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/FileSystem.h"
19 #include "llvm/Support/Path.h"
20 #include "llvm/Support/raw_ostream.h"
22 #define DEBUG_TYPE "cache-pruning"
25 #include <system_error>
29 /// Write a new timestamp file with the given path. This is used for the pruning
31 static void writeTimestampFile(StringRef TimestampFile) {
33 raw_fd_ostream Out(TimestampFile.str(), EC, sys::fs::F_None);
36 /// Prune the cache of files that haven't been accessed in a long time.
37 bool CachePruning::prune() {
38 using namespace std::chrono;
44 if (sys::fs::is_directory(Path, isPathDir))
50 if (Expiration == seconds(0) && PercentageOfAvailableSpace == 0) {
51 DEBUG(dbgs() << "No pruning settings set, exit early\n");
52 // Nothing will be pruned, early exit
56 // Try to stat() the timestamp file.
57 SmallString<128> TimestampFile(Path);
58 sys::path::append(TimestampFile, "llvmcache.timestamp");
59 sys::fs::file_status FileStatus;
60 const auto CurrentTime = system_clock::now();
61 if (auto EC = sys::fs::status(TimestampFile, FileStatus)) {
62 if (EC == errc::no_such_file_or_directory) {
63 // If the timestamp file wasn't there, create one now.
64 writeTimestampFile(TimestampFile);
70 if (Interval == seconds(0)) {
71 // Check whether the time stamp is older than our pruning interval.
72 // If not, do nothing.
73 const auto TimeStampModTime = FileStatus.getLastModificationTime();
74 auto TimeStampAge = CurrentTime - TimeStampModTime;
75 if (TimeStampAge <= Interval) {
76 DEBUG(dbgs() << "Timestamp file too recent ("
77 << duration_cast<seconds>(TimeStampAge).count()
78 << "s old), do not prune.\n");
82 // Write a new timestamp file so that nobody else attempts to prune.
83 // There is a benign race condition here, if two processes happen to
84 // notice at the same time that the timestamp is out-of-date.
85 writeTimestampFile(TimestampFile);
88 bool ShouldComputeSize = (PercentageOfAvailableSpace > 0);
90 // Keep track of space
91 std::set<std::pair<uint64_t, std::string>> FileSizes;
92 uint64_t TotalSize = 0;
93 // Helper to add a path to the set of files to consider for size-based
94 // pruning, sorted by size.
95 auto AddToFileListForSizePruning =
97 if (!ShouldComputeSize)
99 TotalSize += FileStatus.getSize();
101 std::make_pair(FileStatus.getSize(), std::string(Path)));
104 // Walk the entire directory cache, looking for unused files.
106 SmallString<128> CachePathNative;
107 sys::path::native(Path, CachePathNative);
108 // Walk all of the files within this directory.
109 for (sys::fs::directory_iterator File(CachePathNative, EC), FileEnd;
110 File != FileEnd && !EC; File.increment(EC)) {
111 // Do not touch the timestamp.
112 if (File->path() == TimestampFile)
115 // Look at this file. If we can't stat it, there's nothing interesting
117 if (sys::fs::status(File->path(), FileStatus)) {
118 DEBUG(dbgs() << "Ignore " << File->path() << " (can't stat)\n");
122 // If the file hasn't been used recently enough, delete it
123 const auto FileAccessTime = FileStatus.getLastAccessedTime();
124 auto FileAge = CurrentTime - FileAccessTime;
125 if (FileAge > Expiration) {
126 DEBUG(dbgs() << "Remove " << File->path() << " ("
127 << duration_cast<seconds>(FileAge).count() << "s old)\n");
128 sys::fs::remove(File->path());
132 // Leave it here for now, but add it to the list of size-based pruning.
133 AddToFileListForSizePruning(File->path());
136 // Prune for size now if needed
137 if (ShouldComputeSize) {
138 auto ErrOrSpaceInfo = sys::fs::disk_space(Path);
139 if (!ErrOrSpaceInfo) {
140 report_fatal_error("Can't get available size");
142 sys::fs::space_info SpaceInfo = ErrOrSpaceInfo.get();
143 auto AvailableSpace = TotalSize + SpaceInfo.free;
144 auto FileAndSize = FileSizes.rbegin();
145 DEBUG(dbgs() << "Occupancy: " << ((100 * TotalSize) / AvailableSpace)
146 << "% target is: " << PercentageOfAvailableSpace << "\n");
147 // Remove the oldest accessed files first, till we get below the threshold
148 while (((100 * TotalSize) / AvailableSpace) > PercentageOfAvailableSpace &&
149 FileAndSize != FileSizes.rend()) {
151 sys::fs::remove(FileAndSize->second);
153 TotalSize -= FileAndSize->first;
154 DEBUG(dbgs() << " - Remove " << FileAndSize->second << " (size "
155 << FileAndSize->first << "), new occupancy is " << TotalSize