Add initial shared memory object functions

.gitignore

@@ -8,3 +8,5 @@ http/client
 http/server
 mygrep/mygrep
 cpair/cpair
+fb_arc_set/supervisor
+fb_arc_set/generator

fb_arc_set/Makefile

@@ -5,16 +5,16 @@ TARGET_2 = supervisor
 
 all: $(TARGET_1).c $(TARGET_2).c
 	$(CC) $(CFLAGS) $(TARGET_1).c $(TARGET_2).c
-	$(CC) $(TARGET_1).o -o $(TARGET_1)
-	$(CC) $(TARGET_2).o -o $(TARGET_2)
+	$(CC) $(TARGET_1).o -o $(TARGET_1) -lrt
+	$(CC) $(TARGET_2).o -o $(TARGET_2) -lrt
 
 generator: $(TARGET_1).c
 	$(CC) $(CFLAGS) $(TARGET_1).c
-	$(CC) $(TARGET_1).o -o $(TARGET_1)
+	$(CC) $(TARGET_1).o -o $(TARGET_1) -lrt
 
 supervisor: $(TARGET_2).c
 	$(CC) $(CFLAGS) $(TARGET_2).c
-	$(CC) $(TARGET_2).o -o $(TARGET_2)
+	$(CC) $(TARGET_2).o -o $(TARGET_2) -lrt
 
 install:
 	cp $(TARGET_1) /usr/local/bin/graph-$(TARGET_1)

fb_arc_set/generator.c

@@ -0,0 +1,44 @@
+/**
+ * @file generator.c
+ * @author Ivaylo Ivanov 11777707
+ * @date 11.01.2018
+ *
+ * @brief Generator program module.
+ *
+ * The generator program takes a graph as input. The program repeatedly generates a random solution
+ * to the problem as described on the first page and writes its result to the circular buffer. It repeats this
+ * procedure until it is notified by the supervisor to terminate.
+ * The generator program takes as arguments the set of edges of the graph.
+ * Each positional argument is one edge; at least one edge must be given. An edge is specified by a string,
+ * with the indices of the two nodes it connects separated by a -. Since the graph is directed, the edge starts
+ * at the first node and leads to the second node. Note that the number of nodes of the graph is implicitly
+ * provided through the indices in the edges. In the example above the generator program is called with
+ * the graph shown on the first page.
+ * The generator uses the algorithm described on the first page to generate random feedback arc sets for the
+ * given graph. It writes these feedback arc sets to the circular buffer, one at a time; therefore a feedback
+ * arc set is a single element of the circular buffer. The generator may produce debug output, describing
+ * the feedback arc sets which it writes to the circular buffer.
+ *
+ *   SYNOPSIS
+ *   generator EDGE1 EDGE2 ...
+ *
+ *   EXAMPLE
+ *   generator 0-1 1-2 1-3 1-4 2-4 3-6 4-3 4-5 6-0
+ *
+ **/
+#include "shared/shm.c"
+
+int main(int argc, char *argv[]) {
+    if(argc > 1) {
+        fprintf(stderr, "ERROR: Command takes no arguments");
+        exit(EXIT_FAILURE);
+    }
+
+    void* terminate_shm = open_shm(TERMINATE_SHM, TERMINATE_SHM_SIZE);
+
+    write_to_shm(terminate_shm, "1", TERMINATE_SHM_SIZE);
+    puts(terminate_shm);
+    close_shm(terminate_shm, TERMINATE_SHM_SIZE);
+    destroy_shm(TERMINATE_SHM);
+}
+

fb_arc_set/shared/shm.c

@@ -0,0 +1,52 @@
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <string.h>
+
+#define TERMINATE_SHM "/terminate"
+#define TERMINATE_SHM_SIZE 8
+
+void* open_shm(char *shm_name, size_t shm_size) {
+    int shmfd = shm_open(shm_name, O_RDWR | O_CREAT, 0600);
+    if(shmfd == -1) {
+        fprintf(stderr, "ERROR: Failed creating shared memory object");
+        exit(EXIT_FAILURE);
+    }
+
+    if(ftruncate(shmfd, shm_size) < 0) {
+        fprintf(stderr, "ERROR: Failed truncating shared memory object");
+        exit(EXIT_FAILURE);
+    }
+
+    void* shm;
+    shm = mmap(NULL, shm_size, PROT_READ | PROT_WRITE, MAP_SHARED, shmfd, 0);
+
+    if(shm == MAP_FAILED) {
+        fprintf(stderr, "ERROR: Failed mapping shared memory object");
+        exit(EXIT_FAILURE);
+    }
+
+    return shm;
+}
+
+void write_to_shm(void* shm, char *message, size_t message_size) {
+    memcpy(shm, message, message_size);
+}
+
+void close_shm(void* shm, size_t shm_size) {
+    if (munmap(shm, shm_size) == -1) {
+        fprintf(stderr, "ERROR: Failed unmapping shared memory object");
+        exit(EXIT_FAILURE);
+    }
+}
+
+void destroy_shm(char *shm_name) {
+    if (shm_unlink(shm_name) == -1) {
+        fprintf(stderr, "ERROR: Failed unlinking shared memory object");
+        exit(EXIT_FAILURE);
+    }
+}

fb_arc_set/supervisor.c

@@ -0,0 +1,37 @@
+/**
+ * @file supervisor.c
+ * @author Ivaylo Ivanov 11777707
+ * @date 11.01.2018
+ *
+ * @brief Supervisor program module.
+ *
+ * The supervisor sets up the shared memory and the semaphores and initializes the circular buffer required
+ * for the communication with the generators. It then waits for the generators to write solutions to the
+ * circular buffer.
+ * The supervisor program takes no arguments.
+ * Once initialization is complete, the supervisor reads the solutions from the circular buffer and remembers the best solution so far, i.e. the solution with the least edges. Every time a better solution than the
+ * previous best solution is found, the supervisor writes the new solution to standard output. If a generator
+ * writes a solution with 0 edges to the circular buffer, then the graph is acyclic and the supervisor terminates. Otherwise the supervisor keeps reading results from the circular buffer until it receives a SIGINT
+ * or a SIGTERM signal.
+ * Before terminating, the supervisor notifies all generators that they should terminate as well. This can
+ * be done by setting a variable in the shared memory, which is checked by the generator processes before
+ * writing to the buffer. The supervisor then unlinks all shared resources and exits.
+ *
+ *   SYNOPSIS
+ *   supervisor
+ *
+ **/
+#include "shared/shm.c"
+
+int main(int argc, char *argv[]) {
+    if(argc > 1) {
+        fprintf(stderr, "ERROR: Command takes no arguments");
+        exit(EXIT_FAILURE);
+    }
+
+    void* terminate_shm = open_shm(TERMINATE_SHM, TERMINATE_SHM_SIZE);
+
+    write_to_shm(terminate_shm, "1", TERMINATE_SHM_SIZE);
+    close_shm(terminate_shm, TERMINATE_SHM_SIZE);
+    destroy_shm(TERMINATE_SHM);
+}