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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "clang/Serialization/ModuleCache.h"
#include "clang/Serialization/InMemoryModuleCache.h"
#include "clang/Serialization/ModuleFile.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/LockFileManager.h"
#include "llvm/Support/Path.h"
using namespace clang;
/// Write a new timestamp file with the given path.
static void writeTimestampFile(StringRef TimestampFile) {
std::error_code EC;
llvm::raw_fd_ostream Out(TimestampFile.str(), EC, llvm::sys::fs::OF_None);
}
void clang::maybePruneImpl(StringRef Path, time_t PruneInterval,
time_t PruneAfter) {
if (PruneInterval <= 0 || PruneAfter <= 0)
return;
llvm::SmallString<128> TimestampFile(Path);
llvm::sys::path::append(TimestampFile, "modules.timestamp");
// Try to stat() the timestamp file.
llvm::sys::fs::file_status StatBuf;
if (std::error_code EC = llvm::sys::fs::status(TimestampFile, StatBuf)) {
// If the timestamp file wasn't there, create one now.
if (EC == std::errc::no_such_file_or_directory)
writeTimestampFile(TimestampFile);
return;
}
// Check whether the time stamp is older than our pruning interval.
// If not, do nothing.
time_t TimestampModTime =
llvm::sys::toTimeT(StatBuf.getLastModificationTime());
time_t CurrentTime = time(nullptr);
if (CurrentTime - TimestampModTime <= PruneInterval)
return;
// Write a new timestamp file so that nobody else attempts to prune.
// There is a benign race condition here, if two Clang instances happen to
// notice at the same time that the timestamp is out-of-date.
writeTimestampFile(TimestampFile);
// Walk the entire module cache, looking for unused module files and module
// indices.
std::error_code EC;
for (llvm::sys::fs::directory_iterator Dir(Path, EC), DirEnd;
Dir != DirEnd && !EC; Dir.increment(EC)) {
// If we don't have a directory, there's nothing to look into.
if (!llvm::sys::fs::is_directory(Dir->path()))
continue;
// Walk all the files within this directory.
for (llvm::sys::fs::directory_iterator File(Dir->path(), EC), FileEnd;
File != FileEnd && !EC; File.increment(EC)) {
// We only care about module and global module index files.
StringRef Extension = llvm::sys::path::extension(File->path());
if (Extension != ".pcm" && Extension != ".timestamp" &&
llvm::sys::path::filename(File->path()) != "modules.idx")
continue;
// Look at this file. If we can't stat it, there's nothing interesting
// there.
if (llvm::sys::fs::status(File->path(), StatBuf))
continue;
// If the file has been used recently enough, leave it there.
time_t FileAccessTime = llvm::sys::toTimeT(StatBuf.getLastAccessedTime());
if (CurrentTime - FileAccessTime <= PruneAfter)
continue;
// Remove the file.
llvm::sys::fs::remove(File->path());
// Remove the timestamp file.
std::string TimpestampFilename = File->path() + ".timestamp";
llvm::sys::fs::remove(TimpestampFilename);
}
// If we removed all the files in the directory, remove the directory
// itself.
if (llvm::sys::fs::directory_iterator(Dir->path(), EC) ==
llvm::sys::fs::directory_iterator() &&
!EC)
llvm::sys::fs::remove(Dir->path());
}
}
namespace {
class CrossProcessModuleCache : public ModuleCache {
InMemoryModuleCache InMemory;
public:
void prepareForGetLock(StringRef ModuleFilename) override {
// FIXME: Do this in LockFileManager and only if the directory doesn't
// exist.
StringRef Dir = llvm::sys::path::parent_path(ModuleFilename);
llvm::sys::fs::create_directories(Dir);
}
std::unique_ptr<llvm::AdvisoryLock>
getLock(StringRef ModuleFilename) override {
return std::make_unique<llvm::LockFileManager>(ModuleFilename);
}
std::time_t getModuleTimestamp(StringRef ModuleFilename) override {
llvm::sys::fs::file_status Status;
if (llvm::sys::fs::status(ModuleFilename, Status) != std::error_code{})
return 0;
return llvm::sys::toTimeT(Status.getLastModificationTime());
}
void updateModuleTimestamp(StringRef ModuleFilename) override {
// Overwrite the timestamp file contents so that file's mtime changes.
std::error_code EC;
llvm::raw_fd_ostream OS(
serialization::ModuleFile::getTimestampFilename(ModuleFilename), EC,
llvm::sys::fs::OF_TextWithCRLF);
if (EC)
return;
OS << "Timestamp file\n";
OS.close();
OS.clear_error(); // Avoid triggering a fatal error.
}
void maybePrune(StringRef Path, time_t PruneInterval,
time_t PruneAfter) override {
maybePruneImpl(Path, PruneInterval, PruneAfter);
}
InMemoryModuleCache &getInMemoryModuleCache() override { return InMemory; }
const InMemoryModuleCache &getInMemoryModuleCache() const override {
return InMemory;
}
};
} // namespace
IntrusiveRefCntPtr<ModuleCache> clang::createCrossProcessModuleCache() {
return llvm::makeIntrusiveRefCnt<CrossProcessModuleCache>();
}
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