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llvm-mirror/include/llvm/Support/CachePruning.h
Peter Collingbourne 29463000bd Add a ThinLTO cache policy for controlling the maximum cache size in bytes.
This is useful when an upper limit on the cache size needs to be
controlled independently of the amount of the amount of free space.

One use case is a machine with a large number of cache directories
(e.g. a buildbot slave hosting a large number of independent build
jobs). By imposing an upper size limit on each cache directory,
users can more easily estimate the server's capacity.

Differential Revision: https://reviews.llvm.org/D34547

llvm-svn: 306126
2017-06-23 17:05:03 +00:00

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2.8 KiB
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//=- CachePruning.h - Helper to manage the pruning of a cache dir -*- C++ -*-=//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements pruning of a directory intended for cache storage, using
// various policies.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_SUPPORT_CACHE_PRUNING_H
#define LLVM_SUPPORT_CACHE_PRUNING_H
#include "llvm/ADT/StringRef.h"
#include <chrono>
namespace llvm {
template <typename T> class Expected;
/// Policy for the pruneCache() function. A default constructed
/// CachePruningPolicy provides a reasonable default policy.
struct CachePruningPolicy {
/// The pruning interval. This is intended to be used to avoid scanning the
/// directory too often. It does not impact the decision of which file to
/// prune. A value of 0 forces the scan to occur.
std::chrono::seconds Interval = std::chrono::seconds(1200);
/// The expiration for a file. When a file hasn't been accessed for Expiration
/// seconds, it is removed from the cache. A value of 0 disables the
/// expiration-based pruning.
std::chrono::seconds Expiration = std::chrono::hours(7 * 24); // 1w
/// The maximum size for the cache directory, in terms of percentage of the
/// available space on the the disk. Set to 100 to indicate no limit, 50 to
/// indicate that the cache size will not be left over half the available disk
/// space. A value over 100 will be reduced to 100. A value of 0 disables the
/// percentage size-based pruning.
unsigned MaxSizePercentageOfAvailableSpace = 75;
/// The maximum size for the cache directory in bytes. A value over the amount
/// of available space on the disk will be reduced to the amount of available
/// space. A value of 0 disables the absolute size-based pruning.
uint64_t MaxSizeBytes = 0;
};
/// Parse the given string as a cache pruning policy. Defaults are taken from a
/// default constructed CachePruningPolicy object.
/// For example: "prune_interval=30s:prune_after=24h:cache_size=50%"
/// which means a pruning interval of 30 seconds, expiration time of 24 hours
/// and maximum cache size of 50% of available disk space.
Expected<CachePruningPolicy> parseCachePruningPolicy(StringRef PolicyStr);
/// Peform pruning using the supplied policy, returns true if pruning
/// occured, i.e. if Policy.Interval was expired.
///
/// As a safeguard against data loss if the user specifies the wrong directory
/// as their cache directory, this function will ignore files not matching the
/// pattern "llvmcache-*".
bool pruneCache(StringRef Path, CachePruningPolicy Policy);
} // namespace llvm
#endif