add graph caching and garbage collection

commits/commits.go

@@ -1,9 +1,13 @@
 package commits
 
 import (
+	"crypto/md5"
 	"errors"
+	"fmt"
 	"os"
 	"regexp"
+	"sort"
+	"strings"
 	"sync"
 	"time"
 
@@ -16,6 +20,71 @@ import (
 
 type Repo git.Repository
 
+var (
+	mapTex    sync.RWMutex
+	hashCache map[int]map[string]map[string]types.ExpYearFreq
+)
+
+func init() {
+	hashCache = make(map[int]map[string]map[string]types.ExpYearFreq)
+}
+
+func hashSlice(in []string) string {
+	sort.Strings(in)
+	sb := strings.Builder{}
+	for _, s := range in {
+		sb.WriteString(s)
+	}
+	h := md5.New()
+	h.Write([]byte(sb.String()))
+	b := h.Sum(nil)
+	return fmt.Sprintf("%x\n", b)
+}
+
+func GetCachedGraph(year int, authors []string, repoPaths []string) (types.YearFreq, bool) {
+	a := hashSlice(authors)
+	r := hashSlice(repoPaths)
+	mapTex.RLock()
+	defer mapTex.RUnlock()
+	if m1, ok := hashCache[year]; !ok {
+		return types.YearFreq{}, false
+	} else {
+		if m2, ok := m1[a]; !ok {
+			return types.YearFreq{}, false
+		} else {
+			if freq, ok := m2[r]; !ok {
+				return types.YearFreq{}, false
+			} else {
+				if freq.Created.Before(time.Now().Add(-15 * time.Minute)) {
+					return types.YearFreq{}, false
+				} else {
+					return freq.YearFreq, true
+				}
+			}
+		}
+	}
+}
+
+func CacheGraph(year int, authors, repoPaths []string, freq types.YearFreq) {
+	a := hashSlice(authors)
+	r := hashSlice(repoPaths)
+	mapTex.Lock()
+	defer mapTex.Unlock()
+	if _, ok := hashCache[year]; !ok {
+		hashCache[year] = make(map[string]map[string]types.ExpYearFreq)
+	}
+	if _, ok := hashCache[year][a]; !ok {
+		hashCache[year][a] = make(map[string]types.ExpYearFreq)
+	}
+	hashCache[year][a][r] = types.ExpYearFreq{YearFreq: freq, Created: time.Now()}
+	go func() {
+		time.Sleep(time.Minute * 15)
+		mapTex.Lock()
+		defer mapTex.Unlock()
+		delete(hashCache[year][a], r)
+	}()
+}
+
 func GlobalFrequencyChan(year int, authors []string) (types.YearFreq, error) {
 	yearLength := 365
 	if year%4 == 0 {
@@ -26,6 +95,10 @@ func GlobalFrequencyChan(year int, authors []string) (types.YearFreq, error) {
 		return types.YearFreq{}, err
 	}
 	paths := mrconf.GetRepoPaths()
+	cache, ok := GetCachedGraph(year, authors, paths)
+	if ok {
+		return cache, nil
+	}
 	outChan := make(chan types.Commit, 10)
 	var wg sync.WaitGroup
 	for _, p := range paths {
@@ -55,7 +128,7 @@ func GlobalFrequencyChan(year int, authors []string) (types.YearFreq, error) {
 		close(outChan)
 	}()
 	freq := YearFreqFromChan(outChan, year)
-
+	CacheGraph(year, authors, paths, freq)
 	return freq, nil
 }