Merge pull request #107 from evanofslack/cache

Fix posts added to incorrect cache

backend/postgres/post.go

@@ -78,6 +78,8 @@ const (
 	random = "random"
 )
 
+var primes = []int{11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 107, 113, 131, 137, 149, 167, 173, 179, 191, 197, 227, 233, 239, 251, 257, 263}
+
 func (s *PostService) CreatePost(ctx context.Context, post *analogdb.CreatePost) (*analogdb.Post, error) {
 	tx, err := s.db.db.BeginTx(ctx, nil)
 	if err != nil {
@@ -689,7 +691,7 @@ func filterToOrder(filter *analogdb.PostFilter) string {
 			if seed := filter.Seed; seed != nil {
 				return fmt.Sprintf(" ORDER BY MOD(p.time, %d), p.time DESC", *seed)
 			} else {
-				newSeed := seedGenerator()
+				newSeed := newSeed()
 				filter.Seed = &newSeed
 				return fmt.Sprintf(" ORDER BY MOD(p.time, %d), p.time DESC", newSeed)
 			}
@@ -708,11 +710,10 @@ func formatLimit(filter *analogdb.PostFilter) string {
 	return ""
 }
 
-// seedGenerator generates a random prime number
-func seedGenerator() int {
-	prime_seeds := []int{11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97}
-	randomIndex := rand.Intn(len(prime_seeds))
-	return prime_seeds[randomIndex]
+// newSeed generates a random prime number
+func newSeed() int {
+	randomIndex := rand.Intn(len(primes))
+	return primes[randomIndex]
 }
 
 // filterToWhere converts a PostFilter to an SQL WHERE statement

backend/redis/post.go

@@ -25,7 +25,7 @@ const (
 	// name of posts cache
 	postsInstance = "posts"
 	// ttl for all other post service data
-	postsTTL = time.Hour * 4
+	postsTTL = time.Hour * 1
 	// in memory cache size all other post service data
 	postsLocalSize = 100
 )
@@ -78,13 +78,13 @@ func (s *PostService) FindPosts(ctx context.Context, filter *analogdb.PostFilter
 	var count int
 
 	// try to get posts from cache
-	err = s.postCache.get(ctx, postsHash, &posts)
+	postsErr := s.postsCache.get(ctx, postsHash, &posts)
 
 	// try to get posts count from cache
-	err = s.postsCache.get(ctx, postsCountHash, &count)
+	countErr := s.postsCache.get(ctx, postsCountHash, &count)
 
 	// no error means we found in cache
-	if err == nil {
+	if postsErr == nil && countErr == nil {
 		return posts, count, nil
 	}
 
@@ -99,6 +99,7 @@ func (s *PostService) FindPosts(ctx context.Context, filter *analogdb.PostFilter
 	go func() {
 
 		s.rdb.logger.Debug().Ctx(ctx).Str("instance", s.postsCache.instance).Msg("Adding posts and posts counts to cache")
+
 		// create a new context; orignal one will be canceled when request is closed
 		ctx, cancel := context.WithTimeout(context.Background(), cacheOpTimeout)
 		defer cancel()

backend/redis/redis.go

@@ -147,11 +147,6 @@ func (cache *Cache) get(ctx context.Context, key string, item interface{}) error
 			cache.logger.Debug().Ctx(ctx).Str("instance", cache.instance).Msg("Cache miss")
 			cache.stats.incMisses()
 
-			// or error decoding an empty array? this is fine and not an error
-			// } else if strings.Contains(err.Error(), decodeArrayErr) {
-			// 	cache.logger.Debug().Ctx(ctx).Str("instance", cache.instance).Msg("Error decoding array on cache get, proceeding")
-			// 	cache.stats.incMisses()
-
 			// or an actual error
 		} else {
 			cache.logger.Error().Err(err).Ctx(ctx).Str("instance", cache.instance).Msg("Error getting item from cache")

backend/server/posts.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math/rand"
 	"net/http"
 	"strconv"
 	"strings"
@@ -57,6 +58,9 @@ var maxSimilarityLimit = 50
 // default to sorting by time descending (latest)
 var defaultSort = "time"
 
+// seeds for random post order
+var primes = []int{11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 107, 113, 131, 137, 149, 167, 173, 179, 191, 197, 227, 233, 239, 251, 257, 263}
+
 const (
 	postsPath = "/posts"
 	postPath  = "/post"
@@ -265,13 +269,17 @@ func (s *Server) makePostResponse(r *http.Request, filter *analogdb.PostFilter)
 
 // setMeta computes the metadata from a query
 func setMeta(filter *analogdb.PostFilter, posts []*analogdb.Post, count int) (Meta, error) {
+
 	meta := Meta{}
+
 	// totalPosts
 	meta.TotalPosts = count
+
 	// seed
 	if seed := filter.Seed; seed != nil {
 		meta.Seed = *seed
 	}
+
 	// pageSize
 	if limit := filter.Limit; limit != nil {
 		meta.PageSize = *limit
@@ -280,6 +288,7 @@ func setMeta(filter *analogdb.PostFilter, posts []*analogdb.Post, count int) (Me
 			return meta, nil
 		}
 	}
+
 	//pageID
 	if sort := filter.Sort; sort != nil {
 		if *sort == "time" || *sort == "random" {
@@ -290,6 +299,7 @@ func setMeta(filter *analogdb.PostFilter, posts []*analogdb.Post, count int) (Me
 			return Meta{}, errors.New("invalid sort parameter: " + *sort)
 		}
 	}
+
 	//pageUrl
 	if sort := filter.Sort; sort != nil {
 		path := postsPath
@@ -323,6 +333,7 @@ func setMeta(filter *analogdb.PostFilter, posts []*analogdb.Post, count int) (Me
 		}
 		meta.PageURL = path
 	}
+
 	return meta, nil
 }
 
@@ -336,6 +347,11 @@ func paramJoiner(numParams *int) string {
 	}
 }
 
+func newSeed() int {
+	randomIndex := rand.Intn(len(primes))
+	return primes[randomIndex]
+}
+
 // parse URL for query parameters and convert to PostFilter needed to query db
 func parseToFilter(r *http.Request) (*analogdb.PostFilter, error) {
 
@@ -366,7 +382,9 @@ func parseToFilter(r *http.Request) (*analogdb.PostFilter, error) {
 				filter.Sort = &score
 			case "random":
 				random := "random"
+				seed := newSeed()
 				filter.Sort = &random
+				filter.Seed = &seed
 			}
 		} else {
 			return nil, errors.New("invalid sort parameter - valid options: latest, top, random")