Support: Simplify the CachePruning API. NFCI.

[pcc]

Summary

Change the function that implements the pruning into a free function that
takes the policy as a struct argument.

[mehdi_amini]

LGTM.

llvm/include/llvm/LTO/legacy/ThinLTOCodeGenerator.h

 
 #ifndef LLVM_LTO_THINLTOCODEGENERATOR_H
 #define LLVM_LTO_THINLTOCODEGENERATOR_H
 
 #include "llvm-c/lto.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/IR/ModuleSummaryIndex.h"
+#include "llvm/Support/CachePruning.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Target/TargetOptions.h"
 
 #include <string>
 
 namespace llvm {
 class StringRef;
public:
    *    an entry needs to be to be removed.
    *  - Finally, the garbage collector can be instructed to prune the cache till
    *    the occupied space goes below a threshold.
    * @{
    */
 
   struct CachingOptions {
     std::string Path;                    // Path to the cache, empty to disable.
-    int PruningInterval = 1200;          // seconds, -1 to disable pruning.
-    unsigned int Expiration = 7 * 24 * 3600;     // seconds (1w default).
-    unsigned MaxPercentageOfAvailableSpace = 75; // percentage.
+    CachePruningPolicy Policy;
+
+    CachingOptions() {
+      Policy.Interval = std::chrono::seconds(1200);
+      Policy.Expiration = std::chrono::hours(7 * 24); // 1w
+      Policy.PercentageOfAvailableSpace = 75;
+    };
   };
 
   /// Provide a path to a directory where to store the cached files for
   /// incremental build.
   void setCacheDir(std::string Path) { CacheOptions.Path = std::move(Path); }
 
   /// Cache policy: interval (seconds) between two prune of the cache. Set to a
   /// negative value (default) to disable pruning. A value of 0 will be ignored.
   void setCachePruningInterval(int Interval) {
     if (Interval)
-      CacheOptions.PruningInterval = Interval;
+      CacheOptions.Policy.Interval = std::chrono::seconds(Interval);
   }
 
   /// Cache policy: expiration (in seconds) for an entry.
   /// A value of 0 will be ignored.
   void setCacheEntryExpiration(unsigned Expiration) {
     if (Expiration)
-      CacheOptions.Expiration = Expiration;
+      CacheOptions.Policy.Expiration = std::chrono::seconds(Expiration);
   }
 
   /**
    * Sets the maximum cache size that can be persistent across build, 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 space. A value over 100 will be reduced to 100, and a
    * value of 0 will be ignored.
    *
    *
    * The formula looks like:
    *  AvailableSpace = FreeSpace + ExistingCacheSize
    *  NewCacheSize = AvailableSpace * P/100
    *
    */
   void setMaxCacheSizeRelativeToAvailableSpace(unsigned Percentage) {
     if (Percentage)
-      CacheOptions.MaxPercentageOfAvailableSpace = Percentage;
+      CacheOptions.Policy.PercentageOfAvailableSpace = Percentage;
   }
 
   /**@}*/
 
   /// Set the path to a directory where to save temporaries at various stages of
   /// the processing.
   void setSaveTempsDir(std::string Path) { SaveTempsDir = std::move(Path); }
 

llvm/include/llvm/Support/CachePruning.h

 #ifndef LLVM_SUPPORT_CACHE_PRUNING_H
 #define LLVM_SUPPORT_CACHE_PRUNING_H
 
 #include "llvm/ADT/StringRef.h"
 #include <chrono>
 
 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(std::chrono::seconds 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(std::chrono::seconds 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;
-  std::chrono::seconds Expiration = std::chrono::seconds::zero();
+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::zero();
+
+  /// 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::seconds::zero();
+
+  /// 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
+  /// size-based pruning.
   unsigned PercentageOfAvailableSpace = 0;
 };
 
+/// Peform pruning using the supplied policy, returns true if pruning
+/// occured, i.e. if Policy.Interval was expired.
+bool pruneCache(StringRef Path, CachePruningPolicy Policy);
+
 } // namespace llvm
 
 #endif

llvm/lib/LTO/ThinLTOCodeGenerator.cpp

for (auto IndexCount : ModulesOrdering) {
           return;
         }
         ProducedBinaryFiles[count] = writeGeneratedObject(
             count, CacheEntryPath, SavedObjectsDirectoryPath, *OutputBuffer);
       }, IndexCount);
     }
   }
 
-  CachePruning(CacheOptions.Path)
-      .setPruningInterval(std::chrono::seconds(CacheOptions.PruningInterval))
-      .setEntryExpiration(std::chrono::seconds(CacheOptions.Expiration))
-      .setMaxSize(CacheOptions.MaxPercentageOfAvailableSpace)
-      .prune();
+  pruneCache(CacheOptions.Path, CacheOptions.Policy);
 
   // If statistics were requested, print them out now.
   if (llvm::AreStatisticsEnabled())
     llvm::PrintStatistics();
 }

llvm/lib/Support/CachePruning.cpp

 /// Write a new timestamp file with the given path. This is used for the pruning
 /// interval option.
 static void writeTimestampFile(StringRef TimestampFile) {
   std::error_code EC;
   raw_fd_ostream Out(TimestampFile.str(), EC, sys::fs::F_None);
 }
 
 /// Prune the cache of files that haven't been accessed in a long time.
-bool CachePruning::prune() {
+bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
   using namespace std::chrono;
 
   if (Path.empty())
     return false;
 
   bool isPathDir;
   if (sys::fs::is_directory(Path, isPathDir))
     return false;
 
   if (!isPathDir)
     return false;
 
-  if (Expiration == seconds(0) && PercentageOfAvailableSpace == 0) {
+  Policy.PercentageOfAvailableSpace =
+      std::min(Policy.PercentageOfAvailableSpace, 100u);
+
+  if (Policy.Expiration == seconds(0) &&
+      Policy.PercentageOfAvailableSpace == 0) {
     DEBUG(dbgs() << "No pruning settings set, exit early\n");
     // Nothing will be pruned, early exit
     return false;
   }
 
   // Try to stat() the timestamp file.
   SmallString<128> TimestampFile(Path);
   sys::path::append(TimestampFile, "llvmcache.timestamp");
   sys::fs::file_status FileStatus;
   const auto CurrentTime = system_clock::now();
   if (auto EC = sys::fs::status(TimestampFile, FileStatus)) {
     if (EC == errc::no_such_file_or_directory) {
       // If the timestamp file wasn't there, create one now.
       writeTimestampFile(TimestampFile);
     } else {
       // Unknown error?
       return false;
     }
   } else {
-    if (Interval == seconds(0)) {
+    if (Policy.Interval == seconds(0)) {
       // Check whether the time stamp is older than our pruning interval.
       // If not, do nothing.
       const auto TimeStampModTime = FileStatus.getLastModificationTime();
       auto TimeStampAge = CurrentTime - TimeStampModTime;
-      if (TimeStampAge <= Interval) {
+      if (TimeStampAge <= Policy.Interval) {
         DEBUG(dbgs() << "Timestamp file too recent ("
                      << duration_cast<seconds>(TimeStampAge).count()
                      << "s old), do not prune.\n");
         return false;
       }
     }
     // Write a new timestamp file so that nobody else attempts to prune.
     // There is a benign race condition here, if two processes happen to
     // notice at the same time that the timestamp is out-of-date.
     writeTimestampFile(TimestampFile);
   }
 
-  bool ShouldComputeSize = (PercentageOfAvailableSpace > 0);
+  bool ShouldComputeSize = (Policy.PercentageOfAvailableSpace > 0);
 
   // Keep track of space
   std::set<std::pair<uint64_t, std::string>> FileSizes;
   uint64_t TotalSize = 0;
   // Helper to add a path to the set of files to consider for size-based
   // pruning, sorted by size.
   auto AddToFileListForSizePruning =
       [&](StringRef Path) {
for (sys::fs::directory_iterator File(CachePathNative, EC), FileEnd;
     if (sys::fs::status(File->path(), FileStatus)) {
       DEBUG(dbgs() << "Ignore " << File->path() << " (can't stat)\n");
       continue;
     }
 
     // If the file hasn't been used recently enough, delete it
     const auto FileAccessTime = FileStatus.getLastAccessedTime();
     auto FileAge = CurrentTime - FileAccessTime;
-    if (FileAge > Expiration) {
+    if (FileAge > Policy.Expiration) {
       DEBUG(dbgs() << "Remove " << File->path() << " ("
                    << duration_cast<seconds>(FileAge).count() << "s old)\n");
       sys::fs::remove(File->path());
       continue;
     }
 
     // Leave it here for now, but add it to the list of size-based pruning.
     AddToFileListForSizePruning(File->path());
   }
 
   // Prune for size now if needed
   if (ShouldComputeSize) {
     auto ErrOrSpaceInfo = sys::fs::disk_space(Path);
     if (!ErrOrSpaceInfo) {
       report_fatal_error("Can't get available size");
     }
     sys::fs::space_info SpaceInfo = ErrOrSpaceInfo.get();
     auto AvailableSpace = TotalSize + SpaceInfo.free;
     auto FileAndSize = FileSizes.rbegin();
     DEBUG(dbgs() << "Occupancy: " << ((100 * TotalSize) / AvailableSpace)
-                 << "% target is: " << PercentageOfAvailableSpace << "\n");
+                 << "% target is: " << Policy.PercentageOfAvailableSpace
+                 << "\n");
     // Remove the oldest accessed files first, till we get below the threshold
-    while (((100 * TotalSize) / AvailableSpace) > PercentageOfAvailableSpace &&
+    while (((100 * TotalSize) / AvailableSpace) >
+               Policy.PercentageOfAvailableSpace &&
            FileAndSize != FileSizes.rend()) {
       // Remove the file.
       sys::fs::remove(FileAndSize->second);
       // Update size
       TotalSize -= FileAndSize->first;
       DEBUG(dbgs() << " - Remove " << FileAndSize->second << " (size "
                    << FileAndSize->first << "), new occupancy is " << TotalSize
                    << "%\n");
       ++FileAndSize;
     }
   }
   return true;
 }