From cbeda8daaf76ab2c9c1be203ec03f2e10bbfc459 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Mierzwa?= <l.mierzwa@gmail.com>
Date: Sat, 13 Aug 2022 17:51:02 +0100
Subject: [PATCH] feat(api): intern string to save memory

---
 internal/intern/intern.go   | 16 ++++++++++++++++
 internal/mapper/v017/api.go | 25 +++++++++++++++----------
 2 files changed, 31 insertions(+), 10 deletions(-)
 create mode 100644 internal/intern/intern.go

diff --git a/internal/intern/intern.go b/internal/intern/intern.go
new file mode 100644
index 000000000..34ae48a6b
--- /dev/null
+++ b/internal/intern/intern.go
@@ -0,0 +1,16 @@
+package intern
+
+type StringInterner map[string]string
+
+func New() StringInterner {
+	return StringInterner{}
+}
+
+func (si StringInterner) Intern(s string) string {
+	interned, ok := si[s]
+	if ok {
+		return interned
+	}
+	si[s] = s
+	return s
+}
diff --git a/internal/mapper/v017/api.go b/internal/mapper/v017/api.go
index c4c89f2ce..87781c2ae 100644
--- a/internal/mapper/v017/api.go
+++ b/internal/mapper/v017/api.go
@@ -9,6 +9,7 @@ import (
 
 	httptransport "github.com/go-openapi/runtime/client"
 
+	"github.com/prymitive/karma/internal/intern"
 	"github.com/prymitive/karma/internal/mapper"
 	"github.com/prymitive/karma/internal/mapper/v017/client"
 	"github.com/prymitive/karma/internal/mapper/v017/client/alertgroup"
@@ -41,6 +42,8 @@ func newClient(uri string, headers map[string]string, httpTransport http.RoundTr
 
 // Alerts will fetch all alert groups from the API
 func groups(c *client.AlertmanagerAPI, timeout time.Duration) ([]models.AlertGroup, error) {
+	interner := intern.New()
+
 	groups, err := c.Alertgroup.GetAlertGroups(alertgroup.NewGetAlertGroupsParamsWithTimeout(timeout))
 	if err != nil {
 		return []models.AlertGroup{}, err
@@ -51,28 +54,28 @@ func groups(c *client.AlertmanagerAPI, timeout time.Duration) ([]models.AlertGro
 	for _, group := range groups.Payload {
 		ls := models.Labels{}
 		for k, v := range group.Labels {
-			ls = ls.Set(k, v)
+			ls = ls.Set(interner.Intern(k), interner.Intern(v))
 		}
 		sort.Sort(ls)
 		g := models.AlertGroup{
-			Receiver: *group.Receiver.Name,
+			Receiver: interner.Intern(*group.Receiver.Name),
 			Labels:   ls,
 			Alerts:   make(models.AlertList, 0, len(group.Alerts)),
 		}
 		for _, alert := range group.Alerts {
 			ls := models.Labels{}
 			for k, v := range alert.Labels {
-				ls = ls.Set(k, v)
+				ls = ls.Set(interner.Intern(k), interner.Intern(v))
 			}
 			sort.Sort(ls)
 			a := models.Alert{
 				Fingerprint:  *alert.Fingerprint,
-				Receiver:     *group.Receiver.Name,
+				Receiver:     interner.Intern(*group.Receiver.Name),
 				Annotations:  models.AnnotationsFromMap(alert.Annotations),
 				Labels:       ls,
 				StartsAt:     time.Time(*alert.StartsAt),
-				GeneratorURL: alert.GeneratorURL.String(),
-				State:        *alert.Status.State,
+				GeneratorURL: interner.Intern(alert.GeneratorURL.String()),
+				State:        interner.Intern(*alert.Status.State),
 				InhibitedBy:  alert.Status.InhibitedBy,
 				SilencedBy:   alert.Status.SilencedBy,
 			}
@@ -88,6 +91,8 @@ func groups(c *client.AlertmanagerAPI, timeout time.Duration) ([]models.AlertGro
 }
 
 func silences(c *client.AlertmanagerAPI, timeout time.Duration) ([]models.Silence, error) {
+	interner := intern.New()
+
 	silences, err := c.Silence.GetSilences(silence.NewGetSilencesParamsWithTimeout(timeout))
 	if err != nil {
 		return []models.Silence{}, err
@@ -100,13 +105,13 @@ func silences(c *client.AlertmanagerAPI, timeout time.Duration) ([]models.Silenc
 			ID:        *s.ID,
 			StartsAt:  time.Time(*s.StartsAt),
 			EndsAt:    time.Time(*s.EndsAt),
-			CreatedBy: *s.CreatedBy,
-			Comment:   *s.Comment,
+			CreatedBy: interner.Intern(*s.CreatedBy),
+			Comment:   interner.Intern(*s.Comment),
 		}
 		for _, m := range s.Matchers {
 			sm := models.SilenceMatcher{
-				Name:    *m.Name,
-				Value:   *m.Value,
+				Name:    interner.Intern(*m.Name),
+				Value:   interner.Intern(*m.Value),
 				IsRegex: *m.IsRegex,
 				IsEqual: *m.IsEqual,
 			}