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   to you under the Apache License, Version 2.0 (the
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   http://www.apache.org/licenses/LICENSE-2.0

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

.. default-domain:: c

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

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

Synopsis
========

`#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.

.. type:: TSMilestonesType

=============================================== ==========
Value                                           Milestone
=============================================== ==========
:const:`TS_MILESTONE_UA_BEGIN`                  The client connection is accepted.
:const:`TS_MILESTONE_UA_READ_HEADER_DONE`       The request header from the client has been read and parsed.
:const:`TS_MILESTONE_UA_BEGIN_WRITE`            The response header write to the client starts.
:const:`TS_MILESTONE_UA_CLOSE`                  Last I/O activity on the client socket, or connection abort.
:const:`TS_MILESTONE_SERVER_FIRST_CONNECT`      First time origin server connect attempted or shared shared session attached.
:const:`TS_MILESTONE_SERVER_CONNECT`            Most recent time origin server connect attempted or shared session attached.
:const:`TS_MILESTONE_SERVER_CONNECT_END`        More recent time a connection attempt was resolved.
:const:`TS_MILESTONE_SERVER_BEGIN_WRITE`        First byte is written to the origin server connection.
:const:`TS_MILESTONE_SERVER_FIRST_READ`         First byte is read from connection to origin server.
:const:`TS_MILESTONE_SERVER_READ_HEADER_DONE`   Origin server response has been read and parsed.
:const:`TS_MILESTONE_SERVER_CLOSE`              Last I/O activity on origin server connection.
:const:`TS_MILESTONE_CACHE_OPEN_READ_BEGIN`     Initiate read of the cache.
:const:`TS_MILESTONE_CACHE_OPEN_READ_END`       Initial cache read has resolved.
:const:`TS_MILESTONE_CACHE_OPEN_WRITE_BEGIN`    Start open for cache write.
:const:`TS_MILESTONE_CACHE_OPEN_WRITE_END`      Cache has been opened for write.
:const:`TS_MILESTONE_DNS_LOOKUP_BEGIN`          Initiate host resolution in HostDB
:const:`TS_MILESTONE_DNS_LOOKUP_END`            Host resolution resolves.
:const:`TS_MILESTONE_SM_START`                  Transaction state machine is initialized.
:const:`TS_MILESTONE_SM_FINISH`                 Transaction has finished, state machine final logging has started.
:const:`TS_MILESTONE_PLUGIN_ACTIVE`             Amount of time plugins were active plus start time.
:const:`TS_MILESTONE_PLUGIN_TOTAL`              Wall time while plugins were active plus start time.
=============================================== ==========

*  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.

*  :const:`TS_MILESTONE_UA_CLOSE` and :const:`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.

*  :const:`TS_MILESTONE_PLUGIN_ACTIVE` and :const:`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* :const:`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 :const:`TS_MILESTONE_SM_START`.

   :const:`TS_MILESTONE_PLUGIN_ACTIVE` value is the amount of time the plugin was active, that is performing
   computation. :const:`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
   :const:`TS_MILESTONE_PLUGIN_TOTAL` but not in :const:`TS_MILESTONE_PLUGIN_ACTIVE`.

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

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

See Also
========

:manpage:`TSAPI(3ts)`
