Local disk cache: part 1

go/pkg/diskcache/BUILD.bazel

@@ -0,0 +1,33 @@
+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "diskcache",
+    srcs = [
+        "atim_darwin.go",
+        "atim_linux.go",
+        "atim_windows.go",
+        "diskcache.go",
+    ],
+    importpath = "github.com/bazelbuild/remote-apis-sdks/go/pkg/diskcache",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//go/pkg/digest",
+        "@com_github_bazelbuild_remote_apis//build/bazel/remote/execution/v2:remote_execution_go_proto",
+        "@com_github_golang_glog//:go_default_library",
+        "@org_golang_google_protobuf//proto:go_default_library",
+    ],
+)
+
+go_test(
+    name = "diskcache_test",
+    srcs = ["diskcache_test.go"],
+    embed = [":diskcache"],
+    deps = [
+        "//go/pkg/digest",
+        "//go/pkg/testutil",
+        "@com_github_bazelbuild_remote_apis//build/bazel/remote/execution/v2:remote_execution_go_proto",
+        "@com_github_google_go_cmp//cmp:go_default_library",
+        "@com_github_pborman_uuid//:go_default_library",
+        "@org_golang_x_sync//errgroup:go_default_library",
+    ],
+)

go/pkg/diskcache/atim_darwin.go

@@ -0,0 +1,16 @@
+// Utility to get the last accessed time on Darwin.
+package diskcache
+
+import (
+	"os"
+	"syscall"
+	"time"
+)
+
+func GetLastAccessTime(path string) (time.Time, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return time.Unix(info.Sys().(*syscall.Stat_t).Atimespec.Unix()), nil
+}

go/pkg/diskcache/atim_linux.go

@@ -0,0 +1,16 @@
+// Utility to get the last accessed time on Linux.
+package diskcache
+
+import (
+	"os"
+	"syscall"
+	"time"
+)
+
+func GetLastAccessTime(path string) (time.Time, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return time.Unix(info.Sys().(*syscall.Stat_t).Atim.Unix()), nil
+}

go/pkg/diskcache/atim_windows.go

@@ -0,0 +1,18 @@
+// Utility to get the last accessed time on Windows.
+package diskcache
+
+import (
+	"os"
+	"syscall"
+	"time"
+)
+
+// This will return correct values only if `fsutil behavior set disablelastaccess 0` is set.
+// Tracking of last access time is disabled by default on Windows.
+func GetLastAccessTime(path string) (time.Time, error) {
+	info, err := os.Stat(path)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return time.Unix(0, info.Sys().(*syscall.Win32FileAttributeData).LastAccessTime.Nanoseconds()), nil
+}