From f7b52d16f5836f405ad42aadfa838daac4c336f6 Mon Sep 17 00:00:00 2001
From: Travis Person <travisperson@users.noreply.github.com>
Date: Sun, 6 Sep 2020 04:32:05 +0000
Subject: [PATCH 1/2] metrics: add expected height metric

---
 chain/sync.go      | 26 ++++++++++++++++++++++++++
 metrics/metrics.go |  6 ++++++
 2 files changed, 32 insertions(+)

diff --git a/chain/sync.go b/chain/sync.go
index 1b1cbdde9c..cc29e35502 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -125,6 +125,8 @@ type Syncer struct {
 	verifier ffiwrapper.Verifier
 
 	windowSize int
+
+	tickerCtxCancel context.CancelFunc
 }
 
 // NewSyncer creates a new Syncer object.
@@ -166,11 +168,35 @@ func NewSyncer(sm *stmgr.StateManager, bsync *blocksync.BlockSync, connmgr connm
 }
 
 func (syncer *Syncer) Start() {
+	tickerCtx, tickerCtxCancel := context.WithCancel(context.Background())
 	syncer.syncmgr.Start()
+
+	syncer.tickerCtxCancel = tickerCtxCancel
+
+	go syncer.runMetricsTricker(tickerCtx)
+}
+
+func (syncer *Syncer) runMetricsTricker(tickerCtx context.Context) {
+	genesisTime := time.Unix(int64(syncer.Genesis.MinTimestamp()), 0)
+	ticker := build.Clock.Ticker(time.Duration(build.BlockDelaySecs) * time.Second)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ticker.C:
+			sinceGenesis := build.Clock.Now().Sub(genesisTime)
+			expectedHeight := int64(sinceGenesis.Seconds()) / int64(build.BlockDelaySecs)
+
+			stats.Record(tickerCtx, metrics.ChainNodeHeightExpected.M(int64(expectedHeight)))
+		case <-tickerCtx.Done():
+			return
+		}
+	}
 }
 
 func (syncer *Syncer) Stop() {
 	syncer.syncmgr.Stop()
+	syncer.tickerCtxCancel()
 }
 
 // InformNewHead informs the syncer about a new potential tipset
diff --git a/metrics/metrics.go b/metrics/metrics.go
index a6732e8ea0..5dd8652636 100644
--- a/metrics/metrics.go
+++ b/metrics/metrics.go
@@ -30,6 +30,7 @@ var (
 var (
 	LotusInfo                           = stats.Int64("info", "Arbitrary counter to tag lotus info to", stats.UnitDimensionless)
 	ChainNodeHeight                     = stats.Int64("chain/node_height", "Current Height of the node", stats.UnitDimensionless)
+	ChainNodeHeightExpected             = stats.Int64("chain/node_height_expected", "Expected Height of the node", stats.UnitDimensionless)
 	ChainNodeWorkerHeight               = stats.Int64("chain/node_worker_height", "Current Height of workers on the node", stats.UnitDimensionless)
 	MessagePublished                    = stats.Int64("message/published", "Counter for total locally published messages", stats.UnitDimensionless)
 	MessageReceived                     = stats.Int64("message/received", "Counter for total received messages", stats.UnitDimensionless)
@@ -62,6 +63,10 @@ var (
 		Measure:     ChainNodeHeight,
 		Aggregation: view.LastValue(),
 	}
+	ChainNodeHeightExpectedView = &view.View{
+		Measure:     ChainNodeHeightExpected,
+		Aggregation: view.LastValue(),
+	}
 	ChainNodeWorkerHeightView = &view.View{
 		Measure:     ChainNodeWorkerHeight,
 		Aggregation: view.LastValue(),
@@ -138,6 +143,7 @@ var (
 var DefaultViews = append([]*view.View{
 	InfoView,
 	ChainNodeHeightView,
+	ChainNodeHeightExpectedView,
 	ChainNodeWorkerHeightView,
 	BlockReceivedView,
 	BlockValidationFailureView,

From f6f5405a2c8100c0b20606cc92a14fb3d46bf4c5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Magiera?= <magik6k@gmail.com>
Date: Mon, 7 Sep 2020 18:21:45 +0200
Subject: [PATCH 2/2] Fix lint

---
 chain/sync.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/chain/sync.go b/chain/sync.go
index cc29e35502..0bcb290f8d 100644
--- a/chain/sync.go
+++ b/chain/sync.go
@@ -187,7 +187,7 @@ func (syncer *Syncer) runMetricsTricker(tickerCtx context.Context) {
 			sinceGenesis := build.Clock.Now().Sub(genesisTime)
 			expectedHeight := int64(sinceGenesis.Seconds()) / int64(build.BlockDelaySecs)
 
-			stats.Record(tickerCtx, metrics.ChainNodeHeightExpected.M(int64(expectedHeight)))
+			stats.Record(tickerCtx, metrics.ChainNodeHeightExpected.M(expectedHeight))
 		case <-tickerCtx.Done():
 			return
 		}