Method push

src/brpc/stream.cpp:565–572

        _size = 0;
    }
    void push(butil::IOBuf* buf) {
        if (_size == _cap) {
            flush();
        }
        _storage[_size++] = buf;
        _total_length += buf->length();

    }
    size_t total_length() const { return _total_length; }
private:
    butil::IOBuf** _storage;