webkitgtk-2.10.2webkitgtk-2.10.2

1 files changed, 276 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/CodeCache.h b/Source/JavaScriptCore/runtime/CodeCache.h
new file mode 100644
index 000000000..af7dac7e4
--- /dev/null
+++ b/Source/JavaScriptCore/runtime/CodeCache.h
@@ -0,0 +1,276 @@
+/*
+ * Copyright (C) 2012, 2013 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.
+ */
+
+#ifndef CodeCache_h
+#define CodeCache_h
+
+#include "CodeSpecializationKind.h"
+#include "ParserModes.h"
+#include "SourceCode.h"
+#include "Strong.h"
+#include "VariableEnvironment.h"
+#include "WeakRandom.h"
+#include <wtf/CurrentTime.h>
+#include <wtf/Forward.h>
+#include <wtf/RandomNumber.h>
+#include <wtf/text/WTFString.h>
+
+namespace JSC {
+
+class EvalExecutable;
+class FunctionMetadataNode;
+class Identifier;
+class JSScope;
+class ParserError;
+class ProgramExecutable;
+class UnlinkedCodeBlock;
+class UnlinkedEvalCodeBlock;
+class UnlinkedFunctionCodeBlock;
+class UnlinkedFunctionExecutable;
+class UnlinkedProgramCodeBlock;
+class VM;
+class SourceCode;
+class SourceProvider;
+
+class SourceCodeKey {
+public:
+    enum CodeType { EvalType, ProgramType, FunctionType };
+
+    SourceCodeKey()
+    {
+    }
+
+    SourceCodeKey(const SourceCode& sourceCode, const String& name, CodeType codeType, JSParserBuiltinMode builtinMode,
+        JSParserStrictMode strictMode, ThisTDZMode thisTDZMode = ThisTDZMode::CheckIfNeeded)
+        : m_sourceCode(sourceCode)
+        , m_name(name)
+        , m_flags(
+            (static_cast<unsigned>(codeType) << 3)
+            | (static_cast<unsigned>(builtinMode) << 2)
+            | (static_cast<unsigned>(strictMode) << 1)
+            | static_cast<unsigned>(thisTDZMode))
+        , m_hash(string().impl()->hash())
+    {
+    }
+
+    SourceCodeKey(WTF::HashTableDeletedValueType)
+        : m_sourceCode(WTF::HashTableDeletedValue)
+    {
+    }
+
+    bool isHashTableDeletedValue() const { return m_sourceCode.isHashTableDeletedValue(); }
+
+    unsigned hash() const { return m_hash; }
+
+    size_t length() const { return m_sourceCode.length(); }
+
+    bool isNull() const { return m_sourceCode.isNull(); }
+
+    // To save memory, we compute our string on demand. It's expected that source
+    // providers cache their strings to make this efficient.
+    String string() const { return m_sourceCode.toString(); }
+
+    bool operator==(const SourceCodeKey& other) const
+    {
+        return m_hash == other.m_hash
+            && length() == other.length()
+            && m_flags == other.m_flags
+            && m_name == other.m_name
+            && string() == other.string();
+    }
+
+private:
+    SourceCode m_sourceCode;
+    String m_name;
+    unsigned m_flags;
+    unsigned m_hash;
+};
+
+struct SourceCodeKeyHash {
+    static unsigned hash(const SourceCodeKey& key) { return key.hash(); }
+    static bool equal(const SourceCodeKey& a, const SourceCodeKey& b) { return a == b; }
+    static const bool safeToCompareToEmptyOrDeleted = false;
+};
+
+struct SourceCodeKeyHashTraits : SimpleClassHashTraits<SourceCodeKey> {
+    static const bool hasIsEmptyValueFunction = true;
+    static bool isEmptyValue(const SourceCodeKey& sourceCodeKey) { return sourceCodeKey.isNull(); }
+};
+
+struct SourceCodeValue {
+    SourceCodeValue()
+    {
+    }
+
+    SourceCodeValue(VM& vm, JSCell* cell, int64_t age)
+        : cell(vm, cell)
+        , age(age)
+    {
+    }
+
+    Strong<JSCell> cell;
+    int64_t age;
+};
+
+class CodeCacheMap {
+public:
+    typedef HashMap<SourceCodeKey, SourceCodeValue, SourceCodeKeyHash, SourceCodeKeyHashTraits> MapType;
+    typedef MapType::iterator iterator;
+    typedef MapType::AddResult AddResult;
+
+    CodeCacheMap()
+        : m_size(0)
+        , m_sizeAtLastPrune(0)
+        , m_timeAtLastPrune(monotonicallyIncreasingTime())
+        , m_minCapacity(0)
+        , m_capacity(0)
+        , m_age(0)
+    {
+    }
+
+    SourceCodeValue* findCacheAndUpdateAge(const SourceCodeKey& key)
+    {
+        prune();
+
+        iterator findResult = m_map.find(key);
+        if (findResult == m_map.end())
+            return nullptr;
+
+        int64_t age = m_age - findResult->value.age;
+        if (age > m_capacity) {
+            // A requested object is older than the cache's capacity. We can
+            // infer that requested objects are subject to high eviction probability,
+            // so we grow the cache to improve our hit rate.
+            m_capacity += recencyBias * oldObjectSamplingMultiplier * key.length();
+        } else if (age < m_capacity / 2) {
+            // A requested object is much younger than the cache's capacity. We can
+            // infer that requested objects are subject to low eviction probability,
+            // so we shrink the cache to save memory.
+            m_capacity -= recencyBias * key.length();
+            if (m_capacity < m_minCapacity)
+                m_capacity = m_minCapacity;
+        }
+
+        findResult->value.age = m_age;
+        m_age += key.length();
+
+        return &findResult->value;
+    }
+
+    AddResult addCache(const SourceCodeKey& key, const SourceCodeValue& value)
+    {
+        prune();
+
+        AddResult addResult = m_map.add(key, value);
+        ASSERT(addResult.isNewEntry);
+
+        m_size += key.length();
+        m_age += key.length();
+        return addResult;
+    }
+
+    void remove(iterator it)
+    {
+        m_size -= it->key.length();
+        m_map.remove(it);
+    }
+
+    void clear()
+    {
+        m_size = 0;
+        m_age = 0;
+        m_map.clear();
+    }
+
+    int64_t age() { return m_age; }
+
+private:
+    // This constant factor biases cache capacity toward allowing a minimum
+    // working set to enter the cache before it starts evicting.
+    static const double workingSetTime;
+    static const int64_t workingSetMaxBytes = 16000000;
+    static const size_t workingSetMaxEntries = 2000;
+
+    // This constant factor biases cache capacity toward recent activity. We
+    // want to adapt to changing workloads.
+    static const int64_t recencyBias = 4;
+
+    // This constant factor treats a sampled event for one old object as if it
+    // happened for many old objects. Most old objects are evicted before we can
+    // sample them, so we need to extrapolate from the ones we do sample.
+    static const int64_t oldObjectSamplingMultiplier = 32;
+
+    size_t numberOfEntries() const { return static_cast<size_t>(m_map.size()); }
+    bool canPruneQuickly() const { return numberOfEntries() < workingSetMaxEntries; }
+
+    void pruneSlowCase();
+    void prune()
+    {
+        if (m_size <= m_capacity && canPruneQuickly())
+            return;
+
+        if (monotonicallyIncreasingTime() - m_timeAtLastPrune < workingSetTime
+            && m_size - m_sizeAtLastPrune < workingSetMaxBytes
+            && canPruneQuickly())
+                return;
+
+        pruneSlowCase();
+    }
+
+    MapType m_map;
+    int64_t m_size;
+    int64_t m_sizeAtLastPrune;
+    double m_timeAtLastPrune;
+    int64_t m_minCapacity;
+    int64_t m_capacity;
+    int64_t m_age;
+};
+
+// Caches top-level code such as <script>, eval(), new Function, and JSEvaluateScript().
+class CodeCache {
+    WTF_MAKE_FAST_ALLOCATED;
+public:
+    CodeCache();
+    ~CodeCache();
+
+    UnlinkedProgramCodeBlock* getProgramCodeBlock(VM&, ProgramExecutable*, const SourceCode&, JSParserBuiltinMode, JSParserStrictMode, DebuggerMode, ProfilerMode, ParserError&);
+    UnlinkedEvalCodeBlock* getEvalCodeBlock(VM&, EvalExecutable*, const SourceCode&, JSParserBuiltinMode, JSParserStrictMode, ThisTDZMode, DebuggerMode, ProfilerMode, ParserError&, const VariableEnvironment*);
+    UnlinkedFunctionExecutable* getFunctionExecutableFromGlobalCode(VM&, const Identifier&, const SourceCode&, ParserError&);
+
+    void clear()
+    {
+        m_sourceCode.clear();
+    }
+
+private:
+    template <class UnlinkedCodeBlockType, class ExecutableType> 
+    UnlinkedCodeBlockType* getGlobalCodeBlock(VM&, ExecutableType*, const SourceCode&, JSParserBuiltinMode, JSParserStrictMode, ThisTDZMode, DebuggerMode, ProfilerMode, ParserError&, const VariableEnvironment*);
+
+    CodeCacheMap m_sourceCode;
+};
+
+}
+
+#endif // CodeCache_h