Ceph: Designing and Implementing Scalable Storage Systems

RADOS class

The following code sample is a RADOS class which when executed reads the object, calculates the MD5 hash, and then writes it as an attribute to the object without any client involvement. Each time this class is called, it repeats this operation a 1000 times locally to OSD and only notifies the client at the end of this processing. We have the following steps to perform:

1. Create the directory for our new RADOS class:

       mkdir ~/ceph/src/cls/md5

2. Now create the C++ source file:

       ~/ceph/src/cls/md5/cls_md5.cc

3. Place the following code into it:

       #include "objclass/objclass.h"       #include <openssl/md5.h>       CLS_VER(1,0)       CLS_NAME(md5)       cls_handle_t h_class;       cls_method_handle_t h_calc_md5; static int calc_md5(cls_method_context_t hctx, bufferlist ...