[clang] [clang-tools-extra] [clang][modules] Introduce new `ModuleCache` interface (PR #131193)

[Ben Langmuir via cfe-commits]

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@@ -0,0 +1,44 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 "llvm/Support/FileSystem.h"
+#include "llvm/Support/LockFileManager.h"
+#include "llvm/Support/Path.h"
+
+using namespace clang;
+
+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);
+  }
+
+  InMemoryModuleCache &getInMemoryModuleCache() override { return InMemory; }
+  const InMemoryModuleCache &getInMemoryModuleCache() const override {
+    return InMemory;
+  }
+};
+} // namespace
+
+IntrusiveRefCntPtr<ModuleCache> clang::getCrossProcessModuleCache() {
+  return llvm::makeIntrusiveRefCnt<CrossProcessModuleCache>();
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benlangmuir wrote:

This should probably say "**create**CrossProcessModuleCache" instead of "get".  I assumed from the name that it was returning a shared instance.

https://github.com/llvm/llvm-project/pull/131193