From 470029181ca2fcf0289f1b89a7a62fd2e8f6fb4b Mon Sep 17 00:00:00 2001
From: Shady Rafehi <shady@canva.com>
Date: Tue, 4 Jun 2024 15:21:28 +1000
Subject: [PATCH] Skip fetch if revision to check out exists locally

---
 reposerver/repository/repository.go | 17 +++++++++++++----
 util/git/client.go                  | 16 ++++++++++++++++
 util/git/mocks/Client.go            | 18 ++++++++++++++++++
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/reposerver/repository/repository.go b/reposerver/repository/repository.go
index ac738cd513d196..6a8c9817cba23e 100644
--- a/reposerver/repository/repository.go
+++ b/reposerver/repository/repository.go
@@ -2432,10 +2432,19 @@ func checkoutRevision(gitClient git.Client, revision string, submoduleEnabled bo
 		return status.Errorf(codes.Internal, "Failed to initialize git repo: %v", err)
 	}
 
-	// Fetching with no revision first. Fetching with an explicit version can cause repo bloat. https://github.com/argoproj/argo-cd/issues/8845
-	err = gitClient.Fetch("")
-	if err != nil {
-		return status.Errorf(codes.Internal, "Failed to fetch default: %v", err)
+	revisionPresent := gitClient.IsRevisionPresent(revision)
+
+	log.WithFields(map[string]interface{}{
+		"skipFetch": revisionPresent,
+	}).Infof("Checking out revision %v", revision)
+
+	// Fetching can be skipped if the revision is already present locally.
+	if !revisionPresent {
+		// Fetching with no revision first. Fetching with an explicit version can cause repo bloat. https://github.com/argoproj/argo-cd/issues/8845
+		err = gitClient.Fetch("")
+		if err != nil {
+			return status.Errorf(codes.Internal, "Failed to fetch default: %v", err)
+		}
 	}
 
 	err = gitClient.Checkout(revision, submoduleEnabled)
diff --git a/util/git/client.go b/util/git/client.go
index b356f95639d432..dbdebed4b9a556 100644
--- a/util/git/client.go
+++ b/util/git/client.go
@@ -78,6 +78,7 @@ type Client interface {
 	VerifyCommitSignature(string) (string, error)
 	IsAnnotatedTag(string) bool
 	ChangedFiles(revision string, targetRevision string) ([]string, error)
+	IsRevisionPresent(revision string) bool
 }
 
 type EventHandlers struct {
@@ -357,6 +358,21 @@ func (m *nativeGitClient) fetch(revision string) error {
 	return err
 }
 
+// IsRevisionPresent checks to see if the given revision already exists locally.
+func (m *nativeGitClient) IsRevisionPresent(revision string) bool {
+	if revision == "" {
+		return false
+	}
+
+	cmd := exec.Command("git", "cat-file", "-t", revision)
+	out, err := m.runCmdOutput(cmd, runOpts{SkipErrorLogging: true})
+	if out == "commit" && err == nil {
+		return true
+	} else {
+		return false
+	}
+}
+
 // Fetch fetches latest updates from origin
 func (m *nativeGitClient) Fetch(revision string) error {
 	if m.OnFetch != nil {
diff --git a/util/git/mocks/Client.go b/util/git/mocks/Client.go
index 9701ec987eb199..798c07465431af 100644
--- a/util/git/mocks/Client.go
+++ b/util/git/mocks/Client.go
@@ -142,6 +142,24 @@ func (_m *Client) IsAnnotatedTag(_a0 string) bool {
 	return r0
 }
 
+// IsRevisionPresent provides a mock function with given fields: revision
+func (_m *Client) IsRevisionPresent(revision string) bool {
+	ret := _m.Called(revision)
+
+	if len(ret) == 0 {
+		panic("no return value specified for IsRevisionPresent")
+	}
+
+	var r0 bool
+	if rf, ok := ret.Get(0).(func(string) bool); ok {
+		r0 = rf(revision)
+	} else {
+		r0 = ret.Get(0).(bool)
+	}
+
+	return r0
+}
+
 // LsFiles provides a mock function with given fields: path, enableNewGitFileGlobbing
 func (_m *Client) LsFiles(path string, enableNewGitFileGlobbing bool) ([]string, error) {
 	ret := _m.Called(path, enableNewGitFileGlobbing)