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