1 files changed, 159 insertions, 0 deletions
diff --git a/modules/git/last_commit_cache.go b/modules/git/last_commit_cache.go
new file mode 100644
index 0000000..8c7ee5a
--- /dev/null
+++ b/modules/git/last_commit_cache.go
@@ -0,0 +1,159 @@
+// Copyright 2020 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package git
+
+import (
+	"context"
+	"crypto/sha256"
+	"fmt"
+
+	"code.gitea.io/gitea/modules/log"
+	"code.gitea.io/gitea/modules/setting"
+)
+
+// Cache represents a caching interface
+type Cache interface {
+	// Put puts value into cache with key and expire time.
+	Put(key string, val any, timeout int64) error
+	// Get gets cached value by given key.
+	Get(key string) any
+}
+
+func getCacheKey(repoPath, commitID, entryPath string) string {
+	hashBytes := sha256.Sum256([]byte(fmt.Sprintf("%s:%s:%s", repoPath, commitID, entryPath)))
+	return fmt.Sprintf("last_commit:%x", hashBytes)
+}
+
+// LastCommitCache represents a cache to store last commit
+type LastCommitCache struct {
+	repoPath    string
+	ttl         func() int64
+	repo        *Repository
+	commitCache map[string]*Commit
+	cache       Cache
+}
+
+// NewLastCommitCache creates a new last commit cache for repo
+func NewLastCommitCache(count int64, repoPath string, gitRepo *Repository, cache Cache) *LastCommitCache {
+	if cache == nil {
+		return nil
+	}
+	if count < setting.CacheService.LastCommit.CommitsCount {
+		return nil
+	}
+
+	return &LastCommitCache{
+		repoPath: repoPath,
+		repo:     gitRepo,
+		ttl:      setting.LastCommitCacheTTLSeconds,
+		cache:    cache,
+	}
+}
+
+// Put put the last commit id with commit and entry path
+func (c *LastCommitCache) Put(ref, entryPath, commitID string) error {
+	if c == nil || c.cache == nil {
+		return nil
+	}
+	log.Debug("LastCommitCache save: [%s:%s:%s]", ref, entryPath, commitID)
+	return c.cache.Put(getCacheKey(c.repoPath, ref, entryPath), commitID, c.ttl())
+}
+
+// Get gets the last commit information by commit id and entry path
+func (c *LastCommitCache) Get(ref, entryPath string) (*Commit, error) {
+	if c == nil || c.cache == nil {
+		return nil, nil
+	}
+
+	commitID, ok := c.cache.Get(getCacheKey(c.repoPath, ref, entryPath)).(string)
+	if !ok || commitID == "" {
+		return nil, nil
+	}
+
+	log.Debug("LastCommitCache hit level 1: [%s:%s:%s]", ref, entryPath, commitID)
+	if c.commitCache != nil {
+		if commit, ok := c.commitCache[commitID]; ok {
+			log.Debug("LastCommitCache hit level 2: [%s:%s:%s]", ref, entryPath, commitID)
+			return commit, nil
+		}
+	}
+
+	commit, err := c.repo.GetCommit(commitID)
+	if err != nil {
+		return nil, err
+	}
+	if c.commitCache == nil {
+		c.commitCache = make(map[string]*Commit)
+	}
+	c.commitCache[commitID] = commit
+	return commit, nil
+}
+
+// GetCommitByPath gets the last commit for the entry in the provided commit
+func (c *LastCommitCache) GetCommitByPath(commitID, entryPath string) (*Commit, error) {
+	sha, err := NewIDFromString(commitID)
+	if err != nil {
+		return nil, err
+	}
+
+	lastCommit, err := c.Get(sha.String(), entryPath)
+	if err != nil || lastCommit != nil {
+		return lastCommit, err
+	}
+
+	lastCommit, err = c.repo.getCommitByPathWithID(sha, entryPath)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := c.Put(commitID, entryPath, lastCommit.ID.String()); err != nil {
+		log.Error("Unable to cache %s as the last commit for %q in %s %s. Error %v", lastCommit.ID.String(), entryPath, commitID, c.repoPath, err)
+	}
+
+	return lastCommit, nil
+}
+
+// CacheCommit will cache the commit from the gitRepository
+func (c *Commit) CacheCommit(ctx context.Context) error {
+	if c.repo.LastCommitCache == nil {
+		return nil
+	}
+	return c.recursiveCache(ctx, &c.Tree, "", 1)
+}
+
+func (c *Commit) recursiveCache(ctx context.Context, tree *Tree, treePath string, level int) error {
+	if level == 0 {
+		return nil
+	}
+
+	entries, err := tree.ListEntries()
+	if err != nil {
+		return err
+	}
+
+	entryPaths := make([]string, len(entries))
+	for i, entry := range entries {
+		entryPaths[i] = entry.Name()
+	}
+
+	_, err = WalkGitLog(ctx, c.repo, c, treePath, entryPaths...)
+	if err != nil {
+		return err
+	}
+
+	for _, treeEntry := range entries {
+		// entryMap won't contain "" therefore skip this.
+		if treeEntry.IsDir() {
+			subTree, err := tree.SubTree(treeEntry.Name())
+			if err != nil {
+				return err
+			}
+			if err := c.recursiveCache(ctx, subTree, treeEntry.Name(), level-1); err != nil {
+				return err
+			}
+		}
+	}
+
+	return nil
+}