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 if (mprotect( addr, sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE )) {
96 // Handle error by quitting?
98 #endif //nothing to handle for non snapshotting case.
101 //Return a page aligned address for the address being added
102 //as a side effect the numBytes are also changed.
103 void * ReturnPageAlignedAddress(void * addr) {
104 return (void *)(((uintptr_t)addr)&~(PAGESIZE-1));
109 void createSharedLibrary(){
110 #if !USE_CHECKPOINTING
111 //step 1. create shared memory.
112 if( sTheRecord ) return;
113 int fd = shm_open( "/ModelChecker-Snapshotter", O_RDWR | O_CREAT, 0777 ); //universal permissions.
114 if( -1 == fd ) FAILURE("shm_open");
115 if( -1 == ftruncate( fd, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT ) ) FAILURE( "ftruncate" );
116 char * memMapBase = ( char * ) mmap( 0, ( size_t )SHARED_MEMORY_DEFAULT + ( size_t )STACK_SIZE_DEFAULT, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0 );
117 if( MAP_FAILED == memMapBase ) FAILURE("mmap");
118 sTheRecord = ( struct Snapshot_t * )memMapBase;
119 sTheRecord->mSharedMemoryBase = memMapBase + sizeof( struct Snapshot_t );
120 sTheRecord->mStackBase = ( char * )memMapBase + ( size_t )SHARED_MEMORY_DEFAULT;
121 sTheRecord->mStackSize = STACK_SIZE_DEFAULT;
122 sTheRecord->mIDToRollback = -1;
123 sTheRecord->currSnapShotID = 0;
129 void initSnapShotLibrary(unsigned int numbackingpages, unsigned int numsnapshots, unsigned int nummemoryregions, unsigned int numheappages, MyFuncPtr entryPoint){
130 #if USE_CHECKPOINTING
132 sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
133 sigemptyset( &sa.sa_mask );
134 sa.sa_sigaction = HandlePF;
135 if( sigaction( SIGSEGV, &sa, NULL ) == -1 ){
136 printf("SIGACTION CANNOT BE INSTALLED\n");
139 initSnapShotRecord(numbackingpages, numsnapshots, nummemoryregions);
141 basemySpace=MYMALLOC((numheappages+1)*PAGESIZE);
142 void * pagealignedbase=(void *)((((uintptr_t)basemySpace)+PAGESIZE-1)&~(PAGESIZE-1));
143 mySpace = create_mspace_with_base(pagealignedbase, numheappages*PAGESIZE, 1 );
144 addMemoryRegionToSnapShot(pagealignedbase, numheappages);
147 //add a signal to indicate that the process is going to terminate.
149 sa.sa_flags = SA_SIGINFO | SA_NODEFER | SA_RESTART;
150 sigemptyset( &sa.sa_mask );
151 sa.sa_sigaction = HandlePF;
152 if( sigaction( SIGUSR1, &sa, NULL ) == -1 ){
153 printf("SIGACTION CANNOT BE INSTALLED\n");
156 createSharedLibrary();
158 starttime = &(sTheRecord->startTimeGlobal);
159 gettimeofday( starttime, NULL );
161 //step 2 setup the stack context.
163 int alreadySwapped = 0;
164 getcontext( &savedSnapshotContext );
165 if( !alreadySwapped ){
167 ucontext_t currentContext, swappedContext, newContext;
168 getcontext( &newContext );
169 newContext.uc_stack.ss_sp = sTheRecord->mStackBase;
170 newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
171 newContext.uc_link = ¤tContext;
172 makecontext( &newContext, entryPoint, 0 );
173 swapcontext( &swappedContext, &newContext );
176 //add the code to take a snapshot here...
177 //to return to user process, do a second swapcontext...
179 snapshotid = sTheRecord->currSnapShotID;
180 bool swapContext = false;
181 while( !sTheRecord->mbFinalize ){
182 sTheRecord->currSnapShotID=snapshotid+1;
185 ucontext_t currentContext;
191 swapcontext( ¤tContext, &( sTheRecord->mContextToRollback ) );
193 swapcontext( ¤tContext, &savedUserSnapshotContext );
199 char mesg[ 1024 ] = { 0 };
200 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 );
201 DumpIntoLog( "ModelSnapshot", mesg );
204 retVal=waitpid( forkedID, &status, 0 );
205 } while( -1 == retVal && errno == EINTR );
207 if( sTheRecord->mIDToRollback != snapshotid )
217 /* This function assumes that addr is page aligned */
218 void addMemoryRegionToSnapShot( void * addr, unsigned int numPages) {
219 #if USE_CHECKPOINTING
220 unsigned int memoryregion=snapshotrecord->lastRegion++;
221 if (memoryregion==snapshotrecord->maxRegions) {
222 printf("Exceeded supported number of memory regions!\n");
226 snapshotrecord->regionsToSnapShot[ memoryregion ].basePtr=addr;
227 snapshotrecord->regionsToSnapShot[ memoryregion ].sizeInPages=numPages;
228 #endif //NOT REQUIRED IN THE CASE OF FORK BASED SNAPSHOTS.
231 snapshot_id takeSnapshot( ){
232 #if USE_CHECKPOINTING
233 for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
234 if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ ) == -1 ){
236 printf("Failed to mprotect inside of takeSnapShot\n");
240 unsigned int snapshot=snapshotrecord->lastSnapShot++;
241 if (snapshot==snapshotrecord->maxSnapShots) {
242 printf("Out of snapshots\n");
245 snapshotrecord->snapShots[snapshot].firstBackingPage=snapshotrecord->lastBackingPage;
249 swapcontext( &savedUserSnapshotContext, &savedSnapshotContext );
253 void rollBack( snapshot_id theID ){
254 #if USE_CHECKPOINTING
255 std::map< void *, bool, std::less< void * >, MyAlloc< std::pair< const void *, bool > > > duplicateMap;
256 for(unsigned int region=0; region<snapshotrecord->lastRegion;region++) {
257 if( mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages*sizeof(struct SnapShotPage), PROT_READ | PROT_WRITE ) == -1 ){
259 printf("Failed to mprotect inside of takeSnapShot\n");
263 for(unsigned int page=snapshotrecord->snapShots[theID].firstBackingPage; page<snapshotrecord->lastBackingPage; page++) {
265 if( duplicateMap.find( snapshotrecord->backingRecords[page].basePtrOfPage ) != duplicateMap.end() ){
269 duplicateMap[ snapshotrecord->backingRecords[page].basePtrOfPage ] = true;
272 memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(struct SnapShotPage));
275 snapshotrecord->lastSnapShot=theID;
276 snapshotrecord->lastBackingPage=snapshotrecord->snapShots[theID].firstBackingPage;
277 takeSnapshot(); //Make sure current snapshot is still good...All later ones are cleared
279 sTheRecord->mIDToRollback = theID;
281 getcontext( &sTheRecord->mContextToRollback );
285 DumpIntoLog( "ModelSnapshot", "Invoked rollback" );
293 #if !USE_CHECKPOINTING
294 sTheRecord->mbFinalize = true;