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Backport 5786 to v4.x (memory growth with 'vm' module) #6871

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merged 5 commits into from
May 20, 2016
Merged

Backport 5786 to v4.x (memory growth with 'vm' module) #6871

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faa94ff
contextify: cleanup weak ref for global proxy
ofrobots Feb 23, 2016
3d56671
contextify: cleanup weak ref for sandbox
ofrobots Feb 23, 2016
ab00cf5
contextify: replace deprecated SetWeak usage
ofrobots Feb 23, 2016
4d48400
contextify: cache sandbox and context in locals
ofrobots Feb 24, 2016
c6db822
contextify: tie lifetimes of context & sandbox
ofrobots Mar 18, 2016
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122 changes: 49 additions & 73 deletions src/node_contextify.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -43,53 +43,33 @@ using v8::TryCatch;
using v8::UnboundScript;
using v8::V8;
using v8::Value;
using v8::WeakCallbackData;
using v8::WeakCallbackInfo;


class ContextifyContext {
protected:
enum Kind {
kSandbox,
kContext,
kProxyGlobal
};
// V8 reserves the first field in context objects for the debugger. We use the
// second field to hold a reference to the sandbox object.
enum { kSandboxObjectIndex = 1 };

Environment* const env_;
Persistent<Object> sandbox_;
Persistent<Context> context_;
Persistent<Object> proxy_global_;
int references_;

public:
explicit ContextifyContext(Environment* env, Local<Object> sandbox)
: env_(env),
sandbox_(env->isolate(), sandbox),
// Wait for sandbox_, proxy_global_, and context_ to die
references_(0) {
context_.Reset(env->isolate(), CreateV8Context(env));

sandbox_.SetWeak(this, WeakCallback<Object, kSandbox>);
sandbox_.MarkIndependent();
references_++;
ContextifyContext(Environment* env, Local<Object> sandbox_obj) : env_(env) {
Local<Context> v8_context = CreateV8Context(env, sandbox_obj);
context_.Reset(env->isolate(), v8_context);

// Allocation failure or maximum call stack size reached
if (context_.IsEmpty())
return;
context_.SetWeak(this, WeakCallback<Context, kContext>);
context_.SetWeak(this, WeakCallback, v8::WeakCallbackType::kParameter);
context_.MarkIndependent();
references_++;

proxy_global_.Reset(env->isolate(), context()->Global());
proxy_global_.SetWeak(this, WeakCallback<Object, kProxyGlobal>);
proxy_global_.MarkIndependent();
references_++;
}


~ContextifyContext() {
context_.Reset();
proxy_global_.Reset();
sandbox_.Reset();
}


Expand All @@ -103,6 +83,15 @@ class ContextifyContext {
}


inline Local<Object> global_proxy() const {
return context()->Global();
}


inline Local<Object> sandbox() const {
return Local<Object>::Cast(context()->GetEmbedderData(kSandboxObjectIndex));
}

// XXX(isaacs): This function only exists because of a shortcoming of
// the V8 SetNamedPropertyHandler function.
//
Expand Down Expand Up @@ -130,15 +119,15 @@ class ContextifyContext {
Local<Context> context = PersistentToLocal(env()->isolate(), context_);
Local<Object> global =
context->Global()->GetPrototype()->ToObject(env()->isolate());
Local<Object> sandbox = PersistentToLocal(env()->isolate(), sandbox_);
Local<Object> sandbox_obj = sandbox();

Local<Function> clone_property_method;

Local<Array> names = global->GetOwnPropertyNames();
int length = names->Length();
for (int i = 0; i < length; i++) {
Local<String> key = names->Get(i)->ToString(env()->isolate());
bool has = sandbox->HasOwnProperty(key);
bool has = sandbox_obj->HasOwnProperty(context, key).FromJust();
if (!has) {
// Could also do this like so:
//
Expand Down Expand Up @@ -171,7 +160,7 @@ class ContextifyContext {
clone_property_method = Local<Function>::Cast(script->Run());
CHECK(clone_property_method->IsFunction());
}
Local<Value> args[] = { global, key, sandbox };
Local<Value> args[] = { global, key, sandbox_obj };
clone_property_method->Call(global, ARRAY_SIZE(args), args);
}
}
Expand All @@ -195,14 +184,13 @@ class ContextifyContext {
}


Local<Context> CreateV8Context(Environment* env) {
Local<Context> CreateV8Context(Environment* env, Local<Object> sandbox_obj) {
EscapableHandleScope scope(env->isolate());
Local<FunctionTemplate> function_template =
FunctionTemplate::New(env->isolate());
function_template->SetHiddenPrototype(true);

Local<Object> sandbox = PersistentToLocal(env->isolate(), sandbox_);
function_template->SetClassName(sandbox->GetConstructorName());
function_template->SetClassName(sandbox_obj->GetConstructorName());

Local<ObjectTemplate> object_template =
function_template->InstanceTemplate();
Expand All @@ -220,6 +208,17 @@ class ContextifyContext {
CHECK(!ctx.IsEmpty());
ctx->SetSecurityToken(env->context()->GetSecurityToken());

// We need to tie the lifetime of the sandbox object with the lifetime of
// newly created context. We do this by making them hold references to each
// other. The context can directly hold a reference to the sandbox as an
// embedder data field. However, we cannot hold a reference to a v8::Context
// directly in an Object, we instead hold onto the new context's global
// object instead (which then has a reference to the context).
ctx->SetEmbedderData(kSandboxObjectIndex, sandbox_obj);
sandbox_obj->SetHiddenValue(
FIXED_ONE_BYTE_STRING(env->isolate(), "_contextifyHiddenGlobal"),
ctx->Global());

env->AssignToContext(ctx);

return scope.Escape(ctx);
Expand Down Expand Up @@ -313,18 +312,9 @@ class ContextifyContext {
}


template <class T, Kind kind>
static void WeakCallback(const WeakCallbackData<T, ContextifyContext>& data) {
static void WeakCallback(const WeakCallbackInfo<ContextifyContext>& data) {
ContextifyContext* context = data.GetParameter();
if (kind == kSandbox)
context->sandbox_.ClearWeak();
else if (kind == kContext)
context->context_.ClearWeak();
else
context->proxy_global_.ClearWeak();

if (--context->references_ == 0)
delete context;
delete context;
}


Expand All @@ -346,28 +336,26 @@ class ContextifyContext {
static void GlobalPropertyGetterCallback(
Local<Name> property,
const PropertyCallbackInfo<Value>& args) {
Isolate* isolate = args.GetIsolate();

ContextifyContext* ctx =
Unwrap<ContextifyContext>(args.Data().As<Object>());

// Stil initializing
if (ctx->context_.IsEmpty())
return;

Local<Object> sandbox = PersistentToLocal(isolate, ctx->sandbox_);
Local<Context> context = ctx->context();
Local<Object> sandbox = ctx->sandbox();
MaybeLocal<Value> maybe_rv =
sandbox->GetRealNamedProperty(ctx->context(), property);
sandbox->GetRealNamedProperty(context, property);
if (maybe_rv.IsEmpty()) {
Local<Object> proxy_global = PersistentToLocal(isolate,
ctx->proxy_global_);
maybe_rv = proxy_global->GetRealNamedProperty(ctx->context(), property);
maybe_rv =
ctx->global_proxy()->GetRealNamedProperty(context, property);
}

Local<Value> rv;
if (maybe_rv.ToLocal(&rv)) {
if (rv == ctx->sandbox_)
rv = PersistentToLocal(isolate, ctx->proxy_global_);
if (rv == sandbox)
rv = ctx->global_proxy();

args.GetReturnValue().Set(rv);
}
Expand All @@ -378,42 +366,35 @@ class ContextifyContext {
Local<Name> property,
Local<Value> value,
const PropertyCallbackInfo<Value>& args) {
Isolate* isolate = args.GetIsolate();

ContextifyContext* ctx =
Unwrap<ContextifyContext>(args.Data().As<Object>());

// Stil initializing
if (ctx->context_.IsEmpty())
return;

PersistentToLocal(isolate, ctx->sandbox_)->Set(property, value);
ctx->sandbox()->Set(property, value);
}


static void GlobalPropertyQueryCallback(
Local<Name> property,
const PropertyCallbackInfo<Integer>& args) {
Isolate* isolate = args.GetIsolate();

ContextifyContext* ctx =
Unwrap<ContextifyContext>(args.Data().As<Object>());

// Stil initializing
if (ctx->context_.IsEmpty())
return;

Local<Object> sandbox = PersistentToLocal(isolate, ctx->sandbox_);
Local<Context> context = ctx->context();
Maybe<PropertyAttribute> maybe_prop_attr =
sandbox->GetRealNamedPropertyAttributes(ctx->context(), property);
ctx->sandbox()->GetRealNamedPropertyAttributes(context, property);

if (maybe_prop_attr.IsNothing()) {
Local<Object> proxy_global = PersistentToLocal(isolate,
ctx->proxy_global_);

maybe_prop_attr =
proxy_global->GetRealNamedPropertyAttributes(ctx->context(),
property);
ctx->global_proxy()->GetRealNamedPropertyAttributes(context,
property);
}

if (maybe_prop_attr.IsJust()) {
Expand All @@ -426,18 +407,14 @@ class ContextifyContext {
static void GlobalPropertyDeleterCallback(
Local<Name> property,
const PropertyCallbackInfo<Boolean>& args) {
Isolate* isolate = args.GetIsolate();

ContextifyContext* ctx =
Unwrap<ContextifyContext>(args.Data().As<Object>());

// Stil initializing
if (ctx->context_.IsEmpty())
return;

Local<Object> sandbox = PersistentToLocal(isolate, ctx->sandbox_);

Maybe<bool> success = sandbox->Delete(ctx->context(), property);
Maybe<bool> success = ctx->sandbox()->Delete(ctx->context(), property);

if (success.IsJust())
args.GetReturnValue().Set(success.FromJust());
Expand All @@ -453,8 +430,7 @@ class ContextifyContext {
if (ctx->context_.IsEmpty())
return;

Local<Object> sandbox = PersistentToLocal(args.GetIsolate(), ctx->sandbox_);
args.GetReturnValue().Set(sandbox->GetPropertyNames());
args.GetReturnValue().Set(ctx->sandbox()->GetPropertyNames());
}
};

Expand Down
9 changes: 9 additions & 0 deletions test/parallel/test-vm-create-and-run-in-context.js
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
'use strict';
// Flags: --expose-gc
require('../common');
var assert = require('assert');

Expand All @@ -18,3 +19,11 @@ console.error('test updating context');
result = vm.runInContext('var foo = 3;', context);
assert.equal(3, context.foo);
assert.equal('lala', context.thing);

// /~https://github.com/nodejs/node/issues/5768
console.error('run in contextified sandbox without referencing the context');
var sandbox = {x: 1};
vm.createContext(sandbox);
gc();
vm.runInContext('x = 2', sandbox);
// Should not crash.