+/* Coordinator => Machine that initiates the transaction request call for commiting a transaction
+ * Participant => Machines that host the objects involved in a transaction commit */
+
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int dstmInit(void)
{
- //Initialize main object store
+ /* Initialize main object store */
mainobjstore = objstrCreate(DEFAULT_OBJ_STORE_SIZE);
+ /* Create machine lookup table and location lookup table */
if (mhashCreate(HASH_SIZE, LOADFACTOR))
return 1; //failure
}
pthread_exit(NULL);
}
-
+/* This function accepts a new connection request, decodes the control message in the connection
+ * and accordingly calls other functions to process new requests */
void *dstmAccept(void *acceptfd)
{
int numbytes,i, val, retval;
int fd_flags = fcntl((int)acceptfd, F_GETFD), size;
printf("Recieved connection: fd = %d\n", (int)acceptfd);
+ /* Receive control messages from other machines */
if((retval = recv((int)acceptfd, &control, sizeof(char), 0)) <= 0) {
if (retval == 0) {
return; // Testing connection
perror("Error in receiving control from coordinator\n");
return;
}
+
switch(control) {
case READ_REQUEST:
+ /* Read oid requested and search if available */
if((retval = recv((int)acceptfd, &oid, sizeof(unsigned int), 0)) <= 0) {
perror("Error receiving object from cooridnator\n");
- return;
+ return NULL;
}
srcObj = mhashSearch(oid);
h = (objheader_t *) srcObj;
ctrl = OBJECT_NOT_FOUND;
if(send((int)acceptfd, &ctrl, sizeof(char), MSG_NOSIGNAL) < sizeof(char)) {
perror("Error sending control msg to coordinator\n");
+ return NULL;
}
} else {
/* Type */
char msg[]={OBJECT_FOUND, 0, 0, 0, 0};
*((int *)&msg[1])=size;
if(send((int)acceptfd, &msg, sizeof(msg), MSG_NOSIGNAL) < sizeof(msg)) {
- perror("Error sending size of object to coordinator\n");
+ perror("Error sending size of object to coordinator\n");
+ return NULL;
}
if(send((int)acceptfd, h, size, MSG_NOSIGNAL) < size) {
- perror("Error in sending object\n");
+ perror("Error in sending object\n");
+ return NULL;
}
}
break;
break;
case TRANS_REQUEST:
+ /* Read transaction request */
printf("DEBUG -> Recv TRANS_REQUEST\n");
- if((val = readClientReq((int)acceptfd, &transinfo)) != 0) {
+ if((val = readClientReq(&transinfo, (int)acceptfd)) != 0) {
printf("Error in readClientReq\n");
+ return;
}
break;
default:
printf("DEBUG -> dstmAccept: Error Unknown opcode %d\n", control);
}
+
+ /* Close connection */
if (close((int)acceptfd) == -1)
perror("close");
else
pthread_exit(NULL);
}
-// Reads transaction request per thread
-int readClientReq(int acceptfd, trans_commit_data_t *transinfo) {
- char *ptr, control, prevctrl, sendctrl, newctrl;
- void *modptr, *header;
- objheader_t *tmp_header;
+/* This function reads the information available in a transaction request
+ * and makes a function call to process the request */
+int readClientReq(trans_commit_data_t *transinfo, int acceptfd) {
+ char *ptr;
+ void *modptr;
fixed_data_t fixed;
- int sum = 0, i, N, n, val, retval;
+ int sum = 0, i, N, n, val;
- //Reads to process the TRANS_REQUEST protocol further
- // Read fixed_data
+ /* Read fixed_data_t data structure */
N = sizeof(fixed) - 1;
ptr = (char *)&fixed;;
fixed.control = TRANS_REQUEST;
sum += n;
} while(sum < N && n != 0);
- // Read list of mids
+ /* Read list of mids */
int mcount = fixed.mcount;
N = mcount * sizeof(unsigned int);
unsigned int listmid[mcount];
sum += n;
} while(sum < N && n != 0);
- // Read oid and version tuples
+ /* Read oid and version tuples for those objects that are not modified in the transaction */
int numread = fixed.numread;
N = numread * (sizeof(unsigned int) + sizeof(short));
char objread[N];
} while(sum < N && n != 0);
}
- // Read modified objects
+ /* Read modified objects */
if(fixed.nummod != 0) { // If pile contains more than one modified object,
// allocate new object store and recv all modified objects
+ // TODO deallocate this space
if ((modptr = objstrAlloc(mainobjstore, fixed.sum_bytes)) == NULL) {
printf("objstrAlloc error for modified objects %s, %d\n", __FILE__, __LINE__);
return 1;
}
sum = 0;
- do { // Recv the objs that are modified at Coordinator
+ do { // Recv the objs that are modified by the Coordinator
n = recv((int)acceptfd, modptr+sum, fixed.sum_bytes-sum, 0);
sum += n;
} while (sum < fixed.sum_bytes && n != 0);
}
- // Process the information available in the TRANS_REQUEST control
- //Send control message as per all votes from all oids in the machine
- if((prevctrl = handleTransReq(acceptfd, &fixed, transinfo, listmid, objread, modptr)) == 0 ) {
+ /*Process the information read */
+ if((val = processClientReq(&fixed, transinfo, listmid, objread, modptr, acceptfd)) != 0) {
+ printf("Error in processClientReq %s, %d\n", __FILE__, __LINE__);
+ return 1;
+ }
+
+ return 0;
+}
+
+/* This function processes the Coordinator's transaction request using "handleTransReq"
+ * function and sends a reply to the co-ordinator.
+ * Following this it also receives a new control message from the co-ordinator and processes this message*/
+int processClientReq(fixed_data_t *fixed, trans_commit_data_t *transinfo,
+ unsigned int *listmid, char *objread, void *modptr, int acceptfd) {
+ char *ptr, control, sendctrl;
+ objheader_t *tmp_header;
+ void *header;
+ int i = 0, val, retval;
+
+ /* Send reply to the Coordinator */
+ if((retval = handleTransReq(fixed, transinfo, listmid, objread, modptr,acceptfd)) == 0 ) {
printf("Handle Trans Req error %s, %d\n", __FILE__, __LINE__);
return 1;
}
- //Read for new control message from Coordiator
+ /* Read new control message from Coordiator */
if((retval = recv((int)acceptfd, &control, sizeof(char), 0)) <= 0 ) {
perror("Error in receiving control message\n");
return 1;
}
+ /* Process the new control message */
switch(control) {
case TRANS_ABORT:
- //Mark all ref counts as 1 and do garbage collection
+ /* Set all ref counts as 1 and do garbage collection */
ptr = modptr;
- for(i = 0; i< fixed.nummod; i++) {
+ for(i = 0; i< fixed->nummod; i++) {
tmp_header = (objheader_t *)ptr;
tmp_header->rcount = 1;
ptr += sizeof(objheader_t) + classsize[tmp_header->type];
}
- //Unlock objects that was locked in this machine due to this transaction
+ /* Unlock objects that was locked due to this transaction */
for(i = 0; i< transinfo->numlocked; i++) {
- printf("DEBUG-> Unlocking objects\n");
header = mhashSearch(transinfo->objlocked[i]);// find the header address
((objheader_t *)header)->status &= ~(LOCK);
}
- //send ack to coordinator
+ /* Send ack to Coordinator */
printf("DEBUG -> Recv TRANS_ABORT\n");
sendctrl = TRANS_SUCESSFUL;
if(send((int)acceptfd, &sendctrl, sizeof(char), MSG_NOSIGNAL) < sizeof(char)) {
perror("Error sending ACK to coordinator\n");
return 1;
}
-
ptr = NULL;
- return 0;
+ // return 0;
+ break;
+
case TRANS_COMMIT:
+ /* Invoke the transCommit process() */
printf("DEBUG -> Recv TRANS_COMMIT \n");
if((val = transCommitProcess(transinfo, (int)acceptfd)) != 0) {
printf("Error in transCommitProcess %s, %d\n", __FILE__, __LINE__);
+ return 1;
}
break;
//TODO Use fixed.trans_id TID since Client may have died
break;
}
- //Free memory
+ /* Free memory */
printf("DEBUG -> Freeing...\n");
fflush(stdout);
if (transinfo->objmod != NULL) {
return 0;
}
-//This function runs a decision after all objects involved in TRANS_REQUEST
-//and returns the appropriate control message such as TRANS_AGREE, TRANS_DISAGREE or TRANS_SOFT_ABORT to the Ccordinator
-char handleTransReq(int acceptfd, fixed_data_t *fixed, trans_commit_data_t *transinfo, unsigned int *listmid, char *objread, void *modptr) {
- int val;
+/* This function increments counters while running a voting decision on all objects involved
+ * in TRANS_REQUEST */
+
+char handleTransReq(fixed_data_t *fixed, trans_commit_data_t *transinfo, unsigned int *listmid, char *objread, void *modptr, int acceptfd) {
+ int val, i = 0;
short version;
- char control = 0, ctrlmissoid, *ptr;
- int i, j = 0;
+ char control = 0, *ptr;
unsigned int oid;
unsigned int *oidnotfound, *oidlocked, *oidmod;
+ void *mobj;
+ objheader_t *headptr;
+ /* Counters and arrays to formulate decision on control message to be sent */
oidnotfound = (unsigned int *) calloc(fixed->numread + fixed->nummod, sizeof(unsigned int));
oidlocked = (unsigned int *) calloc(fixed->numread + fixed->nummod, sizeof(unsigned int));
oidmod = (unsigned int *) calloc(fixed->nummod, sizeof(unsigned int));
- // Counters and arrays to formulate decision on control message to be sent
- // version match or no match
int objnotfound = 0, objlocked = 0, objmod =0, v_nomatch = 0, v_matchlock = 0, v_matchnolock = 0;
int objmodnotfound = 0, nummodfound = 0;
- void *mobj;
- objheader_t *headptr;
-
- //Process each object present in the pile
+
+ /* modptr points to the beginning of the object store
+ * created at the Pariticipant.
+ * Object store holds the modified objects involved in the transaction request */
ptr = modptr;
- //Process each oid in the machine pile/ group per thread
- //Should be a new function
+ /* Process each oid in the machine pile/ group per thread */
for (i = 0; i < fixed->numread + fixed->nummod; i++) {
- if (i < fixed->numread) {//Object is read
+ if (i < fixed->numread) {//Objs only read and not modified
int incr = sizeof(unsigned int) + sizeof(short);// Offset that points to next position in the objread array
incr *= i;
oid = *((unsigned int *)(objread + incr));
incr += sizeof(unsigned int);
version = *((short *)(objread + incr));
- } else {//Obj is modified
+ } else {//Objs modified
headptr = (objheader_t *) ptr;
oid = headptr->oid;
oidmod[objmod] = oid;//Array containing modified oids
version = headptr->version;
ptr += sizeof(objheader_t) + classsize[headptr->type];
}
- //Check if object is still present in the machine since the beginning of TRANS_REQUEST
- if ((mobj = mhashSearch(oid)) == NULL) {// Obj not found
- //Save the oids not found for later use
+
+ /* Check if object is still present in the machine since the beginning of TRANS_REQUEST */
+
+ if ((mobj = mhashSearch(oid)) == NULL) {/* Obj not found */
+ /* Save the oids not found and number of oids not found for later use */
oidnotfound[objnotfound] = ((objheader_t *)mobj)->oid;
objnotfound++;
- } else { // If obj found in machine (i.e. has not moved)
- //Check if obj is locked
+ } else { /* If Obj found in machine (i.e. has not moved) */
+ /* Check if Obj is locked by any previous transaction */
if ((((objheader_t *)mobj)->status & LOCK) == LOCK) {
- if (version == ((objheader_t *)mobj)->version) { // If version match
- printf("DEBUG -> obj = %d locked\n", ((objheader_t *)mobj)->oid);
+ if (version == ((objheader_t *)mobj)->version) { /* If not locked then match versions */
v_matchlock++;
- } else {//If versions don't match ..HARD ABORT
+ } else {/* If versions don't match ...HARD ABORT */
v_nomatch++;
- //send TRANS_DISAGREE to Coordinator
+ /* Send TRANS_DISAGREE to Coordinator */
control = TRANS_DISAGREE;
- if((val = send(acceptfd, &control, sizeof(char),MSG_NOSIGNAL)) < sizeof(char)) {
+ if((val = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
perror("Error in sending control to the Coordinator\n");
return 0;
}
- printf("DEBUG -> Sending TRANS_DISAGREE accept_fd = %d\n", acceptfd);
+ printf("DEBUG -> Sending TRANS_DISAGREE\n");
return control;
}
- } else {//Obj is not locked , so lock object
+ } else {/* If Obj is not locked then lock object */
((objheader_t *)mobj)->status |= LOCK;
- // TESTING Add sleep to make transactions run for a long time such that
- // we can test for soft abort case
- sleep(1);
- //Save all object oids that are locked on this machine during this transaction request call
+
+ /*TESTING Add random wait to make transactions run for a long time such that
+ * we can test for soft abort case */
+
+ randomdelay();
+
+ /* Save all object oids that are locked on this machine during this transaction request call */
oidlocked[objlocked] = ((objheader_t *)mobj)->oid;
objlocked++;
- if (version == ((objheader_t *)mobj)->version) { //If versions match
+ if (version == ((objheader_t *)mobj)->version) { /* Check if versions match */
v_matchnolock++;
- } else { //If versions don't match
+ } else { /* If versions don't match ...HARD ABORT */
v_nomatch++;
- //send TRANS_DISAGREE to Coordinator
control = TRANS_DISAGREE;
+ /* Send TRANS_DISAGREE to Coordinator */
if((val = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
perror("Error in sending control to the Coordinator\n");
return 0;
}
}
- //Decide what control message(s) to send
- // Should be a new function
- if(v_matchnolock == fixed->numread + fixed->nummod) {
- //send TRANS_AGREE to Coordinator
+ /* Decide what control message to send to Coordinator */
+ if ((val = decideCtrlMessage(fixed, transinfo, &v_matchnolock, &v_matchlock, &v_nomatch, &objnotfound, &objlocked,
+ modptr, oidnotfound, oidlocked, oidmod, acceptfd)) == 0) {
+ printf("Error in decideCtrlMessage %s, %d\n", __FILE__, __LINE__);
+ return 0;
+ }
+
+ return val;
+
+}
+/* This function decides what control message such as TRANS_AGREE, TRANS_DISAGREE or TRANS_SOFT_ABORT
+ * to send to Coordinator based on the votes of oids involved in the transaction */
+int decideCtrlMessage(fixed_data_t *fixed, trans_commit_data_t *transinfo, int *v_matchnolock, int *v_matchlock,
+ int *v_nomatch, int *objnotfound, int *objlocked, void *modptr,
+ unsigned int *oidnotfound, unsigned int *oidlocked, unsigned int *oidmod,
+ int acceptfd) {
+ int val;
+ char control = 0;
+ /* Condition to send TRANS_AGREE */
+ if(*(v_matchnolock) == fixed->numread + fixed->nummod) {
control = TRANS_AGREE;
if((val = send(acceptfd, &control, sizeof(char), MSG_NOSIGNAL)) < sizeof(char)) {
perror("Error in sending control to Coordinator\n");
}
printf("DEBUG -> Sending TRANS_AGREE\n");
}
- //Condition to send TRANS_SOFT_ABORT
- if((v_matchlock > 0 && v_nomatch == 0) || (objnotfound > 0 && v_nomatch == 0)) {
+ /* Condition to send TRANS_SOFT_ABORT */
+ if((*(v_matchlock) > 0 && *(v_nomatch) == 0) || (*(objnotfound) > 0 && *(v_nomatch) == 0)) {
control = TRANS_SOFT_ABORT;
char msg[]={TRANS_SOFT_ABORT, 0,0,0,0};
- *((int*)&msg[1])= objnotfound;
+ *((int*)&msg[1])= *(objnotfound);
printf("DEBUG -> Sending TRANS_SOFT_ABORT\n");
- //Sending control message
+ /* Send control message */
if((val = send(acceptfd, &msg, sizeof(msg),MSG_NOSIGNAL)) < sizeof(msg)) {
perror("Error in sending no of objects that are not found\n");
return 0;
}
- //send number of oids not found and the missing oids if objects are missing in the machine
- if(objnotfound != 0) {
- int size = sizeof(unsigned int)*objnotfound;
- if((val = send(acceptfd, oidnotfound, size ,MSG_NOSIGNAL)) < size) {
+ /* Send number of oids not found and the missing oids if objects are missing in the machine */
+ if(*(objnotfound) != 0) {
+ int size = sizeof(unsigned int)* *(objnotfound);
+ if((val = send(acceptfd, oidnotfound, size ,MSG_NOSIGNAL)) < size) {
perror("Error in sending objects that are not found\n");
return 0;
}
}
}
-
- //Do the following when TRANS_DISAGREE is sent
- if(control == TRANS_DISAGREE) {
- //Set the reference count of the object to 1 in mainstore for garbage collection
- ptr = modptr;
- for(i = 0; i< fixed->nummod; i++) {
- headptr = (objheader_t *) ptr;
- headptr->rcount = 1;
- ptr += sizeof(objheader_t) + classsize[headptr->type];
- }
- //Unlock objects that was locked in the trans
- for(i = 0; i< objlocked ; i++) {
- mobj = mhashSearch(oidlocked[i]);// find the header address
- ((objheader_t *)mobj)->status &= ~(LOCK);
- }
- }
-
- //Fill out the structure required for a trans commit process if pile receives a TRANS_COMMIT
+
+ /* Fill out the trans_commit_data_t data structure. This is required for a trans commit process
+ * if Participant receives a TRANS_COMMIT */
transinfo->objmod = oidmod;
transinfo->objlocked = oidlocked;
transinfo->objnotfound = oidnotfound;
transinfo->modptr = modptr;
transinfo->nummod = fixed->nummod;
- transinfo->numlocked = objlocked;
- transinfo->numnotfound = objnotfound;
+ transinfo->numlocked = *(objlocked);
+ transinfo->numnotfound = *(objnotfound);
return control;
}
-//Process oids in the TRANS_COMMIT requested by the participant and sends an ACK back to Coordinator
+/* This function processes all modified objects involved in a TRANS_COMMIT and updates pointer
+ * addresses in lookup table and also changes version number
+ * Sends an ACK back to Coordinator */
int transCommitProcess(trans_commit_data_t *transinfo, int acceptfd) {
objheader_t *header;
int i = 0, offset = 0;
char control;
- //Process each modified object saved in the mainobject store
+ /* Process each modified object saved in the mainobject store */
for(i=0; i<transinfo->nummod; i++) {
if((header = (objheader_t *) mhashSearch(transinfo->objmod[i])) == NULL) {
printf("mhashsearch returns NULL at %s, %d\n", __FILE__, __LINE__);
}
- //change reference count of older address and free space in objstr ??
- header->rcount = 1; //Not sure what would be th val
- //change ptr address in mhash table
+ /* Change reference count of older address and free space in objstr ?? */
+ header->rcount = 1; //Not sure what would be the val
+
+ /* Change ptr address in mhash table */
printf("DEBUG -> removing object oid = %d\n", transinfo->objmod[i]);
mhashRemove(transinfo->objmod[i]);
mhashInsert(transinfo->objmod[i], (transinfo->modptr + offset));
offset += sizeof(objheader_t) + classsize[header->type];
- //update object version
+
+ /* Update object version number */
header = (objheader_t *) mhashSearch(transinfo->objmod[i]);
header->version += 1;
}
+ /* Unlock locked objects */
for(i=0; i<transinfo->numlocked; i++) {
- //unlock objects
header = (objheader_t *) mhashSearch(transinfo->objlocked[i]);
header->status &= ~(LOCK);
}
//TODO Update location lookup table
- //send ack to coordinator
+ /* Send ack to coordinator */
control = TRANS_SUCESSFUL;
printf("DEBUG-> TRANS_SUCESSFUL\n");
if(send((int)acceptfd, &control, sizeof(char), MSG_NOSIGNAL) < sizeof(char)) {
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