--- /dev/null
+++ libmalloc/libmalloc-283/tests/MallocBenchTest/BMALLOC/bmalloc/bmalloc/IsoDirectory.h
@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2017-2018 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
+ */
+
+#pragma once
+
+#include "Bits.h"
+#include "EligibilityResult.h"
+#include "IsoPage.h"
+#include "Vector.h"
+
+namespace bmalloc {
+
+template<typename Config> class IsoHeapImpl;
+
+class IsoDirectoryBaseBase {
+public:
+    IsoDirectoryBaseBase() { }
+    virtual ~IsoDirectoryBaseBase() { }
+
+    virtual void didDecommit(unsigned index) = 0;
+};
+
+template<typename Config>
+class IsoDirectoryBase : public IsoDirectoryBaseBase {
+public:
+    IsoDirectoryBase(IsoHeapImpl<Config>&);
+    
+    IsoHeapImpl<Config>& heap() { return m_heap; }
+    
+    virtual void didBecome(IsoPage<Config>*, IsoPageTrigger) = 0;
+    
+protected:
+    IsoHeapImpl<Config>& m_heap;
+};
+
+template<typename Config, unsigned passedNumPages>
+class IsoDirectory : public IsoDirectoryBase<Config> {
+public:
+    static constexpr unsigned numPages = passedNumPages;
+    
+    IsoDirectory(IsoHeapImpl<Config>&);
+    
+    // Find the first page that is eligible for allocation and return it. May return null if there is no
+    // such thing. May allocate a new page if we have an uncommitted page.
+    EligibilityResult<Config> takeFirstEligible();
+    
+    void didBecome(IsoPage<Config>*, IsoPageTrigger) override;
+    
+    // This gets called from a bulk decommit function in the Scavenger, so no locks are held. This function
+    // needs to get the heap lock.
+    void didDecommit(unsigned index) override;
+    
+    // Iterate over all empty and committed pages, and put them into the vector. This also records the
+    // pages as being decommitted. It's the caller's job to do the actual decommitting.
+    void scavenge(Vector<DeferredDecommit>&);
+    void scavengeToHighWatermark(Vector<DeferredDecommit>&);
+
+    template<typename Func>
+    void forEachCommittedPage(const Func&);
+    
+private:
+    void scavengePage(size_t, Vector<DeferredDecommit>&);
+
+    // NOTE: I suppose that this could be two bitvectors. But from working on the GC, I found that the
+    // number of bitvectors does not matter as much as whether or not they make intuitive sense.
+    Bits<numPages> m_eligible;
+    Bits<numPages> m_empty;
+    Bits<numPages> m_committed;
+    std::array<IsoPage<Config>*, numPages> m_pages;
+    unsigned m_firstEligible { 0 };
+    unsigned m_highWatermark { 0 };
+};
+
+} // namespace bmalloc
+