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#include "utils.h"
// Helper functions, open and close the queue
int openQueue() {
char cwd [50];
getcwd(cwd, 50);
return msgget(ftok(cwd, 4061), 0666 | IPC_CREAT);
}
int closeQueue(int id) {
return msgctl(id, IPC_RMID, NULL);
}
// Creates a message
struct msgBuffer makeMessage() {
struct msgBuffer temp;
memset(temp.msgText, '\0', MSGSIZE);
temp.msgType = 0;
return temp;
}
// Receives chunks from sendChunkData()
char *getChunkData(int mapperID) {
//Message
struct msgBuffer message = makeMessage();
//Queue ID
int mid = openQueue();
msgrcv(mid, &message, MSGSIZE, mapperID, 0);
if (strncmp("END", message.msgText, 3) == 0)
return NULL;
char* value = malloc(1024);
strcpy(value, message.msgText);
return value;
}
// Sends chunks of size 1024 to the mappers in RR fashion
void sendChunkData(char *inputFile, int nMappers) {
struct msgBuffer message = makeMessage();
// open message queue
int msgid = openQueue();
closeQueue(msgid);
msgid = openQueue();
int map = 0;
FILE* file = fopen(inputFile, "r");
// construct chunks of 1024 bytes
while(fgets(message.msgText, chunkSize + 1, file) != NULL) {
int i = 1023;
while(validChar(message.msgText[i])) {
message.msgText[i--] = '\0';
}
if (fseek(file, (i - 1023), SEEK_CUR) == -1)
break;
message.msgType = (map++ % nMappers) + 1;
if (msgsnd(msgid, &message, MSGSIZE, 0) == -1)
break;
}
for (int i = 1; i <= nMappers; i++) {
struct msgBuffer END = {i, "END"};
if (msgsnd(msgid, &END, MSGSIZE, 0) == -1)
break;
}
fclose(file);
}
// hash function to divide the list of word.txt files across reducers
//http://www.cse.yorku.ca/~oz/hash.html
int hashFunction(char* Qkey, int reducers){
unsigned long hash = 0;
int c;
while ((c = *Qkey++)!='\0')
hash = c + (hash << 6) + (hash << 16) - hash;
return (hash % reducers);
}
// Retrieves file path for the words reducer must reduce and compute the total count for
int getInterData(char *Qkey, int reducerID) {
struct msgBuffer message= makeMessage();
//DEBUG! make sure it work.
int id = openQueue();
if (id == -1)
exit(-1);
if (msgrcv(id, &message, MSGSIZE, reducerID, 0) == -1)
exit(-1);
strcpy(Qkey, message.msgText);
return (strncmp("END", message.msgText, 3) != 0);
}
// Divides the word.txt files in output/MapOut/Map_mapperID folders across nReducers and send filepath
// across nReducers randomly from a hash function
void shuffle(int nMappers, int nReducers) {
struct msgBuffer message = makeMessage();
int id = openQueue();
if (id == -1)
exit(-1);
for (int i = 1; i <= nMappers; i++) {
char newpath[100];
sprintf(newpath, "output/MapOut/Map_%d", i);
DIR *dir = opendir(newpath);
if (dir == NULL)
break;
struct dirent* entry;
while ((entry = readdir(dir)) != NULL) {
if (!strcmp(".", entry->d_name) || !strcmp("..", entry->d_name))
continue;
sprintf(message.msgText, "%s/%s", newpath, entry -> d_name);
message.msgType = (hashFunction(entry -> d_name, nReducers)+1);
if (msgsnd(id, &message, MSGSIZE, 0) == -1)
break;
}
closedir(dir);
}
for (int i = 1; i <= nReducers; i++) {
struct msgBuffer END = {i, "END"};
if (msgsnd(id, &END, MSGSIZE, 0))
break;
}
}
// Check if the character is valid for a word
int validChar(char c){
return (tolower(c) >= 'a' && tolower(c) <='z') ||
(c >= '0' && c <= '9');
}
// Gets words from the buffer
char *getWord(char *chunk, int *i){
char *buffer = (char *)malloc(sizeof(char) * chunkSize);
memset(buffer, '\0', chunkSize);
int j = 0;
while((*i) < strlen(chunk)) {
// read a single word at a time from chunk
if (chunk[(*i)] == '\n' || chunk[(*i)] == ' ' || !validChar(chunk[(*i)]) || chunk[(*i)] == 0x0) {
buffer[j] = '\0';
if(strlen(buffer) > 0){
(*i)++;
return buffer;
}
j = 0;
(*i)++;
continue;
}
buffer[j] = chunk[(*i)];
j++;
(*i)++;
}
if(strlen(buffer) > 0)
return buffer;
return NULL;
}
void createOutputDir(){
mkdir("output", ACCESSPERMS);
mkdir("output/MapOut", ACCESSPERMS);
mkdir("output/ReduceOut", ACCESSPERMS);
}
char *createMapDir(int mapperID){
char *dirName = (char *) malloc(sizeof(char) * 100);
memset(dirName, '\0', 100);
sprintf(dirName, "output/MapOut/Map_%d", mapperID);
mkdir(dirName, ACCESSPERMS);
return dirName;
}
void removeOutputDir(){
pid_t pid = fork();
if(pid == 0){
char *argv[] = {"rm", "-rf", "output", NULL};
if (execvp(*argv, argv) < 0) {
printf("ERROR: exec failed\n");
exit(1);
}
exit(0);
} else{
wait(NULL);
}
}
void bookeepingCode(){
removeOutputDir();
sleep(1);
createOutputDir();
}
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