The handler function is the key component of a continuation. It is supposed to examine the event and event data, and then do something appropriate. The probable action might be to schedule another event for the continuation to received, to open up a connection to a server, or simply to destroy itself.

The continuation's handler function is a function of type TSEventFunc. Its arguments are a continuation, an event, and a pointer to some data (this data is passed to the continuation by the caller - do not confuse this data with the continuation's own data, associated by TSContDataSet). When the continuation is called back, the continuation and an event are passed to the handler function. The continuation is a handle to the same continuation that is invoked. The handler function typically has a switch statement to handle the events it receives:

    static int some_handler (TScont contp, TSEvent event, void *edata)
    {
        .....
            switch(event) {
                case TS_EVENT_SOME_EVENT_1:
                    do_some_thing_1;
                    return;
                case TS_EVENT_SOME_EVENT_2:
                    do_some_thing_2;
                    return;
                case TS_EVENT_SOME_EVENT_3:
                    do_some_thing_3;
                    return;
                default: break;
            }
        return 0;
    }

Caution

You might notice that a continuation cannot determine if more events are "in flight" toward it. Do not use TSContDestroy to delete a continuation before you make sure that all incoming events, such as those sent because of TSHttpTxnHookAdd, have been handled.

The following table lists events and the corresponding type of void *data passed to handler functions:

TS_EVENT_HTTP_READ_REQUEST_HDR

TS_HTTP_READ_REQUEST_HDR_HOOK

TSHttpTxn

TS_EVENT_HTTP_OS_DNS

TS_HTTP_OS_DNS_HOOK

TSHttpTxn

TS_EVENT_HTTP_SEND_REQUEST_HDR

TS_HTTP_SEND_REQUEST_HDR_HOOK

TSHttpTxn

TS_EVENT_HTTP_READ_CACHE_HDR

TS_HTTP_READ_CACHE_HDR_HOOK

TSHttpTxn

TS_EVENT_HTTP_READ_RESPONSE_HDR

TS_HTTP_READ_RESPONSE_HDR_HOOK

TSHttpTxn

TS_EVENT_HTTP_SEND_RESPONSE_HDR

TS_HTTP_SEND_RESPONSE_HDR_HOOK

TSHttpTxn

TS_EVENT_HTTP_SELECT_ALT

TS_HTTP_SELECT_ALT_HOOK

TSHttpTxn

TS_EVENT_HTTP_TXN_START

TS_HTTP_TXN_START_HOOK

TSHttpTxn

TS_EVENT_HTTP_TXN_CLOSE

TS_HTTP_TXN_CLOSE_HOOK

TSHttpTxn

TS_EVENT_HTTP_SSN_START

TS_HTTP_SSN_START_HOOK

TSHttpSsn

TS_EVENT_HTTP_SSN_CLOSE

TS_HTTP_SSN_CLOSE_HOOK

TSHttpSsn

TS_EVENT_NONE

TS_EVENT_CACHE_LOOKUP_COMPLETE

TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK

TSHttpTxn

TS_EVENT_IMMEDIATE

TSVConnClose, TSVIOReenable, TSContSchedule

TS_EVENT_IMMEDIATE

TS_HTTP_REQUEST_TRANSFORM_HOOK

TS_EVENT_IMMEDIATE

TS_HTTP_RESPONSE_TRANSFORM_HOOK

TS_EVENT_CACHE_OPEN_READ

TSCacheRead

Cache VC

TS_EVENT_CACHE_OPEN_READ_FAILED

TSCacheRead

Error code, see TS_CACHE_ERROR_XXX

TS_EVENT_CACHE_OPEN_WRITE

TSCacheWrite

Cache VC

TS_EVENT_CACHE_OPEN_WRITE_FAILED

TSCacheWrite

Error code, see TS_CACHE_ERROR_XXX

TS_EVENT_CACHE_REMOVE

TSCacheRemove

Nothing

TS_EVENT_CACHE_REMOVE_FAILED

TSCacheRemove

Error code, see TS_CACHE_ERROR_XXX

TS_EVENT_NET_ACCEPT

TSNetAccept, TSHttpTxnServerIntercept, TSHttpTxnIntercept: Net VConnection

TS_EVENT_NET_ACCEPT_FAILED

TSNetAccept, TSHttpTxnServerIntercept,
              TSHttpTxnIntercept:   Nothing

TS_EVENT_HOST_LOOKUP

TSHostLookup

Null pointer - error Non null pointer - TSHostLookupResult

TS_EVENT_TIMEOUT

TSContSchedule

TS_EVENT_ERROR

TS_EVENT_VCONN_READ_READY

TSVConnRead

TSVConn

TS_EVENT_VCONN_WRITE_READY

TSVConnWrite

TSVConn

TS_EVENT_VCONN_READ_COMPLETE

TSVConnRead

TSVConn

TS_EVENT_VCONN_WRITE_COMPLETE

TSVConnWrite

TSVConn

TS_EVENT_VCONN_EOS

TSVConnRead

TSVConn

TS_EVENT_NET_CONNECT

TSNetConnect

TSVConn

TS_EVENT_NET_CONNECT_FAILED

TSNetConnect

TSVConn

TS_EVENT_HTTP_CONTINUE

TS_EVENT_HTTP_ERROR

TS_EVENT_MGMT_UPDATE

TSMgmtUpdateRegister

NULL

The continuation functions are listed below:

• TSContCall

• TSContCreate

• TSContDataGet

• TSContDataSet

• TSContDestroy

• TSContMutexGet

• TSContSchedule