From 2ada1a461101f16a0be8ba75200c8ae4f9ff9d84 Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Wed, 2 Jan 2013 18:45:25 -0800
Subject: [PATCH] snapshot: separate struct SnapShot naming
The "struct SnapShot snapshotrecord;" structure is very uninformative in
naming and is distinctly different for mprotect-based and fork-based
snapshotting. This renames the struct in order to more clearly separate
its usage in the different implementations.
---
snapshot.cc | 116 ++++++++++++++++++++++++++--------------------------
1 file changed, 58 insertions(+), 58 deletions(-)
diff --git a/snapshot.cc b/snapshot.cc
index 1931268..fe5110a 100644
--- a/snapshot.cc
+++ b/snapshot.cc
@@ -47,7 +47,7 @@ struct MemoryRegion {
};
/* Primary struct for snapshotting system */
-struct SnapShot {
+struct mprot_snapshotter {
struct MemoryRegion *regionsToSnapShot; //This pointer references an array of memory regions to snapshot
snapshot_page_t *backingStore; //This pointer references an array of snapshotpage's that form the backing store
void *backingStoreBasePtr; //This pointer references an array of snapshotpage's that form the backing store
@@ -63,7 +63,7 @@ struct SnapShot {
unsigned int maxSnapShots; //Stores the total number of snapshots we allow
};
-static struct SnapShot *snapshotrecord = NULL;
+static struct mprot_snapshotter *mprot_snap = NULL;
/** ReturnPageAlignedAddress returns a page aligned address for the
* address being added as a side effect the numBytes are also changed.
@@ -78,19 +78,19 @@ static void * ReturnPageAlignedAddress(void *addr)
*/
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 = (void *)model_malloc(sizeof(snapshot_page_t) * (numbackingpages + 1));
+ mprot_snap = (struct mprot_snapshotter *)model_malloc(sizeof(struct mprot_snapshotter));
+ mprot_snap->regionsToSnapShot = (struct MemoryRegion *)model_malloc(sizeof(struct MemoryRegion) * nummemoryregions);
+ mprot_snap->backingStoreBasePtr = (void *)model_malloc(sizeof(snapshot_page_t) * (numbackingpages + 1));
//Page align the backingstorepages
- snapshotrecord->backingStore = (snapshot_page_t *)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;
+ mprot_snap->backingStore = (snapshot_page_t *)PageAlignAddressUpward(mprot_snap->backingStoreBasePtr);
+ mprot_snap->backingRecords = (struct BackingPageRecord *)model_malloc(sizeof(struct BackingPageRecord) * numbackingpages);
+ mprot_snap->snapShots = (struct SnapShotRecord *)model_malloc(sizeof(struct SnapShotRecord) * numsnapshots);
+ mprot_snap->lastSnapShot = 0;
+ mprot_snap->lastBackingPage = 0;
+ mprot_snap->lastRegion = 0;
+ mprot_snap->maxRegions = nummemoryregions;
+ mprot_snap->maxBackingPages = numbackingpages;
+ mprot_snap->maxSnapShots = numsnapshots;
}
/** HandlePF is the page fault handler for mprotect based snapshotting
@@ -107,16 +107,16 @@ static void HandlePF(int sig, siginfo_t *si, void *unused)
}
void* addr = ReturnPageAlignedAddress(si->si_addr);
- unsigned int backingpage = snapshotrecord->lastBackingPage++; //Could run out of pages...
- if (backingpage == snapshotrecord->maxBackingPages) {
+ unsigned int backingpage = mprot_snap->lastBackingPage++; //Could run out of pages...
+ if (backingpage == mprot_snap->maxBackingPages) {
model_print("Out of backing pages at %p\n", si->si_addr);
exit(EXIT_FAILURE);
}
//copy page
- memcpy(&(snapshotrecord->backingStore[backingpage]), addr, sizeof(snapshot_page_t));
+ memcpy(&(mprot_snap->backingStore[backingpage]), addr, sizeof(snapshot_page_t));
//remember where to copy page back to
- snapshotrecord->backingRecords[backingpage].basePtrOfPage = addr;
+ mprot_snap->backingRecords[backingpage].basePtrOfPage = addr;
//set protection to read/write
if (mprotect(addr, sizeof(snapshot_page_t), PROT_READ | PROT_WRITE)) {
perror("mprotect");
@@ -160,7 +160,7 @@ static void mprot_snapshot_init(unsigned int numbackingpages,
memset(&si, 0, sizeof(si));
si.si_addr = ss.ss_sp;
HandlePF(SIGSEGV, &si, NULL);
- snapshotrecord->lastBackingPage--; //remove the fake page we copied
+ mprot_snap->lastBackingPage--; //remove the fake page we copied
void *basemySpace = model_malloc((numheappages + 1) * PAGESIZE);
void *pagealignedbase = PageAlignAddressUpward(basemySpace);
@@ -177,31 +177,31 @@ static void mprot_snapshot_init(unsigned int numbackingpages,
static void mprot_add_to_snapshot(void *addr, unsigned int numPages)
{
- unsigned int memoryregion = snapshotrecord->lastRegion++;
- if (memoryregion == snapshotrecord->maxRegions) {
+ unsigned int memoryregion = mprot_snap->lastRegion++;
+ if (memoryregion == mprot_snap->maxRegions) {
model_print("Exceeded supported number of memory regions!\n");
exit(EXIT_FAILURE);
}
- snapshotrecord->regionsToSnapShot[memoryregion].basePtr = addr;
- snapshotrecord->regionsToSnapShot[memoryregion].sizeInPages = numPages;
+ mprot_snap->regionsToSnapShot[memoryregion].basePtr = addr;
+ mprot_snap->regionsToSnapShot[memoryregion].sizeInPages = numPages;
}
static snapshot_id mprot_take_snapshot()
{
- for (unsigned int region = 0; region < snapshotrecord->lastRegion; region++) {
- if (mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages * sizeof(snapshot_page_t), PROT_READ) == -1) {
+ for (unsigned int region = 0; region < mprot_snap->lastRegion; region++) {
+ if (mprotect(mprot_snap->regionsToSnapShot[region].basePtr, mprot_snap->regionsToSnapShot[region].sizeInPages * sizeof(snapshot_page_t), PROT_READ) == -1) {
perror("mprotect");
model_print("Failed to mprotect inside of takeSnapShot\n");
exit(EXIT_FAILURE);
}
}
- unsigned int snapshot = snapshotrecord->lastSnapShot++;
- if (snapshot == snapshotrecord->maxSnapShots) {
+ unsigned int snapshot = mprot_snap->lastSnapShot++;
+ if (snapshot == mprot_snap->maxSnapShots) {
model_print("Out of snapshots\n");
exit(EXIT_FAILURE);
}
- snapshotrecord->snapShots[snapshot].firstBackingPage = snapshotrecord->lastBackingPage;
+ mprot_snap->snapShots[snapshot].firstBackingPage = mprot_snap->lastBackingPage;
return snapshot;
}
@@ -209,30 +209,30 @@ static snapshot_id mprot_take_snapshot()
static void mprot_roll_back(snapshot_id theID)
{
#if USE_MPROTECT_SNAPSHOT == 2
- if (snapshotrecord->lastSnapShot == (theID + 1)) {
- for (unsigned int page = snapshotrecord->snapShots[theID].firstBackingPage; page < snapshotrecord->lastBackingPage; page++) {
- memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(snapshot_page_t));
+ if (mprot_snap->lastSnapShot == (theID + 1)) {
+ for (unsigned int page = mprot_snap->snapShots[theID].firstBackingPage; page < mprot_snap->lastBackingPage; page++) {
+ memcpy(mprot_snap->backingRecords[page].basePtrOfPage, &mprot_snap->backingStore[page], sizeof(snapshot_page_t));
}
return;
}
#endif
HashTable< void *, bool, uintptr_t, 4, model_malloc, model_calloc, model_free> duplicateMap;
- for (unsigned int region = 0; region < snapshotrecord->lastRegion; region++) {
- if (mprotect(snapshotrecord->regionsToSnapShot[region].basePtr, snapshotrecord->regionsToSnapShot[region].sizeInPages * sizeof(snapshot_page_t), PROT_READ | PROT_WRITE) == -1) {
+ for (unsigned int region = 0; region < mprot_snap->lastRegion; region++) {
+ if (mprotect(mprot_snap->regionsToSnapShot[region].basePtr, mprot_snap->regionsToSnapShot[region].sizeInPages * sizeof(snapshot_page_t), PROT_READ | PROT_WRITE) == -1) {
perror("mprotect");
model_print("Failed to mprotect inside of takeSnapShot\n");
exit(EXIT_FAILURE);
}
}
- for (unsigned int page = snapshotrecord->snapShots[theID].firstBackingPage; page < snapshotrecord->lastBackingPage; page++) {
- if (!duplicateMap.contains(snapshotrecord->backingRecords[page].basePtrOfPage)) {
- duplicateMap.put(snapshotrecord->backingRecords[page].basePtrOfPage, true);
- memcpy(snapshotrecord->backingRecords[page].basePtrOfPage, &snapshotrecord->backingStore[page], sizeof(snapshot_page_t));
+ for (unsigned int page = mprot_snap->snapShots[theID].firstBackingPage; page < mprot_snap->lastBackingPage; page++) {
+ if (!duplicateMap.contains(mprot_snap->backingRecords[page].basePtrOfPage)) {
+ duplicateMap.put(mprot_snap->backingRecords[page].basePtrOfPage, true);
+ memcpy(mprot_snap->backingRecords[page].basePtrOfPage, &mprot_snap->backingStore[page], sizeof(snapshot_page_t));
}
}
- snapshotrecord->lastSnapShot = theID;
- snapshotrecord->lastBackingPage = snapshotrecord->snapShots[theID].firstBackingPage;
+ mprot_snap->lastSnapShot = theID;
+ mprot_snap->lastBackingPage = mprot_snap->snapShots[theID].firstBackingPage;
mprot_take_snapshot(); //Make sure current snapshot is still good...All later ones are cleared
}
@@ -243,7 +243,7 @@ static void mprot_roll_back(snapshot_id theID)
#define SHARED_MEMORY_DEFAULT (100 * ((size_t)1 << 20)) // 100mb for the shared memory
#define STACK_SIZE_DEFAULT (((size_t)1 << 20) * 20) // 20 mb out of the above 100 mb for my stack
-struct SnapShot {
+struct fork_snapshotter {
void *mSharedMemoryBase;
void *mStackBase;
size_t mStackSize;
@@ -252,7 +252,7 @@ struct SnapShot {
snapshot_id currSnapShotID;
};
-static struct SnapShot *snapshotrecord = NULL;
+static struct fork_snapshotter *fork_snap = NULL;
/** @statics
* These variables are necessary because the stack is shared region and
@@ -277,12 +277,12 @@ static void createSharedMemory()
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;
+ fork_snap = (struct fork_snapshotter *)memMapBase;
+ fork_snap->mSharedMemoryBase = (void *)((uintptr_t)memMapBase + sizeof(struct fork_snapshotter));
+ fork_snap->mStackBase = (void *)((uintptr_t)memMapBase + SHARED_MEMORY_DEFAULT);
+ fork_snap->mStackSize = STACK_SIZE_DEFAULT;
+ fork_snap->mIDToRollback = -1;
+ fork_snap->currSnapShotID = 0;
}
/**
@@ -293,16 +293,16 @@ static void createSharedMemory()
*/
mspace create_shared_mspace()
{
- if (!snapshotrecord)
+ if (!fork_snap)
createSharedMemory();
- return create_mspace_with_base((void *)(snapshotrecord->mSharedMemoryBase), SHARED_MEMORY_DEFAULT - sizeof(struct SnapShot), 1);
+ return create_mspace_with_base((void *)(fork_snap->mSharedMemoryBase), SHARED_MEMORY_DEFAULT - sizeof(struct fork_snapshotter), 1);
}
static void fork_snapshot_init(unsigned int numbackingpages,
unsigned int numsnapshots, unsigned int nummemoryregions,
unsigned int numheappages, VoidFuncPtr entryPoint)
{
- if (!snapshotrecord)
+ if (!fork_snap)
createSharedMemory();
void *base_model_snapshot_space = malloc((numheappages + 1) * PAGESIZE);
@@ -312,7 +312,7 @@ static void fork_snapshot_init(unsigned int numbackingpages,
//step 2 setup the stack context.
ucontext_t newContext;
getcontext(&newContext);
- newContext.uc_stack.ss_sp = snapshotrecord->mStackBase;
+ newContext.uc_stack.ss_sp = fork_snap->mStackBase;
newContext.uc_stack.ss_size = STACK_SIZE_DEFAULT;
makecontext(&newContext, entryPoint, 0);
/* switch to a new entryPoint context, on a new stack */
@@ -320,20 +320,20 @@ static void fork_snapshot_init(unsigned int numbackingpages,
/* switch back here when takesnapshot is called */
pid_t forkedID = 0;
- snapshotid = snapshotrecord->currSnapShotID;
+ snapshotid = fork_snap->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;
+ fork_snap->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));
+ setcontext(&(fork_snap->mContextToRollback));
} else {
/*Child process which is forked as a result of takesnapshot
call should switch back to the takesnapshot context*/
@@ -350,7 +350,7 @@ static void fork_snapshot_init(unsigned int numbackingpages,
retVal = waitpid(forkedID, &status, 0);
} while (-1 == retVal && errno == EINTR);
- if (snapshotrecord->mIDToRollback != snapshotid) {
+ if (fork_snap->mIDToRollback != snapshotid) {
exit(EXIT_SUCCESS);
}
rollback = true;
@@ -367,9 +367,9 @@ static snapshot_id fork_take_snapshot()
static void fork_roll_back(snapshot_id theID)
{
- snapshotrecord->mIDToRollback = theID;
+ fork_snap->mIDToRollback = theID;
volatile int sTemp = 0;
- getcontext(&snapshotrecord->mContextToRollback);
+ getcontext(&fork_snap->mContextToRollback);
/*
* This is used to quit the process on rollback, so that the process
* which needs to rollback can quit allowing the process whose
@@ -384,7 +384,7 @@ static void fork_roll_back(snapshot_id theID)
/*
* This fix obviates the need for a finalize call. hence less dependences for model-checker....
*/
- snapshotrecord->mIDToRollback = -1;
+ fork_snap->mIDToRollback = -1;
}
#endif /* !USE_MPROTECT_SNAPSHOT */
--
2.34.1