v8/src/bootstrapper.h

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// Copyright 2006-2008 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_BOOTSTRAPPER_H_
#define V8_BOOTSTRAPPER_H_
namespace v8 {
namespace internal {
// The Boostrapper is the public interface for creating a JavaScript global
// context.
class Bootstrapper : public AllStatic {
public:
// Requires: Heap::Setup has been called.
static void Initialize(bool create_heap_objects);
static void TearDown();
// Creates a JavaScript Global Context with initial object graph.
// The returned value is a global handle casted to V8Environment*.
static Handle<Context> CreateEnvironment(
Handle<Object> global_object,
v8::Handle<v8::ObjectTemplate> global_template,
v8::ExtensionConfiguration* extensions);
Split window support from V8. Here is a description of the background and design of split window in Chrome and V8: https://docs.google.com/a/google.com/Doc?id=chhjkpg_47fwddxbfr This change list splits the window object into two parts: 1) an inner window object used as the global object of contexts; 2) an outer window object exposed to JavaScript and accessible by the name 'window'. Firefox did it awhile ago, here are some discussions: https://wiki.mozilla.org/Gecko:SplitWindow. One additional benefit of splitting window in Chrome is that accessing global variables don't need security checks anymore, it can improve applications that use many global variables. V8 support of split window: There are a small number of changes on V8 api to support split window: Security context is removed from V8, so does related API functions; A global object can be detached from its context and reused by a new context; Access checks on an object template can be turned on/off by default; An object can turn on its access checks later; V8 has a new object type, ApiGlobalObject, which is the outer window object type. The existing JSGlobalObject becomes the inner window object type. Security checks are moved from JSGlobalObject to ApiGlobalObject. ApiGlobalObject is the one exposed to JavaScript, it is accessible through Context::Global(). ApiGlobalObject's prototype is set to JSGlobalObject so that property lookups are forwarded to JSGlobalObject. ApiGlobalObject forwards all other property access requests to JSGlobalObject, such as SetProperty, DeleteProperty, etc. Security token is moved to a global context, and ApiGlobalObject has a reference to its global context. JSGlobalObject has a reference to its global context as well. When accessing properties on a global object in JavaScript, the domain security check is performed by comparing the security token of the lexical context (Top::global_context()) to the token of global object's context. The check is only needed when the receiver is a window object, such as 'window.document'. Accessing global variables, such as 'var foo = 3; foo' does not need checks because the receiver is the inner window object. When an outer window is detached from its global context (when a frame navigates away from a page), it is completely detached from the inner window. A new context is created for the new page, and the outer global object is reused. At this point, the access check on the DOMWindow wrapper of the old context is turned on. The code in old context is still able to access DOMWindow properties, but it has to go through domain security checks. It is debatable on how to implement the outer window object. Currently each property access function has to check if the receiver is ApiGlobalObject type. This approach might be error-prone that one may forget to check the receiver when adding new functions. It is unlikely a performance issue because accessing global variables are more common than 'window.foo' style coding. I am still working on the ARM port, and I'd like to hear comments and suggestions on the best way to support it in V8. Review URL: http://codereview.chromium.org/7366 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@540 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2008-10-21 19:07:58 +00:00
// Detach the environment from its outer global object.
static void DetachGlobal(Handle<Context> env);
// Traverses the pointers for memory management.
static void Iterate(ObjectVisitor* v);
// Accessors for the native scripts cache. Used in lazy loading.
static Handle<String> NativesSourceLookup(int index);
static bool NativesCacheLookup(Vector<const char> name,
Handle<JSFunction>* handle);
static void NativesCacheAdd(Vector<const char> name, Handle<JSFunction> fun);
// Tells whether bootstrapping is active.
static bool IsActive();
// Encoding/decoding support for fixup flags.
class FixupFlagsUseCodeObject: public BitField<bool, 0, 1> {};
class FixupFlagsArgumentsCount: public BitField<uint32_t, 1, 32-1> {};
// Support for thread preemption.
static int ArchiveSpacePerThread();
static char* ArchiveState(char* to);
static char* RestoreState(char* from);
static void FreeThreadResources();
// This will allocate a char array that is deleted when V8 is shut down.
// It should only be used for strictly finite allocations.
static char* AllocateAutoDeletedArray(int bytes);
};
class NativesExternalStringResource
: public v8::String::ExternalAsciiStringResource {
public:
explicit NativesExternalStringResource(const char* source);
const char* data() const {
return data_;
}
size_t length() const {
return length_;
}
private:
const char* data_;
size_t length_;
};
}} // namespace v8::internal
#endif // V8_BOOTSTRAPPER_H_