bfgminer/cpu-miner.c

/*
 * Copyright 2010 Jeff Garzik
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.  See COPYING for more details.
 */

#include "cpuminer-config.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/time.h>
#include <time.h>
#ifndef WIN32
#include <sys/resource.h>
#endif
#include <getopt.h>
#include <jansson.h>
#include <curl/curl.h>
#include "compat.h"
#include "miner.h"

#define PROGRAM_NAME		"minerd"
#define DEF_RPC_URL		"http://127.0.0.1:8332/"
#define DEF_RPC_USERNAME	"rpcuser"
#define DEF_RPC_PASSWORD	"rpcpass"
#define DEF_RPC_USERPASS	DEF_RPC_USERNAME ":" DEF_RPC_PASSWORD

enum workio_commands {
	WC_GET_WORK,
	WC_SUBMIT_WORK,
};

struct workio_cmd {
	enum workio_commands	cmd;
	struct thr_info		*thr;
	union {
		struct work	*work;
	} u;
};

enum sha256_algos {
	ALGO_C,			/* plain C */
	ALGO_4WAY,		/* parallel SSE2 */
	ALGO_VIA,		/* VIA padlock */
	ALGO_CRYPTOPP,		/* Crypto++ (C) */
	ALGO_CRYPTOPP_ASM32,	/* Crypto++ 32-bit assembly */
	ALGO_SSE2_64,		/* SSE2 for x86_64 */
};

static const char *algo_names[] = {
	[ALGO_C]		= "c",
#ifdef WANT_SSE2_4WAY
	[ALGO_4WAY]		= "4way",
#endif
#ifdef WANT_VIA_PADLOCK
	[ALGO_VIA]		= "via",
#endif
	[ALGO_CRYPTOPP]		= "cryptopp",
#ifdef WANT_CRYPTOPP_ASM32
	[ALGO_CRYPTOPP_ASM32]	= "cryptopp_asm32",
#endif
#ifdef WANT_X8664_SSE2
	[ALGO_SSE2_64]		= "sse2_64",
#endif
};

bool opt_debug = false;
bool opt_protocol = false;
bool want_longpoll = true;
bool have_longpoll = false;
bool use_syslog = false;
static bool opt_quiet = false;
static int opt_retries = 10;
static int opt_fail_pause = 30;
int opt_scantime = 5;
static json_t *opt_config;
static const bool opt_time = true;
static enum sha256_algos opt_algo = ALGO_C;
static int opt_n_threads = 1;
static char *rpc_url;
static char *rpc_userpass;
static char *rpc_user, *rpc_pass;
struct thr_info *thr_info;
static int work_thr_id;
int longpoll_thr_id;
struct work_restart *work_restart = NULL;
pthread_mutex_t time_lock;


struct option_help {
	const char	*name;
	const char	*helptext;
};

static struct option_help options_help[] = {
	{ "help",
	  "(-h) Display this help text" },

	{ "config FILE",
	  "(-c FILE) JSON-format configuration file (default: none)\n"
	  "See example-cfg.json for an example configuration." },

	{ "algo XXX",
	  "(-a XXX) Specify sha256 implementation:\n"
	  "\tc\t\tLinux kernel sha256, implemented in C (default)"
#ifdef WANT_SSE2_4WAY
	  "\n\t4way\t\ttcatm's 4-way SSE2 implementation"
#endif
#ifdef WANT_VIA_PADLOCK
	  "\n\tvia\t\tVIA padlock implementation"
#endif
	  "\n\tcryptopp\tCrypto++ C/C++ implementation"
#ifdef WANT_CRYPTOPP_ASM32
	  "\n\tcryptopp_asm32\tCrypto++ 32-bit assembler implementation"
#endif
#ifdef WANT_X8664_SSE2
	  "\n\tsse2_64\t\tSSE2 implementation for x86_64 machines"
#endif
	  },

	{ "quiet",
	  "(-q) Disable per-thread hashmeter output (default: off)" },

	{ "debug",
	  "(-D) Enable debug output (default: off)" },

	{ "no-longpoll",
	  "Disable X-Long-Polling support (default: enabled)" },

	{ "protocol-dump",
	  "(-P) Verbose dump of protocol-level activities (default: off)" },

	{ "retries N",
	  "(-r N) Number of times to retry, if JSON-RPC call fails\n"
	  "\t(default: 10; use -1 for \"never\")" },

	{ "retry-pause N",
	  "(-R N) Number of seconds to pause, between retries\n"
	  "\t(default: 30)" },

	{ "scantime N",
	  "(-s N) Upper bound on time spent scanning current work,\n"
	  "\tin seconds. (default: 5)" },

#ifdef HAVE_SYSLOG_H
	{ "syslog",
	  "Use system log for output messages (default: standard error)" },
#endif

	{ "threads N",
	  "(-t N) Number of miner threads (default: 1)" },

	{ "url URL",
	  "URL for bitcoin JSON-RPC server "
	  "(default: " DEF_RPC_URL ")" },

	{ "userpass USERNAME:PASSWORD",
	  "Username:Password pair for bitcoin JSON-RPC server "
	  "(default: " DEF_RPC_USERPASS ")" },

	{ "user USERNAME",
	  "(-u USERNAME) Username for bitcoin JSON-RPC server "
	  "(default: " DEF_RPC_USERNAME ")" },

	{ "pass PASSWORD",
	  "(-p USERNAME) Password for bitcoin JSON-RPC server "
	  "(default: " DEF_RPC_PASSWORD ")" },
};

static struct option options[] = {
	{ "algo", 1, NULL, 'a' },
	{ "config", 1, NULL, 'c' },
	{ "debug", 0, NULL, 'D' },
	{ "help", 0, NULL, 'h' },
	{ "no-longpoll", 0, NULL, 1003 },
	{ "pass", 1, NULL, 'p' },
	{ "protocol-dump", 0, NULL, 'P' },
	{ "quiet", 0, NULL, 'q' },
	{ "threads", 1, NULL, 't' },
	{ "retries", 1, NULL, 'r' },
	{ "retry-pause", 1, NULL, 'R' },
	{ "scantime", 1, NULL, 's' },
#ifdef HAVE_SYSLOG_H
	{ "syslog", 0, NULL, 1004 },
#endif
	{ "url", 1, NULL, 1001 },
	{ "user", 1, NULL, 'u' },
	{ "userpass", 1, NULL, 1002 },

	{ }
};

struct work {
	unsigned char	data[128];
	unsigned char	hash1[64];
	unsigned char	midstate[32];
	unsigned char	target[32];

	unsigned char	hash[32];
};

static bool jobj_binary(const json_t *obj, const char *key,
			void *buf, size_t buflen)
{
	const char *hexstr;
	json_t *tmp;

	tmp = json_object_get(obj, key);
	if (!tmp) {
		applog(LOG_ERR, "JSON key '%s' not found", key);
		return false;
	}
	hexstr = json_string_value(tmp);
	if (!hexstr) {
		applog(LOG_ERR, "JSON key '%s' is not a string", key);
		return false;
	}
	if (!hex2bin(buf, hexstr, buflen))
		return false;

	return true;
}

static bool work_decode(const json_t *val, struct work *work)
{
	if (!jobj_binary(val, "midstate",
			 work->midstate, sizeof(work->midstate))) {
		applog(LOG_ERR, "JSON inval midstate");
		goto err_out;
	}

	if (!jobj_binary(val, "data", work->data, sizeof(work->data))) {
		applog(LOG_ERR, "JSON inval data");
		goto err_out;
	}

	if (!jobj_binary(val, "hash1", work->hash1, sizeof(work->hash1))) {
		applog(LOG_ERR, "JSON inval hash1");
		goto err_out;
	}

	if (!jobj_binary(val, "target", work->target, sizeof(work->target))) {
		applog(LOG_ERR, "JSON inval target");
		goto err_out;
	}

	memset(work->hash, 0, sizeof(work->hash));

	return true;

err_out:
	return false;
}

static bool submit_upstream_work(CURL *curl, const struct work *work)
{
	char *hexstr = NULL;
	json_t *val, *res;
	char s[345];
	bool rc = false;

	/* build hex string */
	hexstr = bin2hex(work->data, sizeof(work->data));
	if (!hexstr) {
		applog(LOG_ERR, "submit_upstream_work OOM");
		goto out;
	}

	/* build JSON-RPC request */
	sprintf(s,
	      "{\"method\": \"getwork\", \"params\": [ \"%s\" ], \"id\":1}\r\n",
		hexstr);

	if (opt_debug)
		applog(LOG_DEBUG, "DBG: sending RPC call: %s", s);

	/* issue JSON-RPC request */
	val = json_rpc_call(curl, rpc_url, rpc_userpass, s, false, false);
	if (!val) {
		applog(LOG_ERR, "submit_upstream_work json_rpc_call failed");
		goto out;
	}

	res = json_object_get(val, "result");

	applog(LOG_INFO, "PROOF OF WORK RESULT: %s",
	       json_is_true(res) ? "true (yay!!!)" : "false (booooo)");

	json_decref(val);

	rc = true;

out:
	free(hexstr);
	return rc;
}

static const char *rpc_req =
	"{\"method\": \"getwork\", \"params\": [], \"id\":0}\r\n";

static bool get_upstream_work(CURL *curl, struct work *work)
{
	json_t *val;
	bool rc;

	val = json_rpc_call(curl, rpc_url, rpc_userpass, rpc_req,
			    want_longpoll, false);
	if (!val)
		return false;

	rc = work_decode(json_object_get(val, "result"), work);

	json_decref(val);

	return rc;
}

static void workio_cmd_free(struct workio_cmd *wc)
{
	if (!wc)
		return;

	switch (wc->cmd) {
	case WC_SUBMIT_WORK:
		free(wc->u.work);
		break;
	default: /* do nothing */
		break;
	}

	memset(wc, 0, sizeof(*wc));	/* poison */
	free(wc);
}

static bool workio_get_work(struct workio_cmd *wc, CURL *curl)
{
	struct work *ret_work;
	int failures = 0;

	ret_work = calloc(1, sizeof(*ret_work));
	if (!ret_work)
		return false;

	/* obtain new work from bitcoin via JSON-RPC */
	while (!get_upstream_work(curl, ret_work)) {
		if ((opt_retries >= 0) && (++failures > opt_retries)) {
			applog(LOG_ERR, "json_rpc_call failed, terminating workio thread");
			free(ret_work);
			return false;
		}

		/* pause, then restart work-request loop */
		applog(LOG_ERR, "json_rpc_call failed, retry after %d seconds",
			opt_fail_pause);
		sleep(opt_fail_pause);
	}

	/* send work to requesting thread */
	if (!tq_push(wc->thr->q, ret_work))
		free(ret_work);

	return true;
}

static bool workio_submit_work(struct workio_cmd *wc, CURL *curl)
{
	int failures = 0;

	/* submit solution to bitcoin via JSON-RPC */
	while (!submit_upstream_work(curl, wc->u.work)) {
		if ((opt_retries >= 0) && (++failures > opt_retries)) {
			applog(LOG_ERR, "...terminating workio thread");
			return false;
		}

		/* pause, then restart work-request loop */
		applog(LOG_ERR, "...retry after %d seconds",
			opt_fail_pause);
		sleep(opt_fail_pause);
	}

	return true;
}

static void *workio_thread(void *userdata)
{
	struct thr_info *mythr = userdata;
	CURL *curl;
	bool ok = true;

	curl = curl_easy_init();
	if (!curl) {
		applog(LOG_ERR, "CURL initialization failed");
		return NULL;
	}

	while (ok) {
		struct workio_cmd *wc;

		/* wait for workio_cmd sent to us, on our queue */
		wc = tq_pop(mythr->q, NULL);
		if (!wc) {
			ok = false;
			break;
		}

		/* process workio_cmd */
		switch (wc->cmd) {
		case WC_GET_WORK:
			ok = workio_get_work(wc, curl);
			break;
		case WC_SUBMIT_WORK:
			ok = workio_submit_work(wc, curl);
			break;

		default:		/* should never happen */
			ok = false;
			break;
		}

		workio_cmd_free(wc);
	}

	tq_freeze(mythr->q);
	curl_easy_cleanup(curl);

	return NULL;
}

static void hashmeter(int thr_id, const struct timeval *diff,
		      unsigned long hashes_done)
{
	double khashes, secs;

	khashes = hashes_done / 1000.0;
	secs = (double)diff->tv_sec + ((double)diff->tv_usec / 1000000.0);

	if (!opt_quiet)
		applog(LOG_INFO, "thread %d: %lu hashes, %.2f khash/sec",
		       thr_id, hashes_done,
		       khashes / secs);
}

static bool get_work(struct thr_info *thr, struct work *work)
{
	struct workio_cmd *wc;
	struct work *work_heap;

	/* fill out work request message */
	wc = calloc(1, sizeof(*wc));
	if (!wc)
		return false;

	wc->cmd = WC_GET_WORK;
	wc->thr = thr;

	/* send work request to workio thread */
	if (!tq_push(thr_info[work_thr_id].q, wc)) {
		workio_cmd_free(wc);
		return false;
	}

	/* wait for response, a unit of work */
	work_heap = tq_pop(thr->q, NULL);
	if (!work_heap)
		return false;

	/* copy returned work into storage provided by caller */
	memcpy(work, work_heap, sizeof(*work));
	free(work_heap);

	return true;
}

static bool submit_work(struct thr_info *thr, const struct work *work_in)
{
	struct workio_cmd *wc;

	/* fill out work request message */
	wc = calloc(1, sizeof(*wc));
	if (!wc)
		return false;

	wc->u.work = malloc(sizeof(*work_in));
	if (!wc->u.work)
		goto err_out;

	wc->cmd = WC_SUBMIT_WORK;
	wc->thr = thr;
	memcpy(wc->u.work, work_in, sizeof(*work_in));

	/* send solution to workio thread */
	if (!tq_push(thr_info[work_thr_id].q, wc))
		goto err_out;

	return true;

err_out:
	workio_cmd_free(wc);
	return false;
}

static void *miner_thread(void *userdata)
{
	struct thr_info *mythr = userdata;
	int thr_id = mythr->id;
	uint32_t max_nonce = 0xffffff;

	while (1) {
		struct work work __attribute__((aligned(128)));
		unsigned long hashes_done;
		struct timeval tv_start, tv_end, diff;
		uint64_t max64;
		bool rc;

		/* obtain new work from internal workio thread */
		if (!get_work(mythr, &work)) {
			applog(LOG_ERR, "work retrieval failed, exiting "
				"mining thread %d", mythr->id);
			goto out;
		}

		hashes_done = 0;
		gettimeofday(&tv_start, NULL);

		/* scan nonces for a proof-of-work hash */
		switch (opt_algo) {
		case ALGO_C:
			rc = scanhash_c(thr_id, work.midstate, work.data + 64,
				        work.hash1, work.hash, work.target,
					max_nonce, &hashes_done);
			break;

#ifdef WANT_X8664_SSE2
		case ALGO_SSE2_64: {
			unsigned int rc5 =
			        scanhash_sse2_64(thr_id, work.midstate, work.data + 64,
						 work.hash1, work.hash,
						 work.target,
					         max_nonce, &hashes_done);
			rc = (rc5 == -1) ? false : true;
			}
			break;
#endif

#ifdef WANT_SSE2_4WAY
		case ALGO_4WAY: {
			unsigned int rc4 =
				ScanHash_4WaySSE2(thr_id, work.midstate, work.data + 64,
						  work.hash1, work.hash,
						  work.target,
						  max_nonce, &hashes_done);
			rc = (rc4 == -1) ? false : true;
			}
			break;
#endif

#ifdef WANT_VIA_PADLOCK
		case ALGO_VIA:
			rc = scanhash_via(thr_id, work.data, work.target,
					  max_nonce, &hashes_done);
			break;
#endif
		case ALGO_CRYPTOPP:
			rc = scanhash_cryptopp(thr_id, work.midstate, work.data + 64,
				        work.hash1, work.hash, work.target,
					max_nonce, &hashes_done);
			break;

#ifdef WANT_CRYPTOPP_ASM32
		case ALGO_CRYPTOPP_ASM32:
			rc = scanhash_asm32(thr_id, work.midstate, work.data + 64,
				        work.hash1, work.hash, work.target,
					max_nonce, &hashes_done);
			break;
#endif

		default:
			/* should never happen */
			goto out;
		}

		/* record scanhash elapsed time */
		gettimeofday(&tv_end, NULL);
		timeval_subtract(&diff, &tv_end, &tv_start);

		hashmeter(thr_id, &diff, hashes_done);

		/* adjust max_nonce to meet target scan time */
		if (diff.tv_usec > 500000)
			diff.tv_sec++;
		if (diff.tv_sec > 0) {
			max64 =
			   ((uint64_t)hashes_done * opt_scantime) / diff.tv_sec;
			if (max64 > 0xfffffffaULL)
				max64 = 0xfffffffaULL;
			max_nonce = max64;
		}

		/* if nonce found, submit work */
		if (rc && !submit_work(mythr, &work))
			break;
	}

out:
	tq_freeze(mythr->q);

	return NULL;
}

static void restart_threads(void)
{
	int i;

	for (i = 0; i < opt_n_threads; i++)
		work_restart[i].restart = 1;
}

static void *longpoll_thread(void *userdata)
{
	struct thr_info *mythr = userdata;
	CURL *curl = NULL;
	char *copy_start, *hdr_path, *lp_url = NULL;
	bool need_slash = false;
	int failures = 0;

	hdr_path = tq_pop(mythr->q, NULL);
	if (!hdr_path)
		goto out;
	copy_start = (*hdr_path == '/') ? (hdr_path + 1) : hdr_path;
	if (rpc_url[strlen(rpc_url) - 1] != '/')
		need_slash = true;

	lp_url = malloc(strlen(rpc_url) + strlen(copy_start) + 2);
	if (!lp_url)
		goto out;

	sprintf(lp_url, "%s%s%s", rpc_url, need_slash ? "/" : "", copy_start);

	applog(LOG_INFO, "Long-polling activated for %s", lp_url);

	curl = curl_easy_init();
	if (!curl) {
		applog(LOG_ERR, "CURL initialization failed");
		goto out;
	}

	while (1) {
		json_t *val;

		val = json_rpc_call(curl, lp_url, rpc_userpass, rpc_req,
				    false, true);
		if (val) {
			failures = 0;
			json_decref(val);

			applog(LOG_INFO, "LONGPOLL detected new block");
			restart_threads();
		} else {
			if (failures++ < 10) {
				sleep(30);
				applog(LOG_ERR,
					"longpoll failed, sleeping for 30s\n");
			} else {
				applog(LOG_ERR,
					"longpoll failed, ending thread\n");
				goto out;
			}
		}
	}

out:
	free(hdr_path);
	free(lp_url);
	tq_freeze(mythr->q);
	if (curl)
		curl_easy_cleanup(curl);

	return NULL;
}

static void show_usage(void)
{
	int i;

	printf("minerd version %s\n\n", VERSION);
	printf("Usage:\tminerd [options]\n\nSupported options:\n");
	for (i = 0; i < ARRAY_SIZE(options_help); i++) {
		struct option_help *h;

		h = &options_help[i];
		printf("--%s\n%s\n\n", h->name, h->helptext);
	}

	exit(1);
}

static void parse_arg (int key, char *arg)
{
	int v, i;

	switch(key) {
	case 'a':
		for (i = 0; i < ARRAY_SIZE(algo_names); i++) {
			if (algo_names[i] &&
			    !strcmp(arg, algo_names[i])) {
				opt_algo = i;
				break;
			}
		}
		if (i == ARRAY_SIZE(algo_names))
			show_usage();
		break;
	case 'c': {
		json_error_t err;
		if (opt_config)
			json_decref(opt_config);
		opt_config = json_load_file(arg, &err);
		if (!json_is_object(opt_config)) {
			applog(LOG_ERR, "JSON decode of %s failed", arg);
			show_usage();
		}
		break;
	}
	case 'q':
		opt_quiet = true;
		break;
	case 'D':
		opt_debug = true;
		break;
	case 'p':
		free(rpc_pass);
		rpc_pass = strdup(arg);
		break;
	case 'P':
		opt_protocol = true;
		break;
	case 'r':
		v = atoi(arg);
		if (v < -1 || v > 9999)	/* sanity check */
			show_usage();

		opt_retries = v;
		break;
	case 'R':
		v = atoi(arg);
		if (v < 1 || v > 9999)	/* sanity check */
			show_usage();

		opt_fail_pause = v;
		break;
	case 's':
		v = atoi(arg);
		if (v < 1 || v > 9999)	/* sanity check */
			show_usage();

		opt_scantime = v;
		break;
	case 't':
		v = atoi(arg);
		if (v < 1 || v > 9999)	/* sanity check */
			show_usage();

		opt_n_threads = v;
		break;
	case 'u':
		free(rpc_user);
		rpc_user = strdup(arg);
		break;
	case 1001:			/* --url */
		if (strncmp(arg, "http://", 7) &&
		    strncmp(arg, "https://", 8))
			show_usage();

		free(rpc_url);
		rpc_url = strdup(arg);
		break;
	case 1002:			/* --userpass */
		if (!strchr(arg, ':'))
			show_usage();

		free(rpc_userpass);
		rpc_userpass = strdup(arg);
		break;
	case 1003:
		want_longpoll = false;
		break;
	case 1004:
		use_syslog = true;
		break;
	default:
		show_usage();
	}
}

static void parse_config(void)
{
	int i;
	json_t *val;

	if (!json_is_object(opt_config))
		return;

	for (i = 0; i < ARRAY_SIZE(options); i++) {
		if (!options[i].name)
			break;
		if (!strcmp(options[i].name, "config"))
			continue;

		val = json_object_get(opt_config, options[i].name);
		if (!val)
			continue;

		if (options[i].has_arg && json_is_string(val)) {
			char *s = strdup(json_string_value(val));
			if (!s)
				break;
			parse_arg(options[i].val, s);
			free(s);
		} else if (!options[i].has_arg && json_is_true(val))
			parse_arg(options[i].val, "");
		else
			applog(LOG_ERR, "JSON option %s invalid",
				options[i].name);
	}
}

static void parse_cmdline(int argc, char *argv[])
{
	int key;

	while (1) {
		key = getopt_long(argc, argv, "a:c:qDPr:s:t:h?", options, NULL);
		if (key < 0)
			break;

		parse_arg(key, optarg);
	}

	parse_config();
}

int main (int argc, char *argv[])
{
	struct thr_info *thr;
	int i;

	rpc_url = strdup(DEF_RPC_URL);
	rpc_userpass = strdup(DEF_RPC_USERPASS);

	/* parse command line */
	parse_cmdline(argc, argv);

	if (!rpc_userpass && rpc_user && rpc_pass) {
		rpc_userpass = malloc(strlen(rpc_user) + strlen(rpc_pass) + 2);
		if (!rpc_userpass)
			return 1;
		sprintf(rpc_userpass, "%s:%s", rpc_user, rpc_pass);
	}

	pthread_mutex_init(&time_lock, NULL);

#ifdef HAVE_SYSLOG_H
	if (use_syslog)
		openlog("cpuminer", LOG_PID, LOG_USER);
#endif

	/* set our priority to the highest (aka "nicest, least intrusive") */
	if (setpriority(PRIO_PROCESS, 0, 19))
		perror("setpriority");

	work_restart = calloc(opt_n_threads, sizeof(*work_restart));
	if (!work_restart)
		return 1;

	thr_info = calloc(opt_n_threads + 2, sizeof(*thr));
	if (!thr_info)
		return 1;

	/* init workio thread info */
	work_thr_id = opt_n_threads;
	thr = &thr_info[work_thr_id];
	thr->id = work_thr_id;
	thr->q = tq_new();
	if (!thr->q)
		return 1;

	/* start work I/O thread */
	if (pthread_create(&thr->pth, NULL, workio_thread, thr)) {
		applog(LOG_ERR, "workio thread create failed");
		return 1;
	}

	/* init longpoll thread info */
	if (want_longpoll) {
		longpoll_thr_id = opt_n_threads + 1;
		thr = &thr_info[longpoll_thr_id];
		thr->id = longpoll_thr_id;
		thr->q = tq_new();
		if (!thr->q)
			return 1;

		/* start longpoll thread */
		if (pthread_create(&thr->pth, NULL, longpoll_thread, thr)) {
			applog(LOG_ERR, "longpoll thread create failed");
			return 1;
		}
	} else
		longpoll_thr_id = -1;

	/* start mining threads */
	for (i = 0; i < opt_n_threads; i++) {
		thr = &thr_info[i];

		thr->id = i;
		thr->q = tq_new();
		if (!thr->q)
			return 1;

		if (pthread_create(&thr->pth, NULL, miner_thread, thr)) {
			applog(LOG_ERR, "thread %d create failed", i);
			return 1;
		}

		sleep(1);	/* don't pound RPC server all at once */
	}

	applog(LOG_INFO, "%d miner threads started, "
		"using SHA256 '%s' algorithm.\n",
		opt_n_threads,
		algo_names[opt_algo]);

	/* main loop - simply wait for workio thread to exit */
	pthread_join(thr_info[work_thr_id].pth, NULL);

	applog(LOG_INFO, "workio thread dead, exiting.");

	return 0;
}