11 #include "snapshotimp.h"
16 #include <semaphore.h>
21 //extern declaration definition
22 #define FAILURE(mesg) { printf("failed in the API: %s with errno relative message: %s\n", mesg, strerror( errno ) ); exit( -1 ); }
24 struct SnapShot * snapshotrecord = NULL;
25 struct Snapshot_t * sTheRecord = NULL;
27 struct Snapshot_t * sTheRecord = NULL;
29 void BeginOperation( struct timeval * theStartTime ){
31 gettimeofday( theStartTime, NULL );
35 struct timeval *starttime = NULL;
37 void DumpIntoLog( const char * filename, const char * message ){
39 static pid_t thePID = getpid();
40 char newFn[ 1024 ] ={ 0 };
41 sprintf( newFn,"%s-%d.txt", filename, thePID );
42 FILE * myFile = fopen( newFn, "w+" );
43 struct timeval theEndTime;
44 BeginOperation( &theEndTime );
45 double elapsed = ( theEndTime.tv_sec - starttime->tv_sec ) + ( theEndTime.tv_usec - starttime->tv_usec ) / 1000000.0;
46 fprintf( myFile, "The timestamp %f:--> the message %s: the process id %d\n", elapsed, message, thePID );
52 #if !USE_CHECKPOINTING
53 static ucontext_t savedSnapshotContext;
54 static ucontext_t savedUserSnapshotContext;
55 static int snapshotid = 0;
57 /* Initialize snapshot data structure */
59 void initSnapShotRecord(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions) {
60 snapshotrecord=( struct SnapShot * )MYMALLOC(sizeof(struct SnapShot));
61 snapshotrecord->regionsToSnapShot=( struct MemoryRegion * )MYMALLOC(sizeof(struct MemoryRegion)*nummemoryregions);
62 snapshotrecord->backingStoreBasePtr= ( struct SnapShotPage * )MYMALLOC( sizeof( struct SnapShotPage ) * (numbackingpages + 1) );
63 //Page align the backingstorepages
64 snapshotrecord->backingStore=( struct SnapShotPage * )ReturnPageAlignedAddress((void*) ((uintptr_t)(snapshotrecord->backingStoreBasePtr)+sizeof(struct SnapShotPage)-1));
65 snapshotrecord->backingRecords=( struct BackingPageRecord * )MYMALLOC(sizeof(struct BackingPageRecord)*numbackingpages);
66 snapshotrecord->snapShots= ( struct SnapShotRecord * )MYMALLOC(sizeof(struct SnapShotRecord)*numsnapshots);
67 snapshotrecord->lastSnapShot=0;
68 snapshotrecord->lastBackingPage=0;
69 snapshotrecord->lastRegion=0;
70 snapshotrecord->maxRegions=nummemoryregions;
71 snapshotrecord->maxBackingPages=numbackingpages;
72 snapshotrecord->maxSnapShots=numsnapshots;
74 #endif //nothing to initialize for the fork based snapshotting.
76 void HandlePF( int sig, siginfo_t *si, void * unused){
78 if( si->si_code == SEGV_MAPERR ){
79 printf("Real Fault at %llx\n", ( long long )si->si_addr);
82 void* addr = ReturnPageAlignedAddress(si->si_addr);
83 unsigned int backingpage=snapshotrecord->lastBackingPage++; //Could run out of pages...
84 if (backingpage==snapshotrecord->maxBackingPages) {
85 printf("Out of backing pages at %llx\n", ( long long )si->si_addr);
90 memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(struct SnapShotPage));
91 //remember where to copy page back to
92 snapshotrecord->backingRecords[backingpage].basePtrOfPage=addr;
93 //set protection to read/write
94 mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE );
95 #endif //nothing to handle for non snapshotting case.
98 //Return a page aligned address for the address being added
99 //as a side effect the numBytes are also changed.
100 void * ReturnPageAlignedAddress(void * addr) {
101 return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
106 void createSharedLibrary(){
107 #if !USE_CHECKPOINTING
108 //step 1. create shared memory.
109 if( sTheRecord ) return;
110 int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions.
111 if( -1 == fd ) FAILURE("shm_open");
112 if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" );
113 char * memMapBase = ( char * ) mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
114 if( MAP_FAILED == memMapBase ) FAILURE("mmap");
115 sTheRecord = ( struct Snapshot_t * )memMapBase;
116 sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
117 sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
118 sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
119 sTheRecord->mIDToRollback = -1;
120 sTheRecord->currSnapShotID = 0;
126 void initSnapShotLibrary(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions, unsigned int numheappages, MyFuncPtr entryPoint){
127 #if USE_CHECKPOINTING
129 sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
130 sigemptyset( &sa.sa_mask );
131 sa.sa_sigaction = HandlePF;
132 if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
133 printf("SIGACTION CANNOT BE INSTALLED\n");
136 mySpace = create_mspace( numheappages*PAGESIZE, 1 );
137 initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
138 addMemoryRegionToSnapShot(mySpace, numheappages);
141 //add a signal to indicate that the process is going to terminate.
143 sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
144 sigemptyset( &sa.sa_mask );
145 sa.sa_sigaction = HandlePF;
146 if( sigaction( SIGUSR1, &sa, NULL ) == -1 ){
147 printf("SIGACTION CANNOT BE INSTALLED\n");
150 createSharedLibrary();
152 starttime = &(sTheRecord->startTimeGlobal);
153 gettimeofday( starttime, NULL );
155 //step 2 setup the stack context.
157 int alreadySwapped = 0;
158 getcontext( &savedSnapshotContext );
159 if( !alreadySwapped ){
161 ucontext_t currentContext, swappedContext, newContext;
162 getcontext( &newContext );
163 newContext.uc_stack.ss_sp = sTheRecord->mStackBase;
164 newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
165 newContext.uc_link = ¤tContext;
166 makecontext( &newContext, entryPoint, 0 );
167 swapcontext( &swappedContext, &newContext );
170 //add the code to take a snapshot here...
171 //to return to user process, do a second swapcontext...
173 snapshotid = sTheRecord->currSnapShotID;
174 bool swapContext = false;
175 while( !sTheRecord->mbFinalize ){
176 sTheRecord->currSnapShotID=snapshotid+1;
179 ucontext_t currentContext;
185 swapcontext( ¤tContext, &( sTheRecord->mContextToRollback ) );
187 swapcontext( ¤tContext, &savedUserSnapshotContext );
193 char mesg[ 1024 ] = { 0 };
194 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 );
195 DumpIntoLog( "ModelSnapshot", mesg );
198 retVal=waitpid( forkedID, &status, 0 );
199 } while( -1 == retVal && errno == EINTR );
201 if( sTheRecord->mIDToRollback != snapshotid )
211 /* This function assumes that addr is page aligned */
212 void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) {
213 #if USE_CHECKPOINTING
214 unsigned int memoryregion=snapshotrecord->lastRegion++;
215 if (memoryregion==snapshotrecord->maxRegions) {
216 printf("Exceeded supported number of memory regions!\n");
220 snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
221 snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
222 #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS.
225 snapshot_id takeSnapshot( ){
226 #if USE_CHECKPOINTING
227 for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
228 if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){
229 printf("Failed to mprotect inside of takeSnapShot\n");
233 unsigned int snapshot=snapshotrecord->lastSnapShot++;
234 if (snapshot==snapshotrecord->maxSnapShots) {
235 printf("Out of snapshots\n");
238 snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
242 swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
246 void rollBack( snapshot_id theID ){
247 #if USE_CHECKPOINTING
248 std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
249 for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
250 if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){
251 printf("Failed to mprotect inside of takeSnapShot\n");
255 for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; page++) {
257 if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){
261 duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true;
264 memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage));
267 snapshotrecord->lastSnapShot=theID;
268 snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
269 takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
271 sTheRecord->mIDToRollback = theID;
273 getcontext( &sTheRecord->mContextToRollback );
277 DumpIntoLog( "ModelSnapshot", "Invoked rollback" );
285 #if !USE_CHECKPOINTING
286 sTheRecord->mbFinalize = true;