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

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   except in compliance with the License.  You may obtain a copy of
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   http://www.apache.org/licenses/LICENSE-2.0

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

.. default-domain:: c

TSCacheWrite
************

Synopsis
========

.. code-block:: cpp

    #include <ts/ts.h>

.. function:: TSAction TSCacheWrite(TSCont contp, TSCacheKey key)

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

Asks the Traffic Server cache if :arg:`contp` can start writing the object
corresponding to :arg:`key` to the cache.

If the object can be written, the cache calls :arg:`contp` back with the
event :data:`TS_EVENT_CACHE_OPEN_WRITE`.  In this case, the cache
also passes :arg:`contp` a cache vconnection and :arg:`contp` can then initiate a
write operation on that vconnection using :type:`TSVConnWrite`.  The
object is not committed to the cache until the vconnection is closed.
When all data has been transferred, the user (:arg:`contp`) must do an
:type:`TSVConnClose`.  In case of any errors, the user must do an
``TSVConnAbort(contp, 0)``.

If the object cannot be written, the cache calls :arg:`contp` back with the
event :data:`TS_EVENT_CACHE_OPEN_WRITE_FAILED`.  This can happen,
for example, if there is another object with the same :arg:`key` being
written to the cache.  The user (:arg:`contp`) has the option to cancel the
action returned by :type:`TSCacheWrite`.

Note that reentrant calls are possible, i.e. the cache can call back
the user (:arg:`contp`) in the same call.