From 61b69a8c846cda4506db71b285dafbef79f41bac Mon Sep 17 00:00:00 2001
From: Thomas White <taw@bitwiz.org.uk>
Date: Sun, 8 Jul 2012 22:09:50 +0200
Subject: Write stream without using a lock at all

---
 src/indexamajig.c | 275 +++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 209 insertions(+), 66 deletions(-)

(limited to 'src')

diff --git a/src/indexamajig.c b/src/indexamajig.c
index b09a00aa..3e8ab4de 100644
--- a/src/indexamajig.c
+++ b/src/indexamajig.c
@@ -106,9 +106,7 @@ struct index_args
 	double ir_out;
 
 	/* Output stream */
-	FILE *ofh;
 	const struct copy_hdf5_field *copyme;
-	char *outfile;
 };
 
 
@@ -227,26 +225,30 @@ static char *get_pattern(FILE *fh, char **use_this_one_instead,
 	char *line;
 	char *filename;
 
-	/* Get the next filename */
-	if ( *use_this_one_instead != NULL ) {
+	do {
 
-		line = *use_this_one_instead;
-		*use_this_one_instead = NULL;
+		/* Get the next filename */
+		if ( *use_this_one_instead != NULL ) {
 
-	} else {
+			line = *use_this_one_instead;
+			*use_this_one_instead = NULL;
 
-		char *rval;
+		} else {
+
+			char *rval;
+
+			line = malloc(1024*sizeof(char));
+			rval = fgets(line, 1023, fh);
+			if ( rval == NULL ) {
+				free(line);
+				return NULL;
+			}
 
-		line = malloc(1024*sizeof(char));
-		rval = fgets(line, 1023, fh);
-		if ( rval == NULL ) {
-			free(line);
-			return NULL;
 		}
 
-	}
+		chomp(line);
 
-	chomp(line);
+	} while ( strlen(line) == 0 );
 
 	if ( config_basename ) {
 		char *tmp;
@@ -266,7 +268,8 @@ static char *get_pattern(FILE *fh, char **use_this_one_instead,
 
 
 static void process_image(const struct index_args *iargs,
-                          struct pattern_args *pargs, int cookie)
+                          struct pattern_args *pargs, FILE *ofh,
+                          int cookie)
 {
 	float *data_for_measurement;
 	size_t data_size;
@@ -278,12 +281,7 @@ static void process_image(const struct index_args *iargs,
 	struct beam_params *beam = iargs->beam;
 	int r, check;
 	struct hdfile *hdfile;
-	char *outfile = iargs->outfile;
 	struct image image;
-	char *outfilename = iargs->outfile;
-	int fd;
-	FILE *fh;
-	struct flock fl;
 
 	image.features = NULL;
 	image.data = NULL;
@@ -408,38 +406,9 @@ static void process_image(const struct index_args *iargs,
 		image.reflections = NULL;
 	}
 
-	/* Write Lock */
-	fl.l_type = F_WRLCK;
-	fl.l_whence = SEEK_SET;
-	fl.l_start = 0;
-	fl.l_len = 0;  /* Means "lock the whole file" */
-
-	fd = open(outfile, O_WRONLY);
-	if ( fd == -1 ) {
-		ERROR("Couldn't open output stream ('%s').\n", outfile);
-		exit(1);
-	}
-	if ( fcntl(fd, F_SETLKW, &fl) == -1 ) {
-		ERROR("Couldn't get lock on output stream.\n");
-		exit(1);
-	}
-
-	fh = fdopen(fd, "a");
-	if ( fh == NULL ) {
-		ERROR("Couldn't fdopen() the output stream.\n");
-		exit(1);
-	}
-	write_chunk(fh, &image, hdfile, iargs->stream_flags);
-	fflush(fh);
-
-	/* Unlock stream for other processes */
-	fl.l_type = F_UNLCK; /* set to unlock same region */
-	if ( fcntl(fd, F_SETLK, &fl) == -1 ) {
-		ERROR("fcntl");
-		exit(1);
-	}
-
-	fclose(fh);  /* close(fd) happens as well because fd was not dup'd */
+	write_chunk(ofh, &image, hdfile, iargs->stream_flags);
+	fprintf(ofh, "END\n");
+	fflush(ofh);
 
 	/* Only free cell if found */
 	cell_free(image.indexed_cell);
@@ -454,7 +423,8 @@ static void process_image(const struct index_args *iargs,
 
 
 static void run_work(const struct index_args *iargs,
-                     int filename_pipe, int results_pipe, int cookie)
+                     int filename_pipe, int results_pipe, FILE *ofh,
+                     int cookie)
 {
 	int allDone = 0;
 	FILE *fh;
@@ -489,16 +459,25 @@ static void run_work(const struct index_args *iargs,
 		}
 
 		chomp(line);
-		pargs.filename = line;
-		pargs.indexable = 0;
 
-		process_image(iargs, &pargs, cookie);
+		if ( strlen(line) == 0 ) {
+
+			allDone = 1;
+
+		} else {
+
+			pargs.filename = line;
+			pargs.indexable = 0;
+
+			process_image(iargs, &pargs, ofh, cookie);
+
+			/* Request another image */
+			c = sprintf(buf, "%i\n", pargs.indexable);
+			w = write(results_pipe, buf, c);
+			if ( w < 0 ) {
+				ERROR("write P0\n");
+			}
 
-		/* Request another image */
-		c = sprintf(buf, "%i\n", pargs.indexable);
-		w = write(results_pipe, buf, c);
-		if ( w < 0 ) {
-			ERROR("write P0\n");
 		}
 
 		free(line);
@@ -558,6 +537,118 @@ static int parse_cell_reduction(const char *scellr, int *err,
 }
 
 
+static void run_reader(int *stream_pipe_read, int n_proc, FILE *ofh)
+{
+	int done = 0;
+	int *finished;
+	FILE **fhs;
+	int i;
+	int chunk_finished;
+
+	finished = calloc(n_proc, sizeof(int));
+	if ( finished == NULL ) {
+		ERROR("Couldn't allocate memory for flags!\n");
+		exit(1);
+	}
+
+	fhs = calloc(n_proc, sizeof(FILE *));
+	if ( fhs == NULL ) {
+		ERROR("Couldn't allocate memory for file handles!\n");
+		exit(1);
+	}
+
+	for ( i=0; i<n_proc; i++ ) {
+		fhs[i] = fdopen(stream_pipe_read[i], "r");
+		if ( fhs[i] == NULL ) {
+			ERROR("Couldn't fdopen() stream!\n");
+			exit(1);
+		}
+	}
+
+	while ( !done ) {
+
+		int r, i;
+		struct timeval tv;
+		fd_set fds;
+		int fdmax;
+
+		tv.tv_sec = 5;
+		tv.tv_usec = 0;
+
+		FD_ZERO(&fds);
+		fdmax = 0;
+		for ( i=0; i<n_proc; i++ ) {
+
+			int fd;
+
+			if ( finished[i] ) continue;
+
+			fd = stream_pipe_read[i];
+
+			FD_SET(fd, &fds);
+			if ( fd > fdmax ) fdmax = fd;
+
+		}
+
+		r = select(fdmax+1, &fds, NULL, NULL, &tv);
+
+		if ( r == -1 ) {
+			ERROR("select() failed: %s\n", strerror(errno));
+			continue;
+		}
+
+		if ( r == 0 ) continue; /* Nothing this time.  Try again */
+
+		for ( i=0; i<n_proc; i++ ) {
+
+			if ( finished[i] ) continue;
+
+			if ( !FD_ISSET(stream_pipe_read[i], &fds) ) continue;
+
+			chunk_finished = 0;
+			do {
+
+				char line[1024];
+				char *rval;
+
+				rval = fgets(line, 1024, fhs[i]);
+				if ( rval == NULL ) {
+					if ( feof(fhs[i]) ) {
+						/* Process died */
+						finished[i] = 1;
+					} else {
+						ERROR("fgets() failed: %s\n",
+						      strerror(errno));
+					}
+					continue;
+				}
+
+
+				if ( strcmp(line, "END\n") == 0 ) {
+					chunk_finished = 1;
+				} else {
+					fprintf(ofh, "%s", line);
+				}
+
+			} while ( !chunk_finished );
+
+		}
+
+		done = 1;
+		for ( i=0; i<n_proc; i++ ) {
+			if ( !finished[i] ) done = 0;
+		}
+
+	}
+
+	free(finished);
+
+	for ( i=0; i<n_proc; i++ ) {
+		fclose(fhs[i]);
+	}
+}
+
+
 int main(int argc, char *argv[])
 {
 	int c;
@@ -616,11 +707,14 @@ int main(int argc, char *argv[])
 	int t_last_stats;
 	pid_t *pids;
 	int *filename_pipes;
+	int *stream_pipe_read;
+	int *stream_pipe_write;
 	FILE **result_fhs;
 	fd_set fds;
 	int i;
 	int allDone;
 	int *finished;
+	pid_t pr;
 
 	copyme = new_copy_hdf5_field_list();
 	if ( copyme == NULL ) {
@@ -1007,7 +1101,6 @@ int main(int argc, char *argv[])
 	iargs.indm = indm;
 	iargs.ipriv = ipriv;
 	iargs.peaks = peaks;
-	iargs.ofh = ofh;
 	iargs.beam = beam;
 	iargs.element = element;
 	iargs.stream_flags = stream_flags;
@@ -1016,7 +1109,6 @@ int main(int argc, char *argv[])
 	iargs.ir_inn = ir_inn;
 	iargs.ir_mid = ir_mid;
 	iargs.ir_out = ir_out;
-	iargs.outfile = outfile;
 
 	n_indexable = 0;
 	n_processed = 0;
@@ -1027,6 +1119,8 @@ int main(int argc, char *argv[])
 	FD_ZERO(&fds);
 	filename_pipes = calloc(n_proc, sizeof(int));
 	result_fhs = calloc(n_proc, sizeof(FILE *));
+	stream_pipe_read = calloc(n_proc, sizeof(int));
+	stream_pipe_write = calloc(n_proc, sizeof(int));
 	if ( filename_pipes == NULL ) {
 		ERROR("Couldn't allocate memory for pipes.\n");
 		return 1;
@@ -1035,6 +1129,14 @@ int main(int argc, char *argv[])
 		ERROR("Couldn't allocate memory for pipe file handles.\n");
 		return 1;
 	}
+	if ( stream_pipe_read == NULL ) {
+		ERROR("Couldn't allocate memory for pipes.\n");
+		return 1;
+	}
+	if ( stream_pipe_write == NULL ) {
+		ERROR("Couldn't allocate memory for pipes.\n");
+		return 1;
+	}
 
 	pids = calloc(n_proc, sizeof(pid_t));
 	if ( pids == NULL ) {
@@ -1048,6 +1150,28 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 
+	for ( i=0; i<n_proc; i++ ) {
+
+		int stream_pipe[2];
+
+		if ( pipe(stream_pipe) == - 1 ) {
+			ERROR("pipe() failed!\n");
+			return 1;
+		}
+
+		stream_pipe_read[i] = stream_pipe[0];
+		stream_pipe_write[i] = stream_pipe[1];
+
+	}
+
+	pr = fork();
+	if ( pr == - 1 ) {
+		ERROR("fork() failed (for reader process)\n");
+		return 1;
+	}
+
+	if ( pr == 0 ) run_reader(stream_pipe_read, n_proc, ofh);
+
 	/* Fork the right number of times */
 	for ( i=0; i<n_proc; i++ ) {
 
@@ -1072,11 +1196,19 @@ int main(int argc, char *argv[])
 		}
 
 		if ( p == 0 ) {
+
+			FILE *fh;
+
 			/* Child process gets the 'read' end of the filename
 			 * pipe, and the 'write' end of the result pipe. */
 			close(filename_pipe[1]);
 			close(result_pipe[0]);
-			run_work(&iargs, filename_pipe[0], result_pipe[1], i);
+
+			fh = fdopen(stream_pipe_write[i], "w");
+			run_work(&iargs, filename_pipe[0], result_pipe[1],
+			         fh, i);
+			fclose(fh);
+
 			exit(0);
 		}
 
@@ -1190,7 +1322,10 @@ int main(int argc, char *argv[])
 
 			if ( nextImage == NULL ) {
 				/* No more images */
-				finished[i] = 1;
+				r = write(filename_pipes[i], "\n", 1);
+				if ( r < 0 ) {
+					ERROR("Write pipe\n");
+				}
 			} else {
 
 				r = write(filename_pipes[i], nextImage,
@@ -1226,12 +1361,20 @@ int main(int argc, char *argv[])
 
 	}
 
+	for ( i=0; i<n_proc; i++ ) {
+		int status;
+		waitpid(pids[i], &status, 0);
+	}
+
 	for ( i=0; i<n_proc; i++ ) {
 		close(filename_pipes[i]);
 		fclose(result_fhs[i]);
 	}
+
 	free(filename_pipes);
 	free(result_fhs);
+	free(stream_pipe_read);
+	free(stream_pipe_write);
 	free(pids);
 	free(finished);
 
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