Only rely on shasum for dependency cache hit

paketo-buildpacks · Jul 28, 2023 · df3b845 · df3b845
1 parent eed720d
commit df3b845
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Showing 2 changed files with 30 additions and 13 deletions.
diff --git a/dependency_cache.go b/dependency_cache.go
@@ -163,7 +163,6 @@ type RequestModifierFunc func(request *http.Request) (*http.Request, error)
 func (d *DependencyCache) Artifact(dependency BuildModuleDependency, mods ...RequestModifierFunc) (*os.File, error) {
 
 	var (
-		actual   BuildModuleDependency
 		artifact string
 		file     string
 		uri      = dependency.URI
@@ -190,29 +189,25 @@ func (d *DependencyCache) Artifact(dependency BuildModuleDependency, mods ...Req
 	}
 
 	file = filepath.Join(d.CachePath, fmt.Sprintf("%s.toml", dependency.SHA256))
-	b, err := os.ReadFile(file)
-	if err != nil && !os.IsNotExist(err) {
+	exists, err := sherpa.Exists(file)
+
+	if err != nil {
 		return nil, fmt.Errorf("unable to read %s\n%w", file, err)
 	}
-	if err := toml.Unmarshal(b, &actual); err != nil {
-		return nil, fmt.Errorf("unable to decode download metadata %s\n%w", file, err)
-	}
 
-	if dependency.Equals(actual) {
+	if exists {
 		d.Logger.Bodyf("%s cached download from buildpack", color.GreenString("Reusing"))
 		return os.Open(filepath.Join(d.CachePath, dependency.SHA256, filepath.Base(uri)))
 	}
 
 	file = filepath.Join(d.DownloadPath, fmt.Sprintf("%s.toml", dependency.SHA256))
-	b, err = os.ReadFile(file)
-	if err != nil && !os.IsNotExist(err) {
+	exists, err = sherpa.Exists(file)
+
+	if err != nil {
 		return nil, fmt.Errorf("unable to read %s\n%w", file, err)
 	}
-	if err := toml.Unmarshal(b, &actual); err != nil {
-		return nil, fmt.Errorf("unable to decode download metadata %s\n%w", file, err)
-	}
 
-	if dependency.Equals(actual) {
+	if exists {
 		d.Logger.Bodyf("%s previously cached download", color.GreenString("Reusing"))
 		return os.Open(filepath.Join(d.DownloadPath, dependency.SHA256, filepath.Base(uri)))
 	}

diff --git a/dependency_cache_test.go b/dependency_cache_test.go
@@ -234,6 +234,17 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 			Expect(io.ReadAll(a)).To(Equal([]byte("test-fixture")))
 		})
 
+		it("returns from cache path even with updated metadata", func() {
+			copyFile(filepath.Join("testdata", "test-file"), filepath.Join(cachePath, dependency.SHA256, "test-path"))
+			dependency.DeprecationDate = time.Now()
+			writeTOML(filepath.Join(cachePath, fmt.Sprintf("%s.toml", dependency.SHA256)), dependency)
+
+			a, err := dependencyCache.Artifact(dependency)
+			Expect(err).NotTo(HaveOccurred())
+
+			Expect(io.ReadAll(a)).To(Equal([]byte("test-fixture")))
+		})
+
 		it("returns from download path", func() {
 			copyFile(filepath.Join("testdata", "test-file"), filepath.Join(downloadPath, dependency.SHA256, "test-path"))
 			writeTOML(filepath.Join(downloadPath, fmt.Sprintf("%s.toml", dependency.SHA256)), dependency)
@@ -244,6 +255,17 @@ func testDependencyCache(t *testing.T, context spec.G, it spec.S) {
 			Expect(io.ReadAll(a)).To(Equal([]byte("test-fixture")))
 		})
 
+		it("returns from download path even with updated metadata", func() {
+			copyFile(filepath.Join("testdata", "test-file"), filepath.Join(downloadPath, dependency.SHA256, "test-path"))
+			dependency.DeprecationDate = time.Now()
+			writeTOML(filepath.Join(downloadPath, fmt.Sprintf("%s.toml", dependency.SHA256)), dependency)
+
+			a, err := dependencyCache.Artifact(dependency)
+			Expect(err).NotTo(HaveOccurred())
+
+			Expect(io.ReadAll(a)).To(Equal([]byte("test-fixture")))
+		})
+
 		it("downloads", func() {
 			server.AppendHandlers(ghttp.CombineHandlers(
 				ghttp.VerifyRequest(http.MethodGet, "/test-path", ""),