Add rate limit cache and fixes

This change adds a loop that keeps a cache of credentials rate limits
as reported by the github API. The cache is updated every 30 seconds
and is purely informational for the user.

This change also adds some caching improvements. Functions that return
values from the cache as lists, will now sort by ID or creation date.

Signed-off-by: Gabriel Adrian Samfira <gsamfira@cloudbasesolutions.com>

cache/entity_cache.go

@@ -186,6 +186,8 @@ func (e *EntityCache) FindPoolsMatchingAllTags(entityID string, tags []string) [
 				pools = append(pools, pool)
 			}
 		}
+		// Sort the pools by creation date.
+		sortByCreationDate(pools)
 		return pools
 	}
 	return nil
@@ -200,6 +202,8 @@ func (e *EntityCache) GetEntityPools(entityID string) []params.Pool {
 		for _, pool := range cache.Pools {
 			pools = append(pools, pool)
 		}
+		// Sort the pools by creation date.
+		sortByCreationDate(pools)
 		return pools
 	}
 	return nil
@@ -214,6 +218,8 @@ func (e *EntityCache) GetEntityScaleSets(entityID string) []params.ScaleSet {
 		for _, scaleSet := range cache.ScaleSets {
 			scaleSets = append(scaleSets, scaleSet)
 		}
+		// Sort the scale sets by creation date.
+		sortByID(scaleSets)
 		return scaleSets
 	}
 	return nil
@@ -229,6 +235,7 @@ func (e *EntityCache) GetEntitiesUsingGredentials(credsID uint) []params.GithubE
 			entities = append(entities, cache.Entity)
 		}
 	}
+	sortByCreationDate(entities)
 	return entities
 }
 
@@ -245,9 +252,38 @@ func (e *EntityCache) GetAllEntities() []params.GithubEntity {
 		}
 		entities = append(entities, cache.Entity)
 	}
+	sortByCreationDate(entities)
 	return entities
 }
 
+func (e *EntityCache) GetAllPools() []params.Pool {
+	e.mux.Lock()
+	defer e.mux.Unlock()
+
+	var pools []params.Pool
+	for _, cache := range e.entities {
+		for _, pool := range cache.Pools {
+			pools = append(pools, pool)
+		}
+	}
+	sortByCreationDate(pools)
+	return pools
+}
+
+func (e *EntityCache) GetAllScaleSets() []params.ScaleSet {
+	e.mux.Lock()
+	defer e.mux.Unlock()
+
+	var scaleSets []params.ScaleSet
+	for _, cache := range e.entities {
+		for _, scaleSet := range cache.ScaleSets {
+			scaleSets = append(scaleSets, scaleSet)
+		}
+	}
+	sortByID(scaleSets)
+	return scaleSets
+}
+
 func GetEntity(entityID string) (params.GithubEntity, bool) {
 	return entityCache.GetEntity(entityID)
 }
@@ -315,3 +351,11 @@ func GetEntitiesUsingGredentials(credsID uint) []params.GithubEntity {
 func GetAllEntities() []params.GithubEntity {
 	return entityCache.GetAllEntities()
 }
+
+func GetAllPools() []params.Pool {
+	return entityCache.GetAllPools()
+}
+
+func GetAllScaleSets() []params.ScaleSet {
+	return entityCache.GetAllScaleSets()
+}