/// <summary>
/// Store a result set mapping in a cache
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="cache"></param>
/// <param name="key"></param>
/// <param name="resultSetMapping"></param>
private static void SetMappingCache <T>(ref ConcurrentDictionary <ResultSetMappingIdentity, ResultSetMappingCacheItem> cache,
ResultSetMappingIdentity key, List <ColumnMapping> resultSetMapping)
{
if (!_cachingEnabled)
{
return; // short circuit if caching if disabled
}
cache[key] = ResultSetMappingCacheItem.CreateInstance <T>(resultSetMapping);
}
/// <summary>
/// Retrieve a result set mapping from a cache if it exists
/// </summary>
/// <param name="cache"></param>
/// <param name="key"></param>
/// <param name="resultSetMapping"></param>
/// <returns></returns>
private static bool TryGetMappingCache(ref ConcurrentDictionary <ResultSetMappingIdentity, ResultSetMappingCacheItem> cache,
ResultSetMappingIdentity key, out List <ColumnMapping> resultSetMapping)
{
resultSetMapping = null;
if (!_cachingEnabled)
{
return(false); // short circuit if caching if disabled
}
ResultSetMappingCacheItem cacheItem;
if (cache.TryGetValue(key, out cacheItem))
{
cacheItem.RecordHit();
resultSetMapping = cacheItem.Mappings;
return(true);
}
return(false);
}
/// <summary>
/// Get the mappings for a given type and data reader. Caches in appropriate cache.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="reader"></param>
/// <param name="mapByPosition"></param>
/// <param name="allowUnmappedColumns"></param>
/// <returns></returns>
private static List <ColumnMapping> GetMappings <T>(OracleDataReader reader, bool mapByPosition, bool allowUnmappedColumns)
{
// determine which of the four caches should be used
ConcurrentDictionary <ResultSetMappingIdentity, ResultSetMappingCacheItem> mappingCache =
(mapByPosition
? (allowUnmappedColumns ? _mappingByPositionFlexibleCache : _mappingByPositionCache)
: (allowUnmappedColumns ? _mappingByNameFlexibleCache : _mappingByNameCache));
// a unique id can be derived from the C# type and result set alone
ResultSetMappingIdentity mappingKey = ResultSetMappingIdentity.CreateInstance <T>(reader);
List <ColumnMapping> mappings;
if (!TryGetMappingCache(ref mappingCache, mappingKey, out mappings))
{
// if they are not in cache, then build mappings now and cache them
mappings = BuildMappings <T>(reader, mapByPosition, allowUnmappedColumns);
SetMappingCache <T>(ref mappingCache, mappingKey, mappings);
}
return(mappings);
}
