Simplify unlinkAsync.
It used to rename the file before removing it in a background thread.
A simpler way to delay the removal is simply to open the file.
Since this is a posix specific issue, simplify the windows
implementation.
llvm-svn: 317631
diff --git a/lld/ELF/Filesystem.cpp b/lld/ELF/Filesystem.cpp
index 8848014..5678f22 100644
--- a/lld/ELF/Filesystem.cpp
+++ b/lld/ELF/Filesystem.cpp
@@ -14,8 +14,12 @@
#include "Filesystem.h"
#include "Config.h"
#include "lld/Common/Threads.h"
+#include "llvm/Config/config.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/FileSystem.h"
+#if defined(HAVE_UNISTD_H)
+#include <unistd.h>
+#endif
using namespace llvm;
@@ -35,27 +39,30 @@
// Since LLD can link a 1 GB binary in about 5 seconds, that waste
// actually counts.
//
-// This function spawns a background thread to call unlink.
+// This function spawns a background thread to remove the file.
// The calling thread returns almost immediately.
void elf::unlinkAsync(StringRef Path) {
+// Removing a file is async on windows.
+#if defined(LLVM_ON_WIN32)
+ sys::fs::remove(Path);
+#else
if (!ThreadsEnabled || !sys::fs::exists(Path) ||
!sys::fs::is_regular_file(Path))
return;
- // First, rename Path to avoid race condition. We cannot remove
- // Path from a different thread because we are now going to create
- // Path as a new file. If we do that in a different thread, the new
- // thread can remove the new file.
- SmallString<128> TempPath;
- if (sys::fs::createUniqueFile(Path + "tmp%%%%%%%%", TempPath))
+ // We cannot just remove path from a different thread because we are now going
+ // to create path as a new file.
+ // Instead we open the file and unlink it on this thread. The unlink is fast
+ // since the open fd guarantees that it is not removing the last reference.
+ int FD;
+ if (std::error_code EC = sys::fs::openFileForRead(Path, FD))
return;
- if (sys::fs::rename(Path, TempPath)) {
- sys::fs::remove(TempPath);
- return;
- }
- // Remove TempPath in background.
- runBackground([=] { ::remove(TempPath.str().str().c_str()); });
+ sys::fs::remove(Path);
+
+ // close and therefore remove TempPath in background.
+ runBackground([=] { ::close(FD); });
+#endif
}
// Simulate file creation to see if Path is writable.