// This program demonstrates how to create a pipeline scheduling framework

// that propagates a series of integers and adds one to the result at each

// stage.

//

// The pipeline has the following structure:

//

// o -> o -> o

// | |

// v v

// o -> o -> o

// | |

// v v

// o -> o -> o

// | |

// v v

// o -> o -> o

#include <taskflow/taskflow.hpp>

#include <taskflow/algorithm/pipeline.hpp>

int main() {

tf::Taskflow taskflow("pipeline");

tf::Executor executor;

const size_t num_lines = 4;

// custom data storage

std::array<size_t, num_lines> buffer;

// the pipeline consists of three pipes (serial-parallel-serial)

// and up to four concurrent scheduling tokens

tf::Pipeline pl(num_lines,

tf::Pipe{tf::PipeType::SERIAL, [&buffer](tf::Pipeflow& pf) {

// generate only 5 scheduling tokens

if(pf.token() == 5) {

pf.stop();

}

// save the result of this pipe into the buffer

else {

printf("stage 1: input token = %zu\n", pf.token());

buffer[pf.line()] = pf.token();

}

}},

tf::Pipe{tf::PipeType::PARALLEL, [&buffer](tf::Pipeflow& pf) {

printf(

"stage 2: input buffer[%zu] = %zu\n", pf.line(), buffer[pf.line()]

);

// propagate the previous result to this pipe and increment

// it by one

buffer[pf.line()] = buffer[pf.line()] + 1;

}},

tf::Pipe{tf::PipeType::SERIAL, [&buffer](tf::Pipeflow& pf) {

printf(

"stage 3: input buffer[%zu] = %zu\n", pf.line(), buffer[pf.line()]

);

// propagate the previous result to this pipe and increment

// it by one

buffer[pf.line()] = buffer[pf.line()] + 1;

}}

);

// build the pipeline graph using composition

tf::Task init = taskflow.emplace([](){ std::cout << "ready\n"; })

.name("starting pipeline");

tf::Task task = taskflow.composed_of(pl)

.name("pipeline");

tf::Task stop = taskflow.emplace([](){ std::cout << "stopped\n"; })

.name("pipeline stopped");

// create task dependency

init.precede(task);

task.precede(stop);

// dump the pipeline graph structure (with composition)

taskflow.dump(std::cout);

// run the pipeline

executor.run(taskflow).wait();

return 0;

}