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TSLIFECYCLEHOOKADD(3ts) Apache Traffic Server TSLIFECYCLEHOOKADD(3ts)

NAME

TSLifecycleHookAdd -

SYNOPSIS

#include <ts/ts.h>
void TSLifecycleHookAdd(TSLifecycleHookID id, TSCont contp)

DESCRIPTION

TSLifecycleHookAdd() adds contp to the list of lifecycle hooks specified by id. Lifecycle hooks are based on the Traffic Server process, not on any specific transaction or session. These will typically be called only once during the execution of the Traffic Server process and therefore should be added in TSPluginInit() (which could itself be considered a lifecyle hook). Unlike other hooks, lifecycle hooks may not have a well defined ordering and use of them should not assume that one of the hooks is always called before another unless specifically mentioned.
TS_LIFECYCLE_PORTS_INITIALIZED_HOOK
Called after the proxy server port data structures have been initialized but before connections are accepted on those ports. The sockets corresponding to the ports may or may not be open depending on how the traffic_server process was invoked. Other API functions that depend on server ports should be called from this hook and not TSPluginInit().
Invoked with the event TS_EVENT_LIFECYCLE_PORTS_INITIALIZED and NULL data.

TS_LIFECYCLE_PORTS_READY_HOOK
Called after enabling connections on the proxy server ports. Because Traffic Server is threaded this may or may not be called before any connections are accepted. The hook code may assume that any connection to Traffic Server started after this hook is called will be accepted by Traffic Server, making this a convenient place to signal external processes of that.
Invoked with the event TS_EVENT_LIFECYCLE_PORTS_READY and NULL data.

TS_LIFECYCLE_CACHE_READY_HOOK
Called after Traffic Server cache initialization has finished.
Invoked with the event TS_EVENT_LIFECYCLE_CACHE_READY and NULL data.

TS_LIFECYCLE_MSG_HOOK
Called when triggered by an external process, such as traffic_ctl.
Invoked with the event TS_EVENT_LIFECYCLE_MSG. The data is an instance of the TSPluginMsg. This contains a tag which is a null terminated string and a data payload. The payload cannot be assumed to be null terminated and is created by the external agent.

ORDERING

TS_LIFECYCLE_PORTS_INITIALIZED_HOOK will always be called before TS_LIFECYCLE_PORTS_READY_HOOK.

EXAMPLES

The following example demonstrates how to correctly use TSNetAcceptNamedProtocol(), which requires the proxy ports to be initialized and therefore does not work if called from TSPluginInit() directly. 
#include <ts/ts.h>


#define SSL_PROTOCOL_NAME "whatever"


static int
ssl_proto_handler(TSCont contp, TSEvent event, void* data)
{
   /// Do named protocol handling.
}


static int
local_ssl_init(TSCont contp, TSEvent event, void * edata)
{
   if (TS_EVENT_LIFECYCLE_PORTS_INITIALIZED == event) { // just to be safe.
      TSNetAcceptNamedProtocol(
         TSContCreate(ssl_proto_handler, TSMutexCreate()),
         SSL_PROTOCOL_NAME
      );
   }
   return 0;
}


void
TSPluginInit (int argc, const char * argv[])
{
   TSLifecycleHookAdd(TS_LIFECYCLE_PORTS_INITIALIZED_HOOK, TSContCreate(local_ssl_init, NULL));
}


HISTORY

Lifecycle hooks were introduced to solve process initialization ordering issues TS-1487. Different API calls required different modules of Traffic Server to be initialized for the call to work, but others did not work that late in initialization, which was problematic because all of them could effectively only be called from TSPluginInit() . The solution was to move TSPluginInit() as early as possible in the process initialization and provide hooks for API calls that needed to be invoked later which served essentially as additional pluging initialization points.

SEE ALSO

TSAPI(3ts), TSContCreate(3ts)

COPYRIGHT

2015, dev@trafficserver.apache.org
January 24, 2017 7.0