libgfaipc/src/mutex.cpp

#ifdef _WIN32
#define _CRT_SECURE_NO_WARNINGS
#define _CRT_NONSTDC_NO_WARNINGS
#include <windows.h>
#include <io.h>
#include "../Win32/w32def.h"
#endif	//	_WIN32

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#ifdef __linux__
#include <sys/file.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <linux/limits.h>
#include <sys/shm.h>
#endif	//	__linux__
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "defines.h"
#include "mutex.h"

/////////////////////////////////////////////////////////////////////////////

#define _IS_VALID_SHMID(id)				((id) >= 0)

/////////////////////////////////////////////////////////////////////////////

CGlobalMutex::CGlobalMutex(void) :	m_nShmID(_INVALID_ID), m_pMutex(NULL)
{
	memset(&m_mutexAttr, 0, sizeof(m_mutexAttr));
	::pthread_mutexattr_init(&m_mutexAttr);
	::pthread_mutexattr_setpshared(&m_mutexAttr, PTHREAD_PROCESS_SHARED);
	::pthread_mutexattr_settype(&m_mutexAttr, PTHREAD_MUTEX_RECURSIVE);
	::pthread_mutexattr_setrobust(&m_mutexAttr, PTHREAD_MUTEX_ROBUST);
}

CGlobalMutex::~CGlobalMutex(void)
{
	Release();
}

int CGlobalMutex::Create(const uuid_t &ruuid, const char *pszDir)
{
	if(!pszDir)
		pszDir = "";

	size_t nLenReq = strlen(pszDir) + _UUID_STRING_LEN + 10;

	if(nLenReq > PATH_MAX)
	{
		TRACE("CGlobalMutex::Create: directory name too long\n");
		errno = EINVAL;
		return -1;
	}

	int nRet = -1;
	char szUuid[_UUID_STRING_LEN + 1];
	char szShm[PATH_MAX];
	_uuid_unparse(&ruuid, szUuid, sizeof(szUuid));
	sprintf(szShm, "%s/%s.gfa.mtx", pszDir, szUuid);

	int nFdShm;

	if((nFdShm = ::open(szShm, O_RDWR | O_CREAT | O_TRUNC, _NUMBER_OF_THE_BEAST)) >= 0)
	{
		key_t shmKey;

		if((shmKey = ::ftok(szShm, 'R')) >= 0)
		{
			if((m_nShmID = ::shmget(shmKey, sizeof(pthread_mutex_t), IPC_CREAT | _NUMBER_OF_THE_BEAST)) >= 0)
			{
				struct shmid_ds sds;
				memset(&sds, 0, sizeof(sds));

				if(!::shmctl(m_nShmID, IPC_STAT, (struct shmid_ds*)&sds))
				{
					m_pMutex = (pthread_mutex_t*)::shmat(m_nShmID, NULL, 0);

					if(!sds.shm_atime)
					{
						if(!(nRet = ::pthread_mutex_init(m_pMutex, &m_mutexAttr)))
						{
							TRACE("CGlobalMutex::Create: Created new Mutex\n");
							nRet = 1;
						}
						else
						{
							TRACE("CGlobalMutex::Create failed! Code: %d\n", nRet);
							nRet = -1;
						}
					}
					else
					{
						TRACE("CGlobalMutex::Create: Opened existing Mutex\n");
						nRet = 0;
					}
				}
				else
				{
					TRACE("CGlobalMutex::Create: IPC_STAT failed - errno: %d!\n", errno);
				}
			}
			else
			{
				TRACE("CGlobalMutex::Create: Failed to create SHM on Key: 0x%08X - errno: %d!\n", shmKey, errno);
			}
		}
		else
		{
			TRACE("CGlobalMutex::Create: Failed to create shmKey - errno: %d!\n", errno);
		}

		close(nFdShm);
	}
	else
	{
		TRACE("CGlobalMutex::Create: Failed to open '%s' - errno: %d!\n", szShm, errno);
	}

	return nRet;
}
	
long CGlobalMutex::Release(void)
{
	struct shmid_ds sds;
	sds.shm_nattch = (shmatt_t)-1;

	if(_IS_VALID_SHMID(m_nShmID) && m_pMutex)
	{
		if(!::shmctl(m_nShmID, IPC_STAT, (struct shmid_ds*)&sds))
		{
			if((long)sds.shm_nattch > 1)
			{
				::pthread_mutexattr_destroy(&m_mutexAttr);
				::shmdt(m_pMutex);
				::shmctl(m_nShmID, IPC_STAT, (struct shmid_ds*)&sds);
				TRACE("CGlobalMutex::Release: Still attached: %ld!\n", (long)(sds.shm_nattch));
			}
			else if((long)sds.shm_nattch == 1)
			{
				::pthread_mutex_destroy(m_pMutex);
				::pthread_mutexattr_destroy(&m_mutexAttr);
				::shmdt(m_pMutex);
				::shmctl(m_nShmID, IPC_RMID, NULL);
				sds.shm_nattch = 0;
				TRACE("CGlobalMutex::Release: Mutex removed!\n");
			}
		}
		else
		{
			sds.shm_nattch = (shmatt_t)-1;
			TRACE("CGlobalMutex::Release: IPC_STAT failed!\n");
		}

		m_pMutex = NULL;
		m_nShmID = _INVALID_ID;
	}

	return (long)sds.shm_nattch;
}

bool CGlobalMutex::Lock(void)
{
	if(m_pMutex)
	{
		int nRet = ::pthread_mutex_lock(m_pMutex);
		if(nRet == EOWNERDEAD)
		{
			TRACE("CGlobalMutex::Lock: Former owner process has died - gained ownership!\n");
			::pthread_mutex_consistent(m_pMutex);
			nRet = 0;
		}
//		TRACE("CGlobalMutex::Lock: Locked: %d.\n", m_nShmID);
		return !nRet;
	}
	else
	{
		TRACE("CGlobalMutex::Lock: Invalid Mutex: %p!\n", m_pMutex);
		errno = EINVAL;
		return false;
	}
}

bool CGlobalMutex::TryLock(void)
{
	if(m_pMutex)
	{
		int nRet = ::pthread_mutex_trylock(m_pMutex);
		if(nRet == EOWNERDEAD)
		{
			TRACE("CGlobalMutex::TryLock: Former owner process has died - gained ownership!\n");
			::pthread_mutex_consistent(m_pMutex);
			nRet = 0;
		}
		return !nRet;
	}
	else
	{
		TRACE("CGlobalMutex::TryLock: Invalid Mutex: %p!\n", m_pMutex);
		errno = EINVAL;
		return false;
	}
}

bool CGlobalMutex::Unlock(void)
{
	if(m_pMutex)
	{
//		TRACE("CGlobalMutex::Unlock: Unlocked: %d.\n", m_nShmID);
		return !::pthread_mutex_unlock(m_pMutex);
	}
	else
	{
		TRACE("CGlobalMutex::Unlock: Invalid Mutex: %p!\n", m_pMutex);
		errno = EINVAL;
		return false;
	}
}