[Storage Gateway] DR server implementation

[yinweiishere]

Implement DR server instance (single mode, not distributed mode)

status:

1. write journal and replay journal scenario confirmed;
2. proto confirmed;
3. rpc framework and protocol serialize kit confirmed;
4. develop kit confirmed:c++ (not perf critical, to unify with other components)

[yinweiishere]

status: proto and rpc proto committed for review; framework committed for review;

plan: implement write journal logic; implement replay journal logic;

[yinweiishere]

status: UT single UT finished; implementing write journal metadata

plan: UT suite finish API

[toddyLee]

2016-07-26 status: finish UT samples with/without fixture; finish metadata coding base on ceph-rados s3 , but have some bugs need to fix plan of this week:

1. finish metadata api and test
2. write patent idea

[toddyLee]

2016-08-09 status: finish patent idea modify meta manager interfaces according to review opinions write meta manager sequence flowchart plan of this week:

1. meta manger class refactoring: abstract journal naming and ceph S3 apis from meta manager class
2. replicator design and disccusion

[toddyLee]

2016-08-16 status:

1. commit meta manger implementation ant test
2. first version replicator design, issues need to discuss: (1) to consume the journals in order when parallel replicating (2) re-transmit the journals when failed and keep from consuming unfinished journals plan of this week:
3. finish replicator design and grpc streaming message test
4. meta manager test and GC implement

[toddyLee]

2016-08-23 status:

1. commit meta manager implementation, and there was some review opinion; we need the journal filename and path to be more flexible, so we decide to store the journal path and status to s3 object value, but not in the key. and the design is done.
2. write a grpc streaming test, and the replicator design was delayed plan of this week:
3. rewrite the meta manager implementation according to reviewing opinion

[toddyLee]

2016-08-30 status:

1. rewrite meta manager implementation done
2. add config parser done plan of this week:
3. deploy a storage-gateway service manually with modules owners, and test write/read function on it

[toddyLee]

2016-09-06 status:

1. test progress: journal client get journals from dr_server ok; client write journal ok, but still have some bugs and need performance adjustment.
2. update config parser patch according review opinion plan of this week:
3. continue test write/read function
4. use config in dr_server
5. implementation of journal recycled

[toddyLee]

2016-09-13 status:

1. test write/read : modules works separately, but not work together yet
2. use config in dr_server done
3. journal gc: split to a separate class, in process :50% plan of this week:
4. continue coding journal gc:
5. grpc performance test: multiple threads/multiple streams

[toddyLee]

2016-09-19 status:

1. finish gc class diagram, write gc test code done, not submit yet
2. grpc test: coding, not finish plan of this week:
3. continue coding journal gc:
4. finish grpc performance test: multiple threads/multiple streams