| 1 | //===- InMemoryModuleCache.h - In-memory cache for modules ------*- C++ -*-===// |
|---|---|
| 2 | // |
| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| 4 | // See https://llvm.org/LICENSE.txt for license information. |
| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| 6 | // |
| 7 | //===----------------------------------------------------------------------===// |
| 8 | |
| 9 | #ifndef LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
| 10 | #define LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
| 11 | |
| 12 | #include "llvm/ADT/IntrusiveRefCntPtr.h" |
| 13 | #include "llvm/ADT/Optional.h" |
| 14 | #include "llvm/ADT/StringMap.h" |
| 15 | #include "llvm/Support/MemoryBuffer.h" |
| 16 | #include <memory> |
| 17 | |
| 18 | namespace clang { |
| 19 | |
| 20 | /// In-memory cache for modules. |
| 21 | /// |
| 22 | /// This is a cache for modules for use across a compilation, sharing state |
| 23 | /// between the CompilerInstances in an implicit modules build. It must be |
| 24 | /// shared by each CompilerInstance, ASTReader, ASTWriter, and ModuleManager |
| 25 | /// that are coordinating. |
| 26 | /// |
| 27 | /// Critically, it ensures that a single process has a consistent view of each |
| 28 | /// PCM. This is used by \a CompilerInstance when building PCMs to ensure that |
| 29 | /// each \a ModuleManager sees the same files. |
| 30 | class InMemoryModuleCache : public llvm::RefCountedBase<InMemoryModuleCache> { |
| 31 | struct PCM { |
| 32 | std::unique_ptr<llvm::MemoryBuffer> Buffer; |
| 33 | |
| 34 | /// Track whether this PCM is known to be good (either built or |
| 35 | /// successfully imported by a CompilerInstance/ASTReader using this |
| 36 | /// cache). |
| 37 | bool IsFinal = false; |
| 38 | |
| 39 | PCM() = default; |
| 40 | PCM(std::unique_ptr<llvm::MemoryBuffer> Buffer) |
| 41 | : Buffer(std::move(Buffer)) {} |
| 42 | }; |
| 43 | |
| 44 | /// Cache of buffers. |
| 45 | llvm::StringMap<PCM> PCMs; |
| 46 | |
| 47 | public: |
| 48 | /// There are four states for a PCM. It must monotonically increase. |
| 49 | /// |
| 50 | /// 1. Unknown: the PCM has neither been read from disk nor built. |
| 51 | /// 2. Tentative: the PCM has been read from disk but not yet imported or |
| 52 | /// built. It might work. |
| 53 | /// 3. ToBuild: the PCM read from disk did not work but a new one has not |
| 54 | /// been built yet. |
| 55 | /// 4. Final: indicating that the current PCM was either built in this |
| 56 | /// process or has been successfully imported. |
| 57 | enum State { Unknown, Tentative, ToBuild, Final }; |
| 58 | |
| 59 | /// Get the state of the PCM. |
| 60 | State getPCMState(llvm::StringRef Filename) const; |
| 61 | |
| 62 | /// Store the PCM under the Filename. |
| 63 | /// |
| 64 | /// \pre state is Unknown |
| 65 | /// \post state is Tentative |
| 66 | /// \return a reference to the buffer as a convenience. |
| 67 | llvm::MemoryBuffer &addPCM(llvm::StringRef Filename, |
| 68 | std::unique_ptr<llvm::MemoryBuffer> Buffer); |
| 69 | |
| 70 | /// Store a just-built PCM under the Filename. |
| 71 | /// |
| 72 | /// \pre state is Unknown or ToBuild. |
| 73 | /// \pre state is not Tentative. |
| 74 | /// \return a reference to the buffer as a convenience. |
| 75 | llvm::MemoryBuffer &addBuiltPCM(llvm::StringRef Filename, |
| 76 | std::unique_ptr<llvm::MemoryBuffer> Buffer); |
| 77 | |
| 78 | /// Try to remove a buffer from the cache. No effect if state is Final. |
| 79 | /// |
| 80 | /// \pre state is Tentative/Final. |
| 81 | /// \post Tentative => ToBuild or Final => Final. |
| 82 | /// \return false on success, i.e. if Tentative => ToBuild. |
| 83 | bool tryToDropPCM(llvm::StringRef Filename); |
| 84 | |
| 85 | /// Mark a PCM as final. |
| 86 | /// |
| 87 | /// \pre state is Tentative or Final. |
| 88 | /// \post state is Final. |
| 89 | void finalizePCM(llvm::StringRef Filename); |
| 90 | |
| 91 | /// Get a pointer to the pCM if it exists; else nullptr. |
| 92 | llvm::MemoryBuffer *lookupPCM(llvm::StringRef Filename) const; |
| 93 | |
| 94 | /// Check whether the PCM is final and has been shown to work. |
| 95 | /// |
| 96 | /// \return true iff state is Final. |
| 97 | bool isPCMFinal(llvm::StringRef Filename) const; |
| 98 | |
| 99 | /// Check whether the PCM is waiting to be built. |
| 100 | /// |
| 101 | /// \return true iff state is ToBuild. |
| 102 | bool shouldBuildPCM(llvm::StringRef Filename) const; |
| 103 | }; |
| 104 | |
| 105 | } // end namespace clang |
| 106 | |
| 107 | #endif // LLVM_CLANG_SERIALIZATION_INMEMORYMODULECACHE_H |
| 108 |