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// Copyright (c) 2012 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.
#ifndef PPAPI_PROXY_VAR_SERIALIZATION_RULES_H_
#define PPAPI_PROXY_VAR_SERIALIZATION_RULES_H_
#include "base/memory/ref_counted.h"
#include "ppapi/c/pp_var.h"
#include <string>
namespace ppapi {
namespace proxy {
// Encapsulates the rules for serializing and deserializing vars to and from
// the local process. The renderer and the plugin process each have separate
// bookkeeping rules.
class VarSerializationRules : public base::RefCounted<VarSerializationRules> {
public:
// Caller-owned calls --------------------------------------------------------
//
// A caller-owned call is when doing a function call with a "normal" input
// argument. The caller has a reference to the var, and the caller is
// responsible for freeing that reference.
// Prepares the given var for sending to the remote process. For object vars,
// the returned var will contain the id valid for the host process.
// Otherwise, the returned var is valid in the local process.
virtual PP_Var SendCallerOwned(const PP_Var& var) = 0;
// When receiving a caller-owned variable, normally we don't have to do
// anything. However, in the case of strings, we need to deserialize the
// string from IPC, call the function, and then destroy the temporary string.
// These two functions handle that process.
//
// BeginReceiveCallerOwned takes a var from IPC and returns a new var
// representing the input in the local process.
//
// EndReceiveCallerOwned releases the reference count in the Var tracker for
// the object or string that was added to the tracker. (Note, if the recipient
// took a reference to the Var, it will remain in the tracker after
// EndReceiveCallerOwned).
virtual PP_Var BeginReceiveCallerOwned(const PP_Var& var) = 0;
virtual void EndReceiveCallerOwned(const PP_Var& var) = 0;
// Passing refs -------------------------------------------------------------
//
// A pass-ref transfer is when ownership of a reference is passed from
// one side to the other. Normally, this happens via return values and
// output arguments, as for exceptions. The code generating the value
// (the function returning it in the case of a return value) will AddRef
// the var on behalf of the consumer of the value. Responsibility for
// Release is on the consumer (the caller of the function in the case of a
// return value).
// Creates a var in the context of the local process from the given
// deserialized var. The input var should be the result of calling
// SendPassRef in the remote process. The return value is the var valid in
// the host process for object vars. Otherwise, the return value is a var
// which is valid in the local process.
virtual PP_Var ReceivePassRef(const PP_Var& var) = 0;
// Prepares a var to be sent to the remote side. One local reference will
// be passed to the remote side. Call Begin* before doing the send and End*
// after doing the send
//
// For object vars, the return value from BeginSendPassRef will be the var
// valid for the host process. Otherwise, it is a var that is valid in the
// local process. This same var must be passed to EndSendPassRef.
virtual PP_Var BeginSendPassRef(const PP_Var& var) = 0;
virtual void EndSendPassRef(const PP_Var& var) = 0;
// ---------------------------------------------------------------------------
virtual void ReleaseObjectRef(const PP_Var& var) = 0;
protected:
VarSerializationRules() {}
virtual ~VarSerializationRules() {}
private:
friend class base::RefCounted<VarSerializationRules>;
};
} // namespace proxy
} // namespace ppapi
#endif // PPAPI_PROXY_VAR_SERIALIZATION_RULES_H_
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