From: Timo Kokkonen <timo.t.kokkonen@iki.fi>
Date: Mon, 11 Jul 2016 11:56:48 +0000 (+0300)
Subject: onewire_parser: Keep server handle open at all time
X-Git-Url: http://git.itanic.dy.fi/?p=rrdd;a=commitdiff_plain;h=caedc46c0bfa22e0f8bdfd31132083383ca43994

onewire_parser: Keep server handle open at all time

On libowfs 2.7 there appear to be a problem when releasing the client
resources. At least sockets are left open every now and then. There is
no such problem with 3.1 version.

To resolve the issue with older client library, keep the serve handle
open at all time. Release it only when there is a change with the
server address, which normally does not happen ever.

Signed-off-by: Timo Kokkonen <timo.t.kokkonen@iki.fi>
---

diff --git a/onewire_parser.c b/onewire_parser.c
index eb2ccd2..9f4b404 100644
--- a/onewire_parser.c
+++ b/onewire_parser.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <ownetapi.h>
 
+#include "process.h"
 #include "parser.h"
 #include "debug.h"
 #include "string.h"
@@ -8,6 +9,11 @@
 #include "plugin.h"
 #include "version.h"
 
+static struct mutex server_lock = {
+	.name = "server_addr_lock",
+	.lock = PTHREAD_MUTEX_INITIALIZER,
+};
+
 static int parse_opts(const char *str, char *ow_path, size_t pathlen, double *offset)
 {
 	char *endptr;
@@ -75,8 +81,8 @@ static int make_uncached(char *path, size_t len)
 
 static int onewire_parser(char *rrd_data, const char **parser_data)
 {
-	OWNET_HANDLE h;
-	const char *server_addr;
+	static OWNET_HANDLE handle;
+	static char *server_addr;
 	char buf[24], *tmp;
 	int i = 1, ret;
 	int max_str = RRD_DATA_MAX_LEN;
@@ -86,16 +92,36 @@ static int onewire_parser(char *rrd_data, const char **parser_data)
 		return -1;
 	}
 
-	server_addr = parser_data[0];
-
-	if (!server_addr) {
+	if (!parser_data[0]) {
 		pr_err("Server address not specified\n");
 		return -1;
 	}
 
-	h = OWNET_init(server_addr);
-	if (h < 0) {
+	/*
+	 * No point trying to connect to the server more than
+	 * once. Also we don't know how thread safe libownet is. One
+	 * lock to protect it all.
+	 */
+	mutex_lock(&server_lock);
+	/*
+	 * Keep one server connection alive at all times. This
+	 * prevents file descriptor leak with older libownet.
+	 */
+	if (!server_addr || handle < 0) {
+		if (server_addr)
+			free(server_addr);
+		server_addr = strdup(parser_data[0]);
+		handle = OWNET_init(server_addr);
+	} else if (strcmp(server_addr, parser_data[0])) {
+		OWNET_close(handle);
+		free(server_addr);
+		server_addr = strdup(parser_data[0]);
+		handle = OWNET_init(server_addr);
+	}
+
+	if (handle < 0) {
 		pr_err("Failed to connect to server %s\n", server_addr);
+		mutex_unlock(&server_lock);
 		return -1;
 	}
 
@@ -121,8 +147,9 @@ undefined:
 
 			pr_info("Reading data for entry %s with offset of %.2f\n",
 				ow_path, offset);
-			ret = OWNET_read(h, ow_path, &tmp);
-
+			ret = OWNET_read(handle, ow_path, &tmp);
+			if (ret < 0)
+				goto err;
 			/* Skip leading white space */
 			tmp2 = tmp;
 			for (j = 0; j < ret && *tmp2 == ' '; j++)
@@ -142,6 +169,7 @@ undefined:
 				break;
 
 			ret = make_uncached(ow_path, sizeof(ow_path));
+err:
 			if (retries >= 10 || ret < 0) {
 				pr_err("Failed to read entry %s: %m\n",
 					parser_data[i]);
@@ -179,7 +207,7 @@ next:
 	}
 	rrd_data = 0;
 
-	OWNET_finish();
+	mutex_unlock(&server_lock);
 	return 0;
 }