clang/lib/Serialization/ModuleCache.cpp

//===----------------------------------------------------------------------===//
//
// 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;

namespace {
class CrossProcessModuleCache : public ModuleCache {
  InMemoryModuleCache InMemory;

  std::time_t BuildSessionTimestamp;

public:
  explicit CrossProcessModuleCache(std::time_t BuildSessionTimestamp)
      : BuildSessionTimestamp(BuildSessionTimestamp) {}

  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);
  }

  bool isMarkedUpToDate(StringRef ModuleFilename) override {
    std::string TimestampFilename =
        serialization::ModuleFile::getTimestampFilename(ModuleFilename);
    llvm::sys::fs::file_status Status;
    if (llvm::sys::fs::status(ModuleFilename, Status) != std::error_code{})
      return false;
    return llvm::sys::toTimeT(Status.getLastModificationTime()) >
           BuildSessionTimestamp;
  }

  void markUpToDate(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.
  }

  InMemoryModuleCache &getInMemoryModuleCache() override { return InMemory; }
  const InMemoryModuleCache &getInMemoryModuleCache() const override {
    return InMemory;
  }
};
} // namespace

IntrusiveRefCntPtr<ModuleCache>
clang::createCrossProcessModuleCache(std::time_t BuildSessionTimestamp) {
  return llvm::makeIntrusiveRefCnt<CrossProcessModuleCache>(
      BuildSessionTimestamp);
}