevel.Information,
new LoggingOptions { Keywords = 0x123, Tags = 0x10 });
// Windows 10 introduces the ILoggingTarget interface. LoggingChannel
// implements this interface. This interface allows components to accept
// a logger as an parameter.
this.DoSomething(channel);
/*
If a LoggingActivity is created using a LoggingActivity constructor,
it will use Windows 8.1 semantics:
- If an activity is destroyed (garbage-collected) without being closed
and the associated LoggingChannel is still open, the activity will
write a default Stop event.
- The default Stop event (written by the destructor or by the Close()
method) is encoded as a "simple" event.
The 8.1 semantics are deprecated because the automatic generation of
a Stop event at garbage-collection can be misleading. The Stop event
is intended to mark the a precise point at which an activity is
completed, while the garbage-collection of an abandoned activity is
inherently imprecise and unpredictable.
If a LoggingActivity is created using a StartActivity method, it will
use Windows 10 semantics:
- If an activity is destroyed (garbage-collected) without being closed,
there will be no Stop event for the activity.
- The default Stop event (written by the Close() method) is encoded as
a TraceLogging event with name "ActivityClosed".
*/
// This activity is created with Windows 8.1 semantics.
using (var a1 = new LoggingActivity("Activity1", channel))
{
// The activity Start event is written by the LoggingActivity constructor.
// You would do your activity's work here.
// The activity Stop event is written when the activity is closed (disposed).
// The Windows 10 LoggingActivity adds new methods for writing events
// that are marked as associated with the activity.
a1.LogEvent("Activity event");
// LoggingActivity also implements the ILoggingTarget interface, so you can
// use either a channel or an activity as a logging target.
this.DoSomething(a1);
// The Windows 10 LoggingActivity adds new methods for creating nested activities.
// Note that nested activities are always created with Windows 10 semantics,
// even when nested under an activity that is using Windows 8.1 semantics.
using (var a2 = a1.StartActivity("Activity2"))
{
// Nested task occurs here.
// The Windows 10 LoggingActivity allows you to customize the Stop event.
a2.StopActivity("Activity 2 stop");
}
// Because a1 is using Windows 8.1 semantics, if we did not call Dispose(),
// it would attempt to write a Stop event when it is garbage collected.
// Writing Stop events during garbage collection is not useful, so be sure
// to properly stop, close, or dispose activities.
}
// The Windows 10 StartActivity method creates a new activity, optionally with
// specified fields and characteristics.
// This activity is created with Windows 10 semantics.
using (var a3 = channel.StartActivity("Activity3"))
{
// Because a3 is using Windows 10 semantics, if we did not call Dispose(),
// there would be no Stop event (not even when the activity is garbage
// collected). To get a Stop event, be sure to stop, close, or dispose the
// activity.
}
}