Provides the #[trace_logging_provider]
macro, which allows you to define a
Trace Logging Provider
for use with the Event Tracing for Windows (ETW)
framework.
This macro is intended for use only when targeting Windows. When targeting other platforms, this macro will still work, but will generate code that does nothing.
This framework allows applications to log schematized events, rather than textual strings. ETW analysis tools can reliably identify fields within your events, and treat them as strongly-typed data, rather than text strings.
In ETW, an event provider is a software object that generates events. Event controllers set up event logging sessions, and event consumers read and interpret event data. This crate focuses on enabling applications to create event providers.
Add these dependencies to your Cargo.toml
file:
[dependencies]
win_etw_macros = "0.1.*"
win_etw_provider = "0.1.*"
win_etw_macros
contains the procedural macro that generates eventing code.
win_etw_provider
contains library code that is called by the code that is generated by
win_etw_macros
.
You must assign a new, unique GUID to each event provider. ETW uses this GUID to identify your events that are generated by your provider. Windows contains many event providers, so it is important to be able to select only the events generated by your application. This GUID is also used internally by ETW to identify event metadata (field types), so it is important that your GUID be unique. Otherwise, events from conflicting sources that use the same GUID may be incorrectly interpreted.
There are many tools which can create a GUID, such as:
- In Visual Studio, in the Tools menu, select "Create GUID".
- From a Visual Studio command line, run
uuidgen.exe
. - From an Ubuntu shell, run
uuidgen
.
Add a trait definition to your source code and annotate it with the
#[trace_logging_provider(guid = "...")]
macro, using the GUID that you just created. The trait
definition is only used as input to the procedural macro; the trait is not emitted into your
crate, and cannot be used as a normal trait.
In the trait definition, add method signatures. Each method signature defines an event type. The parameters of each method define the fields of the event type. Only a limited set of field types are supported (enumerated below).
The #[trace_logging_provider]
macro consumes the trait definition and produces a struct
definition with the same name and the same method signatures. (The trait is not available for
use as an ordinary trait.)
# use win_etw_macros::trace_logging_provider;
#[trace_logging_provider(guid = "... your guid here ...")]
pub trait MyAppEvents {
fn http_request(client_address: &SockAddr, is_https: bool, status_code: u32, status: &str);
fn database_connection_created(connection_id: u64, server: &str);
fn database_connection_closed(connection_id: u64);
// ...
}
At initialization time (in your fn main()
, etc.), create an instance of the event provider:
let my_app_events = MyAppEvents::new();
Your application should only create a single instance of each event provider, per process. That is, you should create a single instance of your event provider and share it across your process. Typically, an instance is stored in static variable, using a lazy / atomic assignment. There are many crates and types which can support this usage pattern.
To report an event, call one of the methods defined on the event provider. The method will call into ETW to report the event, but there is no guarantee that the event is stored or forwarded; events can be dropped if event buffer resources are scarce.
my_app_events.client_connected(None, &"192.168.0.42:6667".parse(), false, 100, "OK");
Note that all generated event methods have an added first parameters,
options: Option<&EventOptions>
. This parameter allows you to override per-event parameters,
such as the event level and event correlation IDs. In most cases, you should pass None
.
Only a limited set of field types are supported.
- Integer primitives up to 64 bits:
i8
,i16
,i32
,i64
,u8
,u16
,u32
,u64
- Floating point primitives:
f32
,f64
- Architecture-dependent sizes:
usize
,isize
. - Boolean:
bool
- Slices of all of the supported primitives:
&[u8]
,&[u16]
, etc. - Windows
FILETIME
. The type must be declared exactly asFILETIME
; type aliases or fully-qualified paths (such aswinapi::shared::minwindef::FILETIME
) will not work. The parameter type in the generated code will bewin_etw_provider::FILETIME
, which is a newtype overu64
. std::time::SystemTime
is supported, but it must be declared exactly asSystemTime
; type aliases or fully-qualified paths (such asstd::time::SystemTime
) will not work.SockAddr
,SockAddrV4
, andSockAddrV6
are supported. They must be declared exactly as shown, not using fully-qualified names or type aliases.
There are a variety of tools which can be used to capture and view ETW events.
The simplest tool is the TraceView
tool from the Windows SDK. Typically it is installed
at this path: C:\Program Files (x86)\Windows Kits\10\bin\10.0.<xxxxx>.0\x64\traceview.exe
,
where <xxxxx>
is the release number of the Windows SDK.
Run TraceView
, then select "File", then "Create New Log Session". Select "Manually Entered
GUID or Hashed Name" and enter the GUID that you have assigned to your event provider. Click OK.
The next dialog will prompt you to choose a source of WPP format information; select Auto
and click OK.
At this point, TraceView
should be capturing events (for your assigned GUID) and displaying
them in real time, regardless of which process reported the events.
These tools can also be used to capture ETW events:
- Windows Performance Recorder This tool is intended for capturing system-wide event streams. It is not useful for capturing events for a specific event provider.
- logman is a command-line tool for managing events.
- Tracelog
There are other tools, such as the Windows Performance Recorder, which can capture ETW events.
- Better handling of per-event overrides, rather than using
Option<&EventOptions>
.
- Event Tracing for Windows (ETW) Simplified
- TraceLogging for Event Tracing for Windows (ETW)
- Record and View TraceLogging Events
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