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Simplify lock manager data structures by making a clear separation between

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the data defining the semantics of a lock method (ie, conflict resolution
table and ancillary data, which is all constant) and the hash tables
storing the current state.  The only thing we give up by this is the
ability to use separate hashtables for different lock methods, but there
is no need for that anyway.  Put some extra fields into the LockMethod
definition structs to clean up some other uglinesses, like hard-wired
tests for DEFAULT_LOCKMETHOD and USER_LOCKMETHOD.  This commit doesn't
do anything about the performance issues we were discussing, but it clears
away some of the underbrush that's in the way of fixing that.
This commit is contained in:
Tom Lane
2005-12-09 01:22:04 +00:00
parent 34848052d0
commit c599a247bb
12 changed files with 394 additions and 574 deletions
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31
src/tools/backend/index.html
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@ -128,31 +128,16 @@ Block</a> - data/index buffer cache block</li>
addresses using table name and block number( <a
href="../../include/storage/buf_internals.h">BufferTag</a>)</li>
<li>MultiLevelLockTable (ctl) - control structure for each locking
method. Currently, only multi-level locking is used(<a
href="../../include/storage/lock.h">LOCKMETHODCTL</a>).</li>
<li>MultiLevelLockTable (lock hash) - the <a
<li>Lock Manager Tables (lock hash) - the <a
href="../../include/storage/lock.h">LOCK</a> structure, looked up
using relation, database object ids(<a
href="../../include/storage/lock.h">LOCKTAG)</a>. The lock table
structure contains the lock modes(read/write or shared/exclusive)
and circular linked list of backends (<a
href="../../include/storage/proc.h">PROC</a> structure pointers)
waiting on the lock.</li>
using a <a href="../../include/storage/lock.h">LOCKTAG</a>.
A LOCK structure exists for each lockable object that is currently
locked by any backend. Also, there is a subsidiary <a
href="../../include/storage/lock.h">PROCLOCK</a> structure for each
backend currently interested in a given LOCK</li>
<li>MultiLevelLockTable (xid hash) - lookup of LOCK structure
address using transaction id, LOCK address. It is used to quickly
check if the current transaction already has any locks on a table,
rather than having to search through all the held locks. It also
stores the modes (read/write) of the locks held by the current
transaction. The returned <a
href="../../include/storage/lock.h">XIDLookupEnt</a> structure also
contains a pointer to the backend's PROC.lockQueue.</li>
<li><a href="../../include/storage/proc.h">Proc Header</a> -
information about each backend, including locks held/waiting,
indexed by process id</li>
<li><a href="../../include/storage/proc.h">PGPROC Structures</a> -
information about each backend, including locks held/waiting</li>
</ul>
<p>Each data structure is created by calling <a