Add --maxcount to dpservice-dump

Author: PlagueCZ

docs/deployment/help_dpservice-dump.md

@@ -9,6 +9,7 @@
 | --nodes | REGEX | show graph node traversal, limit to REGEX-matched nodes (empty string for all) |  |
 | --filter | FILTER | show only packets matching a pcap-style FILTER |  |
 | --pcap | FILE | write packets into a PCAP file |  |
+| -c, --maxcount | COUNT | exit after receiving COUNT packets |  |
 | --stop | None | do nothing, only make sure tracing is disabled in dp-service |  |
 
 > This file has been generated by dp_conf_generate.py. As such it should fully reflect the output of `--help`.

tools/dump/dp_conf.json

@@ -33,6 +33,16 @@
       "help": "write packets into a PCAP file",
       "arg": "FILE"
     },
+    {
+      "shopt": "c",
+      "lgopt": "maxcount",
+      "help": "exit after receiving COUNT packets",
+      "arg": "COUNT",
+      "var": "count",
+      "type": "int",
+      "min": 0,
+      "default": 0
+    },
     {
       "lgopt": "stop",
       "help": "do nothing, only make sure tracing is disabled in dp-service",

tools/dump/main.c

@@ -3,6 +3,7 @@
 
 #include <fcntl.h>
 #include <getopt.h>
+#include <limits.h>
 #include <regex.h>
 #include <signal.h>
 #include <stdio.h>
@@ -47,6 +48,8 @@ static char packet_filter[DP_GRAPHTRACE_FILTER_MAXLEN] = "";
 static bool interrupt = false;
 static bool primary_alive = false;
 
+static unsigned int packet_limit = UINT_MAX;
+
 // optimization to prevent 'if (pcap) pcap_dump(); else print_packet();' in a loop
 static void print_packet(struct dp_pcap *dp_pcap, struct rte_mbuf *m, struct timeval *timestamp);
 static void (*dump_func)(struct dp_pcap *dp_pcap, struct rte_mbuf *m, struct timeval *timestamp) = print_packet;
@@ -128,9 +131,14 @@ static int dp_graphtrace_dump(struct dp_graphtrace *graphtrace)
 			// TODO timestamp should be sent by dpservice
 			// ignoring failure for speed
 			gettimeofday(&timestamp, NULL);
-			for (unsigned int i = 0; i < received; ++i)
+			for (unsigned int i = 0; i < received; ++i) {
 				dump_func(&dp_pcap, (struct rte_mbuf *)objs[i], &timestamp);
+				if (--packet_limit == 0)
+					break;
+			}
 			rte_mempool_put_bulk(graphtrace->mempool, objs, received);
+			if (packet_limit == 0)
+				break;
 		}
 		if (available == 0)
 			usleep(WAIT_INTERVAL);
@@ -293,6 +301,9 @@ static int do_graphtrace(void)
 		}
 	}
 
+	if (dp_conf_get_count() > 0)
+		packet_limit = dp_conf_get_count();
+
 	ret = dp_graphtrace_main();
 
 	if (pcap_path)

tools/dump/opts.c

@@ -17,6 +17,7 @@
 enum {
 	OPT_HELP = 'h',
 	OPT_VERSION = 'v',
+	OPT_MAXCOUNT = 'c',
 _OPT_SHOPT_MAX = 255,
 	OPT_FILE_PREFIX,
 	OPT_DROPS,
@@ -27,6 +28,7 @@ _OPT_SHOPT_MAX = 255,
 };
 
 #define OPTSTRING ":hv" \
+	"c:" \
 
 static const struct option dp_conf_longopts[] = {
 	{ "help", 0, 0, OPT_HELP },
@@ -36,12 +38,14 @@ static const struct option dp_conf_longopts[] = {
 	{ "nodes", 1, 0, OPT_NODES },
 	{ "filter", 1, 0, OPT_FILTER },
 	{ "pcap", 1, 0, OPT_PCAP },
+	{ "maxcount", 1, 0, OPT_MAXCOUNT },
 	{ "stop", 0, 0, OPT_STOP },
 	{ NULL, 0, 0, 0 }
 };
 
 static char eal_file_prefix[32];
 static bool showing_drops = false;
+static int count = 0;
 static bool stop_mode = false;
 
 const char *dp_conf_get_eal_file_prefix(void)
@@ -54,6 +58,11 @@ bool dp_conf_is_showing_drops(void)
 	return showing_drops;
 }
 
+int dp_conf_get_count(void)
+{
+	return count;
+}
+
 bool dp_conf_is_stop_mode(void)
 {
 	return stop_mode;
@@ -78,6 +87,7 @@ static inline void dp_argparse_help(const char *progname, FILE *outfile)
 		"     --nodes=REGEX         show graph node traversal, limit to REGEX-matched nodes (empty string for all)\n"
 		"     --filter=FILTER       show only packets matching a pcap-style FILTER\n"
 		"     --pcap=FILE           write packets into a PCAP file\n"
+		" -c, --maxcount=COUNT      exit after receiving COUNT packets\n"
 		"     --stop                do nothing, only make sure tracing is disabled in dp-service\n"
 	, progname);
 }
@@ -96,6 +106,8 @@ static int dp_conf_parse_arg(int opt, const char *arg)
 		return dp_argparse_opt_filter(arg);
 	case OPT_PCAP:
 		return dp_argparse_opt_pcap(arg);
+	case OPT_MAXCOUNT:
+		return dp_argparse_int(arg, &count, 0, INT_MAX);
 	case OPT_STOP:
 		return dp_argparse_store_true(&stop_mode);
 	default:

tools/dump/opts.h

@@ -10,6 +10,7 @@
 
 const char *dp_conf_get_eal_file_prefix(void);
 bool dp_conf_is_showing_drops(void);
+int dp_conf_get_count(void);
 bool dp_conf_is_stop_mode(void);
 
 enum dp_conf_runmode {