doc/developer-guide/api/functions/TSHttpTxnMilestoneGet.en.rst

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.. include:: ../../../common.defs

.. default-domain:: c

TSHttpTxnMilestoneGet
*********************

Get a specified :arg:`milestone` timer value for the current transaction.

Synopsis
========

.. code-block:: cpp

    #include <ts/ts.h>

.. function:: TSReturnCode TSHttpTxnMilestoneGet(TSHttpTxn txnp, TSMilestonesType milestone, TSHRTime * time)

Description
===========

:func:`TSHttpTxnMilestoneGet` will fetch a specific :arg:`milestone` timer
value for the transaction :arg:`txnp`. These timers are calculated during the
lifetime of a transaction and are measured in nanoseconds from the beginning of
the transaction. :arg:`time` is used a pointer to storage to update if the call
is successful.

.. enum:: TSMilestonesType

   An enumeration of the valid indices of transaction milestone data.

   .. enumerator:: TS_MILESTONE_SM_START

      Transaction state machine is initialized.

   .. enumerator:: TS_MILESTONE_UA_BEGIN

      The client connection is accepted.

   .. enumerator:: TS_MILESTONE_UA_READ_HEADER_DONE

      The request header from the client has been read and parsed.

   .. enumerator:: TS_MILESTONE_CACHE_OPEN_READ_BEGIN

      Initiate read of the cache.

   .. enumerator:: TS_MILESTONE_CACHE_OPEN_READ_END

      Initial cache read has resolved.

   .. enumerator:: TS_MILESTONE_CACHE_OPEN_WRITE_BEGIN

      Start open for cache write.

   .. enumerator:: TS_MILESTONE_CACHE_OPEN_WRITE_END

      Cache has been opened for write.

   .. enumerator:: TS_MILESTONE_DNS_LOOKUP_BEGIN

      Initiate host resolution in HostDB

   .. enumerator:: TS_MILESTONE_DNS_LOOKUP_END

      Host resolution resolves.

   .. enumerator:: TS_MILESTONE_SERVER_FIRST_CONNECT

      First time origin server connect attempted or shared session attached.

   .. enumerator:: TS_MILESTONE_SERVER_CONNECT

      Most recent time origin server connect attempted or shared session attached.

   .. enumerator:: TS_MILESTONE_SERVER_CONNECT_END

      More recent time a connection attempt was resolved.

   .. enumerator:: TS_MILESTONE_SERVER_BEGIN_WRITE

      First byte is written to the origin server connection.

   .. enumerator:: TS_MILESTONE_SERVER_FIRST_READ

      First byte is read from connection to origin server.

   .. enumerator:: TS_MILESTONE_SERVER_READ_HEADER_DONE

      Origin server response has been read and parsed.

   .. enumerator:: TS_MILESTONE_UA_BEGIN_WRITE

      The response header write to the client starts.

   .. enumerator:: TS_MILESTONE_SERVER_CLOSE

      Last I/O activity on origin server connection.

   .. enumerator:: TS_MILESTONE_UA_CLOSE

      Last I/O activity on the client socket, or connection abort.

   .. enumerator:: TS_MILESTONE_SM_FINISH

      Transaction has finished, state machine final logging has started.

   .. enumerator:: TS_MILESTONE_PLUGIN_ACTIVE

      Amount of time plugins were active (running plugin code).

   .. enumerator:: TS_MILESTONE_PLUGIN_TOTAL

      Amount of time spent in or waiting for plugins.

   .. enumerator:: TS_MILESTONE_TLS_HANDSHAKE_START

      Timestamp when the server starts the TLS handshake. 0 if no handshake is performed (connection reuse).

   .. enumerator:: TS_MILESTONE_TLS_HANDSHAKE_END

      Timestamp when the server completes the TLS handshake. 0 if no handshake is performed (connection reuse).

   .. enumerator:: TS_MILESTONE_LAST_ENTRY

      A pseudo index which is set to be one more than the last valid index. This is useful for looping over the data.


*  The server connect times predate the transmission of the :literal:`SYN`
   packet. That is, before a connection to the origin server is completed.

*  A connection attempt is resolved when no more connection related activity
   remains to be done, and the connection is either established or has failed.

*  :macro:`TS_MILESTONE_UA_CLOSE` and :macro:`TS_MILESTONE_SERVER_CLOSE` are
   updated continuously during the life of the transaction, every time there is
   I/O activity. The updating stops when the corresponding connection is
   closed, leaving the last I/O time as the final value.

*  The cache :literal:`OPEN` milestones time only the initial setup, the
   *open*, not the full read or write.

*  :macro:`TS_MILESTONE_PLUGIN_ACTIVE` and :macro:`TS_MILESTONE_PLUGIN_TOTAL` are different from the other milestones as
   they measure elapsed time, not event time. The value is the elapsed time *plus* :macro:`TS_MILESTONE_SM_START`. This
   was decided to be more convenient because then these milestones can be handled / displayed in the same way as the
   other milestones, as offsets from :macro:`TS_MILESTONE_SM_START`.

   :macro:`TS_MILESTONE_PLUGIN_ACTIVE` value is the amount of time the plugin was active, that is performing
   computation. :macro:`TS_MILESTONE_PLUGIN_TOTAL` is the wall time which includes any time the transaction was blocked
   while a plugin was active. For instance if a plugin waits on an external event, that waiting time will be in
   :macro:`TS_MILESTONE_PLUGIN_TOTAL` but not in :macro:`TS_MILESTONE_PLUGIN_ACTIVE`.

Return Values
=============

:macro:`TS_SUCCESS` if successful and :arg:`time` was updated, otherwise
:macro:`TS_ERROR`.

See Also
========

:manpage:`TSAPI(3ts)`