Adding go docs and tests for cachejc-use-trigger

3 files changed, 104 insertions, 3 deletions

diff --git a/internal/praefect/datastore/cache.go b/internal/praefect/datastore/cache.go
index e60a84d1a..c6ac53fd9 100644
--- a/internal/praefect/datastore/cache.go
+++ b/internal/praefect/datastore/cache.go
@@ -2,17 +2,20 @@ package datastore
 
 import "sync"
 
+// Cache is a thread-safe cache meant to be used to cache results from a datastore.
 type Cache struct {
 	sync.RWMutex
-	d        map[string]interface{}
+	d map[string]interface{}
 }
 
+// NewCache creates a new cache
 func NewCache() *Cache {
 	return &Cache{
-		d:        make(map[string]interface{}),
+		d: make(map[string]interface{}),
 	}
 }
 
+// Bust creates a new map for cached values, effectively busting the entire cache.
 func (c *Cache) Bust() {
 	c.Lock()
 	defer c.Unlock()
@@ -20,6 +23,8 @@ func (c *Cache) Bust() {
 	c.d = make(map[string]interface{})
 }
 
+// GetFromCache either gets the results stored by key, or saves the results of a function call into its
+// cache
 func (c *Cache) GetFromCache(key string, f func() (interface{}, error)) (interface{}, error) {
 	c.RLock()
 	defer c.RUnlock()
diff --git a/internal/praefect/datastore/cache_test.go b/internal/praefect/datastore/cache_test.go
new file mode 100644
index 000000000..97e0396f3
--- /dev/null
+++ b/internal/praefect/datastore/cache_test.go
@@ -0,0 +1,97 @@
+package datastore_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"gitlab.com/gitlab-org/gitaly/internal/praefect/datastore"
+)
+
+func TestCacheNoHits(t *testing.T) {
+	c := datastore.NewCache()
+
+	testCases := []interface{}{
+		1, "string", struct{}{}, []string{"one", "two", "three"},
+	}
+
+	for i, value := range testCases {
+		var cacheMiss bool
+		res, err := c.GetFromCache(fmt.Sprintf("%d", i), func() (interface{}, error) {
+			cacheMiss = true
+			return value, nil
+		})
+		require.NoError(t, err)
+		require.Equal(t, value, res)
+		require.True(t, cacheMiss)
+	}
+}
+
+func TestCacheAllHits(t *testing.T) {
+	c := datastore.NewCache()
+
+	key, value := "the key", "the value"
+
+	// seed the cache
+	_, err := c.GetFromCache(key, func() (interface{}, error) {
+		return value, nil
+	})
+	require.NoError(t, err)
+
+	testCases := []interface{}{
+		1, "string", struct{}{}, []string{"one", "two", "three"},
+	}
+
+	for _, v := range testCases {
+		var cacheMiss bool
+		res, err := c.GetFromCache(key, func() (interface{}, error) {
+			cacheMiss = true
+			return v, nil
+		})
+		require.NoError(t, err)
+		require.Equal(t, value, res, "we should retrieve the existing value in the cache")
+		require.False(t, cacheMiss)
+	}
+}
+
+
+func TestCacheMissAfterBust(t *testing.T) {
+	c := datastore.NewCache()
+
+	key, value := "the key", "the value"
+
+	// seed the cache
+	_, err := c.GetFromCache(key, func() (interface{}, error) {
+		return value, nil
+	})
+	require.NoError(t, err)
+
+	testCases := []interface{}{
+		1, "string", struct{}{}, []string{"one", "two", "three"},
+	}
+
+	for _, v := range testCases {
+		var cacheMiss bool
+		res, err := c.GetFromCache(key, func() (interface{}, error) {
+			cacheMiss = true
+			return v, nil
+		})
+		require.NoError(t, err)
+		require.Equal(t, value, res, "it should retrieve the existing value in the cache")
+		require.False(t, cacheMiss)
+	}
+
+	c.Bust()
+
+	newValue := []interface{}{"new", "value"}
+	var cacheMiss bool
+
+	res, err := c.GetFromCache(key, func() (interface{}, error) {
+		cacheMiss = true
+		return newValue, nil
+	})
+	require.NoError(t, err)
+	require.Equal(t, newValue, res, "it should return the new value")
+	require.True(t, cacheMiss)
+}
\ No newline at end of file
diff --git a/internal/praefect/datastore/database/sql_datastore.go b/internal/praefect/datastore/database/sql_datastore.go
index 338168191..79eb520b3 100644
--- a/internal/praefect/datastore/database/sql_datastore.go
+++ b/internal/praefect/datastore/database/sql_datastore.go
@@ -55,7 +55,6 @@ func NewSQLDatastore(user, password, address, database, notificationChannel stri
 	return &SQLDatastore{db: db, listener: listener}, nil
 }
 
-
 func (sd *SQLDatastore) Listener() *pq.Listener {
 	return sd.listener
 }