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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
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