public static IndexData ReadFromFile(string filePath)
{
if (!File.Exists(filePath))
{
throw new FileNotFoundException($"Index file under {filePath} not found.");
}
var size = new FileInfo(filePath).Length;
int treeType;
NodeMetaData[] data;
using (var mmf = MemoryMappedFile.CreateFromFile(filePath, FileMode.Open))
{
using (var accessor = mmf.CreateViewAccessor(0, size))
{
accessor.Read(0, out treeType);
accessor.Read(sizeof(int), out int itemCount);
data = new NodeMetaData[itemCount];
long pos = sizeof(int) * 2;
for (var i = 0; i < itemCount; ++i)
{
data[i] = NodeMetaData.Read(accessor, ref pos);
}
}
}
return(new IndexData((TreeType)treeType, data));
}
public static IndexData ReadFromFile(string filePath, long offset, long size)
{
if (!File.Exists(filePath))
{
throw new FileNotFoundException($"Index file under {filePath} not found.");
}
int treeType;
NodeMetaData[] data;
using (var mmf = MemoryMappedFile.CreateFromFile(File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.Read), null, 0L, MemoryMappedFileAccess.Read, HandleInheritability.None, false))
{
using (var accessor = mmf.CreateViewAccessor(offset, size, MemoryMappedFileAccess.Read))
{
accessor.Read(0, out treeType);
accessor.Read(sizeof(int), out int itemCount);
data = new NodeMetaData[itemCount];
long pos = sizeof(int) * 2;
for (var i = 0; i < itemCount; ++i)
{
data[i] = NodeMetaData.Read(accessor, ref pos);
}
}
}
return(new IndexData((TreeType)treeType, data));
}
