X-Git-Url: https://git.ucc.asn.au/?a=blobdiff_plain;f=course%2Fsemester2%2Fpprog%2Fassignment1%2Fmthread%2Fnbody.c;h=de9b8aaac241e4453025acdcafcc4ccf67528d64;hb=df06a43b2727b939ee572a1ddaa39e707aff030a;hp=afd1d607dbd54b89edb9ca8166ea4fcbdebd21b1;hpb=4b52f4b6f00888b393292646bcedb4561f5de714;p=matches%2Fhonours.git diff --git a/course/semester2/pprog/assignment1/mthread/nbody.c b/course/semester2/pprog/assignment1/mthread/nbody.c index afd1d607..de9b8aaa 100644 --- a/course/semester2/pprog/assignment1/mthread/nbody.c +++ b/course/semester2/pprog/assignment1/mthread/nbody.c @@ -7,20 +7,29 @@ #include "nbody.h" // Declarations #include "../single-thread/nbody.c" // Include all functions from the single threaded version +#include "graphics.h" // For declaration of Graphics_Run only + // --- Variable declarations --- // pthread_t compute_thread; // The thread responsible for computations; it spawns worker threads pthread_t * worker_thread = NULL; //Array of worker threads responsible for Force and Position updates System * sub_system = NULL; //Array of Systems used to divide up the main "universe" System for worker threads -pthread_mutex_t mutex_workers; // Mutex used for the barrier between Force and Position updates -pthread_cond_t workers_done_cv; // Conditional used for the barrier between Force and Position updates -unsigned workers_busy; // Number of workers currently doing something +System * nested_sub_system = NULL; //Array of Systems for division of "universe" for the nested worker threads pthread_mutex_t mutex_runstate; // Mutex around the runstate +pthread_attr_t attr; //thread attribute for the workers. + +Barrier force_barrier; // I laughed at this variable name. A bit sad really. +Barrier position_barrier; + + +Barrier graphics_barrier; + + /** * @function Compute_Thread * @purpose Thread - Continuously computes steps for a system of bodies. Seperate from graphics functions. @@ -37,6 +46,9 @@ void * Compute_Thread(void * arg) if (options.num_threads <= 0) options.num_threads = (DEFAULT_WORKING_THREADS > 1) ? DEFAULT_WORKING_THREADS : 1; + if (options.nested_threads <= 0) + options.nested_threads = 1; + // Do a sanity check; there is no point spawning more threads than bodies. if (options.num_threads > s->N) { @@ -46,66 +58,53 @@ void * Compute_Thread(void * arg) options.num_threads = s->N; } + pthread_attr_init(&attr); + pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); //Needs to be detached, so that memory can be reused. + if (options.num_threads > 1) // Allocate worker threads and sub systems, as long as there would be more than 1 { - worker_thread = (pthread_t*)(calloc(options.num_threads, sizeof(pthread_t))); - if (worker_thread == NULL) - { - perror("Couldn't allocate array of worker threads"); - QuitProgram(true); - pthread_exit(NULL); - } - sub_system = (System*)(calloc(options.num_threads, sizeof(System))); - if (sub_system == NULL) + worker_thread = Allocate_Threads(options.num_threads); + sub_system = Split_System(&universe, options.num_threads); + + if (options.nested_threads > 1) + nested_sub_system = Split_System(&universe, options.nested_threads); + + #ifdef PERSISTENT_THREADS + for (unsigned i = 0; i < options.num_threads; ++i) { - perror("Couldn't allocate array of systems for worker threads to use"); - QuitProgram(true); - pthread_exit(NULL); + if (pthread_create(worker_thread+i, & attr, Worker_Thread, (void*)(sub_system+i)) != 0) + { + perror("In compute thread, couldn't create worker thread"); + QuitProgram(true); + pthread_exit(NULL); + } } + #endif //PERSISTENT_THREADS - // Divide up the Body array owned by s into options.num_threads arrays, one for each worker thread - unsigned bodies_per_system = (s->N) / options.num_threads; - unsigned remainder = (s->N) % options.num_threads; - for (unsigned i = 0; i < options.num_threads; ++i) + + } + #ifdef PERSISTENT_THREADS + else + { + while (!ExitCondition()) { - sub_system[i].body = (s->body)+(i*bodies_per_system); - sub_system[i].N = bodies_per_system; - sub_system[i].steps = 0; - if (i == options.num_threads - 1) - sub_system[i].N += remainder; // The last thread gets the remainder + if (options.verbosity != 0 && universe.steps % options.verbosity == 1) + DisplayStatistics(); + // Just do everything in this thread + System_Forces(s, s); + System_Positions(s); } + QuitProgram(false); + pthread_exit(NULL); } - - pthread_attr_t attr; //thread attribute for the workers. - pthread_attr_init(&attr); - pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); //Needs to be detached, so that memory can be reused. - + #else // The main computation loop - while (true) + while (!ExitCondition()) { - - if (runstate != RUN) pthread_exit(NULL); //Check whether the main thread wants to exit - - - - //Check whether the program should quit due to steps being computed, or a timeout - if (options.timeout > 0.0) - { - if ((unsigned)(time(NULL) - options.start_time.tv_sec) >= options.timeout) - QuitProgram(false); - } - - if (options.num_steps > 0 && universe.steps > options.num_steps) - QuitProgram(false); - - if (options.draw_graphics == false && options.verbosity != 0 - && universe.steps % options.verbosity == 1) - { + if (options.verbosity != 0 && universe.steps % options.verbosity == 1) DisplayStatistics(); - } - if (options.num_threads <= 1) { @@ -117,9 +116,6 @@ void * Compute_Thread(void * arg) - - workers_busy = options.num_threads; //All threads working - //Compute forces for (unsigned i = 0; i < options.num_threads; ++i) { @@ -129,19 +125,18 @@ void * Compute_Thread(void * arg) QuitProgram(true); pthread_exit(NULL); } + } - - //Barrier - Wait for forces to be computed - pthread_mutex_lock(&mutex_workers); - while (workers_busy > 0) - pthread_cond_wait(&workers_done_cv, &mutex_workers); - pthread_mutex_unlock(&mutex_workers); + Barrier_Wait(&force_barrier); //All the forces are now computed - - workers_busy = options.num_threads; //All threads working + + if (options.draw_graphics && options.pedantic_graphics) + { + Barrier_Wait(&graphics_barrier); + } //Compute positions for (unsigned i = 0; i < options.num_threads; ++i) @@ -155,19 +150,144 @@ void * Compute_Thread(void * arg) } //Wait for positions to be computed - pthread_mutex_lock(&mutex_workers); - while (workers_busy > 0) - pthread_cond_wait(&workers_done_cv, &mutex_workers); - pthread_mutex_unlock(&mutex_workers); + Barrier_Wait(&position_barrier); + //Update number of steps computed universe.steps += 1; + + + } + QuitProgram(false); + #endif //PERSISTENT_THREADS + return NULL; } +/** + * @function BeforeDraw + * @purpose Called in graphics thread before the draw loop + * When --pedantic-graphics enabled, will wait for position computations to finish before drawing + * Otherwise does nothing + */ +void BeforeDraw() +{ + if (options.verbosity != 0 && universe.steps % options.verbosity == 0) + DisplayStatistics(); + //printf("BEFORE DRAW\n"); + if (!options.pedantic_graphics) + return; + + Barrier_Wait(&position_barrier); + + + Barrier_Enter(&graphics_barrier); +} + +/** + * @function AfterDraw + * @purpose Called in graphics thread after the draw loop + * When --pedantic-graphics is supplied, will signal computation thread that drawing is finished + * So that positions can be safely altered + * Otherwise does nothing + */ +void AfterDraw() +{ + universe.steps += 1; + if (!options.pedantic_graphics) + return; + Barrier_Leave(&graphics_barrier); + +} + +#ifdef PERSISTENT_THREADS + +/** + * @function Worker_Thread + * @purpose Thread - Calculate stuff + */ +void * Worker_Thread(void * arg) +{ + System * s = (System*)(arg); + + + pthread_t * nested_workers = NULL; + System_ForcePair * system_pairs = NULL; + System * nested_position = NULL; + + Barrier nested_barrier; + Barrier_Init(&nested_barrier); + + printf("options.nested_threads == %d\n", (int)(options.nested_threads)); + + if (options.nested_threads != 1) + { + + system_pairs = (System_ForcePair*)(calloc(options.nested_threads, sizeof(System_ForcePair))); + if (system_pairs == NULL) // Handle tedious error cases + { + perror("Couldn't allocate array of system pairs"); + QuitProgram(true); + pthread_exit(NULL); + } + nested_workers = Allocate_Threads(options.nested_threads); + nested_position = + + for (unsigned i = 0; i < options.nested_threads; ++i) + { + system_pairs[i].A = s; + system_pairs[i].B = nested_sub_system+i; + } + } + + while (!ExitCondition()) + { + + if (options.nested_threads == 1) + { + Barrier_Enter(&force_barrier); + System_Forces(s, &universe); + Barrier_Leave(&force_barrier); + } + else + { + for (unsigned i = 0; i < options.nested_threads; ++i) + { + if (pthread_create(nested_workers+i, &attr, Force_Thread, (void*)(system_pairs+i)) != 0) + { + perror("In worker thread, couldn't create nested worker thread (force)"); + QuitProgram(true); + free(nested_workers); + pthread_exit(NULL); + } + } + } + //printf("Computed forces for %p\n", arg); + Barrier_Wait(&force_barrier); + //printf("Computed ALL forces\n"); + + if (options.draw_graphics && options.pedantic_graphics) + Barrier_Wait(&graphics_barrier); + + Barrier_Enter(&position_barrier); + + System_Positions(s); + + Barrier_Leave(&position_barrier); + //printf("Computed positions for %p\n", arg); + Barrier_Wait(&position_barrier); + //printf("Computed ALL positions\n"); + } + printf("Worker thread exits\n"); + QuitProgram(false); + pthread_exit(NULL); +} + +#endif //PERSISTENT_THREADS + /** * @function Force_Thread * @purpose Thread - Calculates the forces on objects in a System @@ -175,19 +295,17 @@ void * Compute_Thread(void * arg) */ void * Force_Thread(void * s) { - - System_Forces((System*)s, &universe); //Simple wrapper + System_ForcePair * pair = (System_ForcePair*)s; + Barrier_Enter(&force_barrier); + + System_Forces(pair->A, pair->B); //Simple wrapper + + Barrier_Leave(&force_barrier); - pthread_mutex_lock(&mutex_workers); - workers_busy -= 1; // Count this thread as done - if (workers_busy == 0) - { - pthread_cond_signal(&workers_done_cv); // All threads done; wake up the compute_thread - } - pthread_mutex_unlock(&mutex_workers); return NULL; } + /** * @function Position_Thread * @purpose Thread - Calculates the positions of objects in a System @@ -195,16 +313,9 @@ void * Force_Thread(void * s) */ void * Position_Thread(void * s) { - + Barrier_Enter(&position_barrier); System_Positions((System*)s); // Simple wrapper - - pthread_mutex_lock(&mutex_workers); - workers_busy -= 1; // Count this thread as done - if (workers_busy == 0) - { - pthread_cond_signal(&workers_done_cv); //All threads done; wake up the compute_thread - } - pthread_mutex_unlock(&mutex_workers); + Barrier_Leave(&position_barrier); return NULL; } @@ -217,7 +328,8 @@ void * Position_Thread(void * s) */ void QuitProgram(bool error) { - + if (runstate == QUIT || runstate == QUIT_ERROR) + return; //Don't do anything if already quitting pthread_mutex_lock(&mutex_runstate); // aquire mutex if (error) // set the runstate runstate = QUIT_ERROR; @@ -247,29 +359,122 @@ void Thread_Cleanup(void) * @function Simulation_Run * @purpose Initialise and start the simulation. Will be called in the main thread. * Replaces the single-threaded macro that does nothing, and sets up the compute thread + * @param argc - Number of arguments - Passed to Graphics_Run if needed + * @param argv - Argument strings - Passed to Graphics_Run if needed */ -void Simulation_Run() +void Simulation_Run(int argc, char ** argv) { atexit(Thread_Cleanup); - if (options.draw_graphics == false) + Barrier_Init(&force_barrier); + Barrier_Init(&position_barrier); + Barrier_Init(&graphics_barrier); + + + if (options.draw_graphics) { + // The graphics are enabled, so create a thread to do computations + // Graphics are done in the main loop + //printf("Graphics are enabled\n"); + #ifdef PERSISTENT_THREADS Compute_Thread((void*)(&universe)); + #else + if (pthread_create(&compute_thread, NULL, Compute_Thread, (void*)&universe) != 0) + { + perror("Error creating compute thread"); + exit(EXIT_FAILURE); + } + #endif //PERSISTENT_THREADS + //printf("Run compute thread\n"); + Graphics_Run(argc, argv); + } + else + + Compute_Thread((void*)(&universe)); // Graphics are disabled, so do computations in the main thread +} - // If there are no graphics, run the computation loop in the main thread - // The call to pthread_exit(NULL) in the computation loop ends the main thread - // This means the main function never calls the Graphics_Run function - // Without this condition here, Graphics_Display would essentially be running a busy loop in the main thread - - fprintf(stderr,"Should not see this\n"); - exit(EXIT_FAILURE); + +void Barrier_Init(Barrier * b) +{ + b->threads_busy = 0; +} + +void Barrier_Enter(Barrier * b) +{ + pthread_mutex_lock(&(b->mutex)); + b->threads_busy += 1; + pthread_mutex_unlock(&(b->mutex)); +} + +void Barrier_Leave(Barrier * b) +{ + pthread_mutex_lock(&(b->mutex)); + b->threads_busy -= 1; + if (b->threads_busy == 0) + { + pthread_cond_signal(&(b->threads_done_cv)); } - - // Create a thread to handle computation loop - if (pthread_create(&compute_thread, NULL, Compute_Thread, (void*)&universe) != 0) + pthread_mutex_unlock(&(b->mutex)); +} + +void Barrier_Wait(Barrier * b) +{ + pthread_mutex_lock(&(b->mutex)); + while (b->threads_busy > 0) + pthread_cond_wait(&(b->threads_done_cv), &(b->mutex)); + pthread_mutex_unlock(&(b->mutex)); +} + +/** + * @function Split_System + * @purpose Helper to divide one system into an array of systems + * Each sub system will have N = (s->N / n) bodies in it + * @param s - The original system (typically &universe) + * @param n - The number of sub systems in the array + * + * WARNING: It is the caller's responsibility to free() the returned array + */ +System * Split_System(System * s, unsigned n) +{ + System * result = (System*)(calloc(n, sizeof(System))); + if (result == NULL) + { + perror("Couldn't create array of sub systems"); + QuitProgram(true); + pthread_exit(NULL); + } + + unsigned n_per_system = (s->N) / n; + unsigned remainder = (s->N) % n; + + for (unsigned i = 0; i < n; ++i) + { + result[i].N = n_per_system; + if (i == n-1) + result[i].N += remainder; + result[i].body = (s->body) + (n_per_system * i); + result[i].steps = 0; + } + return result; +} + +/** + * @function Allocate_Threads + * @purpose Helper function to allocate an array of pthread_t objects + * Handles all the pointless, er, "important" error checking that should be done + * @param n - Number of threads in the array + * + * WARNING: Remember to free() the array!!! + */ +pthread_t * Allocate_Threads(unsigned n) +{ + pthread_t * result = (pthread_t*)(calloc(n, sizeof(pthread_t))); + if (result == NULL) { - perror("Error creating compute thread"); - exit(EXIT_FAILURE); + perror("Unable to allocate memory for threads"); + QuitProgram(true); + pthread_exit(NULL); } + return result; }