Clean up semaphore on interrupt

Necessary since we encourage users to interrupt indexamajig with Ctrl+C
Also, generally improve the signal handling.

1 files changed, 92 insertions, 51 deletions

diff --git a/src/im-sandbox.c b/src/im-sandbox.c
index 6464202c..5e9c4838 100644
--- a/src/im-sandbox.c
+++ b/src/im-sandbox.c
@@ -96,10 +96,6 @@ struct sandbox
 };
 
 
-/* Horrible global variable for signal handler */
-sem_t *zombie_sem;
-
-
 static struct filename_plus_event *get_pattern(FILE *fh, int config_basename,
                                                struct detector *det,
                                                const char *prefix)
@@ -456,8 +452,8 @@ static void try_read(struct sandbox *sb)
 	int fdmax;
 	const int ofd = get_stream_fd(sb->stream);
 
-	tv.tv_sec = 5;
-	tv.tv_usec = 0;
+	tv.tv_sec = 0;
+	tv.tv_usec = 500000;
 
 	FD_ZERO(&fds);
 	fdmax = 0;
@@ -523,21 +519,31 @@ static void start_worker_process(struct sandbox *sb, int slot)
 		size_t ll;
 		int i;
 
-		/* First, disconnect the signal handler */
-		sa.sa_flags = 0;
-		sigemptyset(&sa.sa_mask);
-		sa.sa_handler = SIG_DFL;
-		r = sigaction(SIGCHLD, &sa, NULL);
-		if ( r == -1 ) {
+	        /* First, disconnect the signal handlers */
+	        sa.sa_flags = 0;
+	        sigemptyset(&sa.sa_mask);
+	        sa.sa_handler = SIG_DFL;
+	        r = sigaction(SIGCHLD, &sa, NULL);
+	        if ( r == -1 ) {
 			ERROR("Failed to set signal handler!\n");
-			return;
-		}
+			exit(1);
+	        }
+	        r = sigaction(SIGINT, &sa, NULL);
+	        if ( r == -1 ) {
+			ERROR("Failed to set signal handler!\n");
+			exit(1);
+	        }
+	        r = sigaction(SIGQUIT, &sa, NULL);
+	        if ( r == -1 ) {
+			ERROR("Failed to set signal handler!\n");
+			exit(1);
+	        }
 
 		ll = 64 + strlen(sb->tmpdir);
 		tmp = malloc(ll);
 		if ( tmp == NULL ) {
 			ERROR("Failed to allocate temporary dir\n");
-			return;
+			exit(1);
 		}
 
 		snprintf(tmp, 63, "%s/worker.%i", sb->tmpdir, slot);
@@ -545,14 +551,14 @@ static void start_worker_process(struct sandbox *sb, int slot)
 		if ( stat(tmp, &s) == -1 ) {
 			if ( errno != ENOENT ) {
 				ERROR("Failed to stat temporary folder.\n");
-				return;
+				exit(1);
 			}
 
 			r = mkdir(tmp, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
 			if ( r ) {
 				ERROR("Failed to create temporary folder: %s\n",
 				strerror(errno));
-				return;
+				exit(1);
 			}
 		}
 
@@ -596,13 +602,7 @@ static void start_worker_process(struct sandbox *sb, int slot)
 }
 
 
-static void signal_handler(int sig, siginfo_t *si, void *uc_v)
-{
-	sem_post(zombie_sem);
-}
-
-
-static void handle_zombie(struct sandbox *sb)
+static void handle_zombie(struct sandbox *sb, int respawn)
 {
 	int i;
 
@@ -628,11 +628,15 @@ static void handle_zombie(struct sandbox *sb)
 			}
 
 			if ( WIFSIGNALED(status) ) {
+
+				if ( (WTERMSIG(status) == SIGINT)
+				  || (WTERMSIG(status) == SIGQUIT) ) continue;
+
 				STATUS("Worker %i was killed by signal %i\n",
 				       i, WTERMSIG(status));
 				STATUS("Event ID was: %s\n",
 				       sb->shared->last_ev[i]);
-				start_worker_process(sb, i);
+				if ( respawn ) start_worker_process(sb, i);
 			}
 
 		}
@@ -715,19 +719,47 @@ static int fill_queue(FILE *fh, int config_basename, struct detector *det,
 	return 0;
 }
 
+volatile sig_atomic_t at_zombies = 0;
+volatile sig_atomic_t at_interrupt = 0;
+
+static void sigchld_handler(int sig, siginfo_t *si, void *uc_v)
+{
+	at_zombies = 1;
+}
+
+
+static void sigint_handler(int sig, siginfo_t *si, void *uc_v)
+{
+	at_interrupt = 1;
+}
+
+
+static void check_signals(struct sandbox *sb, const char *semname_q,
+                          int respawn)
+{
+	if ( at_zombies ) {
+		at_zombies = 0;
+		handle_zombie(sb, respawn);
+	}
+
+	if ( at_interrupt ) {
+		sem_unlink(semname_q);
+		exit(0);
+	}
+}
+
 
 void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
                     int config_basename, FILE *fh,
                     Stream *stream, const char *tempdir)
 {
 	int i;
-	struct sigaction sa;
-	int r;
 	struct sandbox *sb;
 	size_t ll;
 	struct stat s;
 	char semname_q[64];
-	char semname_z[64];
+	struct sigaction sa;
+	int r;
 	int allDone = 0;
 
 	if ( n_proc > MAX_NUM_WORKERS ) {
@@ -772,14 +804,6 @@ void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
 		ERROR("Failed to create semaphore: %s\n", strerror(errno));
 		return;
 	}
-	snprintf(semname_z, 64, "indexamajig-z%i", getpid());
-	zombie_sem = sem_open(semname_z, O_CREAT | O_EXCL,
-	                      S_IRUSR | S_IWUSR, 0);
-	if ( zombie_sem == SEM_FAILED ) {
-		ERROR("Failed to create zombie semaphore: %s\n",
-		      strerror(errno));
-		return;
-	}
 
 	sb->pids = calloc(n_proc, sizeof(pid_t));
 	sb->running = calloc(n_proc, sizeof(int));
@@ -792,16 +816,6 @@ void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
 		return;
 	}
 
-	/* Set up signal handler to take action if any children die */
-	sa.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
-	sigemptyset(&sa.sa_mask);
-	sa.sa_sigaction = signal_handler;
-	r = sigaction(SIGCHLD, &sa, NULL);
-	if ( r == -1 ) {
-		ERROR("Failed to set signal handler!\n");
-		return;
-	}
-
 	if ( tempdir == NULL ) {
 		tempdir = "";
 	}
@@ -844,15 +858,38 @@ void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
 		start_worker_process(sb, i);
 	}
 
+	/* Set up signal handler to take action if any children die */
+	sa.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_sigaction = sigchld_handler;
+	r = sigaction(SIGCHLD, &sa, NULL);
+	if ( r == -1 ) {
+	        ERROR("Failed to set signal handler!\n");
+	        return;
+	}
+
+	/* Set up signal handler to clean up semaphore on exit */
+	sa.sa_flags = SA_SIGINFO | SA_NOCLDSTOP;
+	sigemptyset(&sa.sa_mask);
+	sa.sa_sigaction = sigint_handler;
+	r = sigaction(SIGINT, &sa, NULL);
+	if ( r == -1 ) {
+	        ERROR("Failed to set signal handler!\n");
+	        return;
+	}
+	r = sigaction(SIGQUIT, &sa, NULL);
+	if ( r == -1 ) {
+	        ERROR("Failed to set signal handler!\n");
+	        return;
+	}
+
 	do {
 
 		int r;
 		double tNow;
 
 		try_read(sb);
-
-		/* Check for dead workers */
-		if ( sem_trywait(zombie_sem) == 0 ) handle_zombie(sb);
+		check_signals(sb, semname_q, 1);
 
 		/* Top up the queue if necessary */
 		r = 0;
@@ -900,6 +937,7 @@ void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
 		pthread_mutex_unlock(&sb->shared->queue_lock);
 
 	} while ( !allDone );
+
 	fclose(fh);
 
 	/* Indicate to the workers that we are finished, and wake them up one
@@ -915,9 +953,14 @@ void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
 		int status;
 		while ( waitpid(sb->pids[i], &status, WNOHANG) == 0 ) {
 			try_read(sb);
+			check_signals(sb, semname_q, 0);
 		}
+		/* If this worker died and got waited by the zombie handler,
+		 * waitpid() returns -1 and the loop still exits. */
 	}
 
+	sem_unlink(semname_q);
+
 	for ( i=0; i<sb->n_read; i++ ) {
 		fclose(sb->fhs[i]);
 	}
@@ -933,8 +976,6 @@ void create_sandbox(struct index_args *iargs, int n_proc, char *prefix,
 	       100.0 * sb->shared->n_hadcrystals / sb->shared->n_processed,
 	       sb->shared->n_crystals);
 
-	sem_unlink(semname_q);
-	sem_unlink(semname_z);
 	munmap(sb->shared, sizeof(struct sb_shm));
 	free(sb);
 }