80c663882a
Summary: First draft. Unit tests pass. Test Plan: unit tests attached Reviewers: heyongqiang Reviewed By: heyongqiang Differential Revision: https://reviews.facebook.net/D3969
76 lines
2.9 KiB
C++
76 lines
2.9 KiB
C++
/*
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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*/
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#ifndef THRIFT_UTIL_SHARED_PTR_UTIL_H_
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#define THRIFT_UTIL_SHARED_PTR_UTIL_H_ 1
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#include <boost/shared_ptr.hpp>
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#include <boost/type_traits/is_convertible.hpp>
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#include <boost/utility/enable_if.hpp>
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/**
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* Helper macros to allow function overloading even when using
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* boost::shared_ptr.
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*
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* shared_ptr makes overloading really annoying, since shared_ptr defines
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* constructor methods to allow one shared_ptr type to be constructed from any
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* other shared_ptr type. (Even if it would be a compile error to actually try
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* to instantiate the constructor.) These macros add an extra argument to the
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* function to cause it to only be instantiated if a pointer of type T is
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* convertible to a pointer of type U.
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*
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* THRIFT_OVERLOAD_IF should be used in function declarations.
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* THRIFT_OVERLOAD_IF_DEFN should be used in the function definition, if it is
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* defined separately from where it is declared.
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*/
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#define THRIFT_OVERLOAD_IF_DEFN(T, Y) \
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typename ::boost::enable_if<typename ::boost::is_convertible<T*, Y*>::type, \
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void*>::type
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#define THRIFT_OVERLOAD_IF(T, Y) \
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THRIFT_OVERLOAD_IF_DEFN(T, Y) = NULL
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namespace apache { namespace thrift {
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/**
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* A helper functor that can be used as a shared_ptr destructor, but that does
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* nothing at all.
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*
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* This can be used to create a shared_ptr to an object that shouldn't really
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* be destroyed when the last shared_ptr to it goes away. This is useful in
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* some situations to call thrift APIs that require a shared_ptr argument when
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* you have an object on the stack or otherwise owned by some other part of the
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* code.
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*
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* WARNING: If at all possible, please avoid using this class to create
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* shared_ptr. Attempting to use shared_ptrs with manually managed objects is
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* generally a bad idea. This class should only be used in a few rare cases
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* where a temporary shared_ptr is needed, and you can guarantee that all
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* shared_ptrs to the object will be destroyed before the object itself is
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* destroyed.
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*/
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template<class T>
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class NoopPtrDestructor {
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public:
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void operator()(T* obj) {};
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};
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}} // apache::thrift
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#endif // THRIFT_UTIL_SHARED_PTR_UTIL_H_
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