| //===- InMemoryModuleCache.h - In-memory cache for modules ------*- C++ -*-===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
| #define LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
| |
| #include "llvm/ADT/IntrusiveRefCntPtr.h" |
| #include "llvm/ADT/Optional.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include <memory> |
| |
| namespace clang { |
| |
| /// In-memory cache for modules. |
| /// |
| /// This is a cache for modules for use across a compilation, sharing state |
| /// between the CompilerInstances in an implicit modules build. It must be |
| /// shared by each CompilerInstance, ASTReader, ASTWriter, and ModuleManager |
| /// that are coordinating. |
| /// |
| /// Critically, it ensures that a single process has a consistent view of each |
| /// PCM. This is used by \a CompilerInstance when building PCMs to ensure that |
| /// each \a ModuleManager sees the same files. |
| class InMemoryModuleCache : public llvm::RefCountedBase<InMemoryModuleCache> { |
| struct PCM { |
| std::unique_ptr<llvm::MemoryBuffer> Buffer; |
| |
| /// Track whether this PCM is known to be good (either built or |
| /// successfully imported by a CompilerInstance/ASTReader using this |
| /// cache). |
| bool IsFinal = false; |
| |
| PCM() = default; |
| PCM(std::unique_ptr<llvm::MemoryBuffer> Buffer) |
| : Buffer(std::move(Buffer)) {} |
| }; |
| |
| /// Cache of buffers. |
| llvm::StringMap<PCM> PCMs; |
| |
| public: |
| /// There are four states for a PCM. It must monotonically increase. |
| /// |
| /// 1. Unknown: the PCM has neither been read from disk nor built. |
| /// 2. Tentative: the PCM has been read from disk but not yet imported or |
| /// built. It might work. |
| /// 3. ToBuild: the PCM read from disk did not work but a new one has not |
| /// been built yet. |
| /// 4. Final: indicating that the current PCM was either built in this |
| /// process or has been successfully imported. |
| enum State { Unknown, Tentative, ToBuild, Final }; |
| |
| /// Get the state of the PCM. |
| State getPCMState(llvm::StringRef Filename) const; |
| |
| /// Store the PCM under the Filename. |
| /// |
| /// \pre state is Unknown |
| /// \post state is Tentative |
| /// \return a reference to the buffer as a convenience. |
| llvm::MemoryBuffer &addPCM(llvm::StringRef Filename, |
| std::unique_ptr<llvm::MemoryBuffer> Buffer); |
| |
| /// Store a just-built PCM under the Filename. |
| /// |
| /// \pre state is Unknown or ToBuild. |
| /// \pre state is not Tentative. |
| /// \return a reference to the buffer as a convenience. |
| llvm::MemoryBuffer &addBuiltPCM(llvm::StringRef Filename, |
| std::unique_ptr<llvm::MemoryBuffer> Buffer); |
| |
| /// Try to remove a buffer from the cache. No effect if state is Final. |
| /// |
| /// \pre state is Tentative/Final. |
| /// \post Tentative => ToBuild or Final => Final. |
| /// \return false on success, i.e. if Tentative => ToBuild. |
| bool tryToDropPCM(llvm::StringRef Filename); |
| |
| /// Mark a PCM as final. |
| /// |
| /// \pre state is Tentative or Final. |
| /// \post state is Final. |
| void finalizePCM(llvm::StringRef Filename); |
| |
| /// Get a pointer to the pCM if it exists; else nullptr. |
| llvm::MemoryBuffer *lookupPCM(llvm::StringRef Filename) const; |
| |
| /// Check whether the PCM is final and has been shown to work. |
| /// |
| /// \return true iff state is Final. |
| bool isPCMFinal(llvm::StringRef Filename) const; |
| |
| /// Check whether the PCM is waiting to be built. |
| /// |
| /// \return true iff state is ToBuild. |
| bool shouldBuildPCM(llvm::StringRef Filename) const; |
| }; |
| |
| } // end namespace clang |
| |
| #endif // LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |