Add and update comments in env and android_env.go
Bug: 173450116
Test: m nothing
Change-Id: I582a483d11c2ca23fd6e9597e49cdfb7e69152de
diff --git a/cmd/soong_env/soong_env.go b/cmd/soong_env/soong_env.go
index d305d83..8020b17 100644
--- a/cmd/soong_env/soong_env.go
+++ b/cmd/soong_env/soong_env.go
@@ -12,10 +12,11 @@
// See the License for the specific language governing permissions and
// limitations under the License.
-// soong_glob is the command line tool that checks if the list of files matching a glob has
-// changed, and only updates the output file list if it has changed. It is used to optimize
-// out build.ninja regenerations when non-matching files are added. See
-// android/soong/android/glob.go for a longer description.
+// soong_env determines if the given soong environment file (usually ".soong.environment") is stale
+// by comparing its contents to the current corresponding environment variable values.
+// It fails if the file cannot be opened or corrupted, or its contents differ from the current
+// values.
+
package main
import (
@@ -34,6 +35,7 @@
os.Exit(2)
}
+// This is a simple executable packaging, and the real work happens in env.StaleEnvFile.
func main() {
flag.Parse()
diff --git a/env/env.go b/env/env.go
index a98e1f6..735a38a 100644
--- a/env/env.go
+++ b/env/env.go
@@ -27,6 +27,15 @@
type envFileEntry struct{ Key, Value string }
type envFileData []envFileEntry
+// Serializes the given environment variable name/value map into JSON formatted bytes by converting
+// to envFileEntry values and marshaling them.
+//
+// e.g. OUT_DIR = "out"
+// is converted to:
+// {
+// "Key": "OUT_DIR",
+// "Value": "out",
+// },
func EnvFileContents(envDeps map[string]string) ([]byte, error) {
contents := make(envFileData, 0, len(envDeps))
for key, value := range envDeps {
@@ -45,8 +54,11 @@
return data, nil
}
-func StaleEnvFile(filename string) (bool, error) {
- data, err := ioutil.ReadFile(filename)
+// Reads and deserializes a Soong environment file located at the given file path to determine its
+// staleness. If any environment variable values have changed, it prints them out and returns true.
+// Failing to read or parse the file also causes it to return true.
+func StaleEnvFile(filepath string) (bool, error) {
+ data, err := ioutil.ReadFile(filepath)
if err != nil {
return true, err
}
@@ -79,6 +91,7 @@
return false, nil
}
+// Implements sort.Interface so that we can use sort.Sort on envFileData arrays.
func (e envFileData) Len() int {
return len(e)
}
@@ -90,3 +103,5 @@
func (e envFileData) Swap(i, j int) {
e[i], e[j] = e[j], e[i]
}
+
+var _ sort.Interface = envFileData{}