rknfish

CMU 15-445

Experiment Objective#

This experiment is a preliminary implementation of "CMU 15-445/645". It mainly tests the proficiency of using C++.

The course I took is fall2022¹. The relevant code can be downloaded from Release².

This course mainly involves two aspects:

• How to set up the environment
• The use of C++

Environment Setup#

I use the development method of using a virtual machine (Ubuntu) + local computer SSH.

Install the following plugins in vscode:

• C/C++
• CMake
• CMake Tools
• Remote - SSH

First, download and unzip the required code.

wget https://github.com/cmu-db/bustub/archive/refs/tags/v20221128-2022fall.tar.gz
tar -zxvf v20221128-2022fall.tar.gz  

Then, use VScode SSH to directly enter the current directory of the remote computer.

After that, install the necessary software.

sudo build_support/packages.sh

Then, there are several options in Vscode that need to be set.

Click on the bottom

Generate

Then select Clang 12.01 x86_64-pc-linux-gnu to start coding happily.

Debug#

There is a button next to Generate [all], switch it to the one you need.

The test method used is GTest.

Just remove all DIABLE_ in the target Test file and you can start testing.

For example, in the path /test/primer/starter_trie_test.cpp, remove all DIABLE_, and then try to output the result. Press to debug at the breakpoints you set. Press to get the result directly.

Debug

Run result

Use of C++#

There is not much to say about this aspect.

Just grasp the usage of std::unique_ptr.

Here are a few examples.

Traverse the nodes of the trie

auto cur_node = &this->root_; // ! Pointer to a smart pointer
auto par_node = cur_node;

while(cur_node != nullptr) {
  cur_node = cur_node->get()-> GetChildNode(ch);
  ...
  par_node = cur_node;
}

How to dynamically construct a subclass node on a parent class pointer

auto tmp_node = std::make_unique<T>(std::move(*cur_node) , value);
par_node-> get() -> InsertChildNode(ch, std::move(*tmp_node));
cur_node = par_node-> GetChildNode(ch);

Get the value in the subclass space by type casting

auto tmp_node = dynamic_cast<TrieNodeWithValue<T> *>(cur_node->get());

If you are unable to complete it because the course has ended, you can refer to my code.