[rados] Development of RADOS binding of Ceph FS

[jaemyoun]

Development of RADOS binding of Ceph File System
Even though Ceph FS is not NoSQL database, RADOS, Ceph utility, supports object-based storage.

For Ceph benchmark for cloud services. I implemented RADOS binding using rados-java library expect the scan() function.

[busbey]

this should just be set in the pom for the rados client, since it needn't be shared across different datastore bindings..

[busbey]

The travis failure is because you need to add the new module to the list of dependencies for the distribution module.

[jaemyoun]

I fixed all code you mentioned, and an additional error.

[busbey]

We don't rely on SNAPSHOT versions in our releases. Can we rely on a prior version? If not, when is 0.3.0 expected to come out?

[jaemyoun]

I changed the version to 0.2.0 and merged from YCSB master for updating to 0.9.0-SNAPSHOT.

[busbey]

This needs to be protected by a lock, sine rados is static and we instantiate a client for each thread.

Presuming the rados and ioctx objects are themselves threadsafe, then you should synchronize and use a threadcount to decide when it's safe to do shutdown in the cleanup method.

[jaemyoun]

Did you mean these to change Static Strings? The three value will be different depend on user setting.

[busbey]

No, I mean the member variables rados and ioctx are static. We instantiate a RadosClient per worker thread in the client, so access to initializing and cleaning up these static members must be protected by a lock.

If the member classes themselves aren't threadsafe, then you'll need to either guard all uses with a lock or switch to making them non-static.

[busbey]

does rados provide any kind of testing utility jar that could be used to include a test?

[jaemyoun]

I switched rados and ioctxto non-static, and implemented a test.
The test is success in my cluster, but the Travis CI building was failed because there is no the Ceph cluster.

[busbey]

The test is success in my cluster, but the Travis CI building was failed because there is no the Ceph cluster.

Does Ceph have some kind of artifact for making a local test instance that we could make use of? (see the hbase10 or accumulo bindings for examples) If not, we should update the test to make use of the JUnit Assume API to skip the test when a Ceph instance is not present (see the mongodb or riak bindings as an example).

[jaemyoun]

If not, we should update the test to make use of the JUnit Assume API to skip the test when a Ceph instance is not present (see the mongodb or riak bindings as an example).

I was not able to find the test instance for Ceph, so I updated to skip the test using JUnit AssumeNoException.