[compiler-rt] [scudo] Added LRU eviction policy to secondary cache. (PR #99409)

[via llvm-commits]

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@@ -213,23 +225,35 @@ template <typename Config> class MapAllocatorCache {
     if (Config::getDefaultReleaseToOsIntervalMs() != INT32_MIN)
       ReleaseToOsInterval = Config::getDefaultReleaseToOsIntervalMs();
     setOption(Option::ReleaseInterval, static_cast<sptr>(ReleaseToOsInterval));
+
+    // The cache is initially empty
+    LRUHead = CachedBlock::InvalidEntry;
+    LRUTail = CachedBlock::InvalidEntry;
+
+    // Available entries will be retrieved starting from the beginning of the
+    // Entries array
+    AvailableHead = 0;
+    for (u32 I = 0; I < Config::getEntriesArraySize() - 1; I++)
+      Entries[I].Next = static_cast<u16>(I + 1);
+
+    Entries[Config::getEntriesArraySize() - 1].Next = CachedBlock::InvalidEntry;
   }
 
   void store(const Options &Options, LargeBlock::Header *H) EXCLUDES(Mutex) {
     if (!canCache(H->CommitSize))
       return unmap(H);
 
-    bool EntryCached = false;
-    bool EmptyCache = false;
     const s32 Interval = atomic_load_relaxed(&ReleaseToOsIntervalMs);
-    const u64 Time = getMonotonicTimeFast();
     const u32 MaxCount = atomic_load_relaxed(&MaxEntriesCount);
+    u64 Time;
     CachedBlock Entry;
+    Vector<MemMapT, 1U> EvictionMemMaps;
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ChiaHungDuan wrote:

Can we have some comment on why we use 1 as default?

https://github.com/llvm/llvm-project/pull/99409