Merge pull request #48 from benchhub/store/meta/split-node

[failed][store][meta][proto] Split node into info and status

this pr is not finished but merged due to the following reasons

- I am currently unifying project and labels of all my projects at15/ghutil#2
- after reading more code from non time series databases, I feel BenchHub the proejct itself should be structured like a database instead of a normal client and server application #50, some breaking change would be introduced, and just let the tests fail ....

.travis.yml

@@ -3,6 +3,8 @@ language: go
 sudo: true
 git:
   depth: 3
+env:
+  - DUMP=true # gommon/util/testutil.Dump
 
 go:
   - 1.9.x

doc/survey/scheduler/k8s.md

@@ -114,3 +114,54 @@ spec:
       restartPolicy: Never
   backoffLimit: 4
 ````
+
+## Scheduler
+
+- https://github.com/benchhub/benchhub/issues/49
+- official
+  - https://github.com/kubernetes/community/blob/master/contributors/devel/scheduler.md
+- code
+- blog
+  - https://jvns.ca/blog/2017/07/27/how-does-the-kubernetes-scheduler-work/
+  - https://deis.com/blog/2016/schedulers-pt2-kubernetes/ Mothiki (colleague in PayPal) is the author
+
+````text
+pod = pop(queue)
+nodes = filter(nodes)
+nodes = order(nodes)
+node = pick_one(node)
+````
+
+interface
+
+````go
+// scheduler/algorithm/scheduler_interface.go
+type ScheduleAlgorithm interface {
+  // Schedule tries to schedule the given pod to one of the nodes in the node list.
+  // If it succeeds, it will return the name of the node.
+  // If it fails, it will return a FitError error with reasons.
+  Schedule(*v1.Pod, NodeLister) (selectedMachine string, err error)
+}
+
+// scheduler/algorithm/types.go
+type PredicateFailureReason interface {
+  GetReason() string
+}
+
+// FitPredicate is a function that indicates if a pod fits into an existing node.
+// The failure information is given by the error.
+type FitPredicate func(pod *v1.Pod, meta PredicateMetadata, nodeInfo *schedulercache.NodeInfo) (bool, []PredicateFailureReason, error)
+
+// scheduler/algorithm/predicates/error.go
+// PredicateFailureError describes a failure error of predicate.
+type PredicateFailureError struct {
+  PredicateName string
+  PredicateDesc string
+}
+````
+
+implementation generic + mock
+
+````go
+// scheduler/core/generic_scheduler.go
+````

example/pingpong/pingpong.yml

@@ -12,11 +12,16 @@ workload:
   databaseVersion: "0.0.1"
 # NOTE: extra tag is specified in proto file using (gogoproto.moretags) = "yaml:\"nodeAssignments\""
 nodeAssignments:
-  - name: srv
-    # NOTE: custom yaml unmarshaler
-    role: database
-  - name: cli
-    role: loader
+  - selectors:
+    - role: database # NOTE: custom yaml unmarshaler
+    properties:
+      name: srv
+      role: database
+  - selectors:
+    - role: loader
+    properties:
+      name: cli
+      role: loader
 pipelines:
   - name: download
     stages: