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/SmallString.h"
14 #include "llvm/ADT/StringRef.h"
15 #include "llvm/Support/Error.h"
16 #include "llvm/Support/FileSystem.h"
17 #include "llvm/Support/MemoryBuffer.h"
18 #include "llvm/Support/Path.h"
19 #include "llvm/Support/raw_ostream.h"
20 #include <functional>
21 #include <optional>
22
23 namespace clang {
24 namespace clangd {
25 namespace {
26
getShardPathFromFilePath(llvm::StringRef ShardRoot,llvm::StringRef FilePath)27 std::string getShardPathFromFilePath(llvm::StringRef ShardRoot,
28 llvm::StringRef FilePath) {
29 llvm::SmallString<128> ShardRootSS(ShardRoot);
30 llvm::sys::path::append(ShardRootSS, llvm::sys::path::filename(FilePath) +
31 "." + llvm::toHex(digest(FilePath)) +
32 ".idx");
33 return std::string(ShardRootSS);
34 }
35
36 // Uses disk as a storage for index shards.
37 class DiskBackedIndexStorage : public BackgroundIndexStorage {
38 std::string DiskShardRoot;
39
40 public:
41 // Creates `DiskShardRoot` and any parents during construction.
DiskBackedIndexStorage(llvm::StringRef Directory)42 DiskBackedIndexStorage(llvm::StringRef Directory) : DiskShardRoot(Directory) {
43 std::error_code OK;
44 std::error_code EC = llvm::sys::fs::create_directories(DiskShardRoot);
45 if (EC != OK) {
46 elog("Failed to create directory {0} for index storage: {1}",
47 DiskShardRoot, EC.message());
48 }
49 }
50
51 std::unique_ptr<IndexFileIn>
loadShard(llvm::StringRef ShardIdentifier) const52 loadShard(llvm::StringRef ShardIdentifier) const override {
53 const std::string ShardPath =
54 getShardPathFromFilePath(DiskShardRoot, ShardIdentifier);
55 auto Buffer = llvm::MemoryBuffer::getFile(ShardPath);
56 if (!Buffer)
57 return nullptr;
58 if (auto I =
59 readIndexFile(Buffer->get()->getBuffer(), SymbolOrigin::Background))
60 return std::make_unique<IndexFileIn>(std::move(*I));
61 else
62 elog("Error while reading shard {0}: {1}", ShardIdentifier,
63 I.takeError());
64 return nullptr;
65 }
66
storeShard(llvm::StringRef ShardIdentifier,IndexFileOut Shard) const67 llvm::Error storeShard(llvm::StringRef ShardIdentifier,
68 IndexFileOut Shard) const override {
69 auto ShardPath = getShardPathFromFilePath(DiskShardRoot, ShardIdentifier);
70 return llvm::writeToOutput(ShardPath, [&Shard](llvm::raw_ostream &OS) {
71 OS << Shard;
72 return llvm::Error::success();
73 });
74 }
75 };
76
77 // Doesn't persist index shards anywhere (used when the CDB dir is unknown).
78 // We could consider indexing into ~/.clangd/ or so instead.
79 class NullStorage : public BackgroundIndexStorage {
80 public:
81 std::unique_ptr<IndexFileIn>
loadShard(llvm::StringRef ShardIdentifier) const82 loadShard(llvm::StringRef ShardIdentifier) const override {
83 return nullptr;
84 }
85
storeShard(llvm::StringRef ShardIdentifier,IndexFileOut Shard) const86 llvm::Error storeShard(llvm::StringRef ShardIdentifier,
87 IndexFileOut Shard) const override {
88 vlog("Couldn't find project for {0}, indexing in-memory only",
89 ShardIdentifier);
90 return llvm::Error::success();
91 }
92 };
93
94 // Creates and owns IndexStorages for multiple CDBs.
95 // When a CDB root is found, shards are stored in $ROOT/.cache/clangd/index/.
96 // When no root is found, the fallback path is ~/.cache/clangd/index/.
97 class DiskBackedIndexStorageManager {
98 public:
DiskBackedIndexStorageManager(std::function<std::optional<ProjectInfo> (PathRef)> GetProjectInfo)99 DiskBackedIndexStorageManager(
100 std::function<std::optional<ProjectInfo>(PathRef)> GetProjectInfo)
101 : IndexStorageMapMu(std::make_unique<std::mutex>()),
102 GetProjectInfo(std::move(GetProjectInfo)) {
103 llvm::SmallString<128> FallbackDir;
104 if (llvm::sys::path::cache_directory(FallbackDir))
105 llvm::sys::path::append(FallbackDir, "clangd", "index");
106 this->FallbackDir = FallbackDir.str().str();
107 }
108
109 // Creates or fetches to storage from cache for the specified project.
operator ()(PathRef File)110 BackgroundIndexStorage *operator()(PathRef File) {
111 std::lock_guard<std::mutex> Lock(*IndexStorageMapMu);
112 llvm::SmallString<128> StorageDir(FallbackDir);
113 if (auto PI = GetProjectInfo(File)) {
114 StorageDir = PI->SourceRoot;
115 llvm::sys::path::append(StorageDir, ".cache", "clangd", "index");
116 }
117 auto &IndexStorage = IndexStorageMap[StorageDir];
118 if (!IndexStorage)
119 IndexStorage = create(StorageDir);
120 return IndexStorage.get();
121 }
122
123 private:
create(PathRef CDBDirectory)124 std::unique_ptr<BackgroundIndexStorage> create(PathRef CDBDirectory) {
125 if (CDBDirectory.empty()) {
126 elog("Tried to create storage for empty directory!");
127 return std::make_unique<NullStorage>();
128 }
129 return std::make_unique<DiskBackedIndexStorage>(CDBDirectory);
130 }
131
132 Path FallbackDir;
133
134 llvm::StringMap<std::unique_ptr<BackgroundIndexStorage>> IndexStorageMap;
135 std::unique_ptr<std::mutex> IndexStorageMapMu;
136
137 std::function<std::optional<ProjectInfo>(PathRef)> GetProjectInfo;
138 };
139
140 } // namespace
141
142 BackgroundIndexStorage::Factory
createDiskBackedStorageFactory(std::function<std::optional<ProjectInfo> (PathRef)> GetProjectInfo)143 BackgroundIndexStorage::createDiskBackedStorageFactory(
144 std::function<std::optional<ProjectInfo>(PathRef)> GetProjectInfo) {
145 return DiskBackedIndexStorageManager(std::move(GetProjectInfo));
146 }
147
148 } // namespace clangd
149 } // namespace clang
150