1 //=- CachePruning.h - Helper to manage the pruning of a cache dir -*- C++ -*-=//
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 pruning of a directory intended for cache storage, using
13 //===----------------------------------------------------------------------===//
15 #ifndef LLVM_SUPPORT_CACHE_PRUNING_H
16 #define LLVM_SUPPORT_CACHE_PRUNING_H
18 #include "llvm/ADT/StringRef.h"
23 template <typename T> class Expected;
25 /// Policy for the pruneCache() function. A default constructed
26 /// CachePruningPolicy provides a reasonable default policy.
27 struct CachePruningPolicy {
28 /// The pruning interval. This is intended to be used to avoid scanning the
29 /// directory too often. It does not impact the decision of which file to
30 /// prune. A value of 0 forces the scan to occur.
31 std::chrono::seconds Interval = std::chrono::seconds(1200);
33 /// The expiration for a file. When a file hasn't been accessed for Expiration
34 /// seconds, it is removed from the cache. A value of 0 disables the
35 /// expiration-based pruning.
36 std::chrono::seconds Expiration = std::chrono::hours(7 * 24); // 1w
38 /// The maximum size for the cache directory, in terms of percentage of the
39 /// available space on the the disk. Set to 100 to indicate no limit, 50 to
40 /// indicate that the cache size will not be left over half the available disk
41 /// space. A value over 100 will be reduced to 100. A value of 0 disables the
42 /// percentage size-based pruning.
43 unsigned MaxSizePercentageOfAvailableSpace = 75;
45 /// The maximum size for the cache directory in bytes. A value over the amount
46 /// of available space on the disk will be reduced to the amount of available
47 /// space. A value of 0 disables the absolute size-based pruning.
48 uint64_t MaxSizeBytes = 0;
51 /// Parse the given string as a cache pruning policy. Defaults are taken from a
52 /// default constructed CachePruningPolicy object.
53 /// For example: "prune_interval=30s:prune_after=24h:cache_size=50%"
54 /// which means a pruning interval of 30 seconds, expiration time of 24 hours
55 /// and maximum cache size of 50% of available disk space.
56 Expected<CachePruningPolicy> parseCachePruningPolicy(StringRef PolicyStr);
58 /// Peform pruning using the supplied policy, returns true if pruning
59 /// occured, i.e. if Policy.Interval was expired.
61 /// As a safeguard against data loss if the user specifies the wrong directory
62 /// as their cache directory, this function will ignore files not matching the
63 /// pattern "llvmcache-*".
64 bool pruneCache(StringRef Path, CachePruningPolicy Policy);