/// <summary>
/// Maps a file into a set of buffers </summary>
internal virtual ByteBuffer[] Map(MMapIndexInput input, FileStream fc, long offset, long length)
{
if (Number.URShift(length, ChunkSizePower) >= int.MaxValue)
throw new ArgumentException("RandomAccessFile too big for chunk size: " + fc.ToString());
long chunkSize = 1L << ChunkSizePower;
// we always allocate one more buffer, the last one may be a 0 byte one
int nrBuffers = (int)((long)((ulong)length >> ChunkSizePower)) + 1;
ByteBuffer[] buffers = new ByteBuffer[nrBuffers];
/*
public static MemoryMappedFile CreateFromFile(FileStream fileStream, String mapName, Int64 capacity,
MemoryMappedFileAccess access, MemoryMappedFileSecurity memoryMappedFileSecurity,
HandleInheritability inheritability, bool leaveOpen)
*/
if (input.memoryMappedFile == null)
{
input.memoryMappedFile = MemoryMappedFile.CreateFromFile(fc, null, length == 0 ? 100 : length, MemoryMappedFileAccess.Read, null, HandleInheritability.Inheritable, false);
}
long bufferStart = 0L;
for (int bufNr = 0; bufNr < nrBuffers; bufNr++)
{
int bufSize = (int)((length > (bufferStart + chunkSize)) ? chunkSize : (length - bufferStart));
//LUCENE TO-DO
buffers[bufNr] = new MemoryMappedFileByteBuffer(input.memoryMappedFile.CreateViewAccessor(offset + bufferStart, bufSize, MemoryMappedFileAccess.Read), -1, 0, bufSize, bufSize);
//buffers[bufNr] = fc.Map(FileStream.MapMode.READ_ONLY, offset + bufferStart, bufSize);
bufferStart += bufSize;
}
return buffers;
}
/// <summary>
/// Maps a file into a set of buffers </summary>
internal virtual ByteBuffer[] Map(MMapIndexInput input, FileStream fc, long offset, long length)
{
if (Number.URShift(length, ChunkSizePower) >= int.MaxValue)
throw new ArgumentException("RandomAccessFile too big for chunk size: " + fc.ToString());
long chunkSize = 1L << ChunkSizePower;
// we always allocate one more buffer, the last one may be a 0 byte one
int nrBuffers = (int)((long)((ulong)length >> ChunkSizePower)) + 1;
ByteBuffer[] buffers = new ByteBuffer[nrBuffers];
/*
public static MemoryMappedFile CreateFromFile(FileStream fileStream, String mapName, Int64 capacity,
MemoryMappedFileAccess access, MemoryMappedFileSecurity memoryMappedFileSecurity,
HandleInheritability inheritability, bool leaveOpen)
*/
long fileCapacity = length == 0 ? ushort.MaxValue : length;
if (input.memoryMappedFile == null)
{
input.memoryMappedFile = MemoryMappedFile.CreateFromFile(fc, null, fileCapacity, MemoryMappedFileAccess.ReadWrite, null, HandleInheritability.Inheritable, false);
}
long bufferStart = 0L;
for (int bufNr = 0; bufNr < nrBuffers; bufNr++)
{
int bufSize = (int)((length > (bufferStart + chunkSize)) ? chunkSize : (length - bufferStart));
// LUCENENET: We get a file access exception if we create a 0 byte file at the end of the range.
// We can fix this by moving back 1 byte if the bufSize is 0.
int adjust = 0;
if (bufSize == 0 && bufNr == (nrBuffers - 1) && (offset + bufferStart) > 0)
{
adjust = 1;
}
buffers[bufNr] = new MemoryMappedFileByteBuffer(input.memoryMappedFile.CreateViewAccessor((offset + bufferStart) - adjust, bufSize, MemoryMappedFileAccess.Read), -1, 0, bufSize, bufSize);
bufferStart += bufSize;
}
return buffers;
}