正確釋放協議緩衝存儲器

Question

我使用谷歌協議緩衝通過以下方式：

void myfunc() { 
    Buffers::MyBuffer buf; 
    buf.ParseFromArray(data, datalen); 
    ... 
    return; 
} 

的documentation for Protocol Buffers says是針對該對象應該被刪除的緩衝內存。我不是C++的天才，但我認爲delete只應該被分配爲new的對象調用。內存是否清理回來了？

Answer 1

當對象被銷燬時，緩衝區的內存應該被釋放。

void myfunc() { 
    Buffers::MyBuffer buf; // this create your object on stack 
    const char* data= new char[100]; 
    datalen= readSomeData(data, 100); // not best for file, socket, etc. 
    buf.ParseFromArray(data, datalen); // this alocate any needed object 
    // by calling Buffers::SomeInternalBuffer:New 
    // now you may delete the data varible, is not needed 
    delete[] data; // called new, so call delete 
    ... 
    buf.Clear(); // here the read data are lost, 
    // but some objects may not be deleted for future use 

    buf.mutable_someinternalbuffer(); // call Buffers::SomeInternalBuffer:New, 
    // or may not if ParseFromArray already call it 

    ... 
    return; // here buf is out of scope and destroyed 
    // any buffers that are created by New is going to be deleted 
} 

release_foo 爲了保持緩衝被刪除，使用靜態的新方法：如果你需要保留任何SomeInternalBuffer但不MyBuffer使用release_<field>方法

Buffers::MyBuffer* myfunc2() { 
    Buffers::MyBuffer* buf = Buffers::MyBuffer:New(); 
    if(buf->ParseFromArray(data, datalen)) 
     return buf; // return object, no memory dealocation 
    delete buf; // something wrong with data, delete, destroy and dealocate 
    return NULL; // return null 
} 

：

Buffers::SomeInternalBuffer* myfunc3() { 
    Buffers::MyBuffer buf; // this create your object on stack 
    if(buf.ParseFromArray(data, datalen)) 
     return buf.release_someinternalbuffer(); // return object 
    // if ParseFromArray do not call New, method release_someinternalbuffer 
    // will call New and copy data from default value 
    // no memory deallocation for returned object, everything else will deallocate 

    return NULL; // same as in first example 
}