hdfs::native::hadoopReadZero
[−]
[src]
pub unsafe extern fn hadoopReadZero(file: *const hdfsFile, opts: *const hadoopRzOptions, maxLength: int32_t) -> *const hadoopRzBuffer
Perform a byte buffer read. If possible, this will be a zero-copy (mmap) read.
Params
file- The file to read from.opts- An options structure created by hadoopRzOptionsAlloc.maxLength- The maximum length to read. We may read fewer bytes than this length.
Return
On success, we will return a new hadoopRzBuffer. This buffer will
continue to be valid and readable until it is released by
readZeroBufferFree. Failure to release a buffer will lead to a memory
leak. You can access the data within the hadoopRzBuffer with
hadoopRzBufferGet. If you have reached EOF, the data within the
hadoopRzBuffer will be NULL. You must still free hadoopRzBuffer
instances containing NULL.
On failure, we will return NULL plus an errno code.
errno = EOPNOTSUPP indicates that we could not do a zero-copy
read, and there was no ByteBufferPool supplied.