/*
* 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 "WeakRandom.h"
#include
#include
#include
#include
#include
namespace JSC {
class EvalExecutable;
class FunctionBodyNode;
class Identifier;
class JSScope;
class ProgramExecutable;
class UnlinkedCodeBlock;
class UnlinkedEvalCodeBlock;
class UnlinkedFunctionCodeBlock;
class UnlinkedFunctionExecutable;
class UnlinkedProgramCodeBlock;
class VM;
struct ParserError;
class SourceCode;
class SourceProvider;
class SourceCodeKey {
public:
enum CodeType { EvalType, ProgramType, FunctionType };
SourceCodeKey()
{
}
SourceCodeKey(const SourceCode& sourceCode, const String& name, CodeType codeType, JSParserStrictness jsParserStrictness)
: m_sourceCode(sourceCode)
, m_name(name)
, m_flags((codeType 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 {
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 cell;
int64_t age;
};
class CodeCacheMap {
public:
typedef HashMap 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)
{
}
AddResult add(const SourceCodeKey& key, const SourceCodeValue& value)
{
prune();
AddResult addResult = m_map.add(key, value);
if (addResult.isNewEntry) {
m_size += key.length();
m_age += key.length();
return addResult;
}
int64_t age = m_age - addResult.iterator->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 value.age = m_age;
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(m_map.size()); }
bool canPruneQuickly() const { return numberOfEntries() , eval(), new Function, and JSEvaluateScript().
class CodeCache {
public:
static PassOwnPtr create() { return adoptPtr(new CodeCache); }
UnlinkedProgramCodeBlock* getProgramCodeBlock(VM&, ProgramExecutable*, const SourceCode&, JSParserStrictness, DebuggerMode, ProfilerMode, ParserError&);
UnlinkedEvalCodeBlock* getEvalCodeBlock(VM&, EvalExecutable*, const SourceCode&, JSParserStrictness, DebuggerMode, ProfilerMode, ParserError&);
UnlinkedFunctionExecutable* getFunctionExecutableFromGlobalCode(VM&, const Identifier&, const SourceCode&, ParserError&);
~CodeCache();
void clear()
{
m_sourceCode.clear();
}
private:
CodeCache();
template
UnlinkedCodeBlockType* getGlobalCodeBlock(VM&, ExecutableType*, const SourceCode&, JSParserStrictness, DebuggerMode, ProfilerMode, ParserError&);
CodeCacheMap m_sourceCode;
};
}
#endif // CodeCache_h