X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=snapshot.cc;h=e8fdadba28839df18728b42ab7194c46ec01989c;hb=2866fe7049df652f89f3bfc1cc85ad65b3a150f8;hp=8761862ca5f67e01e431fd9de006dab095b7dd6b;hpb=6a3cefc5fc5bcae7b7f94dd9e6199f6b3efdd76e;p=cdsspec-compiler.git

diff --git a/snapshot.cc b/snapshot.cc
index 8761862..e8fdadb 100644
--- a/snapshot.cc
+++ b/snapshot.cc
@@ -4,7 +4,6 @@
 #include <signal.h>
 #include <stdlib.h>
 #include <map>
-#include <set>
 #include <cstring>
 #include <cstdio>
 #include "snapshot.h"
@@ -17,271 +16,291 @@
 #include <errno.h>
 #include <sys/wait.h>
 #include <ucontext.h>
-#include <sys/time.h>
+
 //extern declaration definition
 #define FAILURE(mesg) { printf("failed in the API: %s with errno relative message: %s\n", mesg, strerror( errno ) ); exit( -1 ); }
-#if USE_CHECKPOINTING
+#if USE_MPROTECT_SNAPSHOT
 struct SnapShot * snapshotrecord = NULL;
 struct Snapshot_t * sTheRecord = NULL;
 #else
 struct Snapshot_t * sTheRecord = NULL;
 #endif
-void BeginOperation( struct timeval * theStartTime ){
-#if 1
-	gettimeofday( theStartTime, NULL );
-#endif
-}
-#if SSDEBUG
-struct timeval *starttime = NULL;
-#endif
 void DumpIntoLog( const char * filename, const char * message ){
 #if SSDEBUG
-   static pid_t thePID = getpid();
-   char newFn[ 1024 ] ={ 0 };
-   sprintf( newFn,"%s-%d.txt", filename, thePID );
-   FILE * myFile = fopen( newFn, "w+" );
-   struct timeval theEndTime;
-   BeginOperation( &theEndTime );
-   double elapsed = ( theEndTime.tv_sec - starttime->tv_sec ) + ( theEndTime.tv_usec - starttime->tv_usec ) / 1000000.0;
-   fprintf( myFile, "The timestamp %f:--> the message %s: the process id %d\n", elapsed, message, thePID );
-   fflush( myFile );
-   fclose( myFile );
-   myFile = NULL;
+	static pid_t thePID = getpid();
+	char newFn[ 1024 ] ={ 0 };
+	sprintf( newFn,"%s-%d.txt", filename, thePID );
+	FILE * myFile = fopen( newFn, "w+" );
+	fprintf( myFile, "the message %s: the process id %d\n", message, thePID );
+	fflush( myFile );
+	fclose( myFile );
+	myFile = NULL;
 #endif
 }
-#if !USE_CHECKPOINTING
+#if !USE_MPROTECT_SNAPSHOT
 static ucontext_t savedSnapshotContext;
 static ucontext_t savedUserSnapshotContext;
-static int snapshotid = 0;
+static snapshot_id snapshotid = 0;
 #endif
 /* Initialize snapshot data structure */
-#if USE_CHECKPOINTING
+#if USE_MPROTECT_SNAPSHOT
 void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions) {
-  snapshotrecord=( struct SnapShot * )MYMALLOC(sizeof(struct SnapShot));
-  snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )MYMALLOC(sizeof(struct MemoryRegion)*nummemoryregions);
-  snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )MYMALLOC( sizeof( struct SnapShotPage ) * (numbackingpages + 1) );
-  //Page align the backingstorepages
-  snapshotrecord->backingStore=( struct SnapShotPage * )ReturnPageAlignedAddress((void*) ((uintptr_t)(snapshotrecord->backingStoreBasePtr)+sizeof(struct SnapShotPage)-1));
-  snapshotrecord->backingRecords=( struct BackingPageRecord * )MYMALLOC(sizeof(struct BackingPageRecord)*numbackingpages);
-  snapshotrecord->snapShots= ( struct SnapShotRecord * )MYMALLOC(sizeof(struct SnapShotRecord)*numsnapshots);
-  snapshotrecord->lastSnapShot=0;
-  snapshotrecord->lastBackingPage=0;
-  snapshotrecord->lastRegion=0;
-  snapshotrecord->maxRegions=nummemoryregions;
-  snapshotrecord->maxBackingPages=numbackingpages;
-  snapshotrecord->maxSnapShots=numsnapshots;
+	snapshotrecord=( struct SnapShot * )MYMALLOC(sizeof(struct SnapShot));
+	snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )MYMALLOC(sizeof(struct MemoryRegion)*nummemoryregions);
+	snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )MYMALLOC( sizeof( struct SnapShotPage ) * (numbackingpages + 1) );
+	//Page align the backingstorepages
+	snapshotrecord->backingStore=( struct SnapShotPage * )PageAlignAddressUpward(snapshotrecord->backingStoreBasePtr);
+	snapshotrecord->backingRecords=( struct BackingPageRecord * )MYMALLOC(sizeof(struct BackingPageRecord)*numbackingpages);
+	snapshotrecord->snapShots= ( struct SnapShotRecord * )MYMALLOC(sizeof(struct SnapShotRecord)*numsnapshots);
+	snapshotrecord->lastSnapShot=0;
+	snapshotrecord->lastBackingPage=0;
+	snapshotrecord->lastRegion=0;
+	snapshotrecord->maxRegions=nummemoryregions;
+	snapshotrecord->maxBackingPages=numbackingpages;
+	snapshotrecord->maxSnapShots=numsnapshots;
 }
 #endif //nothing to initialize for the fork based snapshotting.
 
 void HandlePF( int sig, siginfo_t *si, void * unused){
-#if USE_CHECKPOINTING
-  if( si->si_code == SEGV_MAPERR ){
-    printf("Real Fault at %llx\n", ( long long )si->si_addr);
-    exit( EXIT_FAILURE );	
-  }
-  void* addr = ReturnPageAlignedAddress(si->si_addr);
-  unsigned int backingpage=snapshotrecord->lastBackingPage++; //Could run out of pages...
-  if (backingpage==snapshotrecord->maxBackingPages) {
-    printf("Out of backing pages at %llx\n", ( long long )si->si_addr);
-    exit( EXIT_FAILURE );	
-  }
+#if USE_MPROTECT_SNAPSHOT
+	if( si->si_code == SEGV_MAPERR ){
+		printf("Real Fault at %p\n", si->si_addr);
+		exit( EXIT_FAILURE );
+	}
+	void* addr = ReturnPageAlignedAddress(si->si_addr);
+	unsigned int backingpage=snapshotrecord->lastBackingPage++; //Could run out of pages...
+	if (backingpage==snapshotrecord->maxBackingPages) {
+		printf("Out of backing pages at %p\n", si->si_addr);
+		exit( EXIT_FAILURE );
+	}
 
-  //copy page
-  memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(struct SnapShotPage));
-  //remember where to copy page back to
-  snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr;
-  //set protection to read/write
-  mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE );  
+	//copy page
+	memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(struct SnapShotPage));
+	//remember where to copy page back to
+	snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr;
+	//set protection to read/write
+	if (mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE )) {
+		perror("mprotect");
+		// Handle error by quitting?
+	}
 #endif //nothing to handle for non snapshotting case.
 }
 
 //Return a page aligned address for the address being added
 //as a side effect the numBytes are also changed.
 void * ReturnPageAlignedAddress(void * addr) {
-  return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
+	return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
+}
+
+//Return a page aligned address for the address being added
+//as a side effect the numBytes are also changed.
+void * PageAlignAddressUpward(void * addr) {
+	return (void *)((((uintptr_t)addr)+PAGESIZE-1)&~(PAGESIZE-1));
 }
 #ifdef __cplusplus
 extern "C" {
 #endif
-void createSharedLibrary(){
-#if !USE_CHECKPOINTING
-	  //step 1. create shared memory.
-  if( sTheRecord ) return;
-  int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions.
-  if( -1 == fd ) FAILURE("shm_open");
-  if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" );
-  char * memMapBase = ( char * ) mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
-  if( MAP_FAILED == memMapBase ) FAILURE("mmap");
-  sTheRecord = ( struct Snapshot_t * )memMapBase;
-  sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
-  sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
-  sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
-  sTheRecord->mIDToRollback = -1;
-  sTheRecord->currSnapShotID = 0;
+	void createSharedLibrary(){
+#if !USE_MPROTECT_SNAPSHOT
+		//step 1. create shared memory.
+		if( sTheRecord ) return;
+		int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions.
+		if( -1 == fd ) FAILURE("shm_open");
+		if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" );
+		char * memMapBase = ( char * ) mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
+		if( MAP_FAILED == memMapBase ) FAILURE("mmap");
+		sTheRecord = ( struct Snapshot_t * )memMapBase;
+		sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
+		sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
+		sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
+		sTheRecord->mIDToRollback = -1;
+		sTheRecord->currSnapShotID = 0;
 #endif
-}
+	}
 #ifdef __cplusplus
 }
 #endif
-void initSnapShotLibrary(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions , MyFuncPtr entryPoint){
-#if USE_CHECKPOINTING
-  struct sigaction sa;
-  sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
-  sigemptyset( &sa.sa_mask );
-  sa.sa_sigaction = HandlePF;
-  if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
-    printf("SIGACTION CANNOT BE INSTALLED\n");
-    exit(-1);
-  }
-  initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
-  entryPoint();
+void initSnapShotLibrary(unsigned int numbackingpages,
+		unsigned int numsnapshots, unsigned int nummemoryregions,
+		unsigned int numheappages, VoidFuncPtr entryPoint) {
+#if USE_MPROTECT_SNAPSHOT
+	/* Setup a stack for our signal handler....  */
+	stack_t ss;
+	ss.ss_sp = MYMALLOC(SIGSTACKSIZE);
+	ss.ss_size = SIGSTACKSIZE;
+	ss.ss_flags = 0;
+	sigaltstack(&ss, NULL);
+
+	struct sigaction sa;
+	sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART | SA_ONSTACK;
+	sigemptyset( &sa.sa_mask );
+	sa.sa_sigaction = HandlePF;
+	if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
+		printf("SIGACTION CANNOT BE INSTALLED\n");
+		exit(-1);
+	}
+	initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
+
+	// EVIL HACK: We need to make sure that calls into the HandlePF method don't cause dynamic links
+	// The problem is that we end up protecting state in the dynamic linker...
+	// Solution is to call our signal handler before we start protecting stuff...
+
+	siginfo_t si;
+	si.si_addr=ss.ss_sp;
+	HandlePF(SIGSEGV, &si, NULL);
+	snapshotrecord->lastBackingPage--; //remove the fake page we copied
+
+	basemySpace=MYMALLOC((numheappages+1)*PAGESIZE);
+	void * pagealignedbase=PageAlignAddressUpward(basemySpace);
+	mySpace = create_mspace_with_base(pagealignedbase,  numheappages*PAGESIZE, 1 );
+	addMemoryRegionToSnapShot(pagealignedbase, numheappages);
+	entryPoint();
 #else
-  //add a signal to indicate that the process is going to terminate.
-  struct sigaction sa;
-  sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
-  sigemptyset( &sa.sa_mask );
-  sa.sa_sigaction = HandlePF;
-  if( sigaction( SIGUSR1, &sa, NULL ) == -1 ){
-    printf("SIGACTION CANNOT BE INSTALLED\n");
-    exit(-1);
-  }
-  createSharedLibrary();
- #if SSDEBUG
-  starttime = &(sTheRecord->startTimeGlobal);
-  gettimeofday( starttime, NULL );
-#endif
-  //step 2 setup the stack context.
- 
-  int alreadySwapped = 0;
-  getcontext( &savedSnapshotContext );
-  if( !alreadySwapped ){
-    alreadySwapped = 1;
-    ucontext_t currentContext, swappedContext, newContext;
-    getcontext( &newContext );
-    newContext.uc_stack.ss_sp = sTheRecord->mStackBase;
-    newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
-    newContext.uc_link = &currentContext;
-    makecontext( &newContext, entryPoint, 0 );
-    swapcontext( &swappedContext, &newContext );
-  }
-  
-   //add the code to take a snapshot here...
+	//add a signal to indicate that the process is going to terminate.
+	struct sigaction sa;
+	sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
+	sigemptyset( &sa.sa_mask );
+	sa.sa_sigaction = HandlePF;
+	if( sigaction( SIGUSR1, &sa, NULL ) == -1 ){
+		printf("SIGACTION CANNOT BE INSTALLED\n");
+		exit(-1);
+	}
+	createSharedLibrary();
+
+	//step 2 setup the stack context.
+
+	int alreadySwapped = 0;
+	getcontext( &savedSnapshotContext );
+	if( !alreadySwapped ){
+		alreadySwapped = 1;
+		ucontext_t currentContext, swappedContext, newContext;
+		getcontext( &newContext );
+		newContext.uc_stack.ss_sp = sTheRecord->mStackBase;
+		newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
+		newContext.uc_link = &currentContext;
+		makecontext( &newContext, entryPoint, 0 );
+		swapcontext( &swappedContext, &newContext );
+	}
+
+	//add the code to take a snapshot here...
 	//to return to user process, do a second swapcontext...
-  pid_t forkedID = 0;
-  snapshotid = sTheRecord->currSnapShotID;
-  bool swapContext = false;
-  while( !sTheRecord->mbFinalize ){
-    sTheRecord->currSnapShotID=snapshotid+1;
-    forkedID = fork();
-    if( 0 == forkedID ){ 
-      ucontext_t currentContext;
+	pid_t forkedID = 0;
+	snapshotid = sTheRecord->currSnapShotID;
+	bool swapContext = false;
+	while( !sTheRecord->mbFinalize ){
+		sTheRecord->currSnapShotID=snapshotid+1;
+		forkedID = fork();
+		if( 0 == forkedID ){
+			ucontext_t currentContext;
 #if 0
-      int dbg = 0;
-      while( !dbg );
+			int dbg = 0;
+			while( !dbg );
 #endif
-      if( swapContext )
-        swapcontext( &currentContext, &( sTheRecord->mContextToRollback ) );
+			if( swapContext )
+				swapcontext( &currentContext, &( sTheRecord->mContextToRollback ) );
 			else{
-				swapcontext( &currentContext, &savedUserSnapshotContext );      
+				swapcontext( &currentContext, &savedUserSnapshotContext );
 			}
-    } else {
-      int status;
-      int retVal;
+		} else {
+			int status;
+			int retVal;
 #if SSDEBUG
-      char mesg[ 1024 ] = { 0 };
-      sprintf( mesg, "The process id of child is %d and the process id of this process is %d and snapshot id is %d", forkedID, getpid(), snapshotid );
-      DumpIntoLog( "ModelSnapshot", mesg );
+			char mesg[ 1024 ] = { 0 };
+			sprintf( mesg, "The process id of child is %d and the process id of this process is %d and snapshot id is %d", forkedID, getpid(), snapshotid );
+			DumpIntoLog( "ModelSnapshot", mesg );
 #endif
-      do { 
+			do {
 				retVal=waitpid( forkedID, &status, 0 );
-      } while( -1 == retVal && errno == EINTR );
+			} while( -1 == retVal && errno == EINTR );
+
+			if( sTheRecord->mIDToRollback != snapshotid )
+				exit(0);
+			else{
+				swapContext = true;
+			}
+		}
+	}
 
-      if( sTheRecord->mIDToRollback != snapshotid )
-			  exit(0);
-      else{
-         swapContext = true;
-      }
-    }
-  }
-  
 #endif
 }
 /* This function assumes that addr is page aligned */
 void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) {
-#if USE_CHECKPOINTING
-  unsigned int memoryregion=snapshotrecord->lastRegion++;
-  if (memoryregion==snapshotrecord->maxRegions) {
-    printf("Exceeded supported number of memory regions!\n");
-    exit(-1);
-  }
-  
-  snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
-  snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
+#if USE_MPROTECT_SNAPSHOT
+	unsigned int memoryregion=snapshotrecord->lastRegion++;
+	if (memoryregion==snapshotrecord->maxRegions) {
+		printf("Exceeded supported number of memory regions!\n");
+		exit(-1);
+	}
+
+	snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
+	snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
 #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS.
 }
 //take snapshot
 snapshot_id takeSnapshot( ){
-#if USE_CHECKPOINTING
-  for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
-    if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){
-      printf("Failed to mprotect inside of takeSnapShot\n");
-      exit(-1);
-    }		
-  }
-  unsigned int snapshot=snapshotrecord->lastSnapShot++;
-  if (snapshot==snapshotrecord->maxSnapShots) {
-    printf("Out of snapshots\n");
-    exit(-1);
-  }
-  snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
-  
-  return snapshot;
+#if USE_MPROTECT_SNAPSHOT
+	for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
+		if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){
+			perror("mprotect");
+			printf("Failed to mprotect inside of takeSnapShot\n");
+			exit(-1);
+		}
+	}
+	unsigned int snapshot=snapshotrecord->lastSnapShot++;
+	if (snapshot==snapshotrecord->maxSnapShots) {
+		printf("Out of snapshots\n");
+		exit(-1);
+	}
+	snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
+
+	return snapshot;
 #else
-  swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
-  return snapshotid;
+	swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
+	return snapshotid;
 #endif
 }
 void rollBack( snapshot_id theID ){
-#if USE_CHECKPOINTING
-  std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
-  for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
-  if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){
-      printf("Failed to mprotect inside of takeSnapShot\n");
-      exit(-1);
-    }		
-  }
-  for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; page++) {
-    bool oldVal = false;
-    if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){
-      oldVal = true;          
-    }
-    else{
-      duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true;    
-    }
-    if(  !oldVal ){
-      memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage));
-    }
-  }
-  snapshotrecord->lastSnapShot=theID;
-  snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
-  takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
+#if USE_MPROTECT_SNAPSHOT
+	std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
+	for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
+		if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){
+			perror("mprotect");
+			printf("Failed to mprotect inside of takeSnapShot\n");
+			exit(-1);
+		}
+	}
+	for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; page++) {
+		bool oldVal = false;
+		if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){
+			oldVal = true;
+		}
+		else{
+			duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true;
+		}
+		if(  !oldVal ){
+			memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage));
+		}
+	}
+	snapshotrecord->lastSnapShot=theID;
+	snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
+	takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
 #else
-  sTheRecord->mIDToRollback = theID;
-  int sTemp = 0;
-  getcontext( &sTheRecord->mContextToRollback );
-  if( !sTemp ){
-    sTemp = 1;
+	sTheRecord->mIDToRollback = theID;
+	int sTemp = 0;
+	getcontext( &sTheRecord->mContextToRollback );
+	if( !sTemp ){
+		sTemp = 1;
 #if SSDEBUG
-  	DumpIntoLog( "ModelSnapshot", "Invoked rollback" ); 
+		DumpIntoLog( "ModelSnapshot", "Invoked rollback" );
 #endif
-  	exit( 0 );
-  }
+		exit( 0 );
+	}
 #endif
 }
 
 void finalize(){
-#if !USE_CHECKPOINTING
-  sTheRecord->mbFinalize = true;
+#if !USE_MPROTECT_SNAPSHOT
+	sTheRecord->mbFinalize = true;
 #endif
 }