X-Git-Url: https://git.octo.it/?p=collectd.git;a=blobdiff_plain;f=src%2Fmemcached.c;h=11df999d977caeacc5e923e07b3d5d28311dc0e6;hp=cfdf903d5de1424a70045c6f738fb4a452d2c66d;hb=d486225f89ea52d8ed2b4242eba2ad94c409f837;hpb=35a6c9c5fcd87cb78451a974c4d5b5707926845c

diff --git a/src/memcached.c b/src/memcached.c
index cfdf903d..11df999d 100644
--- a/src/memcached.c
+++ b/src/memcached.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2009       Doug MacEachern
  * Copyright (C) 2009       Franck Lombardi
  * Copyright (C) 2012       Nicolas Szalay
+ * Copyright (C) 2017       Pavel Rochnyak
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -26,6 +27,7 @@
  *   Doug MacEachern <dougm at hyperic.com>
  *   Franck Lombardi
  *   Nicolas Szalay
+ *   Pavel Rochnyak <pavel2000 ngs.ru>
  **/
 
 #include "collectd.h"
@@ -38,8 +40,23 @@
 #include <netinet/tcp.h>
 #include <sys/un.h>
 
+#include <poll.h>
+
 #define MEMCACHED_DEF_HOST "127.0.0.1"
 #define MEMCACHED_DEF_PORT "11211"
+#define MEMCACHED_CONNECT_TIMEOUT 10000
+#define MEMCACHED_IO_TIMEOUT 5000
+
+struct prev_s {
+  derive_t hits;
+  derive_t gets;
+  derive_t incr_hits;
+  derive_t incr_misses;
+  derive_t decr_hits;
+  derive_t decr_misses;
+};
+
+typedef struct prev_s prev_t;
 
 struct memcached_s {
   char *name;
@@ -47,16 +64,24 @@ struct memcached_s {
   char *socket;
   char *connhost;
   char *connport;
+  int fd;
+  prev_t prev;
 };
 typedef struct memcached_s memcached_t;
 
-static _Bool memcached_have_instances = 0;
+static bool memcached_have_instances;
 
 static void memcached_free(void *arg) {
   memcached_t *st = arg;
   if (st == NULL)
     return;
 
+  if (st->fd >= 0) {
+    shutdown(st->fd, SHUT_RDWR);
+    close(st->fd);
+    st->fd = -1;
+  }
+
   sfree(st->name);
   sfree(st->host);
   sfree(st->socket);
@@ -67,18 +92,16 @@ static void memcached_free(void *arg) {
 
 static int memcached_connect_unix(memcached_t *st) {
   struct sockaddr_un serv_addr = {0};
-  int fd;
 
   serv_addr.sun_family = AF_UNIX;
   sstrncpy(serv_addr.sun_path, st->socket, sizeof(serv_addr.sun_path));
 
   /* create our socket descriptor */
-  fd = socket(AF_UNIX, SOCK_STREAM, 0);
+  int fd = socket(AF_UNIX, SOCK_STREAM, 0);
   if (fd < 0) {
-    char errbuf[1024];
     ERROR("memcached plugin: memcached_connect_unix: socket(2) failed: %s",
-          sstrerror(errno, errbuf, sizeof(errbuf)));
-    return (-1);
+          STRERRNO);
+    return -1;
   }
 
   /* connect to the memcached daemon */
@@ -86,30 +109,35 @@ static int memcached_connect_unix(memcached_t *st) {
   if (status != 0) {
     shutdown(fd, SHUT_RDWR);
     close(fd);
-    fd = -1;
+    return -1;
+  }
+
+  /* switch to non-blocking mode */
+  int flags = fcntl(fd, F_GETFL);
+  status = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+  if (status != 0) {
+    close(fd);
+    return -1;
   }
 
-  return (fd);
+  return fd;
 } /* int memcached_connect_unix */
 
 static int memcached_connect_inet(memcached_t *st) {
   struct addrinfo *ai_list;
-  int status;
   int fd = -1;
 
   struct addrinfo ai_hints = {.ai_family = AF_UNSPEC,
                               .ai_flags = AI_ADDRCONFIG,
                               .ai_socktype = SOCK_STREAM};
 
-  status = getaddrinfo(st->connhost, st->connport, &ai_hints, &ai_list);
+  int status = getaddrinfo(st->connhost, st->connport, &ai_hints, &ai_list);
   if (status != 0) {
-    char errbuf[1024];
     ERROR("memcached plugin: memcached_connect_inet: "
           "getaddrinfo(%s,%s) failed: %s",
           st->connhost, st->connport,
-          (status == EAI_SYSTEM) ? sstrerror(errno, errbuf, sizeof(errbuf))
-                                 : gai_strerror(status));
-    return (-1);
+          (status == EAI_SYSTEM) ? STRERRNO : gai_strerror(status));
+    return -1;
   }
 
   for (struct addrinfo *ai_ptr = ai_list; ai_ptr != NULL;
@@ -117,84 +145,162 @@ static int memcached_connect_inet(memcached_t *st) {
     /* create our socket descriptor */
     fd = socket(ai_ptr->ai_family, ai_ptr->ai_socktype, ai_ptr->ai_protocol);
     if (fd < 0) {
-      char errbuf[1024];
       WARNING("memcached plugin: memcached_connect_inet: "
               "socket(2) failed: %s",
-              sstrerror(errno, errbuf, sizeof(errbuf)));
+              STRERRNO);
+      continue;
+    }
+
+    /* switch socket to non-blocking mode */
+    int flags = fcntl(fd, F_GETFL);
+    status = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+    if (status != 0) {
+      close(fd);
+      fd = -1;
       continue;
     }
 
     /* connect to the memcached daemon */
     status = (int)connect(fd, ai_ptr->ai_addr, ai_ptr->ai_addrlen);
-    if (status != 0) {
+    if (status != 0 && errno != EINPROGRESS) {
       shutdown(fd, SHUT_RDWR);
       close(fd);
       fd = -1;
       continue;
     }
 
-    /* A socket could be opened and connecting succeeded. We're done. */
+    /* Wait until connection establishes */
+    struct pollfd pollfd = {
+        .fd = fd, .events = POLLOUT,
+    };
+    do
+      status = poll(&pollfd, 1, MEMCACHED_CONNECT_TIMEOUT);
+    while (status < 0 && errno == EINTR);
+    if (status <= 0) {
+      close(fd);
+      fd = -1;
+      continue;
+    }
+
+    /* Check if all is good */
+    int socket_error;
+    status = getsockopt(fd, SOL_SOCKET, SO_ERROR, (void *)&socket_error,
+                        &(socklen_t){sizeof(socket_error)});
+    if (status != 0 || socket_error != 0) {
+      close(fd);
+      fd = -1;
+      continue;
+    }
+    /* A socket is opened and connection succeeded. We're done. */
     break;
   }
 
   freeaddrinfo(ai_list);
-  return (fd);
+  return fd;
 } /* int memcached_connect_inet */
 
-static int memcached_connect(memcached_t *st) {
+static void memcached_connect(memcached_t *st) {
+  if (st->fd >= 0)
+    return;
+
   if (st->socket != NULL)
-    return (memcached_connect_unix(st));
+    st->fd = memcached_connect_unix(st);
   else
-    return (memcached_connect_inet(st));
+    st->fd = memcached_connect_inet(st);
+
+  if (st->fd >= 0)
+    INFO("memcached plugin: Instance \"%s\": connection established.",
+         st->name);
 }
 
 static int memcached_query_daemon(char *buffer, size_t buffer_size,
                                   memcached_t *st) {
-  int fd, status;
+  int status;
   size_t buffer_fill;
 
-  fd = memcached_connect(st);
-  if (fd < 0) {
+  memcached_connect(st);
+  if (st->fd < 0) {
     ERROR("memcached plugin: Instance \"%s\" could not connect to daemon.",
           st->name);
     return -1;
   }
 
-  status = (int)swrite(fd, "stats\r\n", strlen("stats\r\n"));
+  struct pollfd pollfd = {
+      .fd = st->fd, .events = POLLOUT,
+  };
+
+  do
+    status = poll(&pollfd, 1, MEMCACHED_IO_TIMEOUT);
+  while (status < 0 && errno == EINTR);
+
+  if (status <= 0) {
+    ERROR("memcached plugin: poll() failed for write() call.");
+    close(st->fd);
+    st->fd = -1;
+    return -1;
+  }
+
+  status = (int)swrite(st->fd, "stats\r\n", strlen("stats\r\n"));
   if (status != 0) {
-    char errbuf[1024];
-    ERROR("memcached plugin: write(2) failed: %s",
-          sstrerror(errno, errbuf, sizeof(errbuf)));
-    shutdown(fd, SHUT_RDWR);
-    close(fd);
-    return (-1);
+    ERROR("memcached plugin: Instance \"%s\": write(2) failed: %s", st->name,
+          STRERRNO);
+    shutdown(st->fd, SHUT_RDWR);
+    close(st->fd);
+    st->fd = -1;
+    return -1;
   }
 
   /* receive data from the memcached daemon */
   memset(buffer, 0, buffer_size);
 
   buffer_fill = 0;
-  while ((status = (int)recv(fd, buffer + buffer_fill,
-                             buffer_size - buffer_fill, /* flags = */ 0)) !=
-         0) {
+  pollfd.events = POLLIN;
+  while (1) {
+    do
+      status = poll(&pollfd, 1, MEMCACHED_IO_TIMEOUT);
+    while (status < 0 && errno == EINTR);
+
+    if (status <= 0) {
+      ERROR("memcached plugin: Instance \"%s\": Timeout reading from socket",
+            st->name);
+      close(st->fd);
+      st->fd = -1;
+      return -1;
+    }
+
+    do
+      status = (int)recv(st->fd, buffer + buffer_fill,
+                         buffer_size - buffer_fill, /* flags = */ 0);
+    while (status < 0 && errno == EINTR);
+
     char const end_token[5] = {'E', 'N', 'D', '\r', '\n'};
     if (status < 0) {
-      char errbuf[1024];
 
-      if ((errno == EAGAIN) || (errno == EINTR))
+      if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
         continue;
 
-      ERROR("memcached: Error reading from socket: %s",
-            sstrerror(errno, errbuf, sizeof(errbuf)));
-      shutdown(fd, SHUT_RDWR);
-      close(fd);
-      return (-1);
+      ERROR("memcached plugin: Instance \"%s\": Error reading from socket: %s",
+            st->name, STRERRNO);
+      shutdown(st->fd, SHUT_RDWR);
+      close(st->fd);
+      st->fd = -1;
+      return -1;
+    } else if (status == 0) {
+      ERROR("memcached plugin: Instance \"%s\": Connection closed by peer",
+            st->name);
+      close(st->fd);
+      st->fd = -1;
+      return -1;
     }
 
     buffer_fill += (size_t)status;
     if (buffer_fill > buffer_size) {
       buffer_fill = buffer_size;
-      WARNING("memcached plugin: Message was truncated.");
+      WARNING("memcached plugin: Instance \"%s\": Message was truncated.",
+              st->name);
+      shutdown(st->fd, SHUT_RDWR);
+      close(st->fd);
+      st->fd = -1;
       break;
     }
 
@@ -206,13 +312,12 @@ static int memcached_query_daemon(char *buffer, size_t buffer_size,
 
   status = 0;
   if (buffer_fill == 0) {
-    WARNING("memcached plugin: No data returned by memcached.");
+    WARNING("memcached plugin: Instance \"%s\": No data returned by memcached.",
+            st->name);
     status = -1;
   }
 
-  shutdown(fd, SHUT_RDWR);
-  close(fd);
-  return (status);
+  return status;
 } /* int memcached_query_daemon */
 
 static void memcached_init_vl(value_list_t *vl, memcached_t const *st) {
@@ -285,29 +390,74 @@ static void submit_gauge2(const char *type, const char *type_inst,
   plugin_dispatch_values(&vl);
 }
 
+static gauge_t calculate_ratio_percent(derive_t part, derive_t total,
+                                       derive_t *prev_part,
+                                       derive_t *prev_total) {
+  if ((*prev_part == 0) || (*prev_total == 0) || (part < *prev_part) ||
+      (total < *prev_total)) {
+    *prev_part = part;
+    *prev_total = total;
+    return NAN;
+  }
+
+  derive_t num = part - *prev_part;
+  derive_t denom = total - *prev_total;
+
+  *prev_part = part;
+  *prev_total = total;
+
+  if (denom == 0)
+    return NAN;
+
+  if (num == 0)
+    return 0;
+
+  return 100.0 * (gauge_t)num / (gauge_t)denom;
+}
+
+static gauge_t calculate_ratio_percent2(derive_t part1, derive_t part2,
+                                        derive_t *prev1, derive_t *prev2) {
+  if ((*prev1 == 0) || (*prev2 == 0) || (part1 < *prev1) || (part2 < *prev2)) {
+    *prev1 = part1;
+    *prev2 = part2;
+    return NAN;
+  }
+
+  derive_t num = part1 - *prev1;
+  derive_t denom = part2 - *prev2 + num;
+
+  *prev1 = part1;
+  *prev2 = part2;
+
+  if (denom == 0)
+    return NAN;
+
+  if (num == 0)
+    return 0;
+
+  return 100.0 * (gauge_t)num / (gauge_t)denom;
+}
+
 static int memcached_read(user_data_t *user_data) {
   char buf[4096];
   char *fields[3];
-  char *ptr;
   char *line;
-  char *saveptr;
-  int fields_num;
-
-  gauge_t bytes_used = NAN;
-  gauge_t bytes_total = NAN;
-  gauge_t hits = NAN;
-  gauge_t gets = NAN;
-  gauge_t incr_hits = NAN;
-  derive_t incr = 0;
-  gauge_t decr_hits = NAN;
-  derive_t decr = 0;
+
+  derive_t bytes_used = 0;
+  derive_t bytes_total = 0;
+  derive_t get_hits = 0;
+  derive_t cmd_get = 0;
+  derive_t incr_hits = 0;
+  derive_t incr_misses = 0;
+  derive_t decr_hits = 0;
+  derive_t decr_misses = 0;
   derive_t rusage_user = 0;
   derive_t rusage_syst = 0;
   derive_t octets_rx = 0;
   derive_t octets_tx = 0;
 
-  memcached_t *st;
-  st = user_data->data;
+  memcached_t *st = user_data->data;
+  prev_t *prev = &st->prev;
 
   /* get data from daemon */
   if (memcached_query_daemon(buf, sizeof(buf), st) < 0) {
@@ -317,18 +467,15 @@ static int memcached_read(user_data_t *user_data) {
 #define FIELD_IS(cnst)                                                         \
   (((sizeof(cnst) - 1) == name_len) && (strcmp(cnst, fields[1]) == 0))
 
-  ptr = buf;
-  saveptr = NULL;
+  char *ptr = buf;
+  char *saveptr = NULL;
   while ((line = strtok_r(ptr, "\n\r", &saveptr)) != NULL) {
-    int name_len;
-
     ptr = NULL;
 
-    fields_num = strsplit(line, fields, 3);
-    if (fields_num != 3)
+    if (strsplit(line, fields, 3) != 3)
       continue;
 
-    name_len = strlen(fields[1]);
+    int name_len = strlen(fields[1]);
     if (name_len == 0)
       continue;
 
@@ -365,9 +512,9 @@ static int memcached_read(user_data_t *user_data) {
      * Number of bytes used and available (total - used)
      */
     else if (FIELD_IS("bytes")) {
-      bytes_used = atof(fields[2]);
+      bytes_used = atoll(fields[2]);
     } else if (FIELD_IS("limit_maxbytes")) {
-      bytes_total = atof(fields[2]);
+      bytes_total = atoll(fields[2]);
     }
 
     /*
@@ -376,7 +523,14 @@ static int memcached_read(user_data_t *user_data) {
     else if (FIELD_IS("curr_connections")) {
       submit_gauge("memcached_connections", "current", atof(fields[2]), st);
     } else if (FIELD_IS("listen_disabled_num")) {
-      submit_derive("connections", "listen_disabled", atof(fields[2]), st);
+      submit_derive("total_events", "listen_disabled", atoll(fields[2]), st);
+    }
+    /*
+     * Total number of connections opened since the server started running
+     * Report this as connection rate.
+     */
+    else if (FIELD_IS("total_connections")) {
+      submit_derive("connections", "opened", atoll(fields[2]), st);
     }
 
     /*
@@ -386,43 +540,43 @@ static int memcached_read(user_data_t *user_data) {
       const char *name = fields[1] + 4;
       submit_derive("memcached_command", name, atoll(fields[2]), st);
       if (strcmp(name, "get") == 0)
-        gets = atof(fields[2]);
+        cmd_get = atoll(fields[2]);
     }
 
     /*
      * Increment/Decrement
      */
     else if (FIELD_IS("incr_misses")) {
-      derive_t incr_count = atoll(fields[2]);
-      submit_derive("memcached_ops", "incr_misses", incr_count, st);
-      incr += incr_count;
+      incr_misses = atoll(fields[2]);
+      submit_derive("memcached_ops", "incr_misses", incr_misses, st);
     } else if (FIELD_IS("incr_hits")) {
-      derive_t incr_count = atoll(fields[2]);
-      submit_derive("memcached_ops", "incr_hits", incr_count, st);
-      incr_hits = atof(fields[2]);
-      incr += incr_count;
+      incr_hits = atoll(fields[2]);
+      submit_derive("memcached_ops", "incr_hits", incr_hits, st);
     } else if (FIELD_IS("decr_misses")) {
-      derive_t decr_count = atoll(fields[2]);
-      submit_derive("memcached_ops", "decr_misses", decr_count, st);
-      decr += decr_count;
+      decr_misses = atoll(fields[2]);
+      submit_derive("memcached_ops", "decr_misses", decr_misses, st);
     } else if (FIELD_IS("decr_hits")) {
-      derive_t decr_count = atoll(fields[2]);
-      submit_derive("memcached_ops", "decr_hits", decr_count, st);
-      decr_hits = atof(fields[2]);
-      decr += decr_count;
+      decr_hits = atoll(fields[2]);
+      submit_derive("memcached_ops", "decr_hits", decr_hits, st);
     }
 
     /*
-     * Operations on the cache, i. e. cache hits, cache misses and evictions of
-     * items
+     * Operations on the cache:
+     * - get hits/misses
+     * - delete hits/misses
+     * - evictions
      */
     else if (FIELD_IS("get_hits")) {
-      submit_derive("memcached_ops", "hits", atoll(fields[2]), st);
-      hits = atof(fields[2]);
+      get_hits = atoll(fields[2]);
+      submit_derive("memcached_ops", "hits", get_hits, st);
     } else if (FIELD_IS("get_misses")) {
       submit_derive("memcached_ops", "misses", atoll(fields[2]), st);
     } else if (FIELD_IS("evictions")) {
       submit_derive("memcached_ops", "evictions", atoll(fields[2]), st);
+    } else if (FIELD_IS("delete_hits")) {
+      submit_derive("memcached_ops", "delete_hits", atoll(fields[2]), st);
+    } else if (FIELD_IS("delete_misses")) {
+      submit_derive("memcached_ops", "delete_misses", atoll(fields[2]), st);
     }
 
     /*
@@ -435,7 +589,7 @@ static int memcached_read(user_data_t *user_data) {
     }
   } /* while ((line = strtok_r (ptr, "\n\r", &saveptr)) != NULL) */
 
-  if (!isnan(bytes_used) && !isnan(bytes_total) && (bytes_used <= bytes_total))
+  if ((bytes_total > 0) && (bytes_used <= bytes_total))
     submit_gauge2("df", "cache", bytes_used, bytes_total - bytes_used, st);
 
   if ((rusage_user != 0) || (rusage_syst != 0))
@@ -444,37 +598,30 @@ static int memcached_read(user_data_t *user_data) {
   if ((octets_rx != 0) || (octets_tx != 0))
     submit_derive2("memcached_octets", NULL, octets_rx, octets_tx, st);
 
-  if (!isnan(gets) && !isnan(hits)) {
-    gauge_t rate = NAN;
-
-    if (gets != 0.0)
-      rate = 100.0 * hits / gets;
-
-    submit_gauge("percent", "hitratio", rate, st);
+  if ((cmd_get != 0) && (get_hits != 0)) {
+    gauge_t ratio =
+        calculate_ratio_percent(get_hits, cmd_get, &prev->hits, &prev->gets);
+    submit_gauge("percent", "hitratio", ratio, st);
   }
 
-  if (!isnan(incr_hits) && incr != 0) {
-    gauge_t incr_rate = 100.0 * incr_hits / incr;
-    submit_gauge("percent", "incr_hitratio", incr_rate, st);
-    submit_derive("memcached_ops", "incr", incr, st);
+  if ((incr_hits != 0) && (incr_misses != 0)) {
+    gauge_t ratio = calculate_ratio_percent2(
+        incr_hits, incr_misses, &prev->incr_hits, &prev->incr_misses);
+    submit_gauge("percent", "incr_hitratio", ratio, st);
+    submit_derive("memcached_ops", "incr", incr_hits + incr_misses, st);
   }
 
-  if (!isnan(decr_hits) && decr != 0) {
-    gauge_t decr_rate = 100.0 * decr_hits / decr;
-    submit_gauge("percent", "decr_hitratio", decr_rate, st);
-    submit_derive("memcached_ops", "decr", decr, st);
+  if ((decr_hits != 0) && (decr_misses != 0)) {
+    gauge_t ratio = calculate_ratio_percent2(
+        decr_hits, decr_misses, &prev->decr_hits, &prev->decr_misses);
+    submit_gauge("percent", "decr_hitratio", ratio, st);
+    submit_derive("memcached_ops", "decr", decr_hits + decr_misses, st);
   }
 
   return 0;
 } /* int memcached_read */
 
-static int memcached_add_read_callback(memcached_t *st) {
-  char callback_name[3 * DATA_MAX_NAME_LEN];
-  int status;
-
-  ssnprintf(callback_name, sizeof(callback_name), "memcached/%s",
-            (st->name != NULL) ? st->name : "__legacy__");
-
+static int memcached_set_defaults(memcached_t *st) {
   /* If no <Address> used then:
    * - Connect to the destination specified by <Host>, if present.
    *   If not, use the default address.
@@ -490,7 +637,7 @@ static int memcached_add_read_callback(memcached_t *st) {
     if (st->host) {
       st->connhost = strdup(st->host);
       if (st->connhost == NULL)
-        return (ENOMEM);
+        return ENOMEM;
 
       if ((strcmp("127.0.0.1", st->host) == 0) ||
           (strcmp("localhost", st->host) == 0))
@@ -498,28 +645,48 @@ static int memcached_add_read_callback(memcached_t *st) {
     } else {
       st->connhost = strdup(MEMCACHED_DEF_HOST);
       if (st->connhost == NULL)
-        return (ENOMEM);
+        return ENOMEM;
     }
   }
 
   if (st->connport == NULL) {
     st->connport = strdup(MEMCACHED_DEF_PORT);
     if (st->connport == NULL)
-      return (ENOMEM);
+      return ENOMEM;
   }
 
   assert(st->connhost != NULL);
   assert(st->connport != NULL);
 
-  status = plugin_register_complex_read(
+  st->prev.hits = 0;
+  st->prev.gets = 0;
+  st->prev.incr_hits = 0;
+  st->prev.incr_misses = 0;
+  st->prev.decr_hits = 0;
+  st->prev.decr_misses = 0;
+
+  return 0;
+} /* int memcached_set_defaults */
+
+static int memcached_add_read_callback(memcached_t *st) {
+  char callback_name[3 * DATA_MAX_NAME_LEN];
+
+  if (memcached_set_defaults(st) != 0) {
+    memcached_free(st);
+    return -1;
+  }
+
+  snprintf(callback_name, sizeof(callback_name), "memcached/%s",
+           (st->name != NULL) ? st->name : "__legacy__");
+
+  return plugin_register_complex_read(
       /* group = */ "memcached",
       /* name      = */ callback_name,
       /* callback  = */ memcached_read,
-      /* interval  = */ 0, &(user_data_t){
-                               .data = st, .free_func = memcached_free,
-                           });
-
-  return (status);
+      /* interval  = */ 0,
+      &(user_data_t){
+          .data = st, .free_func = memcached_free,
+      });
 } /* int memcached_add_read_callback */
 
 /* Configuration handling functiions
@@ -532,16 +699,15 @@ static int memcached_add_read_callback(memcached_t *st) {
  * </Plugin>
  */
 static int config_add_instance(oconfig_item_t *ci) {
-  memcached_t *st;
   int status = 0;
 
   /* Disable automatic generation of default instance in the init callback. */
-  memcached_have_instances = 1;
+  memcached_have_instances = true;
 
-  st = calloc(1, sizeof(*st));
+  memcached_t *st = calloc(1, sizeof(*st));
   if (st == NULL) {
     ERROR("memcached plugin: calloc failed.");
-    return (ENOMEM);
+    return ENOMEM;
   }
 
   st->name = NULL;
@@ -550,12 +716,14 @@ static int config_add_instance(oconfig_item_t *ci) {
   st->connhost = NULL;
   st->connport = NULL;
 
+  st->fd = -1;
+
   if (strcasecmp(ci->key, "Instance") == 0)
     status = cf_util_get_string(ci, &st->name);
 
   if (status != 0) {
     sfree(st);
-    return (status);
+    return status;
   }
 
   for (int i = 0; i < ci->children_num; i++) {
@@ -578,20 +746,16 @@ static int config_add_instance(oconfig_item_t *ci) {
       break;
   }
 
-  if (status == 0)
-    status = memcached_add_read_callback(st);
-
   if (status != 0) {
     memcached_free(st);
-    return (-1);
+    return -1;
   }
 
-  return (0);
-}
+  return memcached_add_read_callback(st);
+} /* int config_add_instance */
 
 static int memcached_config(oconfig_item_t *ci) {
-  int status = 0;
-  _Bool have_instance_block = 0;
+  bool have_instance_block = 0;
 
   for (int i = 0; i < ci->children_num; i++) {
     oconfig_item_t *child = ci->children + i;
@@ -602,7 +766,7 @@ static int memcached_config(oconfig_item_t *ci) {
     } else if (!have_instance_block) {
       /* Non-instance option: Assume legacy configuration (without <Instance />
        * blocks) and call config_add_instance() with the <Plugin /> block. */
-      return (config_add_instance(ci));
+      return config_add_instance(ci);
     } else
       WARNING("memcached plugin: The configuration option "
               "\"%s\" is not allowed here. Did you "
@@ -611,33 +775,31 @@ static int memcached_config(oconfig_item_t *ci) {
               child->key);
   } /* for (ci->children) */
 
-  return (status);
-}
+  return 0;
+} /* int memcached_config */
 
 static int memcached_init(void) {
-  memcached_t *st;
-  int status;
 
   if (memcached_have_instances)
-    return (0);
+    return 0;
 
   /* No instances were configured, lets start a default instance. */
-  st = calloc(1, sizeof(*st));
+  memcached_t *st = calloc(1, sizeof(*st));
   if (st == NULL)
-    return (ENOMEM);
+    return ENOMEM;
   st->name = NULL;
   st->host = NULL;
   st->socket = NULL;
   st->connhost = NULL;
   st->connport = NULL;
 
-  status = memcached_add_read_callback(st);
+  st->fd = -1;
+
+  int status = memcached_add_read_callback(st);
   if (status == 0)
-    memcached_have_instances = 1;
-  else
-    memcached_free(st);
+    memcached_have_instances = true;
 
-  return (status);
+  return status;
 } /* int memcached_init */
 
 void module_register(void) {