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This commit is contained in:
Raffaele Mignone 2021-03-21 14:01:03 +01:00
parent 954556f28a
commit 06a6ded2e7
Signed by: norangebit
GPG Key ID: F5255658CB220573

58
main.c
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@ -39,74 +39,106 @@ int main() {
if (rank == MASTER) if (rank == MASTER)
initialize(); initialize();
// distribution of the length of the text portion to each process
MPI_Scatter(text_piece, 1, MPI_INT, &private_text_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD); MPI_Scatter(text_piece, 1, MPI_INT, &private_text_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
// allocation of space for text
char *private_text = (char *) malloc(sizeof(char) * (private_text_len + 1)); char *private_text = (char *) malloc(sizeof(char) * (private_text_len + 1));
MPI_Scatterv(text, text_piece, displacements, MPI_CHAR, private_text, private_text_len, MPI_CHAR, MASTER, // distribution of the text portion to each process
MPI_COMM_WORLD); // scatterv is necessary because the last process receives a larger portion of text in case it is not perfectly divisible.
MPI_Scatterv(
text,
text_piece,
displacements,
MPI_CHAR,
private_text,
private_text_len,
MPI_CHAR, MASTER,
MPI_COMM_WORLD
);
private_text[private_text_len] = '\0'; private_text[private_text_len] = '\0';
// sending the remain to the last trial
// this is necessary for the calculation of the offset
if (rank == MASTER) if (rank == MASTER)
MPI_Send(&remain, 1, MPI_INT, size - 1, DEFAULT_TAG, MPI_COMM_WORLD); MPI_Send(&remain, 1, MPI_INT, size - 1, DEFAULT_TAG, MPI_COMM_WORLD);
else if (rank == size -1) else if (rank == size - 1)
MPI_Recv(&remain, 1, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE); MPI_Recv(&remain, 1, MPI_INT, MASTER, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
printf("%d -> input: %s\n", rank, private_text); printf("%d -> input: %s\n", rank, private_text);
printf("%d -> text len: %d\n", rank, private_text_len); printf("%d -> text len: %d\n", rank, private_text_len);
printf("%d -> text len_: %d\n", rank, strlen(private_text));
// distribution of the length of the pattern to each process
MPI_Bcast(&pattern_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD); MPI_Bcast(&pattern_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
// allocation of space for the pattern
// the master has already done so previously
if (rank != MASTER) { if (rank != MASTER) {
pattern = (char *) malloc(sizeof(char) * (pattern_len + 1)); pattern = (char *) malloc(sizeof(char) * (pattern_len + 1));
} }
// distribution of the pattern to each process
MPI_Bcast(pattern, pattern_len + 1, MPI_CHAR, MASTER, MPI_COMM_WORLD); MPI_Bcast(pattern, pattern_len + 1, MPI_CHAR, MASTER, MPI_COMM_WORLD);
// create and build lps array
int lps[pattern_len]; int lps[pattern_len];
create_lps(pattern, pattern_len, lps); create_lps(pattern, pattern_len, lps);
int match_number = 0, residue; int match_number = 0, residue;
// search for matches
int *matches = search_pattern(private_text, pattern, lps, &match_number, &residue); int *matches = search_pattern(private_text, pattern, lps, &match_number, &residue);
// send the residue to the next process
if (rank + 1 != size) { if (rank + 1 != size) {
MPI_Send(&residue, 1, MPI_INT, rank + 1, DEFAULT_TAG, MPI_COMM_WORLD); MPI_Send(&residue, 1, MPI_INT, rank + 1, DEFAULT_TAG, MPI_COMM_WORLD);
} }
// receiving the residue from the previous process
if (rank != 0) { if (rank != 0) {
MPI_Recv(&residue, 1, MPI_INT, rank - 1, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE); MPI_Recv(&residue, 1, MPI_INT, rank - 1, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
if (residue != 0) if (residue != 0)
// search for a split match
find_end(residue, pattern, private_text, &matches, &match_number); find_end(residue, pattern, private_text, &matches, &match_number);
} }
//print_array(matches, match_number); // transformation of match indices from relative to absolute position.
int shift = rank * (private_text_len - remain); // the rest is zero for all but the last process
int shift = rank * (private_text_len - remain);
apply_shift(shift, matches, match_number); apply_shift(shift, matches, match_number);
printf("%d -> result number: %d\n", rank, match_number); printf("%d -> result number: %d\n", rank, match_number);
if (rank == MASTER) { if (rank == MASTER) {
// allocation for the array containing the number of matches of each process
match_numbers = (int *) malloc(sizeof(int) * size); match_numbers = (int *) malloc(sizeof(int) * size);
} }
// collection of the number of matches from each process
MPI_Gather(&match_number, 1, MPI_INT, match_numbers, 1, MPI_INT, MASTER, MPI_COMM_WORLD); MPI_Gather(&match_number, 1, MPI_INT, match_numbers, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
if (rank == MASTER) { if (rank == MASTER) {
// preparation of the data structures needed to receive match indices from all processes
total_match_number = sum_array(match_numbers, size); total_match_number = sum_array(match_numbers, size);
total_matches = (int *) malloc(sizeof(int) * total_match_number); total_matches = (int *) malloc(sizeof(int) * total_match_number);
displacements[0] = 0; displacements[0] = 0;
for (int i = 0; i < size - 1; ++i) { for (int i = 0; i < size - 1; ++i) {
displacements[i + 1] = displacements[i] + match_numbers[i]; displacements[i + 1] = displacements[i] + match_numbers[i];
} }
} }
MPI_Gatherv(matches, match_number, MPI_INT, total_matches, match_numbers, displacements, MPI_INT, MASTER, // collection of match indices from each process
MPI_COMM_WORLD); // gatherv is necessary because each process will have a different number of matches
MPI_Gatherv(
matches,
match_number,
MPI_INT,
total_matches,
match_numbers,
displacements,
MPI_INT, MASTER,
MPI_COMM_WORLD
);
MPI_Finalize(); MPI_Finalize();
@ -139,7 +171,7 @@ void find_end(int residue, char *pattern, char *text, int **matches, int *match_
} }
void initialize() { void initialize() {
text = "questo è un test di esempio. Qui c'è la prima occorenza mamma e qui la seconda mamma";//read_file("data/text.txt", &text_len); text = "testo di esempio mamma altra mamma esempio prova mammamma esempio mamma";//read_file("data/text.txt", &text_len);
pattern = "mamma";//read_file("data/pattern.txt", &pattern_len); pattern = "mamma";//read_file("data/pattern.txt", &pattern_len);
text_len = strlen(text); text_len = strlen(text);