| //===- MemoryBufferCache.h - Cache for loaded memory buffers ----*- 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_BASIC_MEMORYBUFFERCACHE_H |
| #define LLVM_CLANG_BASIC_MEMORYBUFFERCACHE_H |
| |
| #include "llvm/ADT/IntrusiveRefCntPtr.h" |
| #include "llvm/ADT/StringMap.h" |
| #include <memory> |
| |
| namespace llvm { |
| class MemoryBuffer; |
| } // end namespace llvm |
| |
| namespace clang { |
| |
| /// Manage memory buffers across multiple users. |
| /// |
| /// Ensures that multiple users have a consistent view of each buffer. This is |
| /// used by \a CompilerInstance when building PCMs to ensure that each \a |
| /// ModuleManager sees the same files. |
| /// |
| /// \a finalizeCurrentBuffers() should be called before creating a new user. |
| /// This locks in the current buffers, ensuring that no buffer that has already |
| /// been accessed can be purged, preventing use-after-frees. |
| class MemoryBufferCache : public llvm::RefCountedBase<MemoryBufferCache> { |
| struct BufferEntry { |
| std::unique_ptr<llvm::MemoryBuffer> Buffer; |
| |
| /// Track the timeline of when this was added to the cache. |
| unsigned Index; |
| }; |
| |
| /// Cache of buffers. |
| llvm::StringMap<BufferEntry> Buffers; |
| |
| /// Monotonically increasing index. |
| unsigned NextIndex = 0; |
| |
| /// Bumped to prevent "older" buffers from being removed. |
| unsigned FirstRemovableIndex = 0; |
| |
| public: |
| /// Store the Buffer under the Filename. |
| /// |
| /// \pre There is not already buffer is not already in the cache. |
| /// \return a reference to the buffer as a convenience. |
| llvm::MemoryBuffer &addBuffer(llvm::StringRef Filename, |
| std::unique_ptr<llvm::MemoryBuffer> Buffer); |
| |
| /// Try to remove a buffer from the cache. |
| /// |
| /// \return false on success, iff \c !isBufferFinal(). |
| bool tryToRemoveBuffer(llvm::StringRef Filename); |
| |
| /// Get a pointer to the buffer if it exists; else nullptr. |
| llvm::MemoryBuffer *lookupBuffer(llvm::StringRef Filename); |
| |
| /// Check whether the buffer is final. |
| /// |
| /// \return true iff \a finalizeCurrentBuffers() has been called since the |
| /// buffer was added. This prevents buffers from being removed. |
| bool isBufferFinal(llvm::StringRef Filename); |
| |
| /// Finalize the current buffers in the cache. |
| /// |
| /// Should be called when creating a new user to ensure previous uses aren't |
| /// invalidated. |
| void finalizeCurrentBuffers(); |
| }; |
| |
| } // end namespace clang |
| |
| #endif // LLVM_CLANG_BASIC_MEMORYBUFFERCACHE_H |