// Initialize the block with the specified contents.
public Block(BlockContents contents)
{
data_ = contents.Data.Data;
size_ = contents.Data.Size;
owned_ = contents.HeapAllocated;
if (size_ < sizeof(UInt32))
{
size_ = 0; // Error marker
}
else
{
restart_offset_ = (uint)(size_ - (1 + NumRestarts()) * sizeof(UInt32));
if (restart_offset_ > size_ - sizeof(UInt32))
{
// The size is too small for NumRestarts() and therefore
// restart_offset_ wrapped around.
size_ = 0;
}
}
}
public static Status ReadBlock(RandomAccessFile file, ReadOptions options, BlockHandle handle, out BlockContents result)
{
result.Data = new Slice();
result.Cachable = false;
result.HeapAllocated = false;
// Read the block contents as well as the type/crc footer.
// See table_builder.cc for the code that built this structure.
int n = (int)handle.Size;
ByteArrayPointer buf = new ByteArrayPointer(n + kBlockTrailerSize);
Slice contents;
Status s = file.Read(handle.Offset, n + kBlockTrailerSize, out contents, buf);
if (!s.IsOk)
{
return s;
}
if (contents.Size != n + kBlockTrailerSize)
{
return Status.Corruption("truncated block read");
}
// Check the crc of the type and the block contents
ByteArrayPointer data = contents.Data; // Pointer to where Read put the data
if (options.VerifyChecksums)
{
// const uint32_t crc = crc32c::Unmask(DecodeFixed32(data + n + 1));
//const uint32_t actual = crc32c::Value(data, n + 1);
//if (actual != crc) {
// delete[] buf;
// s = Status::Corruption("block checksum mismatch");
// return s;
//}
throw new NotSupportedException("CRC is not supported yet");
}
switch ((CompressionType)data[n])
{
case CompressionType.kNoCompression:
if (data != buf)
{
// File implementation gave us pointer to some other data.
// Use it directly under the assumption that it will be live
// while the file is open.
result.Data = new Slice(data, n);
result.HeapAllocated = false;
result.Cachable = false; // Do not double-cache
}
else
{
result.Data = new Slice(buf, n);
result.HeapAllocated = true;
result.Cachable = true;
}
// Ok
break;
case CompressionType.kSnappyCompression:
throw new NotSupportedException("snappy not supported");
// {
// int ulength = 0;
// if (!port::Snappy_GetUncompressedLength(data, n, &ulength)) {
// delete[] buf;
// return Status::Corruption("corrupted compressed block contents");
// }
// char* ubuf = new char[ulength];
// if (!port::Snappy_Uncompress(data, n, ubuf)) {
// delete[] buf;
// delete[] ubuf;
// return Status::Corruption("corrupted compressed block contents");
// }
// delete[] buf;
// result->data = Slice(ubuf, ulength);
// result->heap_allocated = true;
// result->cachable = true;
// break;
//}
default:
return Status.Corruption("bad block type");
}
return Status.OK;
}
