clang-tools-extra/clangd/ConfigProvider.cpp

   1 //===--- ConfigProvider.cpp - Loading of user configuration ---------------===//
   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 #include "ConfigProvider.h"
  10 #include "Config.h"
  11 #include "ConfigFragment.h"
  12 #include "support/FileCache.h"
  13 #include "support/Path.h"
  14 #include "support/ThreadsafeFS.h"
  15 #include "support/Trace.h"
  16 #include "llvm/ADT/STLExtras.h"
  17 #include "llvm/ADT/StringMap.h"
  18 #include "llvm/ADT/StringRef.h"
  19 #include "llvm/Support/Path.h"
  20 #include <chrono>
  21 #include <mutex>
  22 #include <string>
  23
  24 namespace clang {
  25 namespace clangd {
  26 namespace config {
  27
  28 // Threadsafe cache around reading a YAML config file from disk.
  29 class FileConfigCache : public FileCache {
  30   mutable llvm::SmallVector<CompiledFragment, 1> CachedValue;
  31   std::string Directory;
  32
  33 public:
  34   FileConfigCache(llvm::StringRef Path, llvm::StringRef Directory)
  35       : FileCache(Path), Directory(Directory) {}
  36
  37   void get(const ThreadsafeFS &TFS, DiagnosticCallback DC,
  38            std::chrono::steady_clock::time_point FreshTime, bool Trusted,
  39            std::vector<CompiledFragment> &Out) const {
  40     read(
  41         TFS, FreshTime,
  42         [&](llvm::Optional<llvm::StringRef> Data) {
  43           CachedValue.clear();
  44           if (Data)
  45             for (auto &Fragment : Fragment::parseYAML(*Data, path(), DC)) {
  46               Fragment.Source.Directory = Directory;
  47               Fragment.Source.Trusted = Trusted;
  48               CachedValue.push_back(std::move(Fragment).compile(DC));
  49             }
  50         },
  51         [&]() { llvm::copy(CachedValue, std::back_inserter(Out)); });
  52   }
  53 };
  54
  55 std::unique_ptr<Provider> Provider::fromYAMLFile(llvm::StringRef AbsPath,
  56                                                  llvm::StringRef Directory,
  57                                                  const ThreadsafeFS &FS,
  58                                                  bool Trusted) {
  59   class AbsFileProvider : public Provider {
  60     mutable FileConfigCache Cache; // threadsafe
  61     const ThreadsafeFS &FS;
  62     bool Trusted;
  63
  64     std::vector<CompiledFragment>
  65     getFragments(const Params &P, DiagnosticCallback DC) const override {
  66       std::vector<CompiledFragment> Result;
  67       Cache.get(FS, DC, P.FreshTime, Trusted, Result);
  68       return Result;
  69     };
  70
  71   public:
  72     AbsFileProvider(llvm::StringRef Path, llvm::StringRef Directory,
  73                     const ThreadsafeFS &FS, bool Trusted)
  74         : Cache(Path, Directory), FS(FS), Trusted(Trusted) {
  75       assert(llvm::sys::path::is_absolute(Path));
  76     }
  77   };
  78
  79   return std::make_unique<AbsFileProvider>(AbsPath, Directory, FS, Trusted);
  80 }
  81
  82 std::unique_ptr<Provider>
  83 Provider::fromAncestorRelativeYAMLFiles(llvm::StringRef RelPath,
  84                                         const ThreadsafeFS &FS, bool Trusted) {
  85   class RelFileProvider : public Provider {
  86     std::string RelPath;
  87     const ThreadsafeFS &FS;
  88     bool Trusted;
  89
  90     mutable std::mutex Mu;
  91     // Keys are the (posix-style) ancestor directory, not the config within it.
  92     // We only insert into this map, so pointers to values are stable forever.
  93     // Mutex guards the map itself, not the values (which are threadsafe).
  94     mutable llvm::StringMap<FileConfigCache> Cache;
  95
  96     std::vector<CompiledFragment>
  97     getFragments(const Params &P, DiagnosticCallback DC) const override {
  98       namespace path = llvm::sys::path;
  99
 100       if (P.Path.empty())
 101         return {};
 102
 103       // Compute absolute paths to all ancestors (substrings of P.Path).
 104       llvm::SmallVector<llvm::StringRef, 8> Ancestors;
 105       for (auto Ancestor = absoluteParent(P.Path); !Ancestor.empty();
 106            Ancestor = absoluteParent(Ancestor)) {
 107         Ancestors.emplace_back(Ancestor);
 108       }
 109       // Ensure corresponding cache entries exist in the map.
 110       llvm::SmallVector<FileConfigCache *, 8> Caches;
 111       {
 112         std::lock_guard<std::mutex> Lock(Mu);
 113         for (llvm::StringRef Ancestor : Ancestors) {
 114           auto It = Cache.find(Ancestor);
 115           // Assemble the actual config file path only once.
 116           if (It == Cache.end()) {
 117             llvm::SmallString<256> ConfigPath = Ancestor;
 118             path::append(ConfigPath, RelPath);
 119             // Use native slashes for reading the file, affects diagnostics.
 120             llvm::sys::path::native(ConfigPath);
 121             It = Cache.try_emplace(Ancestor, ConfigPath.str(), Ancestor).first;
 122           }
 123           Caches.push_back(&It->second);
 124         }
 125       }
 126       // Finally query each individual file.
 127       // This will take a (per-file) lock for each file that actually exists.
 128       std::vector<CompiledFragment> Result;
 129       for (FileConfigCache *Cache : llvm::reverse(Caches))
 130         Cache->get(FS, DC, P.FreshTime, Trusted, Result);
 131       return Result;
 132     };
 133
 134   public:
 135     RelFileProvider(llvm::StringRef RelPath, const ThreadsafeFS &FS,
 136                     bool Trusted)
 137         : RelPath(RelPath), FS(FS), Trusted(Trusted) {
 138       assert(llvm::sys::path::is_relative(RelPath));
 139     }
 140   };
 141
 142   return std::make_unique<RelFileProvider>(RelPath, FS, Trusted);
 143 }
 144
 145 std::unique_ptr<Provider>
 146 Provider::combine(std::vector<const Provider *> Providers) {
 147   class CombinedProvider : public Provider {
 148     std::vector<const Provider *> Providers;
 149
 150     std::vector<CompiledFragment>
 151     getFragments(const Params &P, DiagnosticCallback DC) const override {
 152       std::vector<CompiledFragment> Result;
 153       for (const auto &Provider : Providers) {
 154         for (auto &Fragment : Provider->getFragments(P, DC))
 155           Result.push_back(std::move(Fragment));
 156       }
 157       return Result;
 158     }
 159
 160   public:
 161     CombinedProvider(std::vector<const Provider *> Providers)
 162         : Providers(std::move(Providers)) {}
 163   };
 164
 165   return std::make_unique<CombinedProvider>(std::move(Providers));
 166 }
 167
 168 Config Provider::getConfig(const Params &P, DiagnosticCallback DC) const {
 169   trace::Span Tracer("getConfig");
 170   if (!P.Path.empty())
 171     SPAN_ATTACH(Tracer, "path", P.Path);
 172   Config C;
 173   for (const auto &Fragment : getFragments(P, DC))
 174     Fragment(P, C);
 175   return C;
 176 }
 177
 178 } // namespace config
 179 } // namespace clangd
 180 } // namespace clang