Registering a trace provider
Trace providers must register with the trace manager in order
to participate in tracing. Drivers don't have to register as a trace provider
since the devhost process does it through libdriver.so.
To register a trace provider, you must do the following:
Note: For more information on the Fuchsia tracing system, see Fuchsia tracing system.
Register with the trace manager {#register-with-the-trace-manager}
To register as a trace provider, you can use the libtrace-provider library
to provide an asynchronous loop in your component's code.
Note: For more information on tracing libraries, see Tracing libraries.
For example:
- {C++}
Note: This example uses fdio to set up the FIDL channel with Trace Manager. For
more information, see
fdio.
#include <lib/async-loop/cpp/loop.h>
#include <lib/async-loop/default.h>
#include <lib/trace-provider/provider.h>
// further includes
int main(int argc, const char** argv) {
// process argv
async::Loop loop(&kAsyncLoopConfigAttachToCurrentThread);
trace::TraceProviderWithFdio trace_provider(
loop.dispatcher(), "my_trace_provider");
// further setup
loop.Run();
return 0;
}
- {C }
#include <lib/async-loop/cpp/loop.h>
#include <lib/async-loop/default.h>
#include <lib/trace-provider/provider.h>
int main(int argc, char** argv) {
zx_status_t status;
async_loop_t* loop;
trace_provider_t* trace_provider;
// Create a message loop.
status = async_loop_create(&kAsyncLoopConfigNoAttachToCurrentThread, &loop);
if (status != ZX_OK) exit(1);
// Start a thread for the loop to run on.
// Alternatively, use async_loop_run() to run on the current thread.
status = async_loop_start_thread(loop, "loop", NULL);
if (status != ZX_OK) exit(1);
// Create the trace provider.
async_dispatcher_t* dispatcher = async_loop_get_dispatcher(loop);
trace_provider = trace_provider_create(dispatcher);
if (!trace_provider) exit(1);
// Do something...
// Tear down.
trace_provider_destroy(trace_provider);
async_loop_shutdown(loop);
return 0;
}
Give the trace manager component access {#give-trace-manager-component-access}
In the component manifest file (a .cmx file) of your component, you must
specify that it needs to communicate with the Fuchsia trace manager.
Note: For information on component manifests, see Component Manifests.
To give the trace manager component access, specify
fuchsia.tracing.provider.Registry as a "services". For example:
- {.cmx file}
{
"program": {
"binary": "bin/app"
},
"sandbox": {
"services": [
"fuchsia.tracing.provider.Registry"
]
}
}
Once you have registered your component as a trace provider, you can enable tracing in your code. For more information, see Adding tracing in your code.