Revert "Revert "Modify symlink_forest to rerun when soong_build has changed.""
This reverts commit aa5cc2cd6af5da7c65914500fc6e11c6a130060c.
Reason for revert: Fixed the bug in the original draft.
There was an error in how we compared the file's MTime to the
file's contents.
Bug: 300288299
Test: presubmits
Test: build/soong/tests/run_integration_tests.sh
Change-Id: I9e53432c0842c0b9fc13fe20d30ce9af37640c7f
diff --git a/bp2build/symlink_forest.go b/bp2build/symlink_forest.go
index 966b94a..15a6df0 100644
--- a/bp2build/symlink_forest.go
+++ b/bp2build/symlink_forest.go
@@ -22,7 +22,6 @@
"regexp"
"sort"
"strconv"
- "strings"
"sync"
"sync/atomic"
@@ -32,19 +31,12 @@
)
// A tree structure that describes what to do at each directory in the created
-// symlink tree. Currently it is used to enumerate which files/directories
+// symlink tree. Currently, it is used to enumerate which files/directories
// should be excluded from symlinking. Each instance of "node" represents a file
// or a directory. If excluded is true, then that file/directory should be
// excluded from symlinking. Otherwise, the node is not excluded, but one of its
// descendants is (otherwise the node in question would not exist)
-// This is a version int written to a file called symlink_forest_version at the root of the
-// symlink forest. If the version here does not match the version in the file, then we'll
-// clean the whole symlink forest and recreate it. This number can be bumped whenever there's
-// an incompatible change to the forest layout or a bug in incrementality that needs to be fixed
-// on machines that may still have the bug present in their forest.
-const symlinkForestVersion = 2
-
type instructionsNode struct {
name string
excluded bool // If false, this is just an intermediate node
@@ -193,7 +185,7 @@
srcPath := shared.JoinPath(topdir, src)
dstPath := shared.JoinPath(topdir, dst)
- // Check if a symlink already exists.
+ // Check whether a symlink already exists.
if dstInfo, err := os.Lstat(dstPath); err != nil {
if !os.IsNotExist(err) {
fmt.Fprintf(os.Stderr, "Failed to lstat '%s': %s", dst, err)
@@ -240,44 +232,49 @@
return false
}
-// maybeCleanSymlinkForest will remove the whole symlink forest directory if the version recorded
-// in the symlink_forest_version file is not equal to symlinkForestVersion.
-func maybeCleanSymlinkForest(topdir, forest string, verbose bool) error {
- versionFilePath := shared.JoinPath(topdir, forest, "symlink_forest_version")
- versionFileContents, err := os.ReadFile(versionFilePath)
- if err != nil && !os.IsNotExist(err) {
- return err
+// Returns the mtime of the soong_build binary to determine whether we should
+// force symlink_forest to re-execute
+func getSoongBuildMTime() (int64, error) {
+ binaryPath, err := os.Executable()
+ if err != nil {
+ return 0, err
}
- versionFileString := strings.TrimSpace(string(versionFileContents))
- symlinkForestVersionString := strconv.Itoa(symlinkForestVersion)
- if err != nil || versionFileString != symlinkForestVersionString {
- if verbose {
- fmt.Fprintf(os.Stderr, "Old symlink_forest_version was %q, current is %q. Cleaning symlink forest before recreating...\n", versionFileString, symlinkForestVersionString)
- }
- err = os.RemoveAll(shared.JoinPath(topdir, forest))
- if err != nil {
- return err
- }
+
+ info, err := os.Stat(binaryPath)
+ if err != nil {
+ return 0, err
}
- return nil
+
+ return info.ModTime().UnixMilli(), nil
}
-// maybeWriteVersionFile will write the symlink_forest_version file containing symlinkForestVersion
-// if it doesn't exist already. If it exists we know it must contain symlinkForestVersion because
-// we checked for that already in maybeCleanSymlinkForest
-func maybeWriteVersionFile(topdir, forest string) error {
- versionFilePath := shared.JoinPath(topdir, forest, "symlink_forest_version")
- _, err := os.Stat(versionFilePath)
+// cleanSymlinkForest will remove the whole symlink forest directory
+func cleanSymlinkForest(topdir, forest string) error {
+ return os.RemoveAll(shared.JoinPath(topdir, forest))
+}
+
+// This returns whether symlink forest should clean and replant symlinks.
+// It compares the mtime of this executable with the mtime of the last-run
+// soong_build binary. If they differ, then we should clean and replant.
+func shouldCleanSymlinkForest(topdir string, forest string, soongBuildMTime int64) (bool, error) {
+ mtimeFilePath := shared.JoinPath(topdir, forest, "soong_build_mtime")
+ mtimeFileContents, err := os.ReadFile(mtimeFilePath)
if err != nil {
- if !os.IsNotExist(err) {
- return err
- }
- err = os.WriteFile(versionFilePath, []byte(strconv.Itoa(symlinkForestVersion)+"\n"), 0666)
- if err != nil {
- return err
+ if os.IsNotExist(err) {
+ // This is likely the first time this has run with this functionality - clean away!
+ return true, nil
+ } else {
+ return false, err
}
}
- return nil
+ return strconv.FormatInt(soongBuildMTime, 10) != string(mtimeFileContents), nil
+}
+
+func writeSoongBuildMTimeFile(topdir, forest string, mtime int64) error {
+ mtimeFilePath := shared.JoinPath(topdir, forest, "soong_build_mtime")
+ contents := []byte(strconv.FormatInt(mtime, 10))
+
+ return os.WriteFile(mtimeFilePath, contents, 0666)
}
// Recursively plants a symlink forest at forestDir. The symlink tree will
@@ -473,12 +470,26 @@
symlinkCount: atomic.Uint64{},
}
- err := maybeCleanSymlinkForest(topdir, forest, verbose)
+ // Check whether soong_build has been modified since the last run
+ soongBuildMTime, err := getSoongBuildMTime()
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
+ shouldClean, err := shouldCleanSymlinkForest(topdir, forest, soongBuildMTime)
+
+ if err != nil {
+ fmt.Fprintln(os.Stderr, err)
+ os.Exit(1)
+ } else if shouldClean {
+ err = cleanSymlinkForest(topdir, forest)
+ if err != nil {
+ fmt.Fprintln(os.Stderr, err)
+ os.Exit(1)
+ }
+ }
+
instructions := instructionsFromExcludePathList(exclude)
go func() {
context.wg.Add(1)
@@ -491,11 +502,10 @@
deps = append(deps, dep)
}
- err = maybeWriteVersionFile(topdir, forest)
+ err = writeSoongBuildMTimeFile(topdir, forest, soongBuildMTime)
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
-
return deps, context.mkdirCount.Load(), context.symlinkCount.Load()
}