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main.c
56
main.c
@ -39,14 +39,28 @@ int main() {
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if (rank == MASTER)
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initialize();
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// distribution of the length of the text portion to each process
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MPI_Scatter(text_piece, 1, MPI_INT, &private_text_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
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// allocation of space for text
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char *private_text = (char *) malloc(sizeof(char) * (private_text_len + 1));
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MPI_Scatterv(text, text_piece, displacements, MPI_CHAR, private_text, private_text_len, MPI_CHAR, MASTER,
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MPI_COMM_WORLD);
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// distribution of the text portion to each process
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// scatterv is necessary because the last process receives a larger portion of text in case it is not perfectly divisible.
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MPI_Scatterv(
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text,
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text_piece,
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displacements,
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MPI_CHAR,
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private_text,
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private_text_len,
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MPI_CHAR, MASTER,
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MPI_COMM_WORLD
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);
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private_text[private_text_len] = '\0';
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// sending the remain to the last trial
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// this is necessary for the calculation of the offset
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if (rank == MASTER)
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MPI_Send(&remain, 1, MPI_INT, size - 1, DEFAULT_TAG, MPI_COMM_WORLD);
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else if (rank == size - 1)
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@ -54,59 +68,77 @@ int main() {
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printf("%d -> input: %s\n", rank, private_text);
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printf("%d -> text len: %d\n", rank, private_text_len);
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printf("%d -> text len_: %d\n", rank, strlen(private_text));
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// distribution of the length of the pattern to each process
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MPI_Bcast(&pattern_len, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
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// allocation of space for the pattern
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// the master has already done so previously
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if (rank != MASTER) {
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pattern = (char *) malloc(sizeof(char) * (pattern_len + 1));
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}
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// distribution of the pattern to each process
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MPI_Bcast(pattern, pattern_len + 1, MPI_CHAR, MASTER, MPI_COMM_WORLD);
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// create and build lps array
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int lps[pattern_len];
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create_lps(pattern, pattern_len, lps);
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int match_number = 0, residue;
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// search for matches
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int *matches = search_pattern(private_text, pattern, lps, &match_number, &residue);
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// send the residue to the next process
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if (rank + 1 != size) {
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MPI_Send(&residue, 1, MPI_INT, rank + 1, DEFAULT_TAG, MPI_COMM_WORLD);
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}
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// receiving the residue from the previous process
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if (rank != 0) {
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MPI_Recv(&residue, 1, MPI_INT, rank - 1, DEFAULT_TAG, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
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if (residue != 0)
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// search for a split match
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find_end(residue, pattern, private_text, &matches, &match_number);
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}
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//print_array(matches, match_number);
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int shift = rank * (private_text_len - remain);
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// transformation of match indices from relative to absolute position.
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int shift = rank * (private_text_len - remain); // the rest is zero for all but the last process
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apply_shift(shift, matches, match_number);
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printf("%d -> result number: %d\n", rank, match_number);
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if (rank == MASTER) {
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// allocation for the array containing the number of matches of each process
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match_numbers = (int *) malloc(sizeof(int) * size);
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}
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// collection of the number of matches from each process
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MPI_Gather(&match_number, 1, MPI_INT, match_numbers, 1, MPI_INT, MASTER, MPI_COMM_WORLD);
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if (rank == MASTER) {
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// preparation of the data structures needed to receive match indices from all processes
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total_match_number = sum_array(match_numbers, size);
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total_matches = (int *) malloc(sizeof(int) * total_match_number);
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displacements[0] = 0;
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for (int i = 0; i < size - 1; ++i) {
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displacements[i + 1] = displacements[i] + match_numbers[i];
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}
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}
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MPI_Gatherv(matches, match_number, MPI_INT, total_matches, match_numbers, displacements, MPI_INT, MASTER,
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MPI_COMM_WORLD);
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// collection of match indices from each process
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// gatherv is necessary because each process will have a different number of matches
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MPI_Gatherv(
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matches,
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match_number,
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MPI_INT,
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total_matches,
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match_numbers,
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displacements,
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MPI_INT, MASTER,
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MPI_COMM_WORLD
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);
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MPI_Finalize();
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@ -139,7 +171,7 @@ void find_end(int residue, char *pattern, char *text, int **matches, int *match_
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}
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void initialize() {
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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);
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text = "testo di esempio mamma altra mamma esempio prova mammamma esempio mamma";//read_file("data/text.txt", &text_len);
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pattern = "mamma";//read_file("data/pattern.txt", &pattern_len);
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text_len = strlen(text);
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