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/*
Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
Written by Michael I. Bushnell.
This file is part of the GNU Hurd.
The GNU Hurd 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, or (at
your option) any later version.
The GNU Hurd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "ports.h"
#include <assert.h>
#include <error.h>
#include <stdio.h>
#include <mach/message.h>
#include <mach/thread_info.h>
#include <mach/thread_switch.h>
#define STACK_SIZE (64 * 1024)
#define THREAD_PRI 2
/* XXX To reduce starvation, the priority of new threads is initially
depressed. This helps already existing threads complete their job and be
recycled to handle new messages. The duration of this depression is made
a function of the total number of threads because more threads imply
more contention, and the priority of threads blocking on a contended spin
lock is also implicitely depressed.
Then, if permitted, a greater priority is requested to further decrease
the need for additional threads. */
static void
adjust_priority (unsigned int totalthreads)
{
mach_port_t host_priv, self, pset, pset_priv;
unsigned int t;
error_t err;
t = 10 + (((totalthreads - 1) / 100) + 1) * 10;
thread_switch (MACH_PORT_NULL, SWITCH_OPTION_DEPRESS, t);
err = get_privileged_ports (&host_priv, NULL);
if (err)
goto error_host_priv;
self = mach_thread_self ();
err = thread_get_assignment (self, &pset);
if (err)
goto error_pset;
err = host_processor_set_priv (host_priv, pset, &pset_priv);
if (err)
goto error_pset_priv;
err = thread_max_priority (self, pset_priv, 0);
if (err)
goto error_max_priority;
err = thread_priority (self, THREAD_PRI, 0);
if (err)
goto error_priority;
mach_port_deallocate (mach_task_self (), pset_priv);
mach_port_deallocate (mach_task_self (), pset);
mach_port_deallocate (mach_task_self (), self);
mach_port_deallocate (mach_task_self (), host_priv);
return;
error_priority:
error_max_priority:
mach_port_deallocate (mach_task_self (), pset_priv);
error_pset_priv:
mach_port_deallocate (mach_task_self (), pset);
error_pset:
mach_port_deallocate (mach_task_self (), self);
mach_port_deallocate (mach_task_self (), host_priv);
error_host_priv:
if (err != EPERM)
error (0, err, "unable to adjust libports thread priority");
}
void
ports_manage_port_operations_multithread (struct port_bucket *bucket,
ports_demuxer_type demuxer,
int thread_timeout,
int global_timeout,
void (*hook)())
{
/* totalthreads is the number of total threads created. nreqthreads
is the number of threads not currently servicing any client. The
initial values account for the main thread. */
unsigned int totalthreads = 1;
unsigned int nreqthreads = 1;
pthread_attr_t attr;
auto void * thread_function (void *);
pthread_attr_init (&attr);
pthread_attr_setstacksize (&attr, STACK_SIZE);
int
internal_demuxer (mach_msg_header_t *inp,
mach_msg_header_t *outheadp)
{
int status;
struct port_info *pi;
struct rpc_info link;
register mig_reply_header_t *outp = (mig_reply_header_t *) outheadp;
static const mach_msg_type_t RetCodeType = {
/* msgt_name = */ MACH_MSG_TYPE_INTEGER_32,
/* msgt_size = */ 32,
/* msgt_number = */ 1,
/* msgt_inline = */ TRUE,
/* msgt_longform = */ FALSE,
/* msgt_deallocate = */ FALSE,
/* msgt_unused = */ 0
};
if (__atomic_sub_fetch (&nreqthreads, 1, __ATOMIC_RELAXED) == 0)
/* No thread would be listening for requests, spawn one. */
{
pthread_t pthread_id;
error_t err;
__atomic_add_fetch (&totalthreads, 1, __ATOMIC_RELAXED);
__atomic_add_fetch (&nreqthreads, 1, __ATOMIC_RELAXED);
err = pthread_create (&pthread_id, &attr, thread_function, NULL);
if (!err)
pthread_detach (pthread_id);
else
{
__atomic_sub_fetch (&totalthreads, 1, __ATOMIC_RELAXED);
__atomic_sub_fetch (&nreqthreads, 1, __ATOMIC_RELAXED);
/* There is not much we can do at this point. The code
and design of the Hurd servers just don't handle
thread creation failure. */
errno = err;
perror ("pthread_create");
}
}
/* Fill in default response. */
outp->Head.msgh_bits
= MACH_MSGH_BITS(MACH_MSGH_BITS_REMOTE(inp->msgh_bits), 0);
outp->Head.msgh_size = sizeof *outp;
outp->Head.msgh_remote_port = inp->msgh_remote_port;
outp->Head.msgh_local_port = MACH_PORT_NULL;
outp->Head.msgh_seqno = 0;
outp->Head.msgh_id = inp->msgh_id + 100;
outp->RetCodeType = RetCodeType;
outp->RetCode = MIG_BAD_ID;
pi = ports_lookup_port (bucket, inp->msgh_local_port, 0);
if (pi)
{
error_t err = ports_begin_rpc (pi, inp->msgh_id, &link);
if (err)
{
outp->RetCode = err;
status = 1;
}
else
{
pthread_mutex_lock (&_ports_lock);
if (inp->msgh_seqno < pi->cancel_threshold)
hurd_thread_cancel (link.thread);
pthread_mutex_unlock (&_ports_lock);
status = demuxer (inp, outheadp);
ports_end_rpc (pi, &link);
}
ports_port_deref (pi);
}
else
{
outp->RetCode = EOPNOTSUPP;
status = 1;
}
__atomic_add_fetch (&nreqthreads, 1, __ATOMIC_RELAXED);
return status;
}
void *
thread_function (void *arg)
{
int master = (int) arg;
int timeout;
error_t err;
adjust_priority (__atomic_load_n (&totalthreads, __ATOMIC_RELAXED));
if (hook)
(*hook) ();
if (master)
timeout = global_timeout;
else
timeout = thread_timeout;
startover:
do
err = mach_msg_server_timeout (internal_demuxer, 0, bucket->portset,
timeout ? MACH_RCV_TIMEOUT : 0,
timeout);
while (err != MACH_RCV_TIMED_OUT);
if (master)
{
if (__atomic_load_n (&totalthreads, __ATOMIC_RELAXED) != 1)
goto startover;
}
else
{
if (__atomic_sub_fetch (&nreqthreads, 1, __ATOMIC_RELAXED) == 0)
{
/* No other thread is listening for requests, continue. */
__atomic_add_fetch (&nreqthreads, 1, __ATOMIC_RELAXED);
goto startover;
}
__atomic_sub_fetch (&totalthreads, 1, __ATOMIC_RELAXED);
}
return NULL;
}
thread_function ((void *) 1);
}
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