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cache.d
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cache.d
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/* Copyright (C) 2011, 2012 Vladimir Panteleev <[email protected]>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
module cache;
import common;
import database;
version(Posix) import ae.sys.signals;
int dbVersion = 1;
final class CacheSink : NewsSink
{
override void handlePost(Post post)
{
dbVersion++;
}
}
struct Cached(T)
{
int cacheVersion;
T cachedData;
T opCall(lazy T dataSource)
{
if (cacheVersion != dbVersion)
{
cachedData = dataSource;
cacheVersion = dbVersion;
}
return cachedData;
}
}
/// Clears the whole set when the cache is invalidated, to save memory
struct CachedSet(K, T)
{
int cacheVersion;
T[K] cachedData;
T opCall(K key, lazy T dataSource)
{
if (cacheVersion != dbVersion)
{
cachedData = null;
cacheVersion = dbVersion;
}
auto pdata = key in cachedData;
if (pdata)
return *pdata;
else
return cachedData[key] = dataSource;
}
}
static this()
{
new CacheSink();
version(Posix) addSignalHandler(SIGHUP, { dbVersion++; });
}