diff options
| -rw-r--r-- | src/cmd/go/internal/cache/cache.go | 25 | ||||
| -rw-r--r-- | src/cmd/go/testdata/script/mod_list_compiled_concurrent.txt | 41 |
2 files changed, 64 insertions, 2 deletions
diff --git a/src/cmd/go/internal/cache/cache.go b/src/cmd/go/internal/cache/cache.go index 116279c977..168ad32b0e 100644 --- a/src/cmd/go/internal/cache/cache.go +++ b/src/cmd/go/internal/cache/cache.go @@ -322,7 +322,7 @@ func (c *Cache) putIndexEntry(id ActionID, out OutputID, size int64, allowVerify // in verify mode we are double-checking that the cache entries // are entirely reproducible. As just noted, this may be unrealistic // in some cases but the check is also useful for shaking out real bugs. - entry := []byte(fmt.Sprintf("v1 %x %x %20d %20d\n", id, out, size, time.Now().UnixNano())) + entry := fmt.Sprintf("v1 %x %x %20d %20d\n", id, out, size, time.Now().UnixNano()) if verify && allowVerify { old, err := c.get(id) if err == nil && (old.OutputID != out || old.Size != size) { @@ -332,7 +332,28 @@ func (c *Cache) putIndexEntry(id ActionID, out OutputID, size int64, allowVerify } } file := c.fileName(id, "a") - if err := ioutil.WriteFile(file, entry, 0666); err != nil { + + // Copy file to cache directory. + mode := os.O_WRONLY | os.O_CREATE + f, err := os.OpenFile(file, mode, 0666) + if err != nil { + return err + } + _, err = f.WriteString(entry) + if err == nil { + // Truncate the file only *after* writing it. + // (This should be a no-op, but truncate just in case of previous corruption.) + // + // This differs from ioutil.WriteFile, which truncates to 0 *before* writing + // via os.O_TRUNC. Truncating only after writing ensures that a second write + // of the same content to the same file is idempotent, and does not — even + // temporarily! — undo the effect of the first write. + err = f.Truncate(int64(len(entry))) + } + if closeErr := f.Close(); err == nil { + err = closeErr + } + if err != nil { // TODO(bcmills): This Remove potentially races with another go command writing to file. // Can we eliminate it? os.Remove(file) diff --git a/src/cmd/go/testdata/script/mod_list_compiled_concurrent.txt b/src/cmd/go/testdata/script/mod_list_compiled_concurrent.txt new file mode 100644 index 0000000000..b08713dcfd --- /dev/null +++ b/src/cmd/go/testdata/script/mod_list_compiled_concurrent.txt @@ -0,0 +1,41 @@ +env GO111MODULE=on + +[short] skip + +# Regression test for golang.org/issue/29667: +# spurious 'failed to cache compiled Go files' errors. +# This test failed reliably when run with -count=10 +# on a Linux workstation. + +env GOCACHE=$WORK/gocache +mkdir $GOCACHE + +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & +go list -json -compiled -test=false -export=false -deps=true -- . & + +wait + +-- go.mod -- +module sandbox/bar +-- bar.go -- +package bar + +import "C" |