Boost Deadlock Example

gistfile1.txt

# Boost Process Deadlock example

Build with:

```
g++ -o bptest main.cpp -lpthread
```

or just:

```
make
```

Run with:

```
buffer=$(tyger buffer create) && access_url=$(tyger buffer access "${buffer}" --write) && ./bptest $access_url
```

> Note: It is important to create a new buffer to make sure it is empty (causing the read to wait).

main.cpp

#include <iostream>
#include <thread>
#include <boost/process.hpp>


namespace bp = boost::process;

int main(int argc, char** argv)
{
    std::cerr << "Buffer Proxy Test" << std::endl;
    
    std::string access_url = argv[1];

    bp::opstream os;
    bp::child writer("buffer-proxy write " + access_url, bp::std_in < os);

    auto writer_thread = std::thread([&os, &writer](){
        std::cerr << "Writer thread started" << std::endl;
        std::string data("hello world");
        os << data;

        // We will put a delay here to make sure we start the reader
        // before the writer finishes. This causes a deadlock.
        std::this_thread::sleep_for(std::chrono::seconds(1));
        
        os.flush();
        os.pipe().close();
        writer.wait();
        std::cerr << "Writer thread finished" << std::endl;
    });

    bp::ipstream is;
    bp::child reader("buffer-proxy read " + access_url, bp::std_out > is);

    auto reader_thread = std::thread([&is, &reader](){
        std::cerr << "Reader thread started" << std::endl;
        std::string data;
        std::getline(is, data);
        std::cerr << "Read: " << data << std::endl;
        reader.wait();
        std::cerr << "Reader thread finished" << std::endl;
    }); 

    writer_thread.join();
    reader_thread.join();

    return 0;
}

Makefile

bptest: main.cpp
	g++ -o bptest main.cpp -lpthread