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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ppapi/proxy/plugin_var_serialization_rules.h"
#include "ppapi/proxy/plugin_dispatcher.h"
#include "ppapi/proxy/plugin_var_tracker.h"
namespace pp {
namespace proxy {
PluginVarSerializationRules::PluginVarSerializationRules()
: var_tracker_(PluginVarTracker::GetInstance()) {
}
PluginVarSerializationRules::~PluginVarSerializationRules() {
}
PP_Var PluginVarSerializationRules::SendCallerOwned(const PP_Var& var,
std::string* str_val) {
// Objects need special translations to get the IDs valid in the host.
if (var.type == PP_VARTYPE_OBJECT)
return var_tracker_->GetHostObject(var);
// Nothing to do since we manage the refcount, other than retrieve the string
// to use for IPC.
if (var.type == PP_VARTYPE_STRING)
*str_val = var_tracker_->GetString(var);
return var;
}
PP_Var PluginVarSerializationRules::BeginReceiveCallerOwned(
const PP_Var& var,
const std::string* str_val,
Dispatcher* dispatcher) {
if (var.type == PP_VARTYPE_STRING) {
// Convert the string to the context of the current process.
PP_Var ret;
ret.type = PP_VARTYPE_STRING;
ret.value.as_id = var_tracker_->MakeString(*str_val);
return ret;
}
if (var.type == PP_VARTYPE_OBJECT)
return var_tracker_->TrackObjectWithNoReference(var, dispatcher);
return var;
}
void PluginVarSerializationRules::EndReceiveCallerOwned(const PP_Var& var) {
if (var.type == PP_VARTYPE_STRING) {
// Destroy the string BeginReceiveCallerOwned created above.
var_tracker_->Release(var);
} else if (var.type == PP_VARTYPE_OBJECT) {
var_tracker_->StopTrackingObjectWithNoReference(var);
}
}
PP_Var PluginVarSerializationRules::ReceivePassRef(const PP_Var& var,
const std::string& str_val,
Dispatcher* dispatcher) {
if (var.type == PP_VARTYPE_STRING) {
// Convert the string to the context of the current process.
PP_Var ret;
ret.type = PP_VARTYPE_STRING;
ret.value.as_id = var_tracker_->MakeString(str_val);
return ret;
}
// Overview of sending an object with "pass ref" from the browser to the
// plugin:
// Example 1 Example 2
// Plugin Browser Plugin Browser
// Before send 3 2 0 1
// Browser calls BeginSendPassRef 3 2 0 1
// Plugin calls ReceivePassRef 4 1 1 1
// Browser calls EndSendPassRef 4 1 1 1
//
// In example 1 before the send, the plugin has 3 refs which are represented
// as one ref in the browser (since the plugin only tells the browser when
// it's refcount goes from 1 -> 0). The initial state is that the browser
// plugin code started to return a value, which means it gets another ref
// on behalf of the caller. This needs to be transferred to the plugin and
// folded in to its set of refs it maintains (with one ref representing all
// fo them in the browser).
if (var.type == PP_VARTYPE_OBJECT) {
return var_tracker_->ReceiveObjectPassRef(var, dispatcher);
}
// Other types are unchanged.
return var;
}
PP_Var PluginVarSerializationRules::BeginSendPassRef(const PP_Var& var,
std::string* str_val) {
// Overview of sending an object with "pass ref" from the plugin to the
// browser:
// Example 1 Example 2
// Plugin Browser Plugin Browser
// Before send 3 1 1 1
// Plugin calls BeginSendPassRef 3 1 1 1
// Browser calls ReceivePassRef 3 2 1 2
// Plugin calls EndSendPassRef 2 2 0 1
//
// The plugin maintains one ref count in the browser on behalf of the
// entire ref count in the plugin. When the plugin refcount goes to 0, it
// will call the browser to deref the object. This is why in example 2
// transferring the object ref to the browser involves no net change in the
// browser's refcount.
// Objects need special translations to get the IDs valid in the host.
if (var.type == PP_VARTYPE_OBJECT)
return var_tracker_->GetHostObject(var);
if (var.type == PP_VARTYPE_STRING)
*str_val = var_tracker_->GetString(var);
return var;
}
void PluginVarSerializationRules::EndSendPassRef(const PP_Var& var,
Dispatcher* dispatcher) {
// See BeginSendPassRef for an example of why we release our ref here.
// The var we have in our inner class has been converted to a host object
// by BeginSendPassRef. This means it's not a normal var valid in the plugin,
// so we need to use the special ReleaseHostObject.
if (var.type == PP_VARTYPE_OBJECT)
var_tracker_->ReleaseHostObject(dispatcher, var);
}
void PluginVarSerializationRules::ReleaseObjectRef(const PP_Var& var) {
var_tracker_->Release(var);
}
} // namespace proxy
} // namespace pp
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