path: root/ao_write.c

/* SPDX-License-Identifier: GPL-2.0 */

/** \file ao_write.c Paraslash's libao output plugin. */

#include <pthread.h>
#include <ao/ao.h>
#include <lopsub.h>

#include "write_cmd.lsg.h"
#include "para.h"
#include "fd.h"
#include "string.h"
#include "list.h"
#include "sched.h"
#include "buffer_tree.h"
#include "write.h"
#include "error.h"

struct private_aow_data {
	ao_device *dev;
	int bytes_per_frame;

	pthread_t thread;
	pthread_attr_t attr;
	/* The mutex and the condition variable serialize access to ->btrn */
	pthread_mutex_t mutex;
	pthread_cond_t data_available;
	struct btr_node *thread_btrn;
};

static void aow_close(struct writer_node *wn)
{
	struct private_aow_data *pawd = wn->private_data;

	if (!pawd)
		return;
	assert(!pawd->thread_btrn);
	ao_close(pawd->dev);
	free(pawd);
	wn->private_data = NULL;
	ao_shutdown();
}

static void aow_pre_monitor(struct sched *s, void *context)
{
	struct writer_node *wn = context;
	struct private_aow_data *pawd = wn->private_data;
	int ret;

	if (!pawd) { /* not yet started */
		assert(wn->btrn);
		ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
		if (ret != 0)
			goto min_delay;
		return; /* no data available */
	}
	if (!wn->btrn) { /* EOF */
		if (!pawd->thread_btrn) /* ready to exit */
			goto min_delay;
		/* wait for the play thread to terminate */
		goto timeout;
	}
	pthread_mutex_lock(&pawd->mutex);
	ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
	pthread_mutex_unlock(&pawd->mutex);
	if (ret != 0)
		goto min_delay;
	/*
	 * Even though the node status is zero, we might have data available,
	 * but the output buffer is full. If we don't set a timeout here, we
	 * are woken up only if new data arrives, which might be too late and
	 * result in a buffer underrun in the playing thread. To avoid this we
	 * never sleep longer than the (default) buffer time.
	 */
timeout:
	return sched_request_timeout_ms(20, s);
min_delay:
	sched_min_delay(s);
}

static int aow_set_sample_format(unsigned sample_rate, unsigned channels,
		int sample_format, ao_sample_format *result)
{
	memset(result, 0, sizeof(*result));
	switch (sample_format) {
		case SF_U8:
		case SF_U16_LE:
		case SF_U16_BE:
		case SF_FLOAT_LE:
		case SF_FLOAT_BE:
			return -E_BAD_SAMPLE_FORMAT;
		case SF_S8:
			/* no need to set byte_format */
			result->bits = 8;
			break;
		case SF_S16_LE:
			result->bits = 16;
			result->byte_format = AO_FMT_LITTLE;
			break;
		case SF_S16_BE:
			result->bits = 16;
			result->byte_format = AO_FMT_BIG;
			break;
		default:
			PARA_EMERG_LOG("bug: invalid sample format\n");
			exit(EXIT_FAILURE);
	}
	result->channels = channels;
	result->rate = sample_rate;
	return 1;
}

static int aow_open_device(int id, ao_sample_format *asf, ao_option *options,
		ao_device **result)
{
	const char *msg;
	ao_device *dev = ao_open_live(id, asf, options);

	if (dev) {
		*result = dev;
		return 1;
	}
	switch (errno) {
		case AO_ENODRIVER:
			msg = "No driver corresponds to driver_id";
			break;
		case AO_ENOTLIVE:
			msg = "This driver is not a live output device";
			break;
		case AO_EBADOPTION:
			msg = "A valid option key has an invalid value";
			break;
		case AO_EOPENDEVICE:
			msg = "Cannot open the device";
			break;
		case AO_EFAIL:
			msg = "General libao error";
			break;
		default:
			msg = "Unknown ao error";
			break;
	}
	PARA_ERROR_LOG("%s\n", msg);
	return -E_AO_OPEN_LIVE;
}

static void aow_show_drivers(void)
{
	int i, j, num_drivers;
	ao_info **driver_list;

	PARA_DEBUG_LOG("libao drivers available on this host:\n");
	PARA_DEBUG_LOG("~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\n");

	driver_list = ao_driver_info_list(&num_drivers);

	for (i = 0; i < num_drivers; i++) {
		ao_info *info = driver_list[i];
		char *keys = NULL, *tmp = NULL;

		if (info->type == AO_TYPE_FILE)
			continue;
		PARA_DEBUG_LOG("name: %s: %s\n", info->short_name, info->name);
		PARA_DEBUG_LOG("priority: %d\n", info->priority);
		for (j = 0; j < info->option_count; j++) {
			tmp = make_message("%s%s%s", keys? keys : "",
				keys? ", " : "",
				info->options[j]);
			free(keys);
			keys = tmp;
		}
		PARA_DEBUG_LOG("keys: %s\n", keys? keys : "[none]");
		free(keys);
		PARA_DEBUG_LOG("comment: %s\n", info->comment?
			info->comment : "[none]");
	}
}

static int aow_init(struct writer_node *wn, unsigned sample_rate,
		unsigned channels, int sample_format)
{
	int id, ret, i;
	ao_option *aoo = NULL;
	ao_sample_format asf;
	ao_info *info;
	const struct lls_opt_result *r;
	unsigned n;
	struct private_aow_data *pawd = alloc(sizeof(*pawd));

	ao_initialize();
	aow_show_drivers();
	if (WRITE_CMD_OPT_GIVEN(AO, DRIVER, wn->lpr)) {
		ret = -E_AO_BAD_DRIVER;
		id = ao_driver_id(WRITE_CMD_OPT_STRING_VAL(AO, DRIVER, wn->lpr));
	} else {
		ret = -E_AO_DEFAULT_DRIVER;
		id = ao_default_driver_id();
	}
	if (id < 0)
		goto fail;
	info = ao_driver_info(id);
	assert(info && info->short_name);
	if (info->type == AO_TYPE_FILE) {
		ret = -E_AO_FILE_NOT_SUPP;
		goto fail;
	}
	PARA_INFO_LOG("using %s driver\n", info->short_name);
	r = WRITE_CMD_OPT_RESULT(AO, AO_OPTION, wn->lpr);
	n = lls_opt_given(r);
	for (i = 0; i < n; i++) {
		char *o = para_strdup(lls_string_val(i, r));
		char *value;

		ret = -E_AO_BAD_OPTION;
		value = strchr(o, ':');
		if (!value) {
			free(o);
			goto fail;
		}
		*value = '\0';
		value++;
		PARA_INFO_LOG("appending option: key=%s, value=%s\n", o, value);
		ret = ao_append_option(&aoo, o, value);
		free(o);
		if (ret == 0) {
			ret = -E_AO_APPEND_OPTION;
			goto fail;
		}
	}
	ret = aow_set_sample_format(sample_rate, channels, sample_format, &asf);
	if (ret < 0)
		goto fail;
	if (sample_format == SF_S8 || sample_format == SF_U8)
		pawd->bytes_per_frame = channels;
	else
		pawd->bytes_per_frame = channels * 2;
	ret = aow_open_device(id, &asf, aoo, &pawd->dev);
	if (ret < 0)
		goto fail;
	PARA_INFO_LOG("successfully opened %s\n", info->short_name);
	wn->private_data = pawd;
	return 1;
fail:
	free(pawd);
	return ret;
}

static void *aow_play(void *priv)
{
	struct writer_node *wn = priv;
	struct private_aow_data *pawd = wn->private_data;
	struct btr_node *btrn = pawd->thread_btrn;
	size_t frames, bytes;
	char *data;
	int ret;

	pthread_mutex_lock(&pawd->mutex);
	for (;;) {
		for (;;) {
			ret = btr_node_status(btrn, wn->min_iqs, BTR_NT_LEAF);
			if (ret < 0)
				goto fail;
			if (ret > 0) {
				btr_merge(btrn, wn->min_iqs);
				bytes = btr_next_buffer(btrn, &data);
				frames = bytes / pawd->bytes_per_frame;
				if (frames > 0)
					break;
				/* eof and less than a single frame available */
				ret = -E_EOF;
				goto fail;
			}
			/*
			 * No data available, go to sleep and wait for the main
			 * thread to wake us up. pthread_cond_wait() unlocks
			 * the mutex while it waits and locks it again upon
			 * return.
			 */
			ret = pthread_cond_wait(&pawd->data_available,
				&pawd->mutex);
			/* pthread_cond_wait() can never fail here */
			assert(ret == 0);
		}
		assert(frames > 0);
		bytes = frames * pawd->bytes_per_frame;
		pthread_mutex_unlock(&pawd->mutex);
		ret = ao_play(pawd->dev, data, bytes);
		pthread_mutex_lock(&pawd->mutex);
		if (ret == 0) { /* failure */
			ret = -E_AO_PLAY;
			goto fail;
		}
		btr_consume(btrn, bytes);
	}
fail:
	btr_remove_node(&pawd->thread_btrn);
	assert(ret < 0);
	PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
	pthread_mutex_unlock(&pawd->mutex);
	pthread_exit(NULL);
}

static int aow_create_thread(struct writer_node *wn)
{
	struct private_aow_data *pawd = wn->private_data;
	int ret;
	const char *msg;

	/* initialize with default attributes */
	msg = "could not init mutex";
	ret = pthread_mutex_init(&pawd->mutex, NULL);
	if (ret < 0)
		goto fail;

	msg = "could not initialize condition variable";
	ret = pthread_cond_init(&pawd->data_available, NULL);
	if (ret < 0)
		goto fail;

	msg = "could not initialize thread attributes";
	ret = pthread_attr_init(&pawd->attr);
	if (ret < 0)
		goto fail;

	/* schedule this thread under the real-time policy SCHED_FIFO */
	msg = "could not set sched policy";
	ret = pthread_attr_setschedpolicy(&pawd->attr, SCHED_FIFO);
	if (ret < 0)
		goto fail;

	msg = "could not set detach state to joinable";
	ret = pthread_attr_setdetachstate(&pawd->attr, PTHREAD_CREATE_JOINABLE);
	if (ret < 0)
		goto fail;

	msg = "could not create thread";
	ret = pthread_create(&pawd->thread, &pawd->attr, aow_play, wn);
	if (ret < 0)
		goto fail;
	return 1;
fail:
	PARA_ERROR_LOG("%s (%s)\n", msg, strerror(ret));
	return -E_AO_PTHREAD;
}

static int aow_post_monitor(__a_unused struct sched *s, void *context)
{
	struct writer_node *wn = context;
	struct private_aow_data *pawd = wn->private_data;
	int ret;

	if (!pawd) {
		int32_t rate, ch, format;
		struct btr_node_description bnd;

		ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
		if (ret < 0)
			goto remove_btrn;
		if (ret == 0)
			return 0;
		ret = get_btr_sample_rate(wn->btrn, &rate);
		if (ret < 0)
			goto remove_btrn;
		ret = get_btr_channels(wn->btrn, &ch);
		if (ret < 0)
			goto remove_btrn;
		ret = get_btr_sample_format(wn->btrn, &format);
		if (ret < 0)
			goto remove_btrn;
		ret = aow_init(wn, rate, ch, format);
		if (ret < 0)
			goto remove_btrn;
		pawd = wn->private_data;

		/* set up thread btr node */
		bnd.name = "ao_thread_btrn";
		bnd.parent = wn->btrn;
		bnd.child = NULL;
		bnd.handler = NULL;
		bnd.context = pawd;
		pawd->thread_btrn = btr_new_node(&bnd);
		wn->private_data = pawd;

		ret = aow_create_thread(wn);
		if (ret < 0)
			goto remove_thread_btrn;
		return 0;
	}
	if (!wn->btrn) {
		if (!pawd->thread_btrn) {
			pthread_join(pawd->thread, NULL);
			return -E_EOF;
		}
		PARA_INFO_LOG("waiting for play thread to terminate\n");
		return 0;
	}
	pthread_mutex_lock(&pawd->mutex);
	ret = btr_node_status(wn->btrn, wn->min_iqs, BTR_NT_LEAF);
	if (ret > 0) {
		btr_pushdown(wn->btrn);
		if (pthread_cond_signal(&pawd->data_available) != 0) {
			ret = -E_AO_PTHREAD;
			PARA_ERROR_LOG("pthread_cond_signal() failed\n");
			goto remove_thread_btrn;
		}
	}
	if (ret >= 0) {
		pthread_mutex_unlock(&pawd->mutex);
		goto out;
	}
	btr_remove_node(&wn->btrn);
	pthread_cond_signal(&pawd->data_available);
	pthread_mutex_unlock(&pawd->mutex);
	return 0;
remove_thread_btrn:
	btr_remove_node(&pawd->thread_btrn);
remove_btrn:
	btr_remove_node(&wn->btrn);
out:
	return ret;
}

/** \cond doxygen_ignore */
struct writer lsg_write_cmd_com_ao_user_data = {
	.close = aow_close,
	.pre_monitor = aow_pre_monitor,
	.post_monitor = aow_post_monitor,
};
/** \endcond */