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// Copyright 2010 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "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 THE COPYRIGHT
// OWNER 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 V8_LIVEEDIT_H_
#define V8_LIVEEDIT_H_
// Live Edit feature implementation.
// User should be able to change script on already running VM. This feature
// matches hot swap features in other frameworks.
//
// The basic use-case is when user spots some mistake in function body
// from debugger and wishes to change the algorithm without restart.
//
// A single change always has a form of a simple replacement (in pseudo-code):
// script.source[positions, positions+length] = new_string;
// Implementation first determines, which function's body includes this
// change area. Then both old and new versions of script are fully compiled
// in order to analyze, whether the function changed its outer scope
// expectations (or number of parameters). If it didn't, function's code is
// patched with a newly compiled code. If it did change, enclosing function
// gets patched. All inner functions are left untouched, whatever happened
// to them in a new script version. However, new version of code will
// instantiate newly compiled functions.
#include "allocation.h"
#include "compiler.h"
namespace v8 {
namespace internal {
// This class collects some specific information on structure of functions
// in a particular script. It gets called from compiler all the time, but
// actually records any data only when liveedit operation is in process;
// in any other time this class is very cheap.
//
// The primary interest of the Tracker is to record function scope structures
// in order to analyze whether function code maybe safely patched (with new
// code successfully reading existing data from function scopes). The Tracker
// also collects compiled function codes.
class LiveEditFunctionTracker {
public:
explicit LiveEditFunctionTracker(Isolate* isolate, FunctionLiteral* fun);
~LiveEditFunctionTracker();
void RecordFunctionInfo(Handle<SharedFunctionInfo> info,
FunctionLiteral* lit);
void RecordRootFunctionInfo(Handle<Code> code);
static bool IsActive(Isolate* isolate);
private:
#ifdef ENABLE_DEBUGGER_SUPPORT
Isolate* isolate_;
#endif
};
#ifdef ENABLE_DEBUGGER_SUPPORT
class LiveEdit : AllStatic {
public:
static JSArray* GatherCompileInfo(Handle<Script> script,
Handle<String> source);
static void WrapSharedFunctionInfos(Handle<JSArray> array);
MUST_USE_RESULT static MaybeObject* ReplaceFunctionCode(
Handle<JSArray> new_compile_info_array,
Handle<JSArray> shared_info_array);
static MaybeObject* FunctionSourceUpdated(Handle<JSArray> shared_info_array);
// Updates script field in FunctionSharedInfo.
static void SetFunctionScript(Handle<JSValue> function_wrapper,
Handle<Object> script_handle);
MUST_USE_RESULT static MaybeObject* PatchFunctionPositions(
Handle<JSArray> shared_info_array, Handle<JSArray> position_change_array);
// For a script updates its source field. If old_script_name is provided
// (i.e. is a String), also creates a copy of the script with its original
// source and sends notification to debugger.
static Object* ChangeScriptSource(Handle<Script> original_script,
Handle<String> new_source,
Handle<Object> old_script_name);
// In a code of a parent function replaces original function as embedded
// object with a substitution one.
static void ReplaceRefToNestedFunction(Handle<JSValue> parent_function_shared,
Handle<JSValue> orig_function_shared,
Handle<JSValue> subst_function_shared);
// Checks listed functions on stack and return array with corresponding
// FunctionPatchabilityStatus statuses; extra array element may
// contain general error message. Modifies the current stack and
// has restart the lowest found frames and drops all other frames above
// if possible and if do_drop is true.
static Handle<JSArray> CheckAndDropActivations(
Handle<JSArray> shared_info_array, bool do_drop);
// A copy of this is in liveedit-debugger.js.
enum FunctionPatchabilityStatus {
FUNCTION_AVAILABLE_FOR_PATCH = 1,
FUNCTION_BLOCKED_ON_ACTIVE_STACK = 2,
FUNCTION_BLOCKED_ON_OTHER_STACK = 3,
FUNCTION_BLOCKED_UNDER_NATIVE_CODE = 4,
FUNCTION_REPLACED_ON_ACTIVE_STACK = 5
};
// Compares 2 strings line-by-line, then token-wise and returns diff in form
// of array of triplets (pos1, pos1_end, pos2_end) describing list
// of diff chunks.
static Handle<JSArray> CompareStrings(Handle<String> s1,
Handle<String> s2);
};
// A general-purpose comparator between 2 arrays.
class Comparator {
public:
// Holds 2 arrays of some elements allowing to compare any pair of
// element from the first array and element from the second array.
class Input {
public:
virtual int GetLength1() = 0;
virtual int GetLength2() = 0;
virtual bool Equals(int index1, int index2) = 0;
protected:
virtual ~Input() {}
};
// Receives compare result as a series of chunks.
class Output {
public:
// Puts another chunk in result list. Note that technically speaking
// only 3 arguments actually needed with 4th being derivable.
virtual void AddChunk(int pos1, int pos2, int len1, int len2) = 0;
protected:
virtual ~Output() {}
};
// Finds the difference between 2 arrays of elements.
static void CalculateDifference(Input* input,
Output* result_writer);
};
#endif // ENABLE_DEBUGGER_SUPPORT
} } // namespace v8::internal
#endif /* V*_LIVEEDIT_H_ */
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