X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=blobdiff_plain;f=snapshot.cc;h=f129f4cc31da565aeed8bfd0b2a5d1f4b063e8a5;hp=b848d024c4eab7a0efe39f6f9693c680bdae3aa6;hb=27a6b2d336785fa3d30d937a397242c0a6823cfc;hpb=322fd21c16209780d43872cc44bb68d38172eabc diff --git a/snapshot.cc b/snapshot.cc index b848d02..f129f4c 100644 --- a/snapshot.cc +++ b/snapshot.cc @@ -3,8 +3,7 @@ #include #include #include -#include -#include +#include "hashtable.h" #include #include #include "snapshot.h" @@ -17,273 +16,320 @@ #include #include #include -#include -//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 -struct SnapShot * snapshotrecord = NULL; -struct Snapshot_t * sTheRecord = NULL; + +#include "common.h" + +#define FAILURE(mesg) { printf("failed in the API: %s with errno relative message: %s\n", mesg, strerror( errno ) ); exit(EXIT_FAILURE); } + +#ifdef CONFIG_SSDEBUG +#define SSDEBUG printf #else -struct Snapshot_t * sTheRecord = NULL; -#endif -void BeginOperation( struct timeval * theStartTime ){ -#if 1 - gettimeofday( theStartTime, NULL ); -#endif -} -#if SSDEBUG -struct timeval *starttime = NULL; +#define SSDEBUG(...) do { } while (0) #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; -#endif -} -#if !USE_CHECKPOINTING + +/* extern declaration definition */ +struct SnapShot * snapshotrecord = NULL; + +#if !USE_MPROTECT_SNAPSHOT +/** @statics +* These variables are necessary because the stack is shared region and +* there exists a race between all processes executing the same function. +* To avoid the problem above, we require variables allocated in 'safe' regions. +* The bug was actually observed with the forkID, these variables below are +* used to indicate the various contexts to which to switch to. +* +* @savedSnapshotContext: contains the point to which takesnapshot() call should switch to. +* @savedUserSnapshotContext: contains the point to which the process whose snapshotid is equal to the rollbackid should switch to +* @snapshotid: it is a running counter for the various forked processes snapshotid. it is incremented and set in a persistently shared record +*/ 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 -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; + +/** PageAlignedAdressUpdate return a page aligned address for the + * address being added as a side effect the numBytes are also changed. + */ +static void * PageAlignAddressUpward(void * addr) { + return (void *)((((uintptr_t)addr)+PAGESIZE-1)&~(PAGESIZE-1)); } -#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 ); - } - - //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 ); -#endif //nothing to handle for non snapshotting case. + +#if USE_MPROTECT_SNAPSHOT + +/** ReturnPageAlignedAddress returns a page aligned address for the + * address being added as a side effect the numBytes are also changed. + */ +static void * ReturnPageAlignedAddress(void * addr) { + 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 * ReturnPageAlignedAddress(void * addr) { - return (void *)(((uintptr_t)addr)&~(PAGESIZE-1)); +/** The initSnapShotRecord method initialized the snapshotting data + * structures for the mprotect based snapshot. + */ +static void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions) { + snapshotrecord=( struct SnapShot * )model_malloc(sizeof(struct SnapShot)); + snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )model_malloc(sizeof(struct MemoryRegion)*nummemoryregions); + snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )model_malloc( sizeof( struct SnapShotPage ) * (numbackingpages + 1) ); + //Page align the backingstorepages + snapshotrecord->backingStore=( struct SnapShotPage * )PageAlignAddressUpward(snapshotrecord->backingStoreBasePtr); + snapshotrecord->backingRecords=( struct BackingPageRecord * )model_malloc(sizeof(struct BackingPageRecord)*numbackingpages); + snapshotrecord->snapShots= ( struct SnapShotRecord * )model_malloc(sizeof(struct SnapShotRecord)*numsnapshots); + snapshotrecord->lastSnapShot=0; + snapshotrecord->lastBackingPage=0; + snapshotrecord->lastRegion=0; + snapshotrecord->maxRegions=nummemoryregions; + snapshotrecord->maxBackingPages=numbackingpages; + snapshotrecord->maxSnapShots=numsnapshots; } -#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; -#endif + +/** HandlePF is the page fault handler for mprotect based snapshotting + * algorithm. + */ +static void HandlePF( int sig, siginfo_t *si, void * unused){ + if( si->si_code == SEGV_MAPERR ){ + printf("Real Fault at %p\n", si->si_addr); + print_trace(); + 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 + if (mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE )) { + perror("mprotect"); + // Handle error by quitting? + } } -#ifdef __cplusplus +#endif //nothing to handle for non snapshotting case. + +#if !USE_MPROTECT_SNAPSHOT +void createSharedMemory(){ + //step 1. create shared memory. + void * memMapBase = mmap( 0, SHARED_MEMORY_DEFAULT + STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED|MAP_ANON, -1, 0 ); + if( MAP_FAILED == memMapBase ) + FAILURE("mmap"); + + //Setup snapshot record at top of free region + snapshotrecord = ( struct SnapShot * )memMapBase; + snapshotrecord->mSharedMemoryBase = (void *)((uintptr_t)memMapBase + sizeof(struct SnapShot)); + snapshotrecord->mStackBase = (void *)((uintptr_t)memMapBase + SHARED_MEMORY_DEFAULT); + snapshotrecord->mStackSize = STACK_SIZE_DEFAULT; + snapshotrecord->mIDToRollback = -1; + snapshotrecord->currSnapShotID = 0; } #endif -void initSnapShotLibrary(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions, unsigned int numheappages, 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); - mySpace = create_mspace( numheappages*PAGESIZE, 1 ); - addMemoryRegionToSnapShot(mySpace, 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 = ¤tContext; - 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; -#if 0 - int dbg = 0; - while( !dbg ); + + +/** The initSnapshotLibrary function initializes the snapshot library. + * @param entryPoint the function that should run the program. + */ +#if USE_MPROTECT_SNAPSHOT + +void initSnapshotLibrary(unsigned int numbackingpages, + unsigned int numsnapshots, unsigned int nummemoryregions, + unsigned int numheappages, VoidFuncPtr entryPoint) { + /* Setup a stack for our signal handler.... */ + stack_t ss; + ss.ss_sp = PageAlignAddressUpward(model_malloc(SIGSTACKSIZE+PAGESIZE-1)); + 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; +#ifdef MAC + if( sigaction( SIGBUS, &sa, NULL ) == -1 ){ + printf("SIGACTION CANNOT BE INSTALLED\n"); + exit(EXIT_FAILURE); + } #endif - if( swapContext ) - swapcontext( ¤tContext, &( sTheRecord->mContextToRollback ) ); - else{ - swapcontext( ¤tContext, &savedUserSnapshotContext ); + if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){ + printf("SIGACTION CANNOT BE INSTALLED\n"); + exit(EXIT_FAILURE); + } + + 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; + memset(&si, 0, sizeof(si)); + si.si_addr=ss.ss_sp; + HandlePF(SIGSEGV, &si, NULL); + snapshotrecord->lastBackingPage--; //remove the fake page we copied + + basemySpace=model_malloc((numheappages+1)*PAGESIZE); + void * pagealignedbase=PageAlignAddressUpward(basemySpace); + mySpace = create_mspace_with_base(pagealignedbase, numheappages*PAGESIZE, 1 ); + addMemoryRegionToSnapShot(pagealignedbase, numheappages); + entryPoint(); +} +#else +void initSnapshotLibrary(unsigned int numbackingpages, + unsigned int numsnapshots, unsigned int nummemoryregions, + unsigned int numheappages, VoidFuncPtr entryPoint) { + basemySpace=system_malloc((numheappages+1)*PAGESIZE); + void * pagealignedbase=PageAlignAddressUpward(basemySpace); + mySpace = create_mspace_with_base(pagealignedbase, numheappages*PAGESIZE, 1 ); + if (!snapshotrecord) + createSharedMemory(); + + //step 2 setup the stack context. + ucontext_t newContext; + getcontext( &newContext ); + newContext.uc_stack.ss_sp = snapshotrecord->mStackBase; + newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT; + makecontext( &newContext, entryPoint, 0 ); + /* switch to a new entryPoint context, on a new stack */ + swapcontext(&savedSnapshotContext, &newContext); + + /* switch back here when takesnapshot is called */ + pid_t forkedID = 0; + snapshotid = snapshotrecord->currSnapShotID; + /* This bool indicates that the current process's snapshotid is same + as the id to which the rollback needs to occur */ + + bool rollback = false; + while( true ){ + snapshotrecord->currSnapShotID=snapshotid+1; + forkedID = fork(); + + if( 0 == forkedID ){ + /* If the rollback bool is set, switch to the context we need to + return to during a rollback. */ + if( rollback) { + setcontext( &( snapshotrecord->mContextToRollback ) ); + } else { + /*Child process which is forked as a result of takesnapshot + call should switch back to the takesnapshot context*/ + setcontext( &savedUserSnapshotContext ); } - } 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 ); -#endif - do { + } else { + int status; + int retVal; + + SSDEBUG("The process id of child is %d and the process id of this process is %d and snapshot id is %d\n", + forkedID, getpid(), snapshotid ); + + do { retVal=waitpid( forkedID, &status, 0 ); - } while( -1 == retVal && errno == EINTR ); - - if( sTheRecord->mIDToRollback != snapshotid ) - exit(0); - else{ - swapContext = true; - } - } - } - -#endif + } while( -1 == retVal && errno == EINTR ); + + if( snapshotrecord->mIDToRollback != snapshotid ) { + exit(EXIT_SUCCESS); + } + rollback = true; + } + } } -/* This function assumes that addr is page aligned */ +#endif + +/** The addMemoryRegionToSnapShot 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(EXIT_FAILURE); + } + + snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr; + snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages; #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS. } -//take snapshot + +/** The takeSnapshot function takes a snapshot. + * @return The snapshot identifier. + */ snapshot_id takeSnapshot( ){ -#if USE_CHECKPOINTING - for(unsigned int region=0; regionlastRegion;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; regionlastRegion;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(EXIT_FAILURE); + } + } + unsigned int snapshot=snapshotrecord->lastSnapShot++; + if (snapshot==snapshotrecord->maxSnapShots) { + printf("Out of snapshots\n"); + exit(EXIT_FAILURE); + } + snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage; + + return snapshot; #else - swapcontext( &savedUserSnapshotContext, &savedSnapshotContext ); - return snapshotid; + swapcontext( &savedUserSnapshotContext, &savedSnapshotContext ); + SSDEBUG("TAKESNAPSHOT RETURN\n"); + return snapshotid; #endif } + +/** The rollBack function rollback to the given snapshot identifier. + * @param theID is the snapshot identifier to rollback to. + */ 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; regionlastRegion;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; pagelastBackingPage; 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; -#if SSDEBUG - DumpIntoLog( "ModelSnapshot", "Invoked rollback" ); +#if USE_MPROTECT_SNAPSHOT==2 + if (snapshotrecord->lastSnapShot==(theID+1)) { + for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; pagelastBackingPage; page++) { + memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage)); + } + return; + } #endif - exit( 0 ); - } -#endif -} -void finalize(){ -#if !USE_CHECKPOINTING - sTheRecord->mbFinalize = true; +#if USE_MPROTECT_SNAPSHOT + HashTable< void *, bool, uintptr_t, 4, model_malloc, model_calloc, model_free> duplicateMap; + for(unsigned int region=0; regionlastRegion;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(EXIT_FAILURE); + } + } + for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; pagelastBackingPage; page++) { + if( !duplicateMap.contains(snapshotrecord->backingRecords[page].basePtrOfPage )) { + duplicateMap.put(snapshotrecord->backingRecords[page].basePtrOfPage, true); + 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 + snapshotrecord->mIDToRollback = theID; + volatile int sTemp = 0; + getcontext( &snapshotrecord->mContextToRollback ); + /* + * This is used to quit the process on rollback, so that the process + * which needs to rollback can quit allowing the process whose + * snapshotid matches the rollbackid to switch to this context and + * continue.... + */ + if( !sTemp ){ + sTemp = 1; + SSDEBUG("Invoked rollback\n"); + exit(EXIT_SUCCESS); + } + /* + * This fix obviates the need for a finalize call. hence less dependences for model-checker.... + * + */ + snapshotrecord->mIDToRollback = -1; #endif }