237 lines
6.7 KiB
C++
237 lines
6.7 KiB
C++
#include "mthread.hpp"
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#include <iostream>
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#include <complex>
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#include <unistd.h>
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#include <thread>
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#include <chrono>
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#include <cmath>
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#include <algorithm>
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#include <atomic>
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using namespace std;
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mthread::mthread(
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unsigned int x_mn, unsigned int x_mx, complex<double> c_min, complex<double> c_max,
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unsigned int inf_cutoff, unsigned int max_iter, png& image, double *g_vmap, unsigned int *g_histogram,
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mthread **worker_list, unsigned int id, unsigned int jobs, atomic<uint32_t>& progress)
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: x_min_orig(x_mn), x_max_orig(x_mx),
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c_min(c_min), c_max(c_max),
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inf_cutoff(inf_cutoff), max_iter(max_iter), image(image), id(id), worker_cnt(jobs), progress(progress){
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workers = worker_list;
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x_min = x_mn;
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x_max = x_mx;
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y_min = 0;
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y_max = image.height();
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vmap = g_vmap;
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histogram = g_histogram;
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step = (c_max - c_min) / complex<double>(image.height(), image.width());
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my_thread = NULL;
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status.status_lock.lock();
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}
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void mthread::dispatch() {
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if((my_thread) && (my_thread->joinable())) delete my_thread;
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my_thread = new thread([this] {run();});
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}
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mthread::~mthread() {
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if((my_thread) && (my_thread->joinable())) {
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my_thread->join();
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delete my_thread;
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}
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}
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void mthread::join() {
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if((my_thread) && (my_thread->joinable())) my_thread->join();
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}
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bool mthread::find_work() {
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unsigned int worker, workers_finished;
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uint32_t loads[worker_cnt];
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struct mthread_status *peer_status;
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struct mthread_divinfo divinfo;
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workers_finished = 0;
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unique_lock<mutex> ack;
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status.status_lock.lock();
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status.searching = true;
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status.share_finished = true;
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status.status_lock.unlock();
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for(worker = 0; worker < worker_cnt; worker++) {
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//lock other worker so we can request from them
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peer_status = &workers[worker]->status;
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peer_status->status_lock.lock();
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//if they're done, we remember that to see if we exit
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if((peer_status->share_finished) && (worker != id)) {
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workers_finished++;
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}
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/** The reason why we have this bit in code twice is to prevent race conditions.
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* To add the potential canidate worker to our list to be sorted,
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* we need to make sure it's not currently being divided (true if div_syn is set).
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* Since we'll need to check the same later
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* when we actually request to split it's workload,
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* we might as well narrow it down and check everything else.
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* **/
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if((worker == id) ||
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(peer_status->searching) || (peer_status->div_syn) ||
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(peer_status->row_load < min_lines)) {
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loads[worker] = 0;
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peer_status->status_lock.unlock();
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continue;
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}
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//finally, if they're valid, write them down
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loads[worker] = peer_status->row_load;
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peer_status->status_lock.unlock();
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}
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//exit if all workers are finished
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if(workers_finished >= worker_cnt - 1) {
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return false;
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}
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//then we look over and pick our canidates
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for(;;) {
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//find the worker who has the biggest workload
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worker = distance(loads, max_element(loads, &loads[worker_cnt]));
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if(!loads[worker]) return true; //we have found a worker; distance is 0
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peer_status = &workers[worker]->status;
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peer_status->status_lock.lock();
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//re-check to see if canidate is valid (may have changed since added and sorted).
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//If you're wondering why we're doing this bit again, see comment before first time.
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if((peer_status->searching) || (peer_status->div_syn) ||
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(peer_status->row_load < min_lines)) {
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loads[worker] = 0;
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peer_status->status_lock.unlock();
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continue;
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}
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//ack: ask peer to devide
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ack = unique_lock<mutex>(peer_status->ack_lk);
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peer_status->div_syn = true;
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peer_status->status_lock.unlock();
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//when they reset it, they've acknowlaged and have set appropriate messages
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peer_status->msg_notify.wait(ack);
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ack.unlock();
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//area is too small to divide reliably
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if(peer_status->div_error) {
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loads[worker] = 0;
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peer_status->status_lock.lock();
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peer_status->div_error = false;
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peer_status->div_syn = false;
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peer_status->status_lock.unlock();
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continue;
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}
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//otherwise, we modify their struct for them to split their workload
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divinfo = workers[worker]->divide();
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peer_status->syn_ack_lk.unlock();
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//tell them we're done modifying
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peer_status->msg_notify.notify_all();
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//set our own stuff
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y_min = divinfo.y_min;
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y_max = divinfo.y_max;
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x_min = divinfo.x_min;
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x_max = divinfo.x_max;
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//update our status
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status.status_lock.lock();
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status.searching = false;
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status.status_lock.unlock();
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return true;
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}
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return true;
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}
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//makes sure no one is asking for work from us
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void mthread::check_work_request() {
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unique_lock<mutex> syn_ack;
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status.status_lock.lock();
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status.row_load = y_max - on_y;
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//check if anyone's asking us to divide
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if(status.div_syn) {
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status.div_error = status.row_load <= min_lines;
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if(status.div_error) {
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status.ack_lk.unlock();
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status.msg_notify.notify_all();
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}
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else {
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syn_ack = unique_lock<mutex>(status.syn_ack_lk);
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status.ack_lk.unlock();
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status.msg_notify.notify_all();
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status.msg_notify.wait(syn_ack);
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status.row_load = y_max - on_y;
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syn_ack.unlock();
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//new x/y min/max is ajusted by other thread, we can continue as normal.
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}
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}
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status.status_lock.unlock();
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}
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//renders area
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void mthread::render_area() {
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uint32_t image_width = image.width();
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unsigned int iter;
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complex<double> c, z;
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double pixel_value;
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/** pixel is drawn based on if/how many itertions it takes to get to infinity
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* while computing z^2+c. **/
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for(on_y = y_min; on_y < y_max; on_y++) {
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progress++;
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check_work_request();
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for(on_x = x_min; on_x < x_max; on_x++) {
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c = (step * complex<double>(on_x,on_y)) + c_min;
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z = 0;
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for(iter = 0; iter < max_iter; iter++) {
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if(abs(z) >= inf_cutoff) break;
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z = z*z + c;
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}
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if(iter >= max_iter) {
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iter = 0;
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vmap[(on_y * image_width) + on_x] = 0;
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}
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else {
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pixel_value = (iter + 1) - (log((log(pow(abs(z), 2.0)) / 2.0) / log(2.0)));
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vmap[(on_y * image_width) + on_x] = pixel_value;
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histogram[(int)pixel_value]++;
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}
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}
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}
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}
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//alternates states of finding work work and rendering
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void mthread::run() {
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//locks in initilizer
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status.searching = false;
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status.share_finished = false;
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status.div_syn = false;
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status.div_error = false;
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status.status_lock.unlock();
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do {
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render_area();
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} while (find_work());
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}
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struct mthread_divinfo mthread::divide() {
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struct mthread_divinfo ret;
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ret.x_min = x_min;
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ret.x_max = x_max;
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ret.y_min = ((y_max - on_y) / 2) + on_y;
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ret.y_max = y_max;
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y_min = on_y;
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y_max = ret.y_min;
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status.div_syn = false;
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return ret;
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}
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