Requesting Data Notification Tutorial

Purpose

Trace data is written to kernel side chunks. The kernel trace tool API can request notification that data has been written and requires further processing.

Intended audience

This document is intended for application developers writing a trace tool using the kernel trace tool component.

Required background

The trace filters defined in EUser. The kernel trace tool component in general.

Introduction

Requesting data notification is a short task which is performed in combination with related tasks as explained in Kernel Trace Tool Tutorial.

Using Kernel Trace tool to request data notification

The Following tasks will be covered in this tutorial:

• Requesting data notification.

Basic procedure

The high level steps to requesting data notification are shown here:

1. Request data notification, specifying the minimum number of bytes to return.

Using the API

These are the function calls required to

1. Call the RequestData() function of the RBTrace object. This function has two arguments:

   • a TRequestStatus object which takes the value KErrNone when data becomes available, and

   • a TInt specifying the minimum number of bytes to return.

   The TRequestStatus object is intended for use in the test statement of a loop in which the function call is embedded.