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