281 lines
7.6 KiB
C++
281 lines
7.6 KiB
C++
/*
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Copyright (C) 2004-2008 Grame
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Copyright (C) 2016 Filipe Coelho
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#include "JackLinuxFutex.h"
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#include "JackTools.h"
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#include "JackConstants.h"
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#include "JackError.h"
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#include "promiscuous.h"
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#include <climits>
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#include <fcntl.h>
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#include <stdio.h>
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#include <sys/mman.h>
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#include <syscall.h>
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#include <linux/futex.h>
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#if !defined(SYS_futex) && defined(SYS_futex_time64)
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#define SYS_futex SYS_futex_time64
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#endif
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namespace Jack
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{
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JackLinuxFutex::JackLinuxFutex() : JackSynchro(), fSharedMem(-1), fFutex(NULL), fPrivate(false)
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{
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const char* promiscuous = getenv("JACK_PROMISCUOUS_SERVER");
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fPromiscuous = (promiscuous != NULL);
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fPromiscuousGid = jack_group2gid(promiscuous);
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}
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void JackLinuxFutex::BuildName(const char* client_name, const char* server_name, char* res, int size)
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{
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char ext_client_name[SYNC_MAX_NAME_SIZE + 1];
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JackTools::RewriteName(client_name, ext_client_name);
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if (fPromiscuous) {
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snprintf(res, size, "jack_sem.%s_%s", server_name, ext_client_name);
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} else {
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snprintf(res, size, "jack_sem.%d_%s_%s", JackTools::GetUID(), server_name, ext_client_name);
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}
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}
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bool JackLinuxFutex::Signal()
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{
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if (!fFutex) {
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jack_error("JackLinuxFutex::Signal name = %s already deallocated!!", fName);
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return false;
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}
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if (fFlush) {
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return true;
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}
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if (! __sync_bool_compare_and_swap(&fFutex->futex, 0, 1))
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{
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// already unlocked, do not wake futex
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if (! fFutex->internal) return true;
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}
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::syscall(SYS_futex, fFutex, fFutex->internal ? FUTEX_WAKE_PRIVATE : FUTEX_WAKE, 1, NULL, NULL, 0);
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return true;
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}
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bool JackLinuxFutex::SignalAll()
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{
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return Signal();
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}
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bool JackLinuxFutex::Wait()
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{
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if (!fFutex) {
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jack_error("JackLinuxFutex::Wait name = %s already deallocated!!", fName);
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return false;
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}
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if (fFutex->needsChange)
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{
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fFutex->needsChange = false;
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fFutex->internal = !fFutex->internal;
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}
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const int wait_mode = fFutex->internal ? FUTEX_WAIT_PRIVATE : FUTEX_WAIT;
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for (;;)
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{
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if (__sync_bool_compare_and_swap(&fFutex->futex, 1, 0))
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return true;
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if (::syscall(SYS_futex, fFutex, wait_mode, 0, NULL, NULL, 0) != 0)
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if (errno != EAGAIN && errno != EINTR)
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return false;
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}
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}
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bool JackLinuxFutex::TimedWait(long usec)
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{
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if (usec == LONG_MAX)
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return Wait();
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if (!fFutex) {
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jack_error("JackLinuxFutex::TimedWait name = %s already deallocated!!", fName);
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return false;
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}
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if (fFutex->needsChange)
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{
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fFutex->needsChange = false;
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fFutex->internal = !fFutex->internal;
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}
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const uint secs = usec / 1000000;
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const int nsecs = (usec % 1000000) * 1000;
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const timespec timeout = { static_cast<time_t>(secs), nsecs };
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const int wait_mode = fFutex->internal ? FUTEX_WAIT_PRIVATE : FUTEX_WAIT;
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for (;;)
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{
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if (__sync_bool_compare_and_swap(&fFutex->futex, 1, 0))
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return true;
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if (::syscall(SYS_futex, fFutex, wait_mode, 0, &timeout, NULL, 0) != 0)
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if (errno != EAGAIN && errno != EINTR)
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return false;
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}
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}
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// Server side : publish the futex in the global namespace
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bool JackLinuxFutex::Allocate(const char* name, const char* server_name, int value, bool internal)
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{
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BuildName(name, server_name, fName, sizeof(fName));
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jack_log("JackLinuxFutex::Allocate name = %s val = %ld", fName, value);
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if ((fSharedMem = shm_open(fName, O_CREAT | O_RDWR, 0777)) < 0) {
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jack_error("Allocate: can't check in named futex name = %s err = %s", fName, strerror(errno));
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return false;
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}
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if (ftruncate(fSharedMem, sizeof(FutexData)) != 0) {
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jack_error("Allocate: can't set shared memory size in named futex name = %s err = %s", fName, strerror(errno));
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return false;
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}
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if (fPromiscuous && (jack_promiscuous_perms(fSharedMem, fName, fPromiscuousGid) < 0)) {
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close(fSharedMem);
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fSharedMem = -1;
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shm_unlink(fName);
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return false;
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}
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FutexData* futex = (FutexData*)mmap(NULL, sizeof(FutexData), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_LOCKED, fSharedMem, 0);
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if (futex == NULL || futex == MAP_FAILED) {
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jack_error("Allocate: can't check in named futex name = %s err = %s", fName, strerror(errno));
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close(fSharedMem);
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fSharedMem = -1;
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shm_unlink(fName);
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return false;
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}
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fPrivate = internal;
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futex->futex = value;
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futex->internal = internal;
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futex->wasInternal = internal;
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futex->needsChange = false;
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futex->externalCount = 0;
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fFutex = futex;
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return true;
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}
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// Client side : get the published futex from server
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bool JackLinuxFutex::Connect(const char* name, const char* server_name)
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{
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BuildName(name, server_name, fName, sizeof(fName));
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jack_log("JackLinuxFutex::Connect name = %s", fName);
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// Temporary...
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if (fFutex) {
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jack_log("Already connected name = %s", name);
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return true;
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}
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if ((fSharedMem = shm_open(fName, O_RDWR, 0)) < 0) {
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jack_error("Connect: can't connect named futex name = %s err = %s", fName, strerror(errno));
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return false;
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}
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FutexData* futex = (FutexData*)mmap(NULL, sizeof(FutexData), PROT_READ|PROT_WRITE, MAP_SHARED|MAP_LOCKED, fSharedMem, 0);
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if (futex == NULL || futex == MAP_FAILED) {
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jack_error("Connect: can't connect named futex name = %s err = %s", fName, strerror(errno));
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close(fSharedMem);
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fSharedMem = -1;
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return false;
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}
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if (! fPrivate && futex->wasInternal)
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{
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const char* externalSync = getenv("JACK_INTERNAL_CLIENT_SYNC");
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if (externalSync != NULL && strstr(fName, externalSync) != NULL && ++futex->externalCount == 1)
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{
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jack_error("Note: client %s running as external client temporarily", fName);
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futex->needsChange = true;
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}
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}
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fFutex = futex;
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return true;
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}
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bool JackLinuxFutex::ConnectInput(const char* name, const char* server_name)
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{
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return Connect(name, server_name);
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}
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bool JackLinuxFutex::ConnectOutput(const char* name, const char* server_name)
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{
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return Connect(name, server_name);
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}
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bool JackLinuxFutex::Disconnect()
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{
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if (!fFutex) {
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return true;
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}
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if (! fPrivate && fFutex->wasInternal)
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{
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const char* externalSync = getenv("JACK_INTERNAL_CLIENT_SYNC");
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if (externalSync != NULL && strstr(fName, externalSync) != NULL && --fFutex->externalCount == 0)
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{
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jack_error("Note: client %s now running as internal client again", fName);
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fFutex->needsChange = true;
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}
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}
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munmap(fFutex, sizeof(FutexData));
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fFutex = NULL;
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close(fSharedMem);
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fSharedMem = -1;
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return true;
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}
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// Server side : destroy the futex
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void JackLinuxFutex::Destroy()
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{
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if (!fFutex) {
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return;
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}
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munmap(fFutex, sizeof(FutexData));
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fFutex = NULL;
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close(fSharedMem);
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fSharedMem = -1;
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shm_unlink(fName);
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}
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} // end of namespace
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