weex_core/Source/include/JavaScriptCore/heap/CodeBlockSet.h

/*
 * Copyright (C) 2013-2017 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
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 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#pragma once

#include "CollectionScope.h"
#include "GCSegmentedArray.h"
#include <wtf/HashSet.h>
#include <wtf/Lock.h>
#include <wtf/Noncopyable.h>
#include <wtf/PrintStream.h>
#include <wtf/RefPtr.h>

namespace JSC {

class CodeBlock;
class Heap;
class JSCell;
class VM;

// CodeBlockSet tracks all CodeBlocks. Every CodeBlock starts out with one
// reference coming in from GC. The GC is responsible for freeing CodeBlocks
// once they hasOneRef() and nobody is running code from that CodeBlock.

class CodeBlockSet {
    WTF_MAKE_NONCOPYABLE(CodeBlockSet);

public:
    CodeBlockSet();
    ~CodeBlockSet();

    void lastChanceToFinalize(VM&);
    
    // Add a CodeBlock. This is only called by CodeBlock constructors.
    void add(CodeBlock*);
    
    // Clear all mark bits for all CodeBlocks.
    void clearMarksForFullCollection();

    // Mark a pointer that may be a CodeBlock that belongs to the set of DFG
    // blocks. This is defined in CodeBlock.h.
private:
    void mark(const AbstractLocker&, CodeBlock* candidateCodeBlock);
public:
    void mark(const AbstractLocker&, void* candidateCodeBlock);
    
    // Delete all code blocks that are only referenced by this set (i.e. owned
    // by this set), and that have not been marked.
    void deleteUnmarkedAndUnreferenced(VM&, CollectionScope);
    
    void clearCurrentlyExecuting();

    bool contains(const AbstractLocker&, void* candidateCodeBlock);
    Lock& getLock() { return m_lock; }

    // Visits each CodeBlock in the heap until the visitor function returns true
    // to indicate that it is done iterating, or until every CodeBlock has been
    // visited.
    template<typename Functor> void iterate(const Functor&);
    template<typename Functor> void iterate(const AbstractLocker&, const Functor&);
    
    template<typename Functor> void iterateCurrentlyExecuting(const Functor&);
    
    void dump(PrintStream&) const;

private:
    void promoteYoungCodeBlocks(const AbstractLocker&);

    HashSet<CodeBlock*> m_oldCodeBlocks;
    HashSet<CodeBlock*> m_newCodeBlocks;
    HashSet<CodeBlock*> m_currentlyExecuting;
    Lock m_lock;
};

} // namespace JSC