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1 //===--- FS.h - File system related utils ------------------------*- C++-*-===//
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2 //
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3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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4 // See https://llvm.org/LICENSE.txt for license information.
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5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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6 //
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7 //===----------------------------------------------------------------------===//
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8
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9 #ifndef LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
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10 #define LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
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11
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173
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12 #include "support/Path.h"
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150
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13 #include "clang/Basic/LLVM.h"
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14 #include "llvm/ADT/Optional.h"
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173
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15 #include "llvm/ADT/StringMap.h"
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150
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16 #include "llvm/Support/VirtualFileSystem.h"
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17
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18 namespace clang {
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19 namespace clangd {
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20
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21 /// Records status information for files open()ed or stat()ed during preamble
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22 /// build (except for the main file), so we can avoid stat()s on the underlying
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23 /// FS when reusing the preamble. For example, code completion can re-stat files
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24 /// when getting FileID for source locations stored in preamble (e.g. checking
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25 /// whether a location is in the main file).
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26 ///
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27 /// The cache is keyed by absolute path of file name in cached status, as this
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28 /// is what preamble stores.
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29 ///
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30 /// The cache is not thread-safe when updates happen, so the use pattern should
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31 /// be:
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32 /// - One FS writes to the cache from one thread (or several but strictly
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33 /// sequenced), e.g. when building preamble.
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34 /// - Sequence point (no writes after this point, no reads before).
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35 /// - Several FSs can read from the cache, e.g. code completions.
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36 ///
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37 /// Note that the cache is only valid when reusing preamble.
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38 class PreambleFileStatusCache {
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39 public:
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40 /// \p MainFilePath is the absolute path of the main source file this preamble
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41 /// corresponds to. The stat for the main file will not be cached.
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42 PreambleFileStatusCache(llvm::StringRef MainFilePath);
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43
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44 void update(const llvm::vfs::FileSystem &FS, llvm::vfs::Status S);
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45
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46 /// \p Path is a path stored in preamble.
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47 llvm::Optional<llvm::vfs::Status> lookup(llvm::StringRef Path) const;
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48
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49 /// Returns a VFS that collects file status.
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50 /// Only cache stats for files that exist because
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51 /// 1) we only care about existing files when reusing preamble, unlike
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52 /// building preamble.
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53 /// 2) we use the file name in the Status as the cache key.
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54 ///
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55 /// Note that the returned VFS should not outlive the cache.
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56 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
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57 getProducingFS(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS);
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58
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59 /// Returns a VFS that uses the cache collected.
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60 ///
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61 /// Note that the returned VFS should not outlive the cache.
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62 IntrusiveRefCntPtr<llvm::vfs::FileSystem>
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63 getConsumingFS(IntrusiveRefCntPtr<llvm::vfs::FileSystem> FS) const;
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64
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65 private:
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66 std::string MainFilePath;
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67 llvm::StringMap<llvm::vfs::Status> StatCache;
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68 };
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69
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70 /// Returns a version of \p File that doesn't contain dots and dot dots.
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71 /// e.g /a/b/../c -> /a/c
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72 /// /a/b/./c -> /a/b/c
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73 /// FIXME: We should avoid encountering such paths in clangd internals by
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74 /// filtering everything we get over LSP, CDB, etc.
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75 Path removeDots(PathRef File);
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76
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77 } // namespace clangd
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78 } // namespace clang
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79
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80 #endif // LLVM_CLANG_TOOLS_EXTRA_CLANGD_FS_H
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