doc/developer-guide/cache-architecture/core-cache-functions.en.rst

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.. include:: ../../common.defs
.. default-domain:: cpp

.. _core_cache_functions:

Core Cache
**********

Core Cache Constants
====================

.. c:macro:: EVACUATION_SIZE

   The size of the contiguous area to check for evacuation.

Core Cache Types
================

.. type:: span_diskid_t

   Stores a 16 byte ID.

.. cpp:class:: CacheKey

  The hash value for a cache object. Currently a 128 bit MD5 hash.

.. cpp:class:: EvacuationBlock

   A range of content to be evacuated.

.. cpp:class:: CacheProcessor

   The singleton cache management object. This handles threads and global initialization for the cache.

   .. cpp:member:: int start(int n_threads, size_t stacksize)

      Starts the cache processing threads, :arg:`n_threads` are created each with a stack of size :arg:`stacksize`.

.. cpp:class:: Span

   :class:`Span` models a :term:`cache span`. This is a contiguous span of storage.

   .. member:: int64_t blocks

      Number of storage blocks in the span. See :var:`STORE_BLOCK_SIZE`.

   .. member:: int64_t offset

      Offset (in bytes)_ to the start of the span. This is used only if the base storage is a file.

   .. member:: span_diskid_t disk_id

      No idea what this is.

.. cpp:class:: Store

   A singleton containing all of the cache storage description.

   .. member:: unsigned n_disks_in_config

      The number of distinct devices in the configuration.

   .. member:: unsigned n_disks

      The number of valid and distinct devices in the configuration.

   .. member:: Span** disk

      List of spans.

   .. function:: char * read_config()

      Read :file:`storage.config` and initialize the base state of the instance. The return value is :code:`nullptr` on success and a nul-terminated error string on error.

.. cpp:class:: CacheDisk

   A representation of the physical device used for a :cpp:class:`Span`.

Core Cache Functions
====================

.. cpp:function:: int dir_probe(const CacheKey * key, Vol * d, Dir * result, Dir ** last_collision)

  Probe the stripe directory for a candidate directory entry.

.. cpp:function:: void build_vol_hash_table(CacheHostRecord * r)

   Based on the configuration record :arg:`r`, construct the global stripe assignment table.

.. cpp:function:: int cplist_reconfigure()

   Rebuild the assignment of stripes to volumes.

.. cpp:function:: void ink_cache_init(ModuleVersion v)

   Top level cache initialization logic.