clang-tools  12.0.0git
BackgroundIndexStorage.cpp
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1 //== BackgroundIndexStorage.cpp - Provide caching support to BackgroundIndex ==/
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 
10 #include "index/Background.h"
11 #include "support/Logger.h"
12 #include "support/Path.h"
13 #include "llvm/ADT/Optional.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/ADT/ScopeExit.h"
16 #include "llvm/ADT/SmallString.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/Support/Error.h"
20 #include "llvm/Support/FileSystem.h"
21 #include "llvm/Support/FileUtilities.h"
22 #include "llvm/Support/MemoryBuffer.h"
23 #include "llvm/Support/Path.h"
24 #include <functional>
25 
26 namespace clang {
27 namespace clangd {
28 namespace {
29 
30 std::string getShardPathFromFilePath(llvm::StringRef ShardRoot,
31  llvm::StringRef FilePath) {
32  llvm::SmallString<128> ShardRootSS(ShardRoot);
33  llvm::sys::path::append(ShardRootSS, llvm::sys::path::filename(FilePath) +
34  "." + llvm::toHex(digest(FilePath)) +
35  ".idx");
36  return std::string(ShardRootSS.str());
37 }
38 
39 // Uses disk as a storage for index shards.
40 class DiskBackedIndexStorage : public BackgroundIndexStorage {
41  std::string DiskShardRoot;
42 
43 public:
44  // Creates `DiskShardRoot` and any parents during construction.
45  DiskBackedIndexStorage(llvm::StringRef Directory) : DiskShardRoot(Directory) {
46  std::error_code OK;
47  std::error_code EC = llvm::sys::fs::create_directories(DiskShardRoot);
48  if (EC != OK) {
49  elog("Failed to create directory {0} for index storage: {1}",
50  DiskShardRoot, EC.message());
51  }
52  }
53 
54  std::unique_ptr<IndexFileIn>
55  loadShard(llvm::StringRef ShardIdentifier) const override {
56  const std::string ShardPath =
57  getShardPathFromFilePath(DiskShardRoot, ShardIdentifier);
58  auto Buffer = llvm::MemoryBuffer::getFile(ShardPath);
59  if (!Buffer)
60  return nullptr;
61  if (auto I = readIndexFile(Buffer->get()->getBuffer()))
62  return std::make_unique<IndexFileIn>(std::move(*I));
63  else
64  elog("Error while reading shard {0}: {1}", ShardIdentifier,
65  I.takeError());
66  return nullptr;
67  }
68 
69  llvm::Error storeShard(llvm::StringRef ShardIdentifier,
70  IndexFileOut Shard) const override {
71  auto ShardPath = getShardPathFromFilePath(DiskShardRoot, ShardIdentifier);
72  return llvm::writeFileAtomically(ShardPath + ".tmp.%%%%%%%%", ShardPath,
73  [&Shard](llvm::raw_ostream &OS) {
74  OS << Shard;
75  return llvm::Error::success();
76  });
77  }
78 };
79 
80 // Doesn't persist index shards anywhere (used when the CDB dir is unknown).
81 // We could consider indexing into ~/.clangd/ or so instead.
82 class NullStorage : public BackgroundIndexStorage {
83 public:
84  std::unique_ptr<IndexFileIn>
85  loadShard(llvm::StringRef ShardIdentifier) const override {
86  return nullptr;
87  }
88 
89  llvm::Error storeShard(llvm::StringRef ShardIdentifier,
90  IndexFileOut Shard) const override {
91  vlog("Couldn't find project for {0}, indexing in-memory only",
92  ShardIdentifier);
93  return llvm::Error::success();
94  }
95 };
96 
97 // Creates and owns IndexStorages for multiple CDBs.
98 // When a CDB root is found, shards are stored in $ROOT/.cache/clangd/index/.
99 // When no root is found, the fallback path is ~/.cache/clangd/index/.
100 class DiskBackedIndexStorageManager {
101 public:
102  DiskBackedIndexStorageManager(
103  std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo)
104  : IndexStorageMapMu(std::make_unique<std::mutex>()),
105  GetProjectInfo(std::move(GetProjectInfo)) {
106  llvm::SmallString<128> FallbackDir;
107  if (llvm::sys::path::cache_directory(FallbackDir))
108  llvm::sys::path::append(FallbackDir, "clangd", "index");
109  this->FallbackDir = FallbackDir.str().str();
110  }
111 
112  // Creates or fetches to storage from cache for the specified project.
113  BackgroundIndexStorage *operator()(PathRef File) {
114  std::lock_guard<std::mutex> Lock(*IndexStorageMapMu);
115  llvm::SmallString<128> StorageDir(FallbackDir);
116  if (auto PI = GetProjectInfo(File)) {
117  StorageDir = PI->SourceRoot;
118  llvm::sys::path::append(StorageDir, ".cache", "clangd", "index");
119  }
120  auto &IndexStorage = IndexStorageMap[StorageDir];
121  if (!IndexStorage)
122  IndexStorage = create(StorageDir);
123  return IndexStorage.get();
124  }
125 
126 private:
127  std::unique_ptr<BackgroundIndexStorage> create(PathRef CDBDirectory) {
128  if (CDBDirectory.empty()) {
129  elog("Tried to create storage for empty directory!");
130  return std::make_unique<NullStorage>();
131  }
132  return std::make_unique<DiskBackedIndexStorage>(CDBDirectory);
133  }
134 
135  Path FallbackDir;
136 
137  llvm::StringMap<std::unique_ptr<BackgroundIndexStorage>> IndexStorageMap;
138  std::unique_ptr<std::mutex> IndexStorageMapMu;
139 
140  std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo;
141 };
142 
143 } // namespace
144 
147  std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo) {
148  return DiskBackedIndexStorageManager(std::move(GetProjectInfo));
149 }
150 
151 } // namespace clangd
152 } // namespace clang
llvm::unique_function< BackgroundIndexStorage *(PathRef)> Factory
Definition: Background.h:56
static Factory createDiskBackedStorageFactory(std::function< llvm::Optional< ProjectInfo >(PathRef)> GetProjectInfo)
llvm::StringRef PathRef
A typedef to represent a ref to file path.
Definition: Path.h:23
llvm::Expected< IndexFileIn > readIndexFile(llvm::StringRef Data)
void vlog(const char *Fmt, Ts &&... Vals)
Definition: Logger.h:67
void elog(const char *Fmt, Ts &&... Vals)
Definition: Logger.h:56
llvm::raw_string_ostream OS
Definition: TraceTests.cpp:162
std::string Path
A typedef to represent a file path.
Definition: Path.h:20
llvm::StringRef Directory
FileDigest digest(llvm::StringRef Content)
Definition: SourceCode.cpp:560
===– Representation.cpp - ClangDoc Representation --------—*- C++ -*-===//