160 lines
4.2 KiB
C++
160 lines
4.2 KiB
C++
// This program demonstrates how to create a pipeline scheduling framework
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// that describes a generalized token dependencies,
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// propagates a series of integers, and adds one to the result at each
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// stage, using a range of pipes provided by the application.
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//
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// The pipeline has the following structure:
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//
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// o -> o -> o
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// | | |
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// v v v
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// o -> o -> o
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// | | |
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// v v v
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// o -> o -> o
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// | | |
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// v v v
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// o -> o -> o
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//
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// Then, the program resets the pipeline to a new range of five pipes.
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//
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// o -> o -> o -> o -> o
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// | | | | |
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// v v v v v
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// o -> o -> o -> o -> o
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// | | | | |
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// v v v v v
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// o -> o -> o -> o -> o
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// | | | | |
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// v v v v v
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// o -> o -> o -> o -> o
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// The scheduling token has the following dependencies:
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// ___________
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// | |
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// V _____ |
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// | | |
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// | V |
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// 1 2 3 4 5 6 7 8 9 10
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// ^ | |
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// |___| |
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// ^ |
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// |_______|
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//
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// 2 is deferred by 8
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// 5 is dieferred by 2, 7, and 9
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#include <taskflow/taskflow.hpp>
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#include <taskflow/algorithm/pipeline.hpp>
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int main() {
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tf::Taskflow taskflow("pipeline");
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tf::Executor executor;
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const size_t num_lines = 4;
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// define the pipe callable
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auto pipe_callable = [] (tf::Pipeflow& pf) mutable {
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switch(pf.pipe()) {
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// first stage generates only 15 scheduling tokens
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// and describes the token dependencies
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case 0: {
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if(pf.token() == 15) {
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pf.stop();
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}
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else {
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if (pf.token() == 5) {
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switch(pf.num_deferrals()) {
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case 0:
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pf.defer(2);
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printf("1st-time: Token %zu is deferred by 2\n", pf.token());
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pf.defer(7);
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printf("1st-time: Token %zu is deferred by 7\n", pf.token());
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break;
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case 1:
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pf.defer(9);
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printf("snd-time: Token %zu is deferred by 9\n", pf.token());
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break;
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case 2:
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printf("3rd-time: Tokens 2, 7 and 9 resolved dependencies for token %zu\n", pf.token());
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break;
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}
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}
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else if (pf.token() == 2) {
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switch(pf.num_deferrals()) {
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case 0:
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pf.defer(8);
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printf("1st-time: Token %zu is deferred by 8\n", pf.token());
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break;
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case 1:
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printf("2nd-time: Token 8 resolved dependencies for token %zu\n", pf.token());
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break;
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}
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}
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else {
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printf("stage 1: Non-deferred token %zu\n", pf.token());
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}
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}
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}
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break;
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// other stages prints input token
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default: {
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printf("stage %zu : input token %zu (deferrals=%zu)\n",
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pf.pipe()+1, pf.token(), pf.num_deferrals());
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}
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break;
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}
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};
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// create a vector of three pipes
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std::vector< tf::Pipe<std::function<void(tf::Pipeflow&)>> > pipes;
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for(size_t i=0; i<3; i++) {
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pipes.emplace_back(tf::PipeType::SERIAL, pipe_callable);
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}
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// create a pipeline of four parallel lines using the given vector of pipes
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tf::ScalablePipeline<decltype(pipes)::iterator> pl(num_lines, pipes.begin(), pipes.end());
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// build the pipeline graph using composition
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tf::Task init = taskflow.emplace([](){ std::cout << "ready\n"; })
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.name("starting pipeline");
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tf::Task task = taskflow.composed_of(pl)
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.name("pipeline");
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tf::Task stop = taskflow.emplace([](){ std::cout << "stopped\n"; })
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.name("pipeline stopped");
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// create task dependency
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init.precede(task);
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task.precede(stop);
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// dump the pipeline graph structure (with composition)
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taskflow.dump(std::cout);
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// run the pipeline
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executor.run(taskflow).wait();
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// reset the pipeline to a new range of five pipes and starts from
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// the initial state (i.e., token counts from zero)
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for(size_t i=0; i<2; i++) {
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pipes.emplace_back(tf::PipeType::SERIAL, pipe_callable);
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}
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pl.reset(pipes.begin(), pipes.end());
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executor.run(taskflow).wait();
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return 0;
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}
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