private static bool TryLoadMembers()
{
// .NET Core, .NET 4.6+
s_lazyCreateFromFile = LightUpHelper.GetMethod(
s_lazyMemoryMappedFileType,
"CreateFromFile",
FileStreamReadLightUp.FileStreamType.Value,
typeof(string),
typeof(long),
s_lazyMemoryMappedFileAccessType,
s_lazyHandleInheritabilityType,
typeof(bool)
);
// .NET < 4.6
if (s_lazyCreateFromFile == null)
{
if (s_lazyMemoryMappedFileSecurityType != null)
{
s_lazyCreateFromFileClassic = LightUpHelper.GetMethod(
s_lazyMemoryMappedFileType,
"CreateFromFile",
FileStreamReadLightUp.FileStreamType.Value,
typeof(string),
typeof(long),
s_lazyMemoryMappedFileAccessType,
s_lazyMemoryMappedFileSecurityType,
s_lazyHandleInheritabilityType,
typeof(bool));
}
if (s_lazyCreateFromFileClassic == null)
{
return(false);
}
}
s_lazyCreateViewAccessor = LightUpHelper.GetMethod(
s_lazyMemoryMappedFileType,
"CreateViewAccessor",
typeof(long),
typeof(long),
s_lazyMemoryMappedFileAccessType);
if (s_lazyCreateViewAccessor == null)
{
return(false);
}
s_lazySafeMemoryMappedViewHandle = s_lazyMemoryMappedViewAccessorType.GetTypeInfo().GetDeclaredProperty("SafeMemoryMappedViewHandle");
if (s_lazySafeMemoryMappedViewHandle == null)
{
return(false);
}
// .NET Core, .NET 4.5.1+
s_lazyPointerOffset = s_lazyMemoryMappedViewAccessorType.GetTypeInfo().GetDeclaredProperty("PointerOffset");
// .NET < 4.5.1
if (s_lazyPointerOffset == null)
{
s_lazyInternalViewField = s_lazyMemoryMappedViewAccessorType.GetTypeInfo().GetDeclaredField("m_view");
if (s_lazyInternalViewField == null)
{
return(false);
}
s_lazyInternalPointerOffset = s_lazyInternalViewField.FieldType.GetTypeInfo().GetDeclaredProperty("PointerOffset");
if (s_lazyInternalPointerOffset == null)
{
return(false);
}
}
return(true);
}
private static Encoding_GetString LoadGetStringPlatform()
{
// .NET Framework 4.6+ and recent versions of other .NET platforms.
//
// Try to bind to Encoding.GetString(byte*, int);
MethodInfo getStringInfo = LightUpHelper.GetMethod(typeof(Encoding), "GetString", typeof(byte *), typeof(int));
if (getStringInfo != null && getStringInfo.ReturnType == typeof(String))
{
try
{
return((Encoding_GetString)getStringInfo.CreateDelegate(typeof(Encoding_GetString), null));
}
catch (MemberAccessException)
{
}
}
// .NET Framework < 4.6
//
// Try to bind to String.CreateStringFromEncoding(byte*, int, Encoding)
//
// Note that this one is internal and GetRuntimeMethod only searches public methods, which accounts for the different
// pattern from above.
//
// NOTE: Another seeming equivalent is new string(sbyte*, int, Encoding), but don't be fooled. First of all, we can't get
// a delegate to a constructor. Worst than that, even if we could, it is actually about 4x slower than both of these
// and even the portable version (only ~20% slower than these) crushes it.
//
// It spends an inordinate amount of time transitioning to managed code from the VM and then lands in String.CreateString
// (note no FromEncoding suffix), which defensively copies to a new byte array on every call -- defeating the entire purpose
// of this class!
//
// For this reason, desktop callers should not implement an interner that falls back to the unsafe string ctor but instead
// return null and let us find the best decoding approach for the current platform.
//
// Yet another approach is to use new string('\0', GetCharCount) and use unsafe GetChars to fill it.
// However, on .NET < 4.6, there isn't no-op fast path for zero-initialization case so we'd slow down.
// Plus, mutating a System.String is no better than the reflection here.
IEnumerable <MethodInfo> createStringInfos = typeof(String).GetTypeInfo().GetDeclaredMethods("CreateStringFromEncoding");
foreach (var methodInfo in createStringInfos)
{
var parameters = methodInfo.GetParameters();
if (parameters.Length == 3 &&
parameters[0].ParameterType == typeof(byte *) &&
parameters[1].ParameterType == typeof(int) &&
parameters[2].ParameterType == typeof(Encoding) &&
methodInfo.ReturnType == typeof(String))
{
try
{
var createStringFromEncoding = (String_CreateStringFromEncoding)methodInfo.CreateDelegate(typeof(String_CreateStringFromEncoding), null);
return((encoding, bytes, byteCount) => GetStringUsingCreateStringFromEncoding(createStringFromEncoding, bytes, byteCount, encoding));
}
catch (MemberAccessException)
{
}
}
}
// Other platforms: Give up and fall back to GetStringPortable above.
return(null);
}