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

1 files changed, 46 insertions, 15 deletions

diff --git a/llvm/lib/Support/CachePruning.cpp b/llvm/lib/Support/CachePruning.cpp
index aca12363956..303ad219746 100644
--- a/llvm/lib/Support/CachePruning.cpp
+++ b/llvm/lib/Support/CachePruning.cpp
@@ -79,10 +79,10 @@ llvm::parseCachePruningPolicy(StringRef PolicyStr) {
         return DurationOrErr.takeError();
       Policy.Expiration = *DurationOrErr;
     } else if (Key == "cache_size") {
-      if (Value.back() != '%')
-        return make_error<StringError>("'" + Value + "' must be a percentage",
-                                       inconvertibleErrorCode());
-      StringRef SizeStr = Value.slice(0, Value.size() - 1);
+    if (Value.back() != '%')
+      return make_error<StringError>("'" + Value + "' must be a percentage",
+                                     inconvertibleErrorCode());
+      StringRef SizeStr = Value.drop_back();
       uint64_t Size;
       if (SizeStr.getAsInteger(0, Size))
         return make_error<StringError>("'" + SizeStr + "' not an integer",
@@ -91,7 +91,28 @@ llvm::parseCachePruningPolicy(StringRef PolicyStr) {
         return make_error<StringError>("'" + SizeStr +
                                            "' must be between 0 and 100",
                                        inconvertibleErrorCode());
-      Policy.PercentageOfAvailableSpace = Size;
+      Policy.MaxSizePercentageOfAvailableSpace = Size;
+    } else if (Key == "cache_size_bytes") {
+      uint64_t Mult = 1;
+      switch (Value.back()) {
+      case 'k':
+        Mult = 1024;
+        Value = Value.drop_back();
+        break;
+      case 'm':
+        Mult = 1024 * 1024;
+        Value = Value.drop_back();
+        break;
+      case 'g':
+        Mult = 1024 * 1024 * 1024;
+        Value = Value.drop_back();
+        break;
+      }
+      uint64_t Size;
+      if (Value.getAsInteger(0, Size))
+        return make_error<StringError>("'" + Value + "' not an integer",
+                                       inconvertibleErrorCode());
+      Policy.MaxSizeBytes = Size * Mult;
     } else {
       return make_error<StringError>("Unknown key: '" + Key + "'",
                                      inconvertibleErrorCode());
@@ -115,11 +136,12 @@ bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
   if (!isPathDir)
     return false;
 
-  Policy.PercentageOfAvailableSpace =
-      std::min(Policy.PercentageOfAvailableSpace, 100u);
+  Policy.MaxSizePercentageOfAvailableSpace =
+      std::min(Policy.MaxSizePercentageOfAvailableSpace, 100u);
 
   if (Policy.Expiration == seconds(0) &&
-      Policy.PercentageOfAvailableSpace == 0) {
+      Policy.MaxSizePercentageOfAvailableSpace == 0 &&
+      Policy.MaxSizeBytes == 0) {
     DEBUG(dbgs() << "No pruning settings set, exit early\n");
     // Nothing will be pruned, early exit
     return false;
@@ -157,7 +179,8 @@ bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
     writeTimestampFile(TimestampFile);
   }
 
-  bool ShouldComputeSize = (Policy.PercentageOfAvailableSpace > 0);
+  bool ShouldComputeSize =
+      (Policy.MaxSizePercentageOfAvailableSpace > 0 || Policy.MaxSizeBytes > 0);
 
   // Keep track of space
   std::set<std::pair<uint64_t, std::string>> FileSizes;
@@ -216,14 +239,22 @@ bool llvm::pruneCache(StringRef Path, CachePruningPolicy Policy) {
     }
     sys::fs::space_info SpaceInfo = ErrOrSpaceInfo.get();
     auto AvailableSpace = TotalSize + SpaceInfo.free;
-    auto FileAndSize = FileSizes.rbegin();
+
+    if (Policy.MaxSizePercentageOfAvailableSpace == 0)
+      Policy.MaxSizePercentageOfAvailableSpace = 100;
+    if (Policy.MaxSizeBytes == 0)
+      Policy.MaxSizeBytes = AvailableSpace;
+    auto TotalSizeTarget = std::min<uint64_t>(
+        AvailableSpace * Policy.MaxSizePercentageOfAvailableSpace / 100ull,
+        Policy.MaxSizeBytes);
+
     DEBUG(dbgs() << "Occupancy: " << ((100 * TotalSize) / AvailableSpace)
-                 << "% target is: " << Policy.PercentageOfAvailableSpace
-                 << "\n");
+                 << "% target is: " << Policy.MaxSizePercentageOfAvailableSpace
+                 << "%, " << Policy.MaxSizeBytes << " bytes\n");
+
+    auto FileAndSize = FileSizes.rbegin();
     // Remove the oldest accessed files first, till we get below the threshold
-    while (((100 * TotalSize) / AvailableSpace) >
-               Policy.PercentageOfAvailableSpace &&
-           FileAndSize != FileSizes.rend()) {
+    while (TotalSize > TotalSizeTarget && FileAndSize != FileSizes.rend()) {
       // Remove the file.
       sys::fs::remove(FileAndSize->second);
       // Update size