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llvm-mirror/include/llvm/Support/CachePruning.h
Mehdi Amini 551d8a88ab Add Cache Pruning support
Incremental LTO will usea cache to store object files.
This patch handles the pruning part of the cache, exposing
a few knobs:

- Pruning interval: the implementation keeps a "timestamp" file in the
  directory and will scan it only after a given interval since the
  last modification of the timestamp file. This is for performance
  purpose, we don't want to scan continuously the folder.
- Entry expiration: this is the time after which a file that hasn't
  been used is remove from the cache.
- Maximum size: expressed in percentage of the available disk space,
  it helps to avoid that we blow up the disk space.

http://reviews.llvm.org/D18422

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 265209
2016-04-02 03:28:26 +00:00

69 lines
2.3 KiB
C++

//=- 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"
namespace llvm {
/// Handle pruning a directory provided a path and some options to control what
/// to prune.
class CachePruning {
public:
/// Prepare to prune \p Path.
CachePruning(StringRef Path) : Path(Path) {}
/// Define 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 occurs.
CachePruning &setPruningInterval(int PruningInterval) {
Interval = PruningInterval;
return *this;
}
/// Define the expiration for a file. When a file hasn't been accessed for
/// \p ExpireAfter seconds, it is removed from the cache. A value of 0 disable
/// the expiration-based pruning.
CachePruning &setEntryExpiration(unsigned ExpireAfter) {
Expiration = ExpireAfter;
return *this;
}
/// Define 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 disable the size-based pruning.
CachePruning &setMaxSize(unsigned Percentage) {
PercentageOfAvailableSpace = std::min(100u, Percentage);
return *this;
}
/// Peform pruning using the supplied options, returns true if pruning
/// occured, i.e. if PruningInterval was expired.
bool prune();
private:
// Options that matches the setters above.
std::string Path;
unsigned Expiration = 0;
unsigned Interval = 0;
unsigned PercentageOfAvailableSpace = 0;
};
} // namespace llvm
#endif