internal static Func <IDataRecord, T> ProvideLoader <T>(IDataRecord reader, out QueryTalkException exception)
{
exception = null;
object loader;
Type type = typeof(T);
Loader.ColumnInfo[] columns;
Cache.LoaderCacheKey cacheKey = Cache.LoaderCacheKey.Default;
Cache.LoaderCacheValue cacheValue;
var loaderType = Cache.GetLoaderType(type);
int hash = 0;
// check cache
if (Admin.IsLoaderCachingOn)
{
hash = GetLoaderHash(reader);
cacheKey = new Cache.LoaderCacheKey(hash, loaderType, type);
if (Cache.TryGetLoaderCache <T>(reader, cacheKey, out cacheValue))
{
return((Func <IDataRecord, T>)cacheValue.Loader);
}
}
// dynamic loading
if (loaderType == Cache.LoaderType.Dynamic)
{
columns = ReflectReader(reader, out exception);
if (exception != null)
{
exception.Arguments += String.Format("{0} table = {1}", Environment.NewLine, type);
return(null);
}
TryThrowInvalidDataClassException(null, columns);
Type dynamicType = Loader.EmitTable(columns, Guid.NewGuid());
loader = Loader.EmitRowLoaderDynamic(columns, dynamicType);
}
// Row
else if (loaderType == Cache.LoaderType.Row)
{
columns = ReflectRow(type, reader);
TryThrowInvalidDataClassException(type, columns);
loader = Loader.EmitRowLoader <T>(columns);
}
// regular data class
else
{
columns = ReflectClass(type, reader);
TryThrowInvalidDataClassException(type, columns);
loader = Loader.EmitRowLoader <T>(columns);
}
// cache loader
if (Admin.IsLoaderCachingOn)
{
cacheValue = new Cache.LoaderCacheValue(columns, loader);
Cache.Loaders.TryAdd(cacheKey, cacheValue);
}
return((Func <IDataRecord, T>)loader);
}
internal static bool TryGetLoaderCache <T>(IDataRecord reader, Cache.LoaderCacheKey cacheKey, out Cache.LoaderCacheValue cacheValue)
{
if (Cache.Loaders.TryGetValue(cacheKey, out cacheValue))
{
try
{
((Func <IDataRecord, T>)cacheValue.Loader).Invoke(reader);
return(true);
}
// safe:
// The exception is intercepted here only once in order to generate new loader code.
// (Very unlikely to happen.)
catch
{
Cache.Loaders.TryRemove(cacheKey, out cacheValue);
return(false);
}
}
return(false);
}
