From 5644fb2275c6feb4edb472089e050cc489d1a5a1 Mon Sep 17 00:00:00 2001
From: Jaden Weiss <jaden@jadendw.dev>
Date: Wed, 20 May 2020 12:27:27 -0400
Subject: [PATCH] add metrics for transactions

---
 api.go     | 39 ++++++++++++++++++++++++++++++++++++---
 metrics.go |  7 +++++++
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/api.go b/api.go
index 77a3fc34e..e617837c2 100644
--- a/api.go
+++ b/api.go
@@ -1594,14 +1594,41 @@ func (api *API) StartTransaction(ctx context.Context, id string, timeout time.Du
 	if err := api.validate(apiStartTransaction); err != nil {
 		return nil, errors.Wrap(err, "validating api method")
 	}
-	return api.server.StartTransaction(ctx, id, timeout, exclusive, remote)
+	t, err := api.server.StartTransaction(ctx, id, timeout, exclusive, remote)
+	if exclusive {
+		switch err {
+		case nil:
+			api.holder.Stats.Count(MetricExclusiveTransactionRequest, 1, 1.0)
+		case ErrTransactionExclusive:
+			api.holder.Stats.Count(MetricExclusiveTransactionBlocked, 1, 1.0)
+		}
+		if t.Active {
+			api.holder.Stats.Count(MetricExclusiveTransactionActive, 1, 1.0)
+		}
+	} else {
+		switch err {
+		case nil:
+			api.holder.Stats.Count(MetricTransactionStart, 1, 1.0)
+		case ErrTransactionExclusive:
+			api.holder.Stats.Count(MetricTransactionBlocked, 1, 1.0)
+		}
+	}
+	return t, err
 }
 
 func (api *API) FinishTransaction(ctx context.Context, id string, remote bool) (*Transaction, error) {
 	if err := api.validate(apiFinishTransaction); err != nil {
 		return nil, errors.Wrap(err, "validating api method")
 	}
-	return api.server.FinishTransaction(ctx, id, remote)
+	t, err := api.server.FinishTransaction(ctx, id, remote)
+	if err == nil {
+		if t.Exclusive {
+			api.holder.Stats.Count(MetricExclusiveTransactionEnd, 1, 1.0)
+		} else {
+			api.holder.Stats.Count(MetricTransactionEnd, 1, 1.0)
+		}
+	}
+	return t, err
 }
 
 func (api *API) Transactions(ctx context.Context) (map[string]*Transaction, error) {
@@ -1615,7 +1642,13 @@ func (api *API) GetTransaction(ctx context.Context, id string, remote bool) (*Tr
 	if err := api.validate(apiGetTransaction); err != nil {
 		return nil, errors.Wrap(err, "validating api method")
 	}
-	return api.server.GetTransaction(ctx, id, remote)
+	t, err := api.server.GetTransaction(ctx, id, remote)
+	if err == nil {
+		if t.Exclusive && t.Active {
+			api.holder.Stats.Count(MetricExclusiveTransactionActive, 1, 1.0)
+		}
+	}
+	return t, err
 }
 
 type serverInfo struct {
diff --git a/metrics.go b/metrics.go
index c1888e0f6..8d58f8a73 100644
--- a/metrics.go
+++ b/metrics.go
@@ -58,4 +58,11 @@ const (
 	MetricStackInuse                      = "stack_inuse"
 	MetricMallocs                         = "mallocs"
 	MetricFrees                           = "frees"
+	MetricTransactionStart                = "transaction_start"
+	MetricTransactionEnd                  = "trasaction_end"
+	MetricTransactionBlocked              = "transaction_blocked"
+	MetricExclusiveTransactionRequest     = "transaction_exclusive_request"
+	MetricExclusiveTransactionActive      = "transaction_exclusive_active"
+	MetricExclusiveTransactionEnd         = "trasaction_exclusive_end"
+	MetricExclusiveTransactionBlocked     = "transaction_exclusive_blocked"
 )