Add libar2simplified_init_context

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 368 insertions, 0 deletions

diff --git a/libar2simplified_init_context.c b/libar2simplified_init_context.c
new file mode 100644
index 0000000..c7f8b69
--- /dev/null
+++ b/libar2simplified_init_context.c
@@ -0,0 +1,368 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#include <pthread.h>
+#include <semaphore.h>
+
+
+struct user_data;
+
+struct thread_data {
+	size_t index;
+	struct user_data *master;
+	pthread_t thread;
+	sem_t semaphore;
+	int error;
+	void (*function)(void *data);
+	void *function_input;
+};
+
+struct user_data {
+	struct thread_data *threads;
+	size_t nthreads;
+	pthread_mutex_t mutex;
+	sem_t semaphore;
+	uint_least64_t *joined;
+	uint_least64_t resting[];
+};
+
+
+static void *
+alignedalloc(size_t num, size_t size, size_t extra, size_t alignment)
+{
+	void *ptr;
+	int err;
+	if (num > (SIZE_MAX - extra) / size) {
+		errno = ENOMEM;
+		return NULL;
+	}
+	if (alignment < sizeof(void *))
+		alignment = sizeof(void *);
+	err = posix_memalign(&ptr, alignment, num * size + extra);
+	if (err) {
+		errno = err;
+		return NULL;
+	} else {
+		return ptr;
+	}
+}
+
+
+static void *
+allocate(size_t num, size_t size, size_t alignment, struct libar2_context *ctx)
+{
+	size_t pad = (alignment - ((2 * sizeof(size_t)) & (alignment - 1))) & (alignment - 1);
+	char *ptr = alignedalloc(num, size, pad + 2 * sizeof(size_t), alignment);
+	if (ptr) {
+		ptr = &ptr[pad];
+		*(size_t *)ptr = pad;
+		ptr = &ptr[sizeof(size_t)];
+		*(size_t *)ptr = num * size;
+		ptr = &ptr[sizeof(size_t)];
+	}
+	(void) ctx;
+	return ptr;
+}
+
+
+static void
+deallocate(void *ptr, struct libar2_context *ctx)
+{
+	char *p = ptr;
+	p -= sizeof(size_t);
+	libar2_erase(ptr, *(size_t *)p);
+	p -= sizeof(size_t);
+	p -= *(size_t *)p;
+	free(p);
+	(void) ctx;
+}
+
+
+static void *
+thread_loop(void *data_)
+{
+	struct thread_data *data = data_;
+	int err;
+
+	for (;;) {
+		if (sem_wait(&data->semaphore)) {
+			if (errno == EINTR)
+				continue;
+			data->error = errno;
+			return NULL;
+		}
+
+		if (!data->function) {
+			data->error = ENOTRECOVERABLE;
+			return NULL;
+		}
+		data->function(data->function_input);
+
+		err = pthread_mutex_lock(&data->master->mutex);
+		if (err) {
+			data->error = err;
+			return NULL;
+		}
+		data->master->resting[data->index / 64] |= (uint_least64_t)1 << (data->index % 64);
+		pthread_mutex_unlock(&data->master->mutex);
+		if (sem_post(&data->master->semaphore)) {
+			data->error = errno;
+			return NULL;
+		}
+	}
+}
+
+
+static int
+run_thread(size_t index, void (*function)(void *arg), void *arg, struct libar2_context *ctx)
+{
+	struct user_data *data = ctx->user_data;
+	int err;
+
+	err = pthread_mutex_lock(&data->mutex);
+	if (err) {
+		errno = err;
+		return -1;
+	}
+	data->resting[index / 64] ^= (uint_least64_t)1 << (index % 64);
+	pthread_mutex_unlock(&data->mutex);
+
+	if (data->threads[index].error) {
+		errno = data->threads[index].error;
+		return -1;
+	}
+
+	data->threads[index].function = function;
+	data->threads[index].function_input = arg;
+	if (sem_post(&data->threads[index].semaphore))
+		return -1;
+
+	return 0;
+}
+
+
+static int
+destroy_thread_pool(struct libar2_context *ctx)
+{
+	struct user_data *data = ctx->user_data;
+	size_t i;
+	int ret = 0;
+	for (i = data->nthreads; i--;)
+		if (run_thread(i, pthread_exit, NULL, ctx))
+			return -1;
+	for (i = data->nthreads; i--;) {
+		pthread_join(data->threads[i].thread, NULL);
+		sem_destroy(&data->threads[i].semaphore);
+		if (data->threads[i].error)
+			ret = data->threads[i].error;
+	}
+	free(data->threads);
+	sem_destroy(&data->semaphore);
+	pthread_mutex_destroy(&data->mutex);
+	free(data);
+	return ret;
+}
+
+
+static int
+init_thread_pool(size_t desired, size_t *createdp, struct libar2_context *ctx)
+{
+	struct user_data *data;
+	int err;
+	size_t i, size;
+	long int nproc, nproc_limit;
+#ifdef __linux__
+	char path[sizeof("/sys/devices/system/cpu/cpu") + 3 * sizeof(nproc)];
+#endif
+#ifdef _SC_SEM_VALUE_MAX
+	long int semlimit;
+#endif
+
+	if (desired < 2) {
+		*createdp = 0;
+		return 0;
+	}
+
+	nproc = sysconf(_SC_NPROCESSORS_ONLN);
+#ifdef __linux__
+	if (nproc < 1) {
+		nproc_limit = desired > LONG_MAX ? LONG_MAX : (long int)desired;
+		for (nproc = 0; nproc < nproc_limit; nproc++) {
+			sprintf(path, "%s%li", "/sys/devices/system/cpu/cpu", nproc);
+			if (access(path, F_OK))
+				break;
+		}
+	}
+#endif
+	if (nproc < 1)
+		nproc = FALLBACK_NPROC;
+
+#ifdef _SC_SEM_VALUE_MAX
+	semlimit = sysconf(_SC_SEM_VALUE_MAX);
+	if (semlimit >= 1 && semlimit < nproc)
+		nproc = semlimit;
+#endif
+
+	if (nproc == 1) {
+		*createdp = 0;
+		return 0;
+	}
+
+	desired = (size_t)nproc < desired ? (size_t)nproc : desired;
+
+	if (desired > SIZE_MAX - 63 || (desired + 63) / 64 > SIZE_MAX / sizeof(uint_least64_t) / 2) {
+		errno = ENOMEM;
+		return -1;
+	}
+	size = (desired + 63) / 64;
+	size *= sizeof(uint_least64_t) * 2;
+	data = alignedalloc(1, offsetof(struct user_data, resting), size, ALIGNOF(struct user_data));
+	memset(data, 0, offsetof(struct user_data, resting) + size);
+	data->joined = &data->resting[(desired + 63) / 64];
+	ctx->user_data = data;
+
+	*createdp = data->nthreads = desired;
+
+	data->threads = alignedalloc(data->nthreads, sizeof(*data->threads), 0, ALIGNOF(struct thread_data));
+	if (!data->threads)
+		return -1;
+
+	err = pthread_mutex_init(&data->mutex, NULL);
+	if (err) {
+		free(data->threads);
+		return -1;
+	}
+	err = sem_init(&data->semaphore, 0, 0);
+	if (err) {
+		pthread_mutex_destroy(&data->mutex);
+		free(data->threads);
+		return -1;
+	}
+
+	for (i = 0; i < data->nthreads; i++) {
+		memset(&data->threads[i], 0, sizeof(data->threads[i]));
+		data->threads[i].master = data;
+		data->threads[i].index = i;
+		data->resting[i / 64] |= (uint_least64_t)1 << (i % 64);
+		if (sem_init(&data->threads[i].semaphore, 0, 0)) {
+			err = errno;
+			goto fail_post_sem;
+		}
+		err = pthread_create(&data->threads[i].thread, NULL, thread_loop, &data->threads[i]);
+		if (err) {
+			sem_destroy(&data->threads[i].semaphore);
+		fail_post_sem:
+			data->nthreads = i;
+			destroy_thread_pool(ctx);
+			errno = err;
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+
+#if defined(__GNUC__)
+__attribute__((__const__))
+#endif
+static size_t
+lb(uint_least64_t x)
+{
+	size_t r = 0;
+	while (x > 1) {
+		x >>= 1;
+		r += 1;
+	}
+	return r;
+}
+
+static size_t
+await_threads(size_t *indices, size_t n, size_t require, struct libar2_context *ctx)
+{
+	struct user_data *data = ctx->user_data;
+	size_t ret = 0, i;
+	uint_least64_t one;
+	int err;
+
+	memset(data->joined, 0, (data->nthreads + 63) / 64 * sizeof(*data->joined));
+
+	for (i = 0; i < data->nthreads; i += 64) {
+		for (;;) {
+			one = data->resting[i / 64];
+			one ^= data->joined[i / 64];
+			if (!one)
+				break;
+			one &= ~(one - 1);
+			data->joined[i / 64] |= one;
+			if (ret++ < n)
+				indices[ret - 1] = i + lb(one);
+		}
+	}
+
+	for (;;) {
+		if (ret < require) {
+			if (sem_wait(&data->semaphore)) {
+				if (errno == EINTR)
+					continue;
+				return 0;
+			}
+		} else if (sem_trywait(&data->semaphore)) {
+			if (errno == EAGAIN)
+				break;
+			else
+				return 0;
+		}
+
+		err = pthread_mutex_lock(&data->mutex);
+		if (err) {
+			errno = err;
+			return 0;
+		}
+		for (i = 0; i < data->nthreads; i += 64) {
+			one = data->resting[i / 64];
+			one ^= data->joined[i / 64];
+			if (!one)
+				continue;
+			one &= ~(one - 1);
+			data->joined[i / 64] |= one;
+			if (ret++ < n)
+				indices[ret - 1] = i + lb(one);
+			break;
+		}
+		pthread_mutex_unlock(&data->mutex);
+	}
+
+	return ret;
+}
+
+
+static size_t
+get_ready_threads(size_t *indices, size_t n, struct libar2_context *ctx)
+{
+	return await_threads(indices, n, 1, ctx);
+}
+
+
+static int
+join_thread_pool(struct libar2_context *ctx)
+{
+	struct user_data *data = ctx->user_data;
+	if (await_threads(NULL, 0, data->nthreads, ctx))
+		return 0;
+	destroy_thread_pool(ctx);
+	return -1;
+}
+
+
+void
+libar2simplified_init_context(struct libar2_context *ctxp)
+{
+	memset(ctxp, 0, sizeof(*ctxp));
+	ctxp->allocate = allocate;
+	ctxp->deallocate = deallocate;
+	ctxp->init_thread_pool = init_thread_pool;
+	ctxp->get_ready_threads = get_ready_threads;
+	ctxp->run_thread = run_thread;
+	ctxp->join_thread_pool = join_thread_pool;
+	ctxp->destroy_thread_pool = destroy_thread_pool;
+}