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<task id="GUID-E4A950EA-5671-5755-B3EF-5D6B90E19AE6" xml:lang="en"><title>Maintaining
Log Events </title><shortdesc>This tutorial describes how to maintain events using Log Engine. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
<context id="GUID-9230A593-9E3C-52B2-81F3-6C54F7E6015E"><p>You maintain a
log by adding, changing and deleting events with the appropriate calls to
the <xref href="GUID-51C67545-12BA-326D-BD8F-662B24C68ED2.dita"><apiname>CLogClient</apiname></xref> member of your application. When you are
adding or changing events, the arguments are a <xref href="GUID-CDFB61A7-1C74-3F63-9FDF-5A3B8603A010.dita"><apiname>CLogEvent</apiname></xref> and
a <xref href="GUID-E0B34F3E-D4C4-3232-B8B1-7DB35B454646.dita"><apiname>TRequestStatus</apiname></xref> object to hold the return value. When
you are deleting, they are a <xref href="GUID-CDFB61A7-1C74-3F63-9FDF-5A3B8603A010.dita"><apiname>CLogEvent</apiname></xref> and a <xref href="GUID-271367A8-DD4F-3A82-AD88-F3E94F2AA980.dita"><apiname>TLogId</apiname></xref>. </p> <p>It
is sometimes necessary to create a custom event type. If you want to log events
of a custom created event type, you need to initialise a <xref href="GUID-E7CCB043-770E-3722-B735-92B65CC7A0D8.dita"><apiname>CLogEventType</apiname></xref> object
and add it to the log. You add the event type when you install your application,
and delete it if you uninstall the application. You add, change and delete
custom event types by calling the appropriate functions of a <xref href="GUID-51C67545-12BA-326D-BD8F-662B24C68ED2.dita"><apiname>CLogClient</apiname></xref> object: </p> <p> <codeph>iLogClient-&gt;AddEventType(*iLogEventType,
iStatus);</codeph>  </p> <p> <codeph>iLogClient-&gt;ChangeEventType(*iLogEventType,
iStatus);</codeph>  </p> <p> <codeph>iLogClient-&gt;DeleteEventType(aId, iStatus);</codeph>  </p> <p>The
arguments are a <xref href="GUID-E7CCB043-770E-3722-B735-92B65CC7A0D8.dita"><apiname>CLogEventType</apiname></xref> (or <xref href="GUID-530281E6-29FC-33F2-BC9B-610FBA389444.dita"><apiname>TUid</apiname></xref> when
deleting) and a <xref href="GUID-E0B34F3E-D4C4-3232-B8B1-7DB35B454646.dita"><apiname>TRequestStatus</apiname></xref> object. </p><p> To maintain
log events, do the following: 
</p> </context>
<steps id="GUID-41BB11DF-8016-58A1-9291-674C9CE396C3">
<step id="GUID-474DF156-F653-569E-B038-446B11A788A4"><cmd>declare an event
as a member of your log client class </cmd>
<stepxmp><codeblock id="GUID-EA8E98C3-B225-5AFD-A107-5C62603F87D8" xml:space="preserve">CLogEvent* iCurrentEvent;</codeblock> </stepxmp>
</step>
<step id="GUID-09506C94-0251-503D-96CF-03F13296EB8E"><cmd/>
<info>initialise the event using its member functions </info>
<stepxmp><codeblock id="GUID-4300C98A-EEB4-5041-871F-5B76702D6061" xml:space="preserve">iCurrentLogEvent = CLogEvent::NewL();
...
iCurrentLogEvent-&gt;SetTime(time);</codeblock> </stepxmp>
</step>
<step id="GUID-18909AB0-6248-5FE5-A7ED-397F611AD412"><cmd/>
<info>add an event to a log with the <xref href="GUID-91804418-6DCC-3ACF-BA1E-399B112285A3.dita"><apiname>AddEvent()</apiname></xref> function
of a <xref href="GUID-51C67545-12BA-326D-BD8F-662B24C68ED2.dita"><apiname>CLogClient</apiname></xref> object </info>
<stepxmp><codeblock id="GUID-8048721D-C397-5DE3-8B94-113DA2801605" xml:space="preserve">iLogClient-&gt;AddEvent(*iLogEvent, iStatus);</codeblock> </stepxmp>
<info> <xref href="GUID-91804418-6DCC-3ACF-BA1E-399B112285A3.dita"><apiname>AddEvent()</apiname></xref> creates an asynchronous request and no
other asynchronous request must be outstanding when you call it. For this
reason, the <xref href="GUID-CDFB61A7-1C74-3F63-9FDF-5A3B8603A010.dita"><apiname>CLogEvent</apiname></xref> argument is typically read off a
queue of events waiting to be processed. </info>
</step>
<step id="GUID-4AB54E42-D28E-5806-B8F4-2F2A7B69880B"><cmd/>
<info>change an event record with the <xref href="GUID-C8F2B567-6B68-3460-9799-6658DF3771A8.dita"><apiname>ChangeEvent()</apiname></xref> function. </info>
<stepxmp><codeblock id="GUID-B9D07568-3A3B-5A1D-8F91-B470CB95281F" xml:space="preserve">iLogClient-&gt;ChangeEvent(*iLogEvent, iStatus);</codeblock> </stepxmp>
</step>
</steps>
<result id="GUID-306D0963-3299-59BB-BBCA-B0DDFD945F93"><p> Note that it is
not possible to change the event type of an event after
 it has been added to the log. 
</p><p>The events specified by the log engine clients are maintained. </p> </result>
<postreq id="GUID-E9031A12-D139-5D86-A54D-99174D9A8012"><p>You do not normally
need to delete an event. A log has a maximum size which the log engine maintains
automatically by deleting the oldest events when newly added events would
cause the maximum to be exceeded. If you want to delete an event for other
reasons you call the <codeph>DeleteEvent()</codeph> function. <codeph>iLogClient-&gt;DeleteEvent(aLogId,
iStatus);</codeph>  </p> <p>It is important to know that deleting an event
type and deleting the actual events of that type are two separate actions.
If you just delete the type and not the events, the events will remain in
the log but have no type. </p> <p> </p> </postreq>
</taskbody><related-links>
<link href="GUID-BE65B3A7-04E8-5406-B46A-09E2608E0F1F.dita"><linktext>Requesting
Log Engine Notifications</linktext></link>
<link href="GUID-2022F702-9899-5798-8932-D70119C7177D.dita"><linktext>Setting Up
A Log Engine Client</linktext></link>
<link href="GUID-55ECBCF5-FC29-5A4A-A3C6-1CB1C0D562CE.dita"><linktext>Displaying
Log Events</linktext></link>
<link href="GUID-BCB0E50F-B22E-5964-BB68-BEE1870D9C79.dita"><linktext>Configuring
Log Engine </linktext></link>
</related-links></task>