libeio/etp.c

/*
 * libetp implementation
 *
 * Copyright (c) 2007,2008,2009,2010,2011,2012,2013 Marc Alexander Lehmann <libetp@schmorp.de>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#ifndef ETP_API_DECL
# define ETP_API_DECL static
#endif

#ifndef ETP_PRI_MIN
# define ETP_PRI_MIN 0
# define ETP_PRI_MAX 0
#endif

#ifndef ETP_TYPE_QUIT
# define ETP_TYPE_QUIT 0
#endif

#ifndef ETP_TYPE_GROUP
# define ETP_TYPE_GROUP 1
#endif

#define ETP_NUM_PRI (ETP_PRI_MAX - ETP_PRI_MIN + 1)

#define ETP_TICKS ((1000000 + 1023) >> 10)

/* calculate time difference in ~1/ETP_TICKS of a second */
ecb_inline int
etp_tvdiff (struct timeval *tv1, struct timeval *tv2)
{
  return  (tv2->tv_sec  - tv1->tv_sec ) * ETP_TICKS
       + ((tv2->tv_usec - tv1->tv_usec) >> 10);
}

static unsigned int started, idle, wanted = 4;

static void (*want_poll_cb) (void);
static void (*done_poll_cb) (void);
 
static unsigned int max_poll_time;     /* reslock */
static unsigned int max_poll_reqs;     /* reslock */

static unsigned int nreqs;    /* reqlock */
static unsigned int nready;   /* reqlock */
static unsigned int npending; /* reqlock */
static unsigned int max_idle = 4;      /* maximum number of threads that can idle indefinitely */
static unsigned int idle_timeout = 10; /* number of seconds after which an idle threads exit */

static xmutex_t wrklock;
static xmutex_t reslock;
static xmutex_t reqlock;
static xcond_t  reqwait;

struct etp_tmpbuf
{
  void *ptr;
  int len;
};

static void *
etp_tmpbuf_get (struct etp_tmpbuf *buf, int len)
{
  if (buf->len < len)
    {
      free (buf->ptr);
      buf->ptr = malloc (buf->len = len);
    }

  return buf->ptr;
}

typedef struct etp_worker
{
  struct etp_tmpbuf tmpbuf;

  /* locked by wrklock */
  struct etp_worker *prev, *next;

  xthread_t tid;

#ifdef ETP_WORKER_COMMON
  ETP_WORKER_COMMON
#endif
} etp_worker;

static etp_worker wrk_first; /* NOT etp */

#define ETP_WORKER_LOCK(wrk)   X_LOCK   (wrklock)
#define ETP_WORKER_UNLOCK(wrk) X_UNLOCK (wrklock)

/* worker threads management */

static void
etp_worker_clear (etp_worker *wrk)
{
}

static void ecb_cold
etp_worker_free (etp_worker *wrk)
{
  free (wrk->tmpbuf.ptr);

  wrk->next->prev = wrk->prev;
  wrk->prev->next = wrk->next;

  free (wrk);
}

ETP_API_DECL unsigned int
etp_nreqs (void)
{
  int retval;
  if (WORDACCESS_UNSAFE) X_LOCK   (reqlock);
  retval = nreqs;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
  return retval;
}

ETP_API_DECL unsigned int
etp_nready (void)
{
  unsigned int retval;

  if (WORDACCESS_UNSAFE) X_LOCK   (reqlock);
  retval = nready;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);

  return retval;
}

ETP_API_DECL unsigned int
etp_npending (void)
{
  unsigned int retval;

  if (WORDACCESS_UNSAFE) X_LOCK   (reqlock);
  retval = npending;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);

  return retval;
}

ETP_API_DECL unsigned int
etp_nthreads (void)
{
  unsigned int retval;

  if (WORDACCESS_UNSAFE) X_LOCK   (reqlock);
  retval = started;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);

  return retval;
}

/*
 * a somewhat faster data structure might be nice, but
 * with 8 priorities this actually needs <20 insns
 * per shift, the most expensive operation.
 */
typedef struct {
  ETP_REQ *qs[ETP_NUM_PRI], *qe[ETP_NUM_PRI]; /* qstart, qend */
  int size;
} etp_reqq;

static etp_reqq req_queue;
static etp_reqq res_queue;

static void ecb_noinline ecb_cold
reqq_init (etp_reqq *q)
{
  int pri;

  for (pri = 0; pri < ETP_NUM_PRI; ++pri)
    q->qs[pri] = q->qe[pri] = 0;

  q->size = 0;
}

static int ecb_noinline
reqq_push (etp_reqq *q, ETP_REQ *req)
{
  int pri = req->pri;
  req->next = 0;

  if (q->qe[pri])
    {
      q->qe[pri]->next = req;
      q->qe[pri] = req;
    }
  else
    q->qe[pri] = q->qs[pri] = req;

  return q->size++;
}

static ETP_REQ * ecb_noinline
reqq_shift (etp_reqq *q)
{
  int pri;

  if (!q->size)
    return 0;

  --q->size;

  for (pri = ETP_NUM_PRI; pri--; )
    {
      ETP_REQ *req = q->qs[pri];

      if (req)
        {
          if (!(q->qs[pri] = (ETP_REQ *)req->next))
            q->qe[pri] = 0;

          return req;
        }
    }

  abort ();
}

ETP_API_DECL int ecb_cold
etp_init (void (*want_poll)(void), void (*done_poll)(void))
{
  X_MUTEX_CREATE (wrklock);
  X_MUTEX_CREATE (reslock);
  X_MUTEX_CREATE (reqlock);
  X_COND_CREATE  (reqwait);

  reqq_init (&req_queue);
  reqq_init (&res_queue);

  wrk_first.next =
  wrk_first.prev = &wrk_first;

  started  = 0;
  idle     = 0;
  nreqs    = 0;
  nready   = 0;
  npending = 0;

  want_poll_cb = want_poll;
  done_poll_cb = done_poll;

  return 0;
}

/* not yet in etp.c */
X_THREAD_PROC (etp_proc);

static void ecb_cold
etp_start_thread (void)
{
  etp_worker *wrk = calloc (1, sizeof (etp_worker));

  /*TODO*/
  assert (("unable to allocate worker thread data", wrk));

  X_LOCK (wrklock);

  if (xthread_create (&wrk->tid, etp_proc, (void *)wrk))
    {
      wrk->prev = &wrk_first;
      wrk->next = wrk_first.next;
      wrk_first.next->prev = wrk;
      wrk_first.next = wrk;
      ++started;
    }
  else
    free (wrk);

  X_UNLOCK (wrklock);
}

static void
etp_maybe_start_thread (void)
{
  if (ecb_expect_true (etp_nthreads () >= wanted))
    return;
  
  /* todo: maybe use idle here, but might be less exact */
  if (ecb_expect_true (0 <= (int)etp_nthreads () + (int)etp_npending () - (int)etp_nreqs ()))
    return;

  etp_start_thread ();
}

static void ecb_cold
etp_end_thread (void)
{
  ETP_REQ *req = calloc (1, sizeof (ETP_REQ)); /* will be freed by worker */

  req->type = ETP_TYPE_QUIT;
  req->pri  = ETP_PRI_MAX - ETP_PRI_MIN;

  X_LOCK (reqlock);
  reqq_push (&req_queue, req);
  X_COND_SIGNAL (reqwait);
  X_UNLOCK (reqlock);

  X_LOCK (wrklock);
  --started;
  X_UNLOCK (wrklock);
}

ETP_API_DECL int
etp_poll (void)
{
  unsigned int maxreqs;
  unsigned int maxtime;
  struct timeval tv_start, tv_now;

  X_LOCK (reslock);
  maxreqs = max_poll_reqs;
  maxtime = max_poll_time;
  X_UNLOCK (reslock);

  if (maxtime)
    gettimeofday (&tv_start, 0);

  for (;;)
    {
      ETP_REQ *req;

      etp_maybe_start_thread ();

      X_LOCK (reslock);
      req = reqq_shift (&res_queue);

      if (req)
        {
          --npending;

          if (!res_queue.size && done_poll_cb)
            done_poll_cb ();
        }

      X_UNLOCK (reslock);

      if (!req)
        return 0;

      X_LOCK (reqlock);
      --nreqs;
      X_UNLOCK (reqlock);

      if (ecb_expect_false (req->type == ETP_TYPE_GROUP && req->size))
        {
          req->int1 = 1; /* mark request as delayed */
          continue;
        }
      else
        {
          int res = ETP_FINISH (req);
          if (ecb_expect_false (res))
            return res;
        }

      if (ecb_expect_false (maxreqs && !--maxreqs))
        break;

      if (maxtime)
        {
          gettimeofday (&tv_now, 0);

          if (etp_tvdiff (&tv_start, &tv_now) >= maxtime)
            break;
        }
    }

  errno = EAGAIN;
  return -1;
}

ETP_API_DECL void
etp_grp_cancel (ETP_REQ *grp);

ETP_API_DECL void
etp_cancel (ETP_REQ *req)
{
  req->cancelled = 1;

  etp_grp_cancel (req);
}

ETP_API_DECL void
etp_grp_cancel (ETP_REQ *grp)
{
  for (grp = grp->grp_first; grp; grp = grp->grp_next)
    etp_cancel (grp);
}

ETP_API_DECL void
etp_submit (ETP_REQ *req)
{
  req->pri -= ETP_PRI_MIN;

  if (ecb_expect_false (req->pri < ETP_PRI_MIN - ETP_PRI_MIN)) req->pri = ETP_PRI_MIN - ETP_PRI_MIN;
  if (ecb_expect_false (req->pri > ETP_PRI_MAX - ETP_PRI_MIN)) req->pri = ETP_PRI_MAX - ETP_PRI_MIN;

  if (ecb_expect_false (req->type == ETP_TYPE_GROUP))
    {
      /* I hope this is worth it :/ */
      X_LOCK (reqlock);
      ++nreqs;
      X_UNLOCK (reqlock);

      X_LOCK (reslock);

      ++npending;

      if (!reqq_push (&res_queue, req) && want_poll_cb)
        want_poll_cb ();

      X_UNLOCK (reslock);
    }
  else
    {
      X_LOCK (reqlock);
      ++nreqs;
      ++nready;
      reqq_push (&req_queue, req);
      X_COND_SIGNAL (reqwait);
      X_UNLOCK (reqlock);

      etp_maybe_start_thread ();
    }
}

ETP_API_DECL void ecb_cold
etp_set_max_poll_time (double nseconds)
{
  if (WORDACCESS_UNSAFE) X_LOCK   (reslock);
  max_poll_time = nseconds * ETP_TICKS;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reslock);
}

ETP_API_DECL void ecb_cold
etp_set_max_poll_reqs (unsigned int maxreqs)
{
  if (WORDACCESS_UNSAFE) X_LOCK   (reslock);
  max_poll_reqs = maxreqs;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reslock);
}

ETP_API_DECL void ecb_cold
etp_set_max_idle (unsigned int nthreads)
{
  if (WORDACCESS_UNSAFE) X_LOCK   (reqlock);
  max_idle = nthreads;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
}

ETP_API_DECL void ecb_cold
etp_set_idle_timeout (unsigned int seconds)
{
  if (WORDACCESS_UNSAFE) X_LOCK   (reqlock);
  idle_timeout = seconds;
  if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
}

ETP_API_DECL void ecb_cold
etp_set_min_parallel (unsigned int nthreads)
{
  if (wanted < nthreads)
    wanted = nthreads;
}

ETP_API_DECL void ecb_cold
etp_set_max_parallel (unsigned int nthreads)
{
  if (wanted > nthreads)
    wanted = nthreads;

  while (started > wanted)
    etp_end_thread ();
}

Revision:	1.3
Committed:	Thu Jun 25 15:59:57 2015 UTC (11 years, 2 months ago) by root
Content type:	text/plain
Branch:	MAIN
Changes since 1.2:	+19 -1 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/*
2			* libetp implementation
3			*
4			* Copyright (c) 2007,2008,2009,2010,2011,2012,2013 Marc Alexander Lehmann <libetp@schmorp.de>
5			* All rights reserved.
6			*
7			* Redistribution and use in source and binary forms, with or without modifica-
8			* tion, are permitted provided that the following conditions are met:
9			*
10			* 1. Redistributions of source code must retain the above copyright notice,
11			* this list of conditions and the following disclaimer.
12			*
13			* 2. Redistributions in binary form must reproduce the above copyright
14			* notice, this list of conditions and the following disclaimer in the
15			* documentation and/or other materials provided with the distribution.
16			*
17			* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
18			* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
19			* CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
20			* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
21			* CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
22			* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
23			* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
24			* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
25			* ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
26			* OF THE POSSIBILITY OF SUCH DAMAGE.
27			*
28			* Alternatively, the contents of this file may be used under the terms of
29			* the GNU General Public License ("GPL") version 2 or any later version,
30			* in which case the provisions of the GPL are applicable instead of
31			* the above. If you wish to allow the use of your version of this file
32			* only under the terms of the GPL and not to allow others to use your
33			* version of this file under the BSD license, indicate your decision
34			* by deleting the provisions above and replace them with the notice
35			* and other provisions required by the GPL. If you do not delete the
36			* provisions above, a recipient may use your version of this file under
37			* either the BSD or the GPL.
38			*/
39
40			#ifndef ETP_API_DECL
41			# define ETP_API_DECL static
42			#endif
43
44			#ifndef ETP_PRI_MIN
45			# define ETP_PRI_MIN 0
46			# define ETP_PRI_MAX 0
47			#endif
48
49			#ifndef ETP_TYPE_QUIT
50			# define ETP_TYPE_QUIT 0
51			#endif
52
53			#ifndef ETP_TYPE_GROUP
54			# define ETP_TYPE_GROUP 1
55			#endif
56
57			#define ETP_NUM_PRI (ETP_PRI_MAX - ETP_PRI_MIN + 1)
58
59			#define ETP_TICKS ((1000000 + 1023) >> 10)
60
61			/* calculate time difference in ~1/ETP_TICKS of a second */
62			ecb_inline int
63			etp_tvdiff (struct timeval tv1, struct timeval tv2)
64			{
65			return (tv2->tv_sec - tv1->tv_sec ) * ETP_TICKS
66			+ ((tv2->tv_usec - tv1->tv_usec) >> 10);
67			}
68
69			static unsigned int started, idle, wanted = 4;
70
71			static void (*want_poll_cb) (void);
72			static void (*done_poll_cb) (void);
73
74			static unsigned int max_poll_time; /* reslock */
75			static unsigned int max_poll_reqs; /* reslock */
76
77			static unsigned int nreqs; /* reqlock */
78			static unsigned int nready; /* reqlock */
79			static unsigned int npending; /* reqlock */
80			static unsigned int max_idle = 4; /* maximum number of threads that can idle indefinitely */
81			static unsigned int idle_timeout = 10; /* number of seconds after which an idle threads exit */
82
83			static xmutex_t wrklock;
84			static xmutex_t reslock;
85			static xmutex_t reqlock;
86			static xcond_t reqwait;
87
88	root	1.3	struct etp_tmpbuf
89			{
90			void *ptr;
91			int len;
92			};
93
94			static void *
95			etp_tmpbuf_get (struct etp_tmpbuf *buf, int len)
96			{
97			if (buf->len < len)
98			{
99			free (buf->ptr);
100			buf->ptr = malloc (buf->len = len);
101			}
102
103			return buf->ptr;
104			}
105
106	root	1.1	typedef struct etp_worker
107			{
108	root	1.3	struct etp_tmpbuf tmpbuf;
109	root	1.1
110			/* locked by wrklock */
111			struct etp_worker prev, next;
112
113			xthread_t tid;
114
115			#ifdef ETP_WORKER_COMMON
116			ETP_WORKER_COMMON
117			#endif
118			} etp_worker;
119
120			static etp_worker wrk_first; /* NOT etp */
121
122			#define ETP_WORKER_LOCK(wrk) X_LOCK (wrklock)
123			#define ETP_WORKER_UNLOCK(wrk) X_UNLOCK (wrklock)
124
125			/* worker threads management */
126
127			static void
128			etp_worker_clear (etp_worker *wrk)
129			{
130			}
131
132			static void ecb_cold
133			etp_worker_free (etp_worker *wrk)
134			{
135			free (wrk->tmpbuf.ptr);
136
137			wrk->next->prev = wrk->prev;
138			wrk->prev->next = wrk->next;
139
140			free (wrk);
141			}
142
143			ETP_API_DECL unsigned int
144			etp_nreqs (void)
145			{
146			int retval;
147			if (WORDACCESS_UNSAFE) X_LOCK (reqlock);
148			retval = nreqs;
149			if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
150			return retval;
151			}
152
153			ETP_API_DECL unsigned int
154			etp_nready (void)
155			{
156			unsigned int retval;
157
158			if (WORDACCESS_UNSAFE) X_LOCK (reqlock);
159			retval = nready;
160			if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
161
162			return retval;
163			}
164
165			ETP_API_DECL unsigned int
166			etp_npending (void)
167			{
168			unsigned int retval;
169
170			if (WORDACCESS_UNSAFE) X_LOCK (reqlock);
171			retval = npending;
172			if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
173
174			return retval;
175			}
176
177			ETP_API_DECL unsigned int
178			etp_nthreads (void)
179			{
180			unsigned int retval;
181
182			if (WORDACCESS_UNSAFE) X_LOCK (reqlock);
183			retval = started;
184			if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
185
186			return retval;
187			}
188
189			/*
190			* a somewhat faster data structure might be nice, but
191			* with 8 priorities this actually needs <20 insns
192			* per shift, the most expensive operation.
193			*/
194			typedef struct {
195			ETP_REQ qs[ETP_NUM_PRI], qe[ETP_NUM_PRI]; /* qstart, qend */
196			int size;
197			} etp_reqq;
198
199			static etp_reqq req_queue;
200			static etp_reqq res_queue;
201
202			static void ecb_noinline ecb_cold
203			reqq_init (etp_reqq *q)
204			{
205			int pri;
206
207			for (pri = 0; pri < ETP_NUM_PRI; ++pri)
208			q->qs[pri] = q->qe[pri] = 0;
209
210			q->size = 0;
211			}
212
213			static int ecb_noinline
214			reqq_push (etp_reqq q, ETP_REQ req)
215			{
216			int pri = req->pri;
217			req->next = 0;
218
219			if (q->qe[pri])
220			{
221			q->qe[pri]->next = req;
222			q->qe[pri] = req;
223			}
224			else
225			q->qe[pri] = q->qs[pri] = req;
226
227			return q->size++;
228			}
229
230			static ETP_REQ * ecb_noinline
231			reqq_shift (etp_reqq *q)
232			{
233			int pri;
234
235			if (!q->size)
236			return 0;
237
238			--q->size;
239
240			for (pri = ETP_NUM_PRI; pri--; )
241			{
242	root	1.2	ETP_REQ *req = q->qs[pri];
243	root	1.1
244			if (req)
245			{
246	root	1.2	if (!(q->qs[pri] = (ETP_REQ *)req->next))
247	root	1.1	q->qe[pri] = 0;
248
249			return req;
250			}
251			}
252
253			abort ();
254			}
255
256			ETP_API_DECL int ecb_cold
257			etp_init (void (want_poll)(void), void (done_poll)(void))
258			{
259			X_MUTEX_CREATE (wrklock);
260			X_MUTEX_CREATE (reslock);
261			X_MUTEX_CREATE (reqlock);
262			X_COND_CREATE (reqwait);
263
264			reqq_init (&req_queue);
265			reqq_init (&res_queue);
266
267			wrk_first.next =
268			wrk_first.prev = &wrk_first;
269
270			started = 0;
271			idle = 0;
272			nreqs = 0;
273			nready = 0;
274			npending = 0;
275
276			want_poll_cb = want_poll;
277			done_poll_cb = done_poll;
278
279			return 0;
280			}
281
282			/* not yet in etp.c */
283			X_THREAD_PROC (etp_proc);
284
285			static void ecb_cold
286			etp_start_thread (void)
287			{
288			etp_worker *wrk = calloc (1, sizeof (etp_worker));
289
290			/TODO/
291			assert (("unable to allocate worker thread data", wrk));
292
293			X_LOCK (wrklock);
294
295			if (xthread_create (&wrk->tid, etp_proc, (void *)wrk))
296			{
297			wrk->prev = &wrk_first;
298			wrk->next = wrk_first.next;
299			wrk_first.next->prev = wrk;
300			wrk_first.next = wrk;
301			++started;
302			}
303			else
304			free (wrk);
305
306			X_UNLOCK (wrklock);
307			}
308
309			static void
310			etp_maybe_start_thread (void)
311			{
312			if (ecb_expect_true (etp_nthreads () >= wanted))
313			return;
314
315			/* todo: maybe use idle here, but might be less exact */
316			if (ecb_expect_true (0 <= (int)etp_nthreads () + (int)etp_npending () - (int)etp_nreqs ()))
317			return;
318
319			etp_start_thread ();
320			}
321
322			static void ecb_cold
323			etp_end_thread (void)
324			{
325	root	1.2	ETP_REQ req = calloc (1, sizeof (ETP_REQ)); / will be freed by worker */
326	root	1.1
327			req->type = ETP_TYPE_QUIT;
328			req->pri = ETP_PRI_MAX - ETP_PRI_MIN;
329
330			X_LOCK (reqlock);
331			reqq_push (&req_queue, req);
332			X_COND_SIGNAL (reqwait);
333			X_UNLOCK (reqlock);
334
335			X_LOCK (wrklock);
336			--started;
337			X_UNLOCK (wrklock);
338			}
339
340			ETP_API_DECL int
341			etp_poll (void)
342			{
343			unsigned int maxreqs;
344			unsigned int maxtime;
345			struct timeval tv_start, tv_now;
346
347			X_LOCK (reslock);
348			maxreqs = max_poll_reqs;
349			maxtime = max_poll_time;
350			X_UNLOCK (reslock);
351
352			if (maxtime)
353			gettimeofday (&tv_start, 0);
354
355			for (;;)
356			{
357			ETP_REQ *req;
358
359			etp_maybe_start_thread ();
360
361			X_LOCK (reslock);
362			req = reqq_shift (&res_queue);
363
364			if (req)
365			{
366			--npending;
367
368			if (!res_queue.size && done_poll_cb)
369			done_poll_cb ();
370			}
371
372			X_UNLOCK (reslock);
373
374			if (!req)
375			return 0;
376
377			X_LOCK (reqlock);
378			--nreqs;
379			X_UNLOCK (reqlock);
380
381			if (ecb_expect_false (req->type == ETP_TYPE_GROUP && req->size))
382			{
383			req->int1 = 1; /* mark request as delayed */
384			continue;
385			}
386			else
387			{
388			int res = ETP_FINISH (req);
389			if (ecb_expect_false (res))
390			return res;
391			}
392
393			if (ecb_expect_false (maxreqs && !--maxreqs))
394			break;
395
396			if (maxtime)
397			{
398			gettimeofday (&tv_now, 0);
399
400			if (etp_tvdiff (&tv_start, &tv_now) >= maxtime)
401			break;
402			}
403			}
404
405			errno = EAGAIN;
406			return -1;
407			}
408
409			ETP_API_DECL void
410			etp_grp_cancel (ETP_REQ *grp);
411
412			ETP_API_DECL void
413			etp_cancel (ETP_REQ *req)
414			{
415			req->cancelled = 1;
416
417			etp_grp_cancel (req);
418			}
419
420			ETP_API_DECL void
421			etp_grp_cancel (ETP_REQ *grp)
422			{
423			for (grp = grp->grp_first; grp; grp = grp->grp_next)
424			etp_cancel (grp);
425			}
426
427			ETP_API_DECL void
428			etp_submit (ETP_REQ *req)
429			{
430			req->pri -= ETP_PRI_MIN;
431
432			if (ecb_expect_false (req->pri < ETP_PRI_MIN - ETP_PRI_MIN)) req->pri = ETP_PRI_MIN - ETP_PRI_MIN;
433			if (ecb_expect_false (req->pri > ETP_PRI_MAX - ETP_PRI_MIN)) req->pri = ETP_PRI_MAX - ETP_PRI_MIN;
434
435			if (ecb_expect_false (req->type == ETP_TYPE_GROUP))
436			{
437			/* I hope this is worth it :/ */
438			X_LOCK (reqlock);
439			++nreqs;
440			X_UNLOCK (reqlock);
441
442			X_LOCK (reslock);
443
444			++npending;
445
446			if (!reqq_push (&res_queue, req) && want_poll_cb)
447			want_poll_cb ();
448
449			X_UNLOCK (reslock);
450			}
451			else
452			{
453			X_LOCK (reqlock);
454			++nreqs;
455			++nready;
456			reqq_push (&req_queue, req);
457			X_COND_SIGNAL (reqwait);
458			X_UNLOCK (reqlock);
459
460			etp_maybe_start_thread ();
461			}
462			}
463
464			ETP_API_DECL void ecb_cold
465			etp_set_max_poll_time (double nseconds)
466			{
467			if (WORDACCESS_UNSAFE) X_LOCK (reslock);
468			max_poll_time = nseconds * ETP_TICKS;
469			if (WORDACCESS_UNSAFE) X_UNLOCK (reslock);
470			}
471
472			ETP_API_DECL void ecb_cold
473			etp_set_max_poll_reqs (unsigned int maxreqs)
474			{
475			if (WORDACCESS_UNSAFE) X_LOCK (reslock);
476			max_poll_reqs = maxreqs;
477			if (WORDACCESS_UNSAFE) X_UNLOCK (reslock);
478			}
479
480			ETP_API_DECL void ecb_cold
481			etp_set_max_idle (unsigned int nthreads)
482			{
483			if (WORDACCESS_UNSAFE) X_LOCK (reqlock);
484			max_idle = nthreads;
485			if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
486			}
487
488			ETP_API_DECL void ecb_cold
489			etp_set_idle_timeout (unsigned int seconds)
490			{
491			if (WORDACCESS_UNSAFE) X_LOCK (reqlock);
492			idle_timeout = seconds;
493			if (WORDACCESS_UNSAFE) X_UNLOCK (reqlock);
494			}
495
496			ETP_API_DECL void ecb_cold
497			etp_set_min_parallel (unsigned int nthreads)
498			{
499			if (wanted < nthreads)
500			wanted = nthreads;
501			}
502
503			ETP_API_DECL void ecb_cold
504			etp_set_max_parallel (unsigned int nthreads)
505			{
506			if (wanted > nthreads)
507			wanted = nthreads;
508
509			while (started > wanted)
510			etp_end_thread ();
511			}
512