diff options
Diffstat (limited to 'sesman/libscp/libscp_lock.c')
| -rw-r--r-- | sesman/libscp/libscp_lock.c | 204 |
1 files changed, 103 insertions, 101 deletions
diff --git a/sesman/libscp/libscp_lock.c b/sesman/libscp/libscp_lock.c index 9556b872..4db05422 100644 --- a/sesman/libscp/libscp_lock.c +++ b/sesman/libscp/libscp_lock.c @@ -1,25 +1,23 @@ -/* - 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. - - This program 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. - - xrdp: A Remote Desktop Protocol server. - Copyright (C) Jay Sorg 2005-2010 - - session manager - linux only - -*/ +/** + * xrdp: A Remote Desktop Protocol server. + * + * Copyright (C) Jay Sorg 2004-2012 + * + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + * + * session manager + * linux only + */ #include "libscp_lock.h" @@ -37,110 +35,114 @@ int lock_fork_waiting_count; /* threads suspended until the fork finish void DEFAULT_CC scp_lock_init(void) { - /* initializing fork lock */ - pthread_mutexattr_init(&lock_fork_attr); - pthread_mutex_init(&lock_fork, &lock_fork_attr); - sem_init(&lock_fork_req, 0, 0); - sem_init(&lock_fork_wait, 0, 0); - - /* here we don't use locking because lock_init() should be called BEFORE */ - /* any thread is created */ - lock_fork_blockers_count=0; - lock_fork_waiting_count=0; - lock_fork_forkers_count=0; + /* initializing fork lock */ + pthread_mutexattr_init(&lock_fork_attr); + pthread_mutex_init(&lock_fork, &lock_fork_attr); + sem_init(&lock_fork_req, 0, 0); + sem_init(&lock_fork_wait, 0, 0); + + /* here we don't use locking because lock_init() should be called BEFORE */ + /* any thread is created */ + lock_fork_blockers_count = 0; + lock_fork_waiting_count = 0; + lock_fork_forkers_count = 0; } /******************************************************************************/ void DEFAULT_CC scp_lock_fork_request(void) { - /* lock mutex */ - pthread_mutex_lock(&lock_fork); - if (lock_fork_blockers_count == 0) - { - /* if noone is blocking fork(), then we're allowed to fork */ - sem_post(&lock_fork_req); - } - lock_fork_forkers_count++; - pthread_mutex_unlock(&lock_fork); - - /* we wait to be allowed to fork() */ - sem_wait(&lock_fork_req); + /* lock mutex */ + pthread_mutex_lock(&lock_fork); + + if (lock_fork_blockers_count == 0) + { + /* if noone is blocking fork(), then we're allowed to fork */ + sem_post(&lock_fork_req); + } + + lock_fork_forkers_count++; + pthread_mutex_unlock(&lock_fork); + + /* we wait to be allowed to fork() */ + sem_wait(&lock_fork_req); } /******************************************************************************/ void DEFAULT_CC scp_lock_fork_release(void) { - pthread_mutex_lock(&lock_fork); - lock_fork_forkers_count--; - - /* if there's someone else that want to fork, we let him fork() */ - if (lock_fork_forkers_count > 0) - { - sem_post(&lock_fork_req); - } - - for (;lock_fork_waiting_count > 0; lock_fork_waiting_count--) - { - /* waking up the other processes */ - sem_post(&lock_fork_wait); - } - pthread_mutex_unlock(&lock_fork); + pthread_mutex_lock(&lock_fork); + lock_fork_forkers_count--; + + /* if there's someone else that want to fork, we let him fork() */ + if (lock_fork_forkers_count > 0) + { + sem_post(&lock_fork_req); + } + + for (; lock_fork_waiting_count > 0; lock_fork_waiting_count--) + { + /* waking up the other processes */ + sem_post(&lock_fork_wait); + } + + pthread_mutex_unlock(&lock_fork); } /******************************************************************************/ void DEFAULT_CC scp_lock_fork_critical_section_end(int blocking) { - //LOG_DBG("lock_fork_critical_secection_end()",0); - /* lock mutex */ - pthread_mutex_lock(&lock_fork); - - if (blocking == LIBSCP_LOCK_FORK_BLOCKER) - { - lock_fork_blockers_count--; - } - - /* if there's someone who wants to fork and we're the last blocking */ - /* then we let him go */ - if ((lock_fork_blockers_count == 0) && (lock_fork_forkers_count>0)) - { - sem_post(&lock_fork_req); - } - pthread_mutex_unlock(&lock_fork); + //LOG_DBG("lock_fork_critical_secection_end()",0); + /* lock mutex */ + pthread_mutex_lock(&lock_fork); + + if (blocking == LIBSCP_LOCK_FORK_BLOCKER) + { + lock_fork_blockers_count--; + } + + /* if there's someone who wants to fork and we're the last blocking */ + /* then we let him go */ + if ((lock_fork_blockers_count == 0) && (lock_fork_forkers_count > 0)) + { + sem_post(&lock_fork_req); + } + + pthread_mutex_unlock(&lock_fork); } /******************************************************************************/ int DEFAULT_CC scp_lock_fork_critical_section_start(void) { - //LOG_DBG("lock_fork_critical_secection_start()",0); - do - { - pthread_mutex_lock(&lock_fork); - - /* someone requested to fork */ - if (lock_fork_forkers_count > 0) + //LOG_DBG("lock_fork_critical_secection_start()",0); + do { - lock_fork_waiting_count++; - pthread_mutex_unlock(&lock_fork); - - /* we wait until the fork finishes */ - sem_wait(&lock_fork_wait); - + pthread_mutex_lock(&lock_fork); + + /* someone requested to fork */ + if (lock_fork_forkers_count > 0) + { + lock_fork_waiting_count++; + pthread_mutex_unlock(&lock_fork); + + /* we wait until the fork finishes */ + sem_wait(&lock_fork_wait); + + } + else + { + /* no fork, so we can go on... */ + lock_fork_blockers_count++; + pthread_mutex_unlock(&lock_fork); + + return LIBSCP_LOCK_FORK_BLOCKER; + } } - else - { - /* no fork, so we can go on... */ - lock_fork_blockers_count++; - pthread_mutex_unlock(&lock_fork); - - return LIBSCP_LOCK_FORK_BLOCKER; - } - } while (1); + while (1); - /* we'll never get here */ - return LIBSCP_LOCK_FORK_WAITING; + /* we'll never get here */ + return LIBSCP_LOCK_FORK_WAITING; } - |