1 //===-CachePruning.cpp - LLVM Cache Directory Pruning ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the pruning of a directory based on least recently used.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Support/CachePruning.h"
16 #include "llvm/Support/Debug.h"
17 #include "llvm/Support/Errc.h"
18 #include "llvm/Support/Error.h"
19 #include "llvm/Support/FileSystem.h"
20 #include "llvm/Support/Path.h"
21 #include "llvm/Support/raw_ostream.h"
23 #define DEBUG_TYPE "cache-pruning"
26 #include <system_error>
30 /// Write a new timestamp file with the given path. This is used for the pruning
32 static void writeTimestampFile(StringRef TimestampFile) {
34 raw_fd_ostream Out(TimestampFile.str(), EC, sys::fs::F_None);
37 static Expected<std::chrono::seconds> parseDuration(StringRef Duration) {
39 return make_error<StringError>("Duration must not be empty",
40 inconvertibleErrorCode());
42 StringRef NumStr = Duration.slice(0, Duration.size()-1);
44 if (NumStr.getAsInteger(0, Num))
45 return make_error<StringError>("'" + NumStr + "' not an integer",
46 inconvertibleErrorCode());
48 switch (Duration.back()) {
50 return std::chrono::seconds(Num);
52 return std::chrono::minutes(Num);
54 return std::chrono::hours(Num);
56 return make_error<StringError>("'" + Duration +
57 "' must end with one of 's', 'm' or 'h'",
58 inconvertibleErrorCode());
62 Expected<CachePruningPolicy>
63 llvm::parseCachePruningPolicy(StringRef PolicyStr) {
64 CachePruningPolicy Policy;
65 std::pair<StringRef, StringRef> P = {"", PolicyStr};
66 while (!P.second.empty()) {
67 P = P.second.split(':');
70 std::tie(Key, Value) = P.first.split('=');
71 if (Key == "prune_interval") {
72 auto DurationOrErr = parseDuration(Value);
74 return DurationOrErr.takeError();
75 Policy.Interval = *DurationOrErr;
76 } else if (Key == "prune_after") {
77 auto DurationOrErr = parseDuration(Value);
79 return DurationOrErr.takeError();
80 Policy.Expiration = *DurationOrErr;
81 } else if (Key == "cache_size") {
82 if (Value.back() != '%')
83 return make_error<StringError>("'" + Value + "' must be a percentage",
84 inconvertibleErrorCode());
85 StringRef SizeStr = Value.drop_back();
87 if (SizeStr.getAsInteger(0, Size))
88 return make_error<StringError>("'" + SizeStr + "' not an integer",
89 inconvertibleErrorCode());
91 return make_error<StringError>("'" + SizeStr +
92 "' must be between 0 and 100",
93 inconvertibleErrorCode());
94 Policy.MaxSizePercentageOfAvailableSpace = Size;
95 } else if (Key == "cache_size_bytes") {
97 switch (tolower(Value.back())) {
100 Value = Value.drop_back();
104 Value = Value.drop_back();
107 Mult = 1024 * 1024 * 1024;
108 Value = Value.drop_back();
112 if (Value.getAsInteger(0, Size))
113 return make_error<StringError>("'" + Value + "' not an integer",
114 inconvertibleErrorCode());
115 Policy.MaxSizeBytes = Size * Mult;
116 } else if (Key == "cache_size_files") {
117 if (Value.getAsInteger(0, Policy.MaxSizeFiles))
118 return make_error<StringError>("'" + Value + "' not an integer",
119 inconvertibleErrorCode());
121 return make_error<StringError>("Unknown key: '" + Key + "'",
122 inconvertibleErrorCode());
129 /// Prune the cache of files that haven't been accessed in a long time.
130 bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
131 using namespace std::chrono;
137 if (sys::fs::is_directory(Path, isPathDir))
143 Policy.MaxSizePercentageOfAvailableSpace =
144 std::min(Policy.MaxSizePercentageOfAvailableSpace, 100u);
146 if (Policy.Expiration == seconds(0) &&
147 Policy.MaxSizePercentageOfAvailableSpace == 0 &&
148 Policy.MaxSizeBytes == 0 && Policy.MaxSizeFiles == 0) {
149 LLVM_DEBUG(dbgs() << "No pruning settings set, exit early\n");
150 // Nothing will be pruned, early exit
154 // Try to stat() the timestamp file.
155 SmallString<128> TimestampFile(Path);
156 sys::path::append(TimestampFile, "llvmcache.timestamp");
157 sys::fs::file_status FileStatus;
158 const auto CurrentTime = system_clock::now();
159 if (auto EC = sys::fs::status(TimestampFile, FileStatus)) {
160 if (EC == errc::no_such_file_or_directory) {
161 // If the timestamp file wasn't there, create one now.
162 writeTimestampFile(TimestampFile);
168 if (!Policy.Interval)
170 if (Policy.Interval != seconds(0)) {
171 // Check whether the time stamp is older than our pruning interval.
172 // If not, do nothing.
173 const auto TimeStampModTime = FileStatus.getLastModificationTime();
174 auto TimeStampAge = CurrentTime - TimeStampModTime;
175 if (TimeStampAge <= *Policy.Interval) {
176 LLVM_DEBUG(dbgs() << "Timestamp file too recent ("
177 << duration_cast<seconds>(TimeStampAge).count()
178 << "s old), do not prune.\n");
182 // Write a new timestamp file so that nobody else attempts to prune.
183 // There is a benign race condition here, if two processes happen to
184 // notice at the same time that the timestamp is out-of-date.
185 writeTimestampFile(TimestampFile);
188 // Keep track of space. Needs to be kept ordered by size for determinism.
189 std::set<std::pair<uint64_t, std::string>> FileSizes;
190 uint64_t TotalSize = 0;
192 // Walk the entire directory cache, looking for unused files.
194 SmallString<128> CachePathNative;
195 sys::path::native(Path, CachePathNative);
196 // Walk all of the files within this directory.
197 for (sys::fs::directory_iterator File(CachePathNative, EC), FileEnd;
198 File != FileEnd && !EC; File.increment(EC)) {
199 // Ignore any files not beginning with the string "llvmcache-". This
200 // includes the timestamp file as well as any files created by the user.
201 // This acts as a safeguard against data loss if the user specifies the
202 // wrong directory as their cache directory.
203 if (!sys::path::filename(File->path()).startswith("llvmcache-"))
206 // Look at this file. If we can't stat it, there's nothing interesting
208 ErrorOr<sys::fs::basic_file_status> StatusOrErr = File->status();
210 LLVM_DEBUG(dbgs() << "Ignore " << File->path() << " (can't stat)\n");
214 // If the file hasn't been used recently enough, delete it
215 const auto FileAccessTime = StatusOrErr->getLastAccessedTime();
216 auto FileAge = CurrentTime - FileAccessTime;
217 if (Policy.Expiration != seconds(0) && FileAge > Policy.Expiration) {
218 LLVM_DEBUG(dbgs() << "Remove " << File->path() << " ("
219 << duration_cast<seconds>(FileAge).count()
221 sys::fs::remove(File->path());
225 // Leave it here for now, but add it to the list of size-based pruning.
226 TotalSize += StatusOrErr->getSize();
227 FileSizes.insert({StatusOrErr->getSize(), std::string(File->path())});
230 auto FileAndSize = FileSizes.rbegin();
231 size_t NumFiles = FileSizes.size();
233 auto RemoveCacheFile = [&]() {
235 sys::fs::remove(FileAndSize->second);
237 TotalSize -= FileAndSize->first;
239 LLVM_DEBUG(dbgs() << " - Remove " << FileAndSize->second << " (size "
240 << FileAndSize->first << "), new occupancy is "
241 << TotalSize << "%\n");
245 // Prune for number of files.
246 if (Policy.MaxSizeFiles)
247 while (NumFiles > Policy.MaxSizeFiles)
250 // Prune for size now if needed
251 if (Policy.MaxSizePercentageOfAvailableSpace > 0 || Policy.MaxSizeBytes > 0) {
252 auto ErrOrSpaceInfo = sys::fs::disk_space(Path);
253 if (!ErrOrSpaceInfo) {
254 report_fatal_error("Can't get available size");
256 sys::fs::space_info SpaceInfo = ErrOrSpaceInfo.get();
257 auto AvailableSpace = TotalSize + SpaceInfo.free;
259 if (Policy.MaxSizePercentageOfAvailableSpace == 0)
260 Policy.MaxSizePercentageOfAvailableSpace = 100;
261 if (Policy.MaxSizeBytes == 0)
262 Policy.MaxSizeBytes = AvailableSpace;
263 auto TotalSizeTarget = std::min<uint64_t>(
264 AvailableSpace * Policy.MaxSizePercentageOfAvailableSpace / 100ull,
265 Policy.MaxSizeBytes);
267 LLVM_DEBUG(dbgs() << "Occupancy: " << ((100 * TotalSize) / AvailableSpace)
269 << Policy.MaxSizePercentageOfAvailableSpace << "%, "
270 << Policy.MaxSizeBytes << " bytes\n");
272 // Remove the oldest accessed files first, till we get below the threshold.
273 while (TotalSize > TotalSizeTarget && FileAndSize != FileSizes.rend())