Extract all configurable caching values to const.go

5 files changed, 35 insertions, 30 deletions

diff --git a/internal/source/gitlab/cache/cache.go b/internal/source/gitlab/cache/cache.go
index c538419f..85f44e11 100644
--- a/internal/source/gitlab/cache/cache.go
+++ b/internal/source/gitlab/cache/cache.go
@@ -23,25 +23,29 @@ func NewCache(client api.Client) *Cache {
 // Resolve is going to return a Lookup based on a domain name. The caching
 // algorithm works as follows:
 // - We first check if the cache entry exists, and if it is up-to-date. If it
-//   is fresh we return the &Lookup entry from cache and it is a cache hit.
-// - If entry is not up-to-date, we schedule an asynchronous retrieval of the
-//   latest configuration we are going to obtain through the API, and we
-//   immediately return an old value, to avoid blocking clients. In this case
-//   it is also a cache hit.
-// - If cache entry has not been populated with a Lookup information yet, we
-//   block all the clients and make them wait until we retrieve the Lookup from
-//   the GitLab API.
+//   is fresh we return the lookup entry from cache and it is a cache hit.
+// - If entry is not up-to-date, what means that it has been created in a cache
+//   more than `shortCacheExpiry` duration ago,  we schedule an asynchronous
+//   retrieval of the latest configuration we are going to obtain through the
+//   API, and we immediately return an old value, to avoid blocking clients. In
+//   this case it is also a cache hit.
+// - If cache entry has not been populated with a lookup information yet, we
+//   block all the clients and make them wait until we retrieve the lookup from
+//   the GitLab API. Clients should not wait for longer than
+//   `retrievalTimeout`. It is a cache miss.
 //
-// We are going to retrieve a Lookup from GitLab API using Retriever type. In
+// We are going to retrieve a lookup from GitLab API using a retriever type. In
 // case of failures (when GitLab API client returns an error) we will retry the
-// operation a few times. In case of an erroneous response, we will cache it,
-// and it get recycled as every other cache entry.
+// operation a few times, waiting `maxRetrievalInterval` in between, total
+// amount of requests is defined as `maxRetrievalRetries`. In case of an
+// erroneous response, we will cache it, and it get recycled as every other
+// cache entry.
 //
 // Examples:
 // 1. Everything works
 //  - a client opens pages
 //  - we create a new cache entry
-//  - cache entry needs warm up
+//  - cache entry needs a warm up
 //  - a client waits until we retrieve a lookup
 //  - we successfuly retrieve a lookup
 //  - we cache this response
@@ -49,19 +53,19 @@ func NewCache(client api.Client) *Cache {
 // 2. A domain does not exist
 //  - a client opens pages
 //  - we create a new cache entry
-//  - cache entry needs warm up
+//  - cache entry needs a warm up
 //  - a client waits until we retrieve a lookup
-//  - GitLab responded with a lookup that contains information about domain
-//    not being found
-//  - we cache this response
-//  - we pass this lookup upstream to all theclient
+//  - GitLab responded with a lookup and 204 HTTP status
+//  - we cache this response with domain being `nil`
+//  - we pass this lookup upstream to all the clients
 // 3. GitLab is not responding
 //  - a client opens pages
 //  - we create a new cache entry
-//  - cache entry needs warm up
+//  - cache entry needs a warm up
 //  - a client waits until we retrieve a lookup
 //  - GitLab does not respond or responds with an error
-//  - we retry this information a few times
+//  - we retry this retrieval every `maxRetrievalInterval`
+//  - we retry this retrieval `maxRetrievalRetries` in total
 //  - we create a lookup that contains information about an error
 //  - we cache this response
 //  - we pass this lookup upstream to all the clients
diff --git a/internal/source/gitlab/cache/const.go b/internal/source/gitlab/cache/const.go
new file mode 100644
index 00000000..5b11dc23
--- /dev/null
+++ b/internal/source/gitlab/cache/const.go
@@ -0,0 +1,11 @@
+package cache
+
+import "time"
+
+var (
+	shortCacheExpiry     = 30 * time.Second
+	longCacheExpiry      = 10 * time.Minute
+	retrievalTimeout     = 5 * time.Second
+	maxRetrievalRetries  = 3
+	maxRetrievalInterval = time.Second
+)
diff --git a/internal/source/gitlab/cache/entry.go b/internal/source/gitlab/cache/entry.go
index 45a89db5..9d81cc85 100644
--- a/internal/source/gitlab/cache/entry.go
+++ b/internal/source/gitlab/cache/entry.go
@@ -9,11 +9,6 @@ import (
 	"gitlab.com/gitlab-org/gitlab-pages/internal/source/gitlab/api"
 )
 
-var (
-	retrievalTimeout = 5 * time.Second
-	shortCacheExpiry = 30 * time.Second
-)
-
 // Entry represents a cache object that can be retrieved asynchronously and
 // holds a pointer to *api.Lookup when the domain lookup has been retrieved
 // successfully
diff --git a/internal/source/gitlab/cache/memstore.go b/internal/source/gitlab/cache/memstore.go
index 8b22bde0..49e920ae 100644
--- a/internal/source/gitlab/cache/memstore.go
+++ b/internal/source/gitlab/cache/memstore.go
@@ -12,11 +12,9 @@ type memstore struct {
 	mux   *sync.Mutex
 }
 
-var expiration = 10 * time.Minute
-
 func newMemStore() Store {
 	return &memstore{
-		store: cache.New(expiration, time.Minute),
+		store: cache.New(longCacheExpiry, time.Minute),
 		mux:   &sync.Mutex{},
 	}
 }
diff --git a/internal/source/gitlab/cache/retriever.go b/internal/source/gitlab/cache/retriever.go
index 65d8249b..2db2eca8 100644
--- a/internal/source/gitlab/cache/retriever.go
+++ b/internal/source/gitlab/cache/retriever.go
@@ -9,9 +9,6 @@ import (
 	"gitlab.com/gitlab-org/gitlab-pages/internal/source/gitlab/api"
 )
 
-var maxRetrievalInterval = time.Second
-var maxRetrievalRetries = 3
-
 // Retriever is an utility type that performs an HTTP request with backoff in
 // case of errors
 type Retriever struct {