From: Matwey V. Kornilov <matwey.kornilov@gmail.com>
Date: Wed, 5 Jan 2022 14:20:06 +0000 (+0300)
Subject: Initial implementation for epics plugin
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=75cb76e14912826c267397347b4ab28b080e730b;p=thirdparty%2Fcollectd.git

Initial implementation for epics plugin

EPICS is Experimental Physics and Industrial Control System.

Reference: https://epics-controls.org/

Signed-off-by: Matwey V. Kornilov <matwey.kornilov@gmail.com>
---

diff --git a/Makefile.am b/Makefile.am
index 2d1cb823d..64c719c48 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1064,6 +1064,14 @@ entropy_la_SOURCES = src/entropy.c
 entropy_la_LDFLAGS = $(PLUGIN_LDFLAGS)
 endif
 
+if BUILD_PLUGIN_EPICS
+pkglib_LTLIBRARIES += epics.la
+epics_la_CFLAGS = $(AM_CFLAGS) $(BUILD_WITH_EPICS_BASE_CFLAGS)
+epics_la_SOURCES = src/epics.c
+epics_la_LDFLAGS = $(PLUGIN_LDFLAGS)
+epics_la_LIBADD = -lpthread $(BUILD_WITH_EPICS_BASE_LIBS)
+endif
+
 if BUILD_PLUGIN_EXEC
 pkglib_LTLIBRARIES += exec.la
 exec_la_SOURCES = src/exec.c
diff --git a/README.md b/README.md
index 32e9a4a4a..88b97162e 100644
--- a/README.md
+++ b/README.md
@@ -149,6 +149,10 @@ Features
     - entropy
       Amount of entropy available to the system.
 
+    - epics
+      Collect data from EPICS message bus.
+      <https://epics-controls.org>
+
     - ethstat
       Network interface card statistics.
 
diff --git a/configure.ac b/configure.ac
index 96e196e84..652c3aea6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2079,6 +2079,35 @@ AC_SUBST([BUILD_WITH_CUDA_LIBS])
 
 # }}}
 
+# --with-epics-base {{{
+AC_ARG_WITH([epics-base],
+  [AS_HELP_STRING([--with-epics-base@<:@=PREFIX@:>@], [Path to epics-base.])],
+  [
+    with_epics_base="$withval"
+    if test "x$withval" = "xno"; then
+      with_epics_base="no (disabled on command line)"
+    fi
+  ],
+  [with_epics_base="yes"]
+)
+
+if test "x$with_epics_base" = "xyes"; then
+PKG_CHECK_MODULES([EPICS_BASE], [epics-base],
+  [with_epics_base="yes"],
+  [with_epics_base="no (pkg-config could not find epics-base)"]
+)
+fi
+
+if test "x$with_epics_base" = "xyes"; then
+  BUILD_WITH_EPICS_BASE_CFLAGS="$EPICS_BASE_CFLAGS"
+  BUILD_WITH_EPICS_BASE_LIBS="$EPICS_BASE_LIBS -lca"
+fi
+
+AC_SUBST([BUILD_WITH_EPICS_BASE_CFLAGS])
+AC_SUBST([BUILD_WITH_EPICS_BASE_LIBS])
+
+# }}}
+
 # --with-libaquaero5 {{{
 AC_ARG_WITH([libaquaero5],
   [AS_HELP_STRING([--with-libaquaero5@<:@=PREFIX@:>@], [Path to aquatools-ng source code.])],
@@ -6740,6 +6769,7 @@ plugin_dpdkevents="no"
 plugin_dpdkstat="no"
 plugin_dpdk_telemetry="no"
 plugin_entropy="no"
+plugin_epics="no"
 plugin_ethstat="no"
 plugin_fhcount="no"
 plugin_fscache="no"
@@ -7219,6 +7249,7 @@ AC_PLUGIN([dpdk_telemetry],      [$plugin_dpdk_telemetry],    [Metrics from DPDK
 AC_PLUGIN([drbd],                [$plugin_drbd],              [DRBD statistics])
 AC_PLUGIN([email],               [yes],                       [EMail statistics])
 AC_PLUGIN([entropy],             [$plugin_entropy],           [Entropy statistics])
+AC_PLUGIN([epics],               [$with_epics_base],          [EPICS CA plugin])
 AC_PLUGIN([ethstat],             [$plugin_ethstat],           [Stats from NIC driver])
 AC_PLUGIN([exec],                [yes],                       [Execution of external programs])
 AC_PLUGIN([fhcount],             [$plugin_fhcount],           [File handles statistics])
@@ -7552,6 +7583,7 @@ AC_MSG_RESULT([    YACC  . . . . . . . . $YACC])
 AC_MSG_RESULT([    YFLAGS  . . . . . . . $YFLAGS])
 AC_MSG_RESULT()
 AC_MSG_RESULT([  Libraries:])
+AC_MSG_RESULT([    epics . . . . . . . . $with_epics_base])
 AC_MSG_RESULT([    intel mic . . . . . . $with_mic])
 AC_MSG_RESULT([    libaquaero5 . . . . . $with_libaquaero5])
 AC_MSG_RESULT([    libatasmart . . . . . $with_libatasmart])
@@ -7669,6 +7701,7 @@ AC_MSG_RESULT([    drbd  . . . . . . . . $enable_drbd])
 AC_MSG_RESULT([    email . . . . . . . . $enable_email])
 AC_MSG_RESULT([    entropy . . . . . . . $enable_entropy])
 AC_MSG_RESULT([    ethstat . . . . . . . $enable_ethstat])
+AC_MSG_RESULT([    epics . . . . . . . . $enable_epics])
 AC_MSG_RESULT([    exec  . . . . . . . . $enable_exec])
 AC_MSG_RESULT([    fhcount . . . . . . . $enable_fhcount])
 AC_MSG_RESULT([    filecount . . . . . . $enable_filecount])
diff --git a/src/collectd.conf.in b/src/collectd.conf.in
index dc38189ec..c2aa004d5 100644
--- a/src/collectd.conf.in
+++ b/src/collectd.conf.in
@@ -127,6 +127,7 @@
 #@BUILD_PLUGIN_DRBD_TRUE@LoadPlugin drbd
 #@BUILD_PLUGIN_EMAIL_TRUE@LoadPlugin email
 #@BUILD_PLUGIN_ENTROPY_TRUE@LoadPlugin entropy
+#@BUILD_PLUGIN_ENTROPY_TRUE@LoadPlugin epics
 #@BUILD_PLUGIN_ETHSTAT_TRUE@LoadPlugin ethstat
 #@BUILD_PLUGIN_EXEC_TRUE@LoadPlugin exec
 #@BUILD_PLUGIN_FHCOUNT_TRUE@LoadPlugin fhcount
@@ -737,6 +738,14 @@
 #	MaxConns 5
 #</Plugin>
 
+#<Plugin epics>
+#	<Variable "Cavity1:Temp">
+#		Type "gauge"
+#	</Variable>
+#
+#	Label "Cavity1:Name"
+#</Plugin>
+
 #<Plugin ethstat>
 #	Interface "eth0"
 #	Map "rx_csum_offload_errors" "if_rx_errors" "checksum_offload"
diff --git a/src/collectd.conf.pod b/src/collectd.conf.pod
index 9b7be761f..99bd12961 100644
--- a/src/collectd.conf.pod
+++ b/src/collectd.conf.pod
@@ -3318,6 +3318,51 @@ at most B<16384> to prevent typos and dumb mistakes.
 
 =back
 
+=head2 Plugin C<epics>
+
+The I<epics plugin> collects data from EPICS (Experimental Physics and
+Industrial Control System) message bus.
+
+Note that in addition to the plugin configuration, the host OS has to be
+configured to be part of the message bus: caRepeater daemon is up and running
+and appropriate EPICS environment variables are set, if required. Consult EPICS
+documentation for details.
+
+B<Synopsis:>
+
+ <Plugin epics>
+   <Variable "Cavity1:Temp">
+     Type "gauge"
+   </Variable>
+   Label "Cavity1:Name"
+ </Plugin>
+
+B<Options:>
+
+=over 4
+
+=item E<lt>B<Variable> I<PVName>E<gt>
+
+The plugin configuration consists of multiple E<lt>B<Variable>E<gt> blocks,
+each per monitored EPICS Process Variable (PV). The variables are constantly
+monitored and their values are latched once per I<global Interval>.
+
+=item B<Type> I<Type>
+
+This is mandatory option to specify internal collectd type for this particular
+PV. PV data type announced by EPICS and the I<Type> specified here must be in a
+reasonable agreement.
+
+=item B<Label> I<PVName>
+
+Additionally, string-typed PV can be monitored as a B<Label>. For instance,
+this can potentially be useful for tracking an experiment ID. Note that in
+addition to configuring B<Label> the appropriate label-avare collectd writing
+plugin has to be enabled. For instance, I<write_prometheus plugin>,
+I<write_influxdb_udp plugin>, or I<write_http plugin> with InfluxDB B<Format>.
+
+=back
+
 =head2 Plugin C<ethstat>
 
 The I<ethstat plugin> collects information about network interface cards (NICs)
diff --git a/src/epics.c b/src/epics.c
new file mode 100644
index 000000000..9367432cc
--- /dev/null
+++ b/src/epics.c
@@ -0,0 +1,527 @@
+/**
+ * collectd - src/epics.c
+ * Copyright (C) 2022       Matwey V. Kornilov
+ *
+ * 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
+ * Free Software Foundation; only version 2 of the License is applicable.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ *
+ * Authors:
+ *   Matwey V. Kornilov <matwey.kornilov at gmail.com>
+ **/
+
+#include "collectd.h"
+#include "plugin.h"
+#include "utils/common/common.h"
+
+#include <cadef.h>
+
+struct pv {
+  char *name;
+
+  chtype ch_type;
+  chid id;
+  evid eid;
+
+  union {
+    value_list_t value;
+    char *label;
+  };
+
+  bool is_active;
+  bool is_label;
+};
+
+static struct {
+  struct pv *pvs;
+  int pvs_num;
+
+  pthread_mutex_t lock;
+  pthread_t thread_id;
+
+  bool thread_loop;
+} epics_plugin = {.lock = PTHREAD_MUTEX_INITIALIZER};
+
+static void free_pvs() {
+  for (int i = 0; i < epics_plugin.pvs_num; ++i) {
+    struct pv *p = &epics_plugin.pvs[i];
+
+    if (p->is_label) {
+      free(p->label);
+    } else if (p->value.values) {
+      free(p->value.values);
+    }
+    free(p->name);
+  }
+
+  free(epics_plugin.pvs);
+  epics_plugin.pvs = NULL;
+  epics_plugin.pvs_num = 0;
+}
+
+static int printf_handler(const char *pformat, va_list args) {
+#if COLLECT_DEBUG
+  char msg[1024] = ""; // Size inherits from plugin_log()
+
+  int status = vsnprintf(msg, sizeof(msg), pformat, args);
+
+  if (status < 0) {
+    return status;
+  }
+
+  msg[strcspn(msg, "\r\n")] = '\0';
+  plugin_log(LOG_DEBUG, "%s", msg);
+
+  return status;
+#else
+  return 0;
+#endif
+}
+
+static int deduce_channel_type(int ch_type, int ds_type) {
+  if (ds_type == DS_TYPE_COUNTER &&
+      (ch_type == DBR_SHORT || ch_type == DBR_LONG)) {
+    return DBR_LONG;
+  } else if (ds_type == DS_TYPE_GAUGE &&
+             (ch_type == DBR_FLOAT || ch_type == DBR_DOUBLE ||
+              ch_type == DBR_ENUM)) {
+    return DBR_DOUBLE;
+  } else if (ds_type == DS_TYPE_DERIVE &&
+             (ch_type == DBR_SHORT || ch_type == DBR_LONG)) {
+    return DBR_LONG;
+  } else if (ds_type == DS_TYPE_ABSOLUTE &&
+             (ch_type == DBR_SHORT || ch_type == DBR_LONG)) {
+    return DBR_LONG;
+  }
+
+  return -1;
+}
+
+static void handle_var_event(struct pv *p, evargs args) {
+  const data_set_t *ds = plugin_get_ds(p->value.type);
+  const size_t values_len = p->value.values_len;
+  value_t *values = p->value.values;
+
+  if (ds == NULL) {
+    ERROR("epics plugin: Unknown type \"%s\" for channel \"%s\". See "
+          "types.db(5) for details.",
+          p->value.type, p->name);
+
+    return;
+  }
+
+  const int ds_type = ds->ds[0].type;
+
+  if (args.count != values_len) {
+    ERROR(
+        "epics plugin: Unexpected channel element count %lu for channel \"%s\"",
+        args.count, p->name);
+    return;
+  }
+
+  pthread_mutex_lock(&epics_plugin.lock);
+
+  if (ds_type == DS_TYPE_COUNTER && args.type == DBR_LONG) {
+    const long *value = (const long *)args.dbr;
+
+    for (size_t i = 0; i < values_len; ++i) {
+      values[i].counter = value[i];
+    }
+  } else if (ds_type == DS_TYPE_DERIVE && args.type == DBR_LONG) {
+    const long *value = (const long *)args.dbr;
+
+    for (size_t i = 0; i < values_len; ++i) {
+      values[i].derive = value[i];
+    }
+  } else if (ds_type == DS_TYPE_ABSOLUTE && args.type == DBR_LONG) {
+    const long *value = (const long *)args.dbr;
+
+    for (size_t i = 0; i < values_len; ++i) {
+      values[i].absolute = value[i];
+    }
+  } else if (ds_type == DS_TYPE_GAUGE && args.type == DBR_DOUBLE) {
+    const double *value = (const double *)args.dbr;
+
+    for (size_t i = 0; i < values_len; ++i) {
+      values[i].gauge = value[i];
+    }
+  } else {
+    WARNING("epics plugin: Unexpected data type \"%s\" for channel type \"%s\"",
+            DS_TYPE_TO_STRING(ds_type), dbf_type_to_text(args.type));
+  }
+
+  pthread_mutex_unlock(&epics_plugin.lock);
+}
+
+static void handle_label_event(struct pv *p, evargs args) {
+  const char *value = (const char *)args.dbr;
+
+  if (args.count != 1) {
+    ERROR(
+        "epics plugin: Unexpected channel element count %lu for channel \"%s\"",
+        args.count, p->name);
+    return;
+  }
+
+  pthread_mutex_lock(&epics_plugin.lock);
+
+  free(p->label);
+
+  p->label = strdup(value);
+  if (p->label == NULL) {
+    ERROR("epics plugin: Cannot allocate memory for \"%s\" value", p->name);
+
+    return;
+  }
+
+  pthread_mutex_unlock(&epics_plugin.lock);
+}
+
+static void event_handler(evargs args) {
+  struct pv *p = (struct pv *)args.usr;
+
+  if (args.status != ECA_NORMAL) {
+    ERROR("epics plugin: Error %s at channel \"%s\"", ca_message(args.status),
+          p->name);
+
+    return;
+  }
+
+  if (p->is_label) {
+    handle_label_event(p, args);
+  } else {
+    handle_var_event(p, args);
+  }
+}
+
+static void handle_conn_up(struct pv *p) {
+  if (p->eid) {
+    INFO("epics plugin: Channel \"%s\" reconnected", p->name);
+
+    p->is_active = 1;
+
+    return;
+  }
+
+  if (p->is_label) {
+    p->ch_type = DBR_STRING;
+  } else {
+    const data_set_t *ds = plugin_get_ds(p->value.type);
+
+    if (ds == NULL) {
+      ERROR("epics plugin: Unknown type \"%s\" for channel \"%s\". See "
+            "types.db(5) for details.",
+            p->value.type, p->name);
+
+      return;
+    }
+
+    p->ch_type = deduce_channel_type(ca_field_type(p->id), ds->ds[0].type);
+    if (p->ch_type < 0) {
+      ERROR("epics plugin: Variable type \"%s\" doesn't match channel type "
+            "\"%s\" for channel \"%s\"",
+            DS_TYPE_TO_STRING(ds->ds[0].type), dbf_type_to_text(p->ch_type),
+            p->name);
+
+      return;
+    }
+
+    if (ca_element_count(p->id) != ds->ds_num) {
+      ERROR("epics plugin: Variable element number %lu doesn't match channel "
+            "element count %lu for channel \"%s\"",
+            ds->ds_num, ca_element_count(p->id), p->name);
+
+      return;
+    }
+
+    p->value.values_len = ds->ds_num;
+    p->value.values = calloc(p->value.values_len, sizeof(value_t));
+    if (p->value.values == NULL) {
+      ERROR("epics plugin: Cannot allocate memory for %lu values or channel "
+            "\"%s\"",
+            ds->ds_num, p->name);
+
+      return;
+    }
+  }
+
+  int ret =
+      ca_create_subscription(p->ch_type, ca_element_count(p->id), p->id,
+                             DBE_VALUE | DBE_ALARM, event_handler, p, &p->eid);
+  if (ret != ECA_NORMAL) {
+    ERROR("epics plugin: CA error %s occurred while trying to create "
+          "subscription for channel \"%s\"",
+          ca_message(ret), p->name);
+
+    return;
+  }
+
+  p->is_active = 1;
+}
+
+static void handle_conn_down(struct pv *p) {
+  WARNING("epics plugin: Channel \"%s\" disconnected", p->name);
+
+  p->is_active = 0;
+}
+
+static void connection_handler(struct connection_handler_args args) {
+  struct pv *p = (struct pv *)ca_puser(args.chid);
+
+  switch (args.op) {
+  case CA_OP_CONN_UP:
+    handle_conn_up(p);
+    break;
+  case CA_OP_CONN_DOWN:
+    handle_conn_down(p);
+    break;
+  }
+}
+
+static void *epics_thread(void *args) {
+  long ret = ca_context_create(ca_disable_preemptive_callback);
+  if (ret != ECA_NORMAL) {
+    // FIXME: report error back to start_thread()
+    ERROR("epics plugin: CA error %s occurred while trying to start channel "
+          "access",
+          ca_message(ret));
+    return (void *)1;
+  }
+
+  ca_replace_printf_handler(&printf_handler);
+
+  for (int i = 0; i < epics_plugin.pvs_num; ++i) {
+    struct pv *p = &epics_plugin.pvs[i];
+
+    ret = ca_create_channel(p->name, &connection_handler, p, 0, &p->id);
+    if (ret != ECA_NORMAL) {
+      ERROR("epics plugin: CA error %s occurred while trying to create channel "
+            "\"%s\"",
+            ca_message(ret), p->name);
+      ret = 1;
+      goto error;
+    }
+  }
+
+  const double timeout = 2.0;
+  while (epics_plugin.thread_loop != 0) {
+    ca_pend_event(timeout);
+  }
+
+error:
+  for (int i = 0; i < epics_plugin.pvs_num; ++i) {
+    struct pv *p = &epics_plugin.pvs[i];
+
+    if (p->eid) {
+      ca_clear_subscription(p->eid);
+    }
+    ca_clear_channel(p->id);
+  }
+
+  ca_context_destroy();
+
+  return (void *)ret;
+}
+
+static int start_thread(void) {
+  pthread_mutex_lock(&epics_plugin.lock);
+
+  int ret = 0;
+  if (epics_plugin.thread_loop != 0) {
+    goto epics_unlock;
+  }
+
+  epics_plugin.thread_loop = 1;
+  ret = plugin_thread_create(&epics_plugin.thread_id, epics_thread, (void *)0,
+                             "epics");
+  if (ret != 0) {
+    epics_plugin.thread_loop = 0;
+    ERROR("epics plugin: Starting thread failed: %d", ret);
+
+    goto epics_unlock;
+  }
+
+  // FIXME: wait untill ca_context_create success
+
+epics_unlock:
+  pthread_mutex_unlock(&epics_plugin.lock);
+
+  return ret;
+}
+
+static int stop_thread(void) {
+  pthread_mutex_lock(&epics_plugin.lock);
+
+  epics_plugin.thread_loop = 0;
+
+  pthread_mutex_unlock(&epics_plugin.lock);
+
+  return pthread_join(epics_plugin.thread_id, NULL);
+}
+
+static int epics_config_variable(oconfig_item_t *ci, struct pv *p) {
+
+  if (cf_util_get_string(ci, &p->name) != 0 || p->name == NULL) {
+    ERROR("epics plugin: Wrong variable configuration");
+
+    return -1;
+  }
+
+  for (oconfig_item_t *c = ci->children; c != ci->children + ci->children_num;
+       ++c) {
+    if (strcasecmp(c->key, "Type") == 0) {
+      if (cf_util_get_string_buffer(c, p->value.type, sizeof(p->value.type)) !=
+          0) {
+
+        return -1;
+      }
+
+      sstrncpy(p->value.type_instance, p->name, sizeof(p->value.type_instance));
+    } else {
+      ERROR(
+          "epics plugin: Unknown configuration key \"%s\" for variable \"%s\"",
+          c->key, p->name);
+
+      return -1;
+    }
+  }
+
+  sstrncpy(p->value.plugin, "epics", sizeof(p->value.plugin));
+
+  return 0;
+}
+
+static int epics_config_label(oconfig_item_t *ci, struct pv *p) {
+  if (cf_util_get_string(ci, &p->name) != 0 || p->name == NULL) {
+    ERROR("epics plugin: Wrong label configuration");
+
+    return -1;
+  }
+
+  p->is_label = 1;
+
+  return 0;
+}
+
+static int epics_config(oconfig_item_t *ci) {
+  if (ci->children_num == 0) {
+    ERROR("epics plugin: No variables are specified");
+
+    return -1;
+  }
+
+  struct pv *pvs =
+      realloc(epics_plugin.pvs,
+              sizeof(struct pv) * (epics_plugin.pvs_num + ci->children_num));
+  if (pvs == NULL) {
+    ERROR("epics plugin: Cannot allocate memory for PV list");
+
+    return -1;
+  }
+
+  epics_plugin.pvs = pvs;
+  memset(epics_plugin.pvs + epics_plugin.pvs_num, 0,
+         sizeof(struct pv) * ci->children_num);
+  for (oconfig_item_t *c = ci->children; c != ci->children + ci->children_num;
+       ++c, ++epics_plugin.pvs_num) {
+    struct pv *p = &epics_plugin.pvs[epics_plugin.pvs_num];
+
+    if (strcasecmp(c->key, "Variable") == 0) {
+      if (epics_config_variable(c, p) != 0)
+        goto error;
+    } else if (strcasecmp(c->key, "Label") == 0) {
+      if (epics_config_label(c, p) != 0)
+        goto error;
+    } else {
+      ERROR("epics plugin: Unknown configuration key \"%s\"", ci->key);
+      goto error;
+    }
+  }
+
+  return 0;
+
+error:
+  free_pvs();
+
+  return -1;
+}
+
+static int epics_init(void) { return start_thread(); }
+
+static int epics_shutdown(void) {
+  stop_thread();
+  free_pvs();
+
+  return 0;
+}
+
+static int epics_read(void) {
+  int ret = 0;
+
+  meta_data_t *md = meta_data_create();
+  if (md == NULL) {
+    ERROR("epics plugin: Cannot allocate memory for meta data");
+
+    return -1;
+  }
+
+  pthread_mutex_lock(&epics_plugin.lock);
+
+  cdtime_t time = cdtime();
+
+  for (int i = 0; i < epics_plugin.pvs_num; ++i) {
+    struct pv *p = &epics_plugin.pvs[i];
+
+    if (!p->is_active || !p->is_label) {
+      continue;
+    }
+
+    ret = meta_data_add_string(md, p->name, p->label);
+    if (ret != 0) {
+      ERROR("epics plugin: Cannot add value for meta \"%s\"", p->name);
+
+      goto error;
+    }
+  }
+
+  for (int i = 0; i < epics_plugin.pvs_num; ++i) {
+    struct pv *p = &epics_plugin.pvs[i];
+
+    if (!p->is_active || p->is_label) {
+      continue;
+    }
+
+    p->value.time = time;
+    p->value.meta = md;
+
+    ret = plugin_dispatch_values(&p->value);
+    if (ret != 0) {
+      ERROR("epics plugin: Cannot dispatch values for \"%s\"", p->name);
+
+      goto error;
+    }
+  }
+
+  ret = 0;
+error:
+  pthread_mutex_unlock(&epics_plugin.lock);
+  meta_data_destroy(md);
+
+  return ret;
+}
+
+void module_register(void) {
+  plugin_register_complex_config("epics", epics_config);
+  plugin_register_read("epics", epics_read);
+  plugin_register_init("epics", epics_init);
+  plugin_register_shutdown("epics", epics_shutdown);
+}