[#41] container: Produce notification to control container estimations

Basic income settlements depends on container estimation that
should be collected in P2P communication between storage nodes
and then stored in container contract. To synchronize these
actions there are two separate notification that inner ring
should produce in consensus.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

container/config.yml

@@ -15,3 +15,11 @@ events:
         type: ByteArray
       - name: signature
         type: ByteArray
+  - name: StartEstimation
+    parameters:
+      - name: epoch
+        type: Integer
+  - name: StopEstimation
+    parameters:
+      - name: epoch
+        type: Integer

container/container_contract.go

@@ -372,6 +372,54 @@ func ProcessEpoch(epochNum int) {
 	}
 }
 
+func StartContainerEstimation(epoch int) bool {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	innerRing := contract.Call(netmapContractAddr, "innerRingList").([]irNode)
+	threshold := len(innerRing)/3*2 + 1
+
+	irKey := innerRingInvoker(innerRing)
+	if len(irKey) == 0 {
+		panic("startEstimation: only inner ring nodes can invoke this")
+	}
+
+	hashCandidate := invokeID([]interface{}{epoch}, []byte("startEstimation"))
+
+	n := vote(ctx, hashCandidate, irKey)
+	if n >= threshold {
+		removeVotes(ctx, hashCandidate)
+		runtime.Notify("StartEstimation", epoch)
+		runtime.Log("startEstimation: notification has been produced")
+	} else {
+		runtime.Log("startEstimation: processed invoke from inner ring")
+	}
+
+	return true
+}
+
+func StopContainerEstimation(epoch int) bool {
+	netmapContractAddr := storage.Get(ctx, netmapContractKey).([]byte)
+	innerRing := contract.Call(netmapContractAddr, "innerRingList").([]irNode)
+	threshold := len(innerRing)/3*2 + 1
+
+	irKey := innerRingInvoker(innerRing)
+	if len(irKey) == 0 {
+		panic("stopEstimation: only inner ring nodes can invoke this")
+	}
+
+	hashCandidate := invokeID([]interface{}{epoch}, []byte("stopEstimation"))
+
+	n := vote(ctx, hashCandidate, irKey)
+	if n >= threshold {
+		removeVotes(ctx, hashCandidate)
+		runtime.Notify("StopEstimation", epoch)
+		runtime.Log("stopEstimation: notification has been produced")
+	} else {
+		runtime.Log("stopEstimation: processed invoke from inner ring")
+	}
+
+	return true
+}
+
 func Version() int {
 	return version
 }