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
9 #include "GlobalCompilationDatabase.h"
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
getShardPathFromFilePath(llvm::StringRef ShardRoot,llvm::StringRef FilePath)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.
DiskBackedIndexStorage(llvm::StringRef Directory)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>
loadShard(llvm::StringRef ShardIdentifier) const55 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
storeShard(llvm::StringRef ShardIdentifier,IndexFileOut Shard) const69 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>
loadShard(llvm::StringRef ShardIdentifier) const85 loadShard(llvm::StringRef ShardIdentifier) const override {
86 return nullptr;
87 }
88
storeShard(llvm::StringRef ShardIdentifier,IndexFileOut Shard) const89 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:
DiskBackedIndexStorageManager(std::function<llvm::Optional<ProjectInfo> (PathRef)> GetProjectInfo)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.
operator ()(PathRef File)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:
create(PathRef CDBDirectory)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
145 BackgroundIndexStorage::Factory
createDiskBackedStorageFactory(std::function<llvm::Optional<ProjectInfo> (PathRef)> GetProjectInfo)146 BackgroundIndexStorage::createDiskBackedStorageFactory(
147 std::function<llvm::Optional<ProjectInfo>(PathRef)> GetProjectInfo) {
148 return DiskBackedIndexStorageManager(std::move(GetProjectInfo));
149 }
150
151 } // namespace clangd
152 } // namespace clang
153