~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2010 Brian Aker

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 *

 *  You should have received a copy of the GNU General Public License

 *  along with this program; if not, write to the Free Software

 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include <config.h>

#include <drizzled/table/cache.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <drizzled/identifier.h>

#include <drizzled/open_tables_state.h>

#include <drizzled/pthread_globals.h>

#include <drizzled/session.h>

#include <drizzled/sql_base.h>

#include <drizzled/sys_var.h>

#include <drizzled/table.h>

#include <drizzled/table/concurrent.h>

#include <drizzled/table/unused.h>

namespace drizzled {

namespace table {

CacheMap Cache::cache;

boost::mutex Cache::_mutex;

CacheMap& getCache()

{

  return Cache::getCache();

}

/*

  Remove table from the open table cache

  SYNOPSIS

  free_cache_entry()

  entry		Table to remove

  NOTE

  We need to have a lock on table::Cache::mutex() when calling this

*/

static void free_cache_entry(table::Concurrent *table)

{

  table->intern_close_table();

  if (not table->in_use)

  {

    getUnused().unlink(table);

  }

  boost::checked_delete(table);

}

void remove_table(table::Concurrent *arg)

{

  CacheRange ppp;

  ppp= getCache().equal_range(arg->getShare()->getCacheKey());

  for (CacheMap::const_iterator iter= ppp.first;

         iter != ppp.second; ++iter)

  {

    table::Concurrent *found_table= iter->second;

    if (found_table == arg)

    {

      free_cache_entry(arg);

      getCache().erase(iter);

      return;

    }

  }

}

/*

  Wait until all threads has closed the tables in the list

  We have also to wait if there is thread that has a lock on this table even

  if the table is closed

*/

bool Cache::areTablesUsed(Table *table, bool wait_for_name_lock)

{

  do

  {

    const identifier::Table::Key &key(table->getShare()->getCacheKey());

    table::CacheRange ppp= table::getCache().equal_range(key);

    for (table::CacheMap::const_iterator iter= ppp.first; iter != ppp.second; ++iter)

    {

      Table *search= iter->second;

      if (search->in_use == table->in_use)

        continue;                               // Name locked by this thread

      /*

        We can't use the table under any of the following conditions:

        - There is an name lock on it (Table is to be deleted or altered)

        - If we are in flush table and we didn't execute the flush

        - If the table engine is open and it's an old version

        (We must wait until all engines are shut down to use the table)

      */

      if ( (search->locked_by_name && wait_for_name_lock) ||

           (search->is_name_opened() && search->needs_reopen_or_name_lock()))

        return 1;

    }

  } while ((table=table->getNext()));

  return 0;

}

/*

  Invalidate any cache entries that are for some DB

  SYNOPSIS

  removeSchema()

  db		Database name. This will be in lower case if

  lower_case_table_name is set

NOTE:

We can't use hash_delete when looping hash_elements. We mark them first

and afterwards delete those marked unused.

*/

void Cache::removeSchema(const identifier::Schema &schema_identifier)

{

  boost::mutex::scoped_lock scopedLock(_mutex);

  for (table::CacheMap::const_iterator iter= table::getCache().begin();

       iter != table::getCache().end();

       iter++)

  {

    table::Concurrent *table= iter->second;

    if (not schema_identifier.getPath().compare(table->getShare()->getSchemaName()))

    {

      table->getMutableShare()->resetVersion();			/* Free when thread is ready */

      if (not table->in_use)

        table::getUnused().relink(table);

    }

  }

  table::getUnused().cullByVersion();

}

/*

  Mark all entries with the table as deleted to force an reopen of the table

  The table will be closed (not stored in cache) by the current thread when

  close_thread_tables() is called.

  PREREQUISITES

  Lock on table::Cache::mutex()()

  RETURN

  0  This thread now have exclusive access to this table and no other thread

  can access the table until close_thread_tables() is called.

  1  Table is in use by another thread

*/

bool Cache::removeTable(Session& session, const identifier::Table &identifier, uint32_t flags)

{

  const identifier::Table::Key &key(identifier.getKey());

  bool result= false;

  bool signalled= false;

  for (;;)

  {

    result= signalled= false;

    table::CacheRange ppp;

    ppp= table::getCache().equal_range(key);

    for (table::CacheMap::const_iterator iter= ppp.first;

         iter != ppp.second; ++iter)

    {

      table::Concurrent *table= iter->second;

      Session *in_use;

      table->getMutableShare()->resetVersion();		/* Free when thread is ready */

      if (not (in_use= table->in_use))

      {

        table::getUnused().relink(table);

      }

      else if (in_use != &session)

      {

        /*

          Mark that table is going to be deleted from cache. This will

          force threads that are in lockTables() (but not yet

          in thr_multi_lock()) to abort it's locks, close all tables and retry

        */

        if (table->is_name_opened())

        {

          result= true;

        }

        /*

          Now we must abort all tables locks used by this thread

          as the thread may be waiting to get a lock for another table.

          Note that we need to hold table::Cache::mutex() while going through the

          list. So that the other thread cannot change it. The other

          thread must also hold table::Cache::mutex() whenever changing the

          open_tables list. Aborting the MERGE lock after a child was

          closed and before the parent is closed would be fatal.

        */

        for (Table *session_table= in_use->open_tables.open_tables_;

             session_table ;

             session_table= session_table->getNext())

        {

          /* Do not handle locks of MERGE children. */

          if (session_table->db_stat)	// If table is open

            signalled|= session.abortLockForThread(session_table);

        }

      }

      else

      {

        result= result || (flags & RTFC_OWNED_BY_Session_FLAG);

      }

    }

    table::getUnused().cullByVersion();

    /* Remove table from table definition cache if it's not in use */

    table::instance::release(identifier);

    if (result && (flags & RTFC_WAIT_OTHER_THREAD_FLAG))

    {

      /*

        Signal any thread waiting for tables to be freed to

        reopen their tables

      */

      locking::broadcast_refresh();

      if (not (flags & RTFC_CHECK_KILLED_FLAG) || not session.getKilled())

      {

        dropping_tables++;

        if (likely(signalled))

        {

          boost::mutex::scoped_lock scoped(table::Cache::mutex(), boost::adopt_lock_t());

          COND_refresh.wait(scoped);

          scoped.release();

        }

        else

        {

          /*

            It can happen that another thread has opened the

            table but has not yet locked any table at all. Since

            it can be locked waiting for a table that our thread

            has done LOCK Table x WRITE on previously, we need to

            ensure that the thread actually hears our signal

            before we go to sleep. Thus we wait for a short time

            and then we retry another loop in the

            table::Cache::removeTable routine.

          */

          boost::xtime xt;

          xtime_get(&xt, boost::TIME_UTC);

          xt.sec += 10;

          boost::mutex::scoped_lock scoped(table::Cache::mutex(), boost::adopt_lock_t());

          COND_refresh.timed_wait(scoped, xt);

          scoped.release();

        }

        dropping_tables--;

        continue;

      }

    }

    break;

  }

  return result;

}

void Cache::insert(table::Concurrent* arg)

{

  CacheMap::iterator returnable= cache.insert(std::make_pair(arg->getShare()->getCacheKey(), arg));

	assert(returnable != cache.end());

}

} /* namespace table */

} /* namespace drizzled */