From 92b4922d1814a8b65375a0bafc59d92465d59a62 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Cl=C3=A9ment=20Nussbaumer?=
 <clement.nussbaumer@postfinance.ch>
Date: Tue, 6 Feb 2024 18:17:32 +0100
Subject: [PATCH] chore: remove "caching" of results and simplify code
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Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Clément Nussbaumer <clement.nussbaumer@postfinance.ch>
---
 internal/kubenurse/handler.go                 |  8 +++----
 .../kubenurse/{k8s-auth.go => k8s_auth.go}    |  0
 internal/kubenurse/server.go                  |  2 +-
 internal/servicecheck/cache.go                | 22 -------------------
 internal/servicecheck/servicecheck.go         | 10 ++-------
 internal/servicecheck/types.go                | 10 ++-------
 6 files changed, 9 insertions(+), 43 deletions(-)
 rename internal/kubenurse/{k8s-auth.go => k8s_auth.go} (100%)
 delete mode 100644 internal/servicecheck/cache.go

diff --git a/internal/kubenurse/handler.go b/internal/kubenurse/handler.go
index 0b95ba70..e71dcb97 100644
--- a/internal/kubenurse/handler.go
+++ b/internal/kubenurse/handler.go
@@ -38,15 +38,15 @@ func (s *Server) aliveHandler() func(w http.ResponseWriter, r *http.Request) {
 			Neighbourhood      []servicecheck.Neighbour `json:"neighbourhood"`
 		}
 
-		// Run checks now
-		res, haserr := s.checker.Run()
-		if haserr {
+		res := s.checker.LastCheckResult
+		if res == nil {
 			w.WriteHeader(http.StatusInternalServerError)
+			return
 		}
 
 		// Add additional data
 		out := Output{
-			Result:             res,
+			Result:             *res,
 			Headers:            r.Header,
 			UserAgent:          r.UserAgent(),
 			RequestURI:         r.RequestURI,
diff --git a/internal/kubenurse/k8s-auth.go b/internal/kubenurse/k8s_auth.go
similarity index 100%
rename from internal/kubenurse/k8s-auth.go
rename to internal/kubenurse/k8s_auth.go
diff --git a/internal/kubenurse/server.go b/internal/kubenurse/server.go
index f85a927a..1059ab05 100644
--- a/internal/kubenurse/server.go
+++ b/internal/kubenurse/server.go
@@ -118,7 +118,7 @@ func New(ctx context.Context, c client.Client) (*Server, error) { //nolint:funle
 	}
 
 	// setup checker
-	chk, err := servicecheck.New(ctx, c, promRegistry, server.allowUnschedulable, 3*time.Second, histogramBuckets)
+	chk, err := servicecheck.New(ctx, c, promRegistry, server.allowUnschedulable, 1*time.Second, histogramBuckets)
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/servicecheck/cache.go b/internal/servicecheck/cache.go
deleted file mode 100644
index 72fbf22c..00000000
--- a/internal/servicecheck/cache.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package servicecheck
-
-import "time"
-
-// retrieveResultFromCache returns the latest check result from cache, if any.
-// If the result is expired or none is available, this function will return nil.
-func (c *Checker) retrieveResultFromCache() *Result {
-	if c.cachedResult != nil && c.cachedResult.expiration.After(time.Now()) {
-		return c.cachedResult.result
-	}
-
-	return nil
-}
-
-// cacheResult sets a check result to the cache and expires it after the
-// Checker.cacheTTL is exceeded.
-func (c *Checker) cacheResult(result *Result) {
-	c.cachedResult = &CachedResult{
-		result:     result,
-		expiration: time.Now().Add(c.cacheTTL),
-	}
-}
diff --git a/internal/servicecheck/servicecheck.go b/internal/servicecheck/servicecheck.go
index 7178513f..eee65e37 100644
--- a/internal/servicecheck/servicecheck.go
+++ b/internal/servicecheck/servicecheck.go
@@ -96,12 +96,6 @@ func (c *Checker) Run() (Result, bool) {
 		err    error
 	)
 
-	// Check if a result is cached and return it
-	cacheRes := c.retrieveResultFromCache()
-	if cacheRes != nil {
-		return *cacheRes, false
-	}
-
 	// Run Checks
 	res := Result{}
 
@@ -134,8 +128,8 @@ func (c *Checker) Run() (Result, bool) {
 		}
 	}
 
-	// Cache result
-	c.cacheResult(&res)
+	// Cache result (used for /alive handler)
+	c.LastCheckResult = &res
 
 	return res, haserr
 }
diff --git a/internal/servicecheck/types.go b/internal/servicecheck/types.go
index c1d72e5e..fede2c3c 100644
--- a/internal/servicecheck/types.go
+++ b/internal/servicecheck/types.go
@@ -45,8 +45,8 @@ type Checker struct {
 	// Http Client for https requests
 	httpClient *http.Client
 
-	// cachedResult represents a cached check result
-	cachedResult *CachedResult
+	// LastCheckResult represents a cached check result
+	LastCheckResult *Result
 
 	// cacheTTL defines the TTL of how long a cached result is valid
 	cacheTTL time.Duration
@@ -67,9 +67,3 @@ type Result struct {
 
 // Check is the signature used by all checks that the checker can execute.
 type Check func(ctx context.Context) (string, error)
-
-// CachedResult represents a cached check result that is valid until the expiration.
-type CachedResult struct {
-	result     *Result
-	expiration time.Time
-}