[collectd] [PATCH] Add an input plugin for the Ceph distributed fs

Colin McCabe cmccabe at alumni.cmu.edu
Fri Sep 16 04:01:42 CEST 2011


From: Colin Patrick McCabe <cmccabe at alumni.cmu.edu>

Ceph is a distributed, fault-tolerant filesystem. See
http://ceph.newdream.net/ for details.

Ceph daemons export performance counter information through a unix
domain socket. This plugin reads this performance counter information,
which is formatted using JSON. The names of the counters are determined
dynamically from the JSON output.

Signed-off-by: Colin McCabe <colin.mccabe at dreamhost.com>
---
 configure.in    |    7 +
 src/Makefile.am |   10 +
 src/ceph.c      |  807 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 824 insertions(+), 0 deletions(-)
 create mode 100644 src/ceph.c

diff --git a/configure.in b/configure.in
index 9b6397f..05123b5 100644
--- a/configure.in
+++ b/configure.in
@@ -4573,6 +4573,13 @@ AC_ARG_ENABLE([all-plugins],
 		],
 		[enable_all_plugins="auto"])
 
+# --with-ceph {{{
+AC_ARG_WITH([ceph], [AS_HELP_STRING([--with-ceph], [Input plugin for the Ceph distributed filesystem])], [], [with_ceph=check])
+AS_IF([test "x$with_ceph" == "xyes"],
+      [PKG_CHECK_MODULES([JSONC], [json], [], [AC_MSG_ERROR([json-c library not found!])])])
+AM_CONDITIONAL(BUILD_PLUGIN_CEPH, test "x$with_ceph" == "xyes")
+# }}}
+
 m4_divert_once([HELP_ENABLE], [])
 
 AC_PLUGIN([amqp],        [$with_librabbitmq],  [AMQP output plugin])
diff --git a/src/Makefile.am b/src/Makefile.am
index 795de57..f522925 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -986,6 +986,16 @@ collectd_LDADD += "-dlopen" snmp.la
 collectd_DEPENDENCIES += snmp.la
 endif
 
+if BUILD_PLUGIN_CEPH
+pkglib_LTLIBRARIES += ceph.la
+ceph_la_SOURCES = ceph.c
+ceph_la_LDFLAGS = -module -avoid-version
+ceph_la_CFLAGS = $(AM_CFLAGS) -ljson
+ceph_la_LIBADD = -ljson
+collectd_LDADD += "-dlopen" ceph.la
+collectd_DEPENDENCIES += ceph.la
+endif
+
 if BUILD_PLUGIN_SWAP
 pkglib_LTLIBRARIES += swap.la
 swap_la_SOURCES = swap.c
diff --git a/src/ceph.c b/src/ceph.c
new file mode 100644
index 0000000..c72133c
--- /dev/null
+++ b/src/ceph.c
@@ -0,0 +1,807 @@
+/**
+ * collectd - src/ceph.c
+ * Copyright (C) 2011  New Dream Network
+ *
+ * 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:
+ *   Colin McCabe <cmccabe at alumni.cmu.edu>
+ **/
+
+#define _BSD_SOURCE
+
+#include "collectd.h"
+#include "common.h"
+#include "plugin.h"
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <json/json.h>
+#include <json/json_object_private.h> /* need for struct json_object_iter */
+#include <limits.h>
+#include <poll.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#define RETRY_ON_EINTR(ret, expr) \
+	while(1) { \
+		ret = expr; \
+		if (ret >= 0) \
+			break; \
+		ret = -errno; \
+		if (ret != -EINTR) \
+			break; \
+	}
+
+/** Timeout interval in seconds */
+#define CEPH_TIMEOUT_INTERVAL 1
+
+/** Maximum path length for a UNIX domain socket on this system */
+#define UNIX_DOMAIN_SOCK_PATH_MAX (sizeof(((struct sockaddr_un*)0)->sun_path))
+
+/******* ceph_daemon *******/
+struct ceph_daemon
+{
+	/** Version of the admin_socket interface */
+	uint32_t version;
+
+	/** Path to the socket that we use to talk to the ceph daemon */
+	char asok_path[UNIX_DOMAIN_SOCK_PATH_MAX];
+
+	/** The set of  key/value pairs that this daemon reports
+	 * dset.type		The daemon name
+	 * dset.ds_num		Number of data sources (key/value pairs) 
+	 * dset.ds		Dynamically allocated array of key/value pairs
+	 */
+	struct data_set_s dset;
+
+	int *pc_types;
+};
+
+enum perfcounter_type_d {
+	PERFCOUNTER_LONGRUNAVG = 0x4,
+	PERFCOUNTER_COUNTER = 0x8,
+};
+
+/** Array of daemons to monitor */
+static struct ceph_daemon **g_daemons = NULL;
+
+/** Number of elements in g_daemons */
+static int g_num_daemons = 0;
+
+static void ceph_daemon_print(const struct ceph_daemon *d)
+{
+	DEBUG("name=%s, asok_path=%s", d->dset.type, d->asok_path);
+}
+
+static void ceph_daemons_print(void)
+{
+	int i;
+	for (i = 0; i < g_num_daemons; ++i) {
+		ceph_daemon_print(g_daemons[i]);
+	}
+}
+
+static void ceph_daemon_free(struct ceph_daemon *d)
+{
+	plugin_unregister_data_set(d->dset.type);
+	sfree(d->dset.ds);
+	sfree(d);
+}
+
+static int ceph_daemon_add_ds_entry(struct ceph_daemon *d,
+				    const char *name, int pc_type)
+{
+	struct data_source_s *ds;
+	int *pc_types_new;
+	if (strlen(name) + 1 > DATA_MAX_NAME_LEN)
+		return -ENAMETOOLONG;
+	struct data_source_s *ds_array = realloc(d->dset.ds,
+		 sizeof(struct data_source_s) * (d->dset.ds_num + 1));
+	if (!ds_array)
+		return -ENOMEM;
+	pc_types_new = realloc(d->pc_types,
+		sizeof(int) * (d->dset.ds_num + 1));
+	if (!pc_types_new)
+		return -ENOMEM;
+	d->dset.ds = ds_array;
+	d->pc_types = pc_types_new;
+	d->pc_types[d->dset.ds_num] = pc_type;
+	ds = &ds_array[d->dset.ds_num++];
+	snprintf(ds->name, DATA_MAX_NAME_LEN, "%s", name);
+	ds->type = (pc_type & PERFCOUNTER_COUNTER) ?
+		DS_TYPE_COUNTER : DS_TYPE_GAUGE;
+	ds->min = NAN;
+	ds->max = NAN;
+	return 0;
+}
+
+/******* ceph_config *******/
+static int cc_handle_str(struct oconfig_item_s *item, char *dest, int dest_len)
+{
+	const char *val;
+	if (item->values_num != 1) {
+		return -ENOTSUP; 
+	}
+	if (item->values[0].type != OCONFIG_TYPE_STRING) {
+		return -ENOTSUP; 
+	}
+	val = item->values[0].value.string;
+	if (snprintf(dest, dest_len, "%s", val) > (dest_len - 1)) {
+		ERROR("ceph plugin: configuration parameter '%s' is too long.\n",
+		      item->key);
+		return -ENAMETOOLONG;
+	}
+	return 0;
+}
+
+static int ceph_config(oconfig_item_t *ci)
+{
+	int ret, i;
+	struct ceph_daemon *array, *nd, cd;
+	memset(&cd, 0, sizeof(struct ceph_daemon));
+
+	for (i = 0; i < ci->children_num; ++i) {
+		oconfig_item_t *child = ci->children + i;
+		if (strcasecmp("Name", child->key) == 0) {
+			ret = cc_handle_str(child, cd.dset.type,
+					    DATA_MAX_NAME_LEN);
+			if (ret)
+				return ret;
+		}
+		else if (strcasecmp("SocketPath", child->key) == 0) {
+			ret = cc_handle_str(child, cd.asok_path,
+					    sizeof(cd.asok_path));
+			if (ret)
+				return ret;
+		}
+		else {
+			WARNING("ceph plugin: ignoring unknown option %s",
+				child->key);
+		}
+	}
+	if (cd.dset.type[0] == '\0') {
+		ERROR("ceph plugin: you must configure a daemon name.\n");
+		return -EINVAL;
+	}
+	else if (cd.asok_path[0] == '\0') {
+		ERROR("ceph plugin(name=%s): you must configure an administrative "
+		      "socket path.\n", cd.dset.type);
+		return -EINVAL;
+	}
+	else if (!((cd.asok_path[0] == '/') ||
+	      (cd.asok_path[0] == '.' && cd.asok_path[1] == '/'))) {
+		ERROR("ceph plugin(name=%s): administrative socket paths must begin with "
+		      "'/' or './' Can't parse: '%s'\n",
+		      cd.dset.type, cd.asok_path);
+		return -EINVAL;
+	}
+	array = realloc(g_daemons,
+			sizeof(struct ceph_daemon *) * (g_num_daemons + 1));
+	if (array == NULL) {
+		/* The positive return value here indicates that this is a
+		 * runtime error, not a configuration error.  */
+		return ENOMEM;
+	}
+	g_daemons = (struct ceph_daemon**)array;
+	nd = malloc(sizeof(struct ceph_daemon));
+	if (!nd)
+		return ENOMEM;
+	memcpy(nd, &cd, sizeof(struct ceph_daemon));
+	g_daemons[g_num_daemons++] = nd;
+	return 0;
+}
+
+/******* JSON parsing *******/
+typedef int (*node_handler_t)(void*, json_object*, const char*);
+
+/** Perform a depth-first traversal of the JSON parse tree,
+ * calling node_handler at each node.*/
+static int traverse_json_impl(json_object *jo, char *key, int max_key,
+			node_handler_t handler, void *handler_arg)
+{
+	struct json_object_iter iter;
+	int ret, plen, klen;
+
+	if (json_object_get_type(jo) != json_type_object)
+		return 0;
+	plen = strlen(key);
+	json_object_object_foreachC(jo, iter) {
+		klen = strlen(iter.key);
+		if (plen + klen + 2 > max_key)
+			return -ENAMETOOLONG;
+		if (plen != 0)
+			strncat(key, ".", max_key); /* really should be strcat */
+		strncat(key, iter.key, max_key);
+
+		ret = handler(handler_arg, iter.val, key);
+		if (ret == 1) {
+			ret = traverse_json_impl(iter.val, key, max_key,
+					    handler, handler_arg);
+		}
+		else if (ret != 0) {
+			return ret;
+		}
+
+		key[plen] = '\0';
+	}
+	return 0;
+}
+
+static int traverse_json(const char *json,
+			node_handler_t handler, void *handler_arg)
+{
+	json_object *root;
+	char buf[128];
+	buf[0] = '\0';
+	root = json_tokener_parse(json);
+	if (!root)
+		return -EDOM;
+	return traverse_json_impl(root, buf, sizeof(buf),
+				     handler, handler_arg);
+}
+
+static int node_handler_define_schema(void *arg, json_object *jo,
+				      const char *key)
+{
+	struct ceph_daemon *d = (struct ceph_daemon *)arg;
+	int pc_type;
+	if (json_object_get_type(jo) == json_type_object)
+		return 1;
+	else if (json_object_get_type(jo) != json_type_int)
+		return -EDOM;
+	pc_type = json_object_get_int(jo);
+	DEBUG("ceph_daemon_add_ds_entry(d=%s,key=%s,pc_type=%04x)",
+	      d->dset.type, key, pc_type);
+	return ceph_daemon_add_ds_entry(d, key, pc_type);
+}
+
+/** A set of values_t data that we build up in memory while parsing the JSON. */
+struct values_tmp {
+	struct ceph_daemon *d;
+	int values_len;
+	value_t values[0];
+};
+
+int get_matching_value(const struct data_set_s *dset,
+		   const char *name, value_t *values, int num_values)
+{
+	int idx;
+	for (idx = 0; idx < num_values; ++idx) {
+		if (strcmp(dset->ds[idx].name, name) == 0) {
+			return idx;
+		}
+		return idx;
+	}
+	return -1;
+}
+
+static int node_handler_fetch_data(void *arg, json_object *jo,
+				      const char *key)
+{
+	int idx;
+	value_t *uv;
+	struct values_tmp *vtmp = (struct values_tmp*)arg;
+
+	idx = get_matching_value(&vtmp->d->dset, key,
+				 vtmp->values, vtmp->values_len);
+	if (idx == -1)
+		return 1;
+	uv = vtmp->values + idx;
+	if (vtmp->d->pc_types[idx] & PERFCOUNTER_LONGRUNAVG) {
+		json_object *avgcount, *sum; 
+		uint64_t avgcounti;
+		double sumd;
+		if (json_object_get_type(jo) != json_type_object)
+			return -EINVAL;
+		avgcount = json_object_object_get(jo, "avgcount");
+		sum = json_object_object_get(jo, "sum");
+		if ((!avgcount) || (!sum))
+			return -EINVAL;
+		avgcounti = json_object_get_int(avgcount);
+		if (avgcounti == 0)
+			avgcounti = 1;
+		sumd = json_object_get_int(sum);
+		uv->gauge = sumd / avgcounti;
+	}
+	else if (vtmp->d->pc_types[idx] & PERFCOUNTER_COUNTER) {
+		/* We use json_object_get_double here because anything > 32 
+		 * bits may get truncated by json_object_get_int */
+		uv->counter = json_object_get_double(jo);
+	}
+	else {
+		uv->gauge = json_object_get_double(jo);
+	}
+	return 0;
+}
+
+/******* network I/O *******/
+enum cstate_t {
+	CSTATE_UNCONNECTED = 0,
+	CSTATE_WRITE_REQUEST,
+	CSTATE_READ_VERSION,
+	CSTATE_READ_AMT,
+	CSTATE_READ_JSON,
+};
+
+enum request_type_t {
+	ASOK_REQ_VERSION = 0,
+	ASOK_REQ_DATA = 1,
+	ASOK_REQ_SCHEMA = 2,
+	ASOK_REQ_NONE = 1000,
+};
+
+struct cconn
+{
+	/** The Ceph daemon that we're talking to */
+	struct ceph_daemon *d;
+
+	/** Request type */
+	uint32_t request_type;
+
+	/** The connection state */
+	enum cstate_t state;
+
+	/** The socket we use to talk to this daemon */ 
+	int asok;
+
+	/** The amount of data remaining to read / write. */
+	uint32_t amt;
+
+	/** Length of the JSON to read */
+	uint32_t json_len;
+
+	/** Buffer containing JSON data */
+	char *json;
+};
+
+static int cconn_connect(struct cconn *io)
+{
+	struct sockaddr_un address;
+	int flags, fd, err;
+	if (io->state != CSTATE_UNCONNECTED) {
+		ERROR("cconn_connect: io->state != CSTATE_UNCONNECTED");
+		return -EDOM;
+	}
+	fd = socket(PF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0) {
+		int err = -errno;
+		ERROR("cconn_connect: socket(PF_UNIX, SOCK_STREAM, 0) failed: "
+		      "error %d", err);
+		return err;
+	}
+	memset(&address, 0, sizeof(struct sockaddr_un));
+	address.sun_family = AF_UNIX;
+	snprintf(address.sun_path, sizeof(address.sun_path),
+		 "%s", io->d->asok_path);
+	RETRY_ON_EINTR(err, connect(fd, (struct sockaddr *) &address, 
+			sizeof(struct sockaddr_un)));
+	if (err < 0) {
+		ERROR("cconn_connect: connect(%d) failed: error %d", fd, err);
+		return err;
+	}
+
+	flags = fcntl(fd, F_GETFL, 0);
+	if (fcntl(fd, F_SETFL, flags | O_NONBLOCK) != 0) {
+		err = -errno;
+		ERROR("cconn_connect: fcntl(%d, O_NONBLOCK) error %d", fd, err);
+		return err;
+	}
+	io->asok = fd;
+	io->state = CSTATE_WRITE_REQUEST;
+	io->amt = 0;
+	io->json_len = 0;
+	io->json = NULL;
+	return 0;
+}
+
+static void cconn_close(struct cconn *io)
+{
+	io->state = CSTATE_UNCONNECTED;
+	if (io->asok != -1) {
+		int res;
+		RETRY_ON_EINTR(res, close(io->asok));
+	}
+	io->asok = -1;
+	io->amt = 0;
+	io->json_len = 0;
+	sfree(io->json);
+	io->json = NULL;
+}
+
+/* Process incoming JSON counter data */
+static int cconn_process_data(struct cconn *io)
+{
+	int ret;
+	value_list_t vl = VALUE_LIST_INIT;
+	struct values_tmp *vtmp = calloc(1, sizeof(struct values_tmp) +
+				(sizeof(value_t) * io->d->dset.ds_num));
+	if (!vtmp)
+		return -ENOMEM;
+	vtmp->d = io->d;
+	vtmp->values_len = io->d->dset.ds_num;
+	ret = traverse_json(io->json, node_handler_fetch_data, vtmp);
+	if (ret)
+		goto done;
+	sstrncpy(vl.host, hostname_g, sizeof(vl.host));
+	sstrncpy(vl.plugin, "ceph", sizeof(vl.plugin));
+	sstrncpy(vl.type, io->d->dset.type, sizeof(vl.type));
+	vl.values = vtmp->values;
+	vl.values_len = vtmp->values_len;
+	DEBUG("cconn_process_data(io=%s): vl.values_len=%d, json=\"%s\"",
+	      io->d->dset.type, vl.values_len, io->json);
+	ret = plugin_dispatch_values(&vl);
+done:
+	sfree(vtmp);
+	return ret;
+}
+
+static int cconn_process_json(struct cconn *io)
+{
+	switch (io->request_type) {
+	case ASOK_REQ_DATA:
+		return cconn_process_data(io);
+	case ASOK_REQ_SCHEMA:
+		return traverse_json(io->json,
+			     node_handler_define_schema, io->d);
+	default:
+		return -EDOM;
+	}
+}
+
+static int cconn_validate_revents(struct cconn *io, int revents)
+{
+	if (revents & POLLERR) {
+		ERROR("cconn_validate_revents(name=%s): got POLLERR",
+		      io->d->dset.type);
+		return -EIO;
+	}
+	switch (io->state) {
+	case CSTATE_WRITE_REQUEST:
+		return (revents & POLLOUT) ? 0 : -EINVAL;
+	case CSTATE_READ_VERSION:
+	case CSTATE_READ_AMT:
+	case CSTATE_READ_JSON:
+		return (revents & POLLIN) ? 0 : -EINVAL;
+		return (revents & POLLIN) ? 0 : -EINVAL;
+	default:
+		ERROR("cconn_validate_revents(name=%s) got to illegal state on line %d",
+		      io->d->dset.type, __LINE__);
+		return -EDOM;
+	}
+}
+
+/** Handle a network event for a connection */
+static int cconn_handle_event(struct cconn *io)
+{
+	int ret;
+	switch (io->state) {
+	case CSTATE_UNCONNECTED:
+		ERROR("cconn_handle_event(name=%s) got to illegal state on line %d",
+		      io->d->dset.type, __LINE__);
+		return -EDOM;
+	case CSTATE_WRITE_REQUEST: {
+		uint32_t cmd = htonl(io->request_type);
+		RETRY_ON_EINTR(ret, write(io->asok, ((char*)&cmd) + io->amt,
+					       sizeof(cmd) - io->amt));
+		DEBUG("cconn_handle_event(name=%s,state=%d,amt=%d,ret=%d)",
+		      io->d->dset.type, io->state, io->amt, ret);
+		if (ret < 0)
+			return ret;
+		io->amt += ret;
+		if (io->amt >= sizeof(cmd)) {
+			io->amt = 0;
+			switch (io->request_type) {
+			case ASOK_REQ_VERSION:
+				io->state = CSTATE_READ_VERSION;
+				break;
+			default:
+				io->state = CSTATE_READ_AMT;
+				break;
+			}
+		}
+		return 0;
+	}
+	case CSTATE_READ_VERSION: {
+		RETRY_ON_EINTR(ret, read(io->asok, 
+			((char*)(&io->d->version)) + io->amt,
+			sizeof(io->d->version) - io->amt));
+		DEBUG("cconn_handle_event(name=%s,state=%d,ret=%d)",
+		      io->d->dset.type, io->state, ret);
+		if (ret < 0)
+			return ret;
+		io->amt += ret;
+		if (io->amt >= sizeof(io->d->version)) {
+			io->d->version = ntohl(io->d->version);
+			if (io->d->version != 1) {
+				ERROR("cconn_handle_event(name=%s) not "
+				      "expecting version %d!", 
+				      io->d->dset.type, io->d->version);
+				return -ENOTSUP;
+			}
+			DEBUG("cconn_handle_event(name=%s): identified as "
+			      "version %d", io->d->dset.type, io->d->version);
+			io->amt = 0;
+			cconn_close(io);
+			io->request_type = ASOK_REQ_SCHEMA;
+		}
+		return 0;
+	}
+	case CSTATE_READ_AMT: {
+		RETRY_ON_EINTR(ret, read(io->asok, 
+			((char*)(&io->json_len)) + io->amt,
+			sizeof(io->json_len) - io->amt));
+		DEBUG("cconn_handle_event(name=%s,state=%d,ret=%d)",
+		      io->d->dset.type, io->state, ret);
+		if (ret < 0)
+			return ret;
+		io->amt += ret;
+		if (io->amt >= sizeof(io->json_len)) {
+			io->json_len = ntohl(io->json_len);
+			io->amt = 0;
+			io->state = CSTATE_READ_JSON;
+			io->json = calloc(1, io->json_len + 1);
+			if (!io->json)
+				return -ENOMEM;
+		}
+		return 0;
+	}
+	case CSTATE_READ_JSON: {
+		RETRY_ON_EINTR(ret, read(io->asok, io->json + io->amt,
+					      io->json_len - io->amt));
+		DEBUG("cconn_handle_event(name=%s,state=%d,ret=%d)",
+		      io->d->dset.type, io->state, ret);
+		if (ret < 0)
+			return ret;
+		io->amt += ret;
+		if (io->amt >= io->json_len) {
+			ret = cconn_process_json(io);
+			if (ret)
+				return ret;
+			cconn_close(io);
+			io->request_type = ASOK_REQ_NONE;
+		}
+		return 0;
+	}
+	default:
+		ERROR("cconn_handle_event(name=%s) got to illegal state on "
+		      "line %d", io->d->dset.type, __LINE__);
+		return -EDOM;
+	}
+}
+
+static int cconn_prepare(struct cconn *io, struct pollfd* fds)
+{
+	int ret;
+	if (io->request_type == ASOK_REQ_NONE) {
+		/* The request has already been serviced. */
+		return 0;
+	}
+	else if ((io->request_type == ASOK_REQ_DATA) &&
+			 (io->d->dset.ds_num == 0)) {
+		/* If there are no counters to report on, don't bother
+		 * connecting */
+		return 0;
+	}
+
+	switch (io->state) {
+	case CSTATE_UNCONNECTED:
+		ret = cconn_connect(io);
+		if (ret > 0)
+			return -ret;
+		else if (ret < 0)
+			return ret;
+		fds->fd = io->asok;
+		fds->events = POLLOUT;
+		return 1;
+	case CSTATE_WRITE_REQUEST:
+		fds->fd = io->asok;
+		fds->events = POLLOUT;
+		return 1;
+	case CSTATE_READ_VERSION:
+	case CSTATE_READ_AMT:
+	case CSTATE_READ_JSON:
+		fds->fd = io->asok;
+		fds->events = POLLIN;
+		return 1;
+	default:
+		ERROR("cconn_prepare(name=%s) got to illegal state on line %d",
+		      io->d->dset.type, __LINE__);
+		return -EDOM;
+	}
+}
+
+/** Returns the difference between two struct timevals in milliseconds.
+ * On overflow, we return max/min int.
+ */
+static int milli_diff(const struct timeval *t1, const struct timeval *t2)
+{
+	int64_t ret;
+	int sec_diff = t1->tv_sec - t2->tv_sec;
+	int usec_diff = t1->tv_usec - t2->tv_usec;
+	ret = usec_diff / 1000;
+	ret += (sec_diff * 1000);
+	if (ret > INT_MAX)
+		return INT_MAX;
+	else if (ret < INT_MIN)
+		return INT_MIN;
+	return (int)ret;
+}
+
+/** This handles the actual network I/O to talk to the Ceph daemons.
+ */
+static int cconn_main_loop(uint32_t request_type)
+{
+	int i, ret, some_unreachable = 0;
+	struct timeval end_tv;
+	struct cconn io_array[g_num_daemons];
+
+	DEBUG("entering cconn_main_loop(request_type = %d)", request_type);
+
+	/* create cconn array */
+	memset(io_array, 0, sizeof(io_array));
+	for (i = 0; i < g_num_daemons; ++i) {
+		io_array[i].d = g_daemons[i];
+		io_array[i].request_type = request_type;
+		io_array[i].state = CSTATE_UNCONNECTED;
+	}
+
+	/** Calculate the time at which we should give up */
+	gettimeofday(&end_tv, NULL);
+	end_tv.tv_sec += CEPH_TIMEOUT_INTERVAL;
+
+	while (1) {
+		int nfds, diff;
+		struct timeval tv;
+		struct cconn *polled_io_array[g_num_daemons];
+		struct pollfd fds[g_num_daemons];
+		memset(fds, 0, sizeof(fds));
+		nfds = 0;
+		for (i = 0; i < g_num_daemons; ++i) {
+			struct cconn *io = io_array + i;
+			ret = cconn_prepare(io, fds + nfds);
+			if (ret < 0) {
+				WARNING("ERROR: cconn_prepare(name=%s,i=%d,st=%d)=%d",
+				      io->d->dset.type, i, io->state, ret);
+				cconn_close(io);
+				io->request_type = ASOK_REQ_NONE;
+				some_unreachable = 1;
+			}
+			else if (ret == 1) {
+				DEBUG("did cconn_prepare(name=%s,i=%d,st=%d)",
+				      io->d->dset.type, i, io->state);
+				polled_io_array[nfds++] = io_array + i;
+			}
+		}
+		if (nfds == 0) {
+			/* finished */
+			ret = 0;
+			DEBUG("cconn_main_loop: no more cconn to manage.");
+			goto done;
+		}
+		gettimeofday(&tv, NULL);
+		diff = milli_diff(&end_tv, &tv);
+		if (diff <= 0) {
+			/* Timed out */
+			ret = -ETIMEDOUT;
+			WARNING("ERROR: cconn_main_loop: timed out.\n");
+			goto done;
+		}
+		RETRY_ON_EINTR(ret, poll(fds, nfds, diff));
+		if (ret < 0) {
+			ERROR("poll(2) error: %d", ret);
+			goto done;
+		}
+		for (i = 0; i < nfds; ++i) {
+			struct cconn *io = polled_io_array[i];
+			int revents = fds[i].revents;
+			if (revents == 0) {
+				/* do nothing */
+			}
+			else if (cconn_validate_revents(io, revents)) {
+				WARNING("ERROR: cconn(name=%s,i=%d,st=%d): "
+					"revents validation error: "
+					"revents=0x%08x", io->d->dset.type, i,
+					io->state, revents);
+				cconn_close(io);
+				io->request_type = ASOK_REQ_NONE;
+				some_unreachable = 1;
+			}
+			else {
+				int ret = cconn_handle_event(io);
+				if (ret) {
+					WARNING("ERROR: cconn_handle_event(name=%s,"
+						"i=%d,st=%d): error %d",
+						io->d->dset.type, i,
+						io->state, ret);
+					cconn_close(io);
+					io->request_type = ASOK_REQ_NONE;
+					some_unreachable = 1;
+				}
+			}
+		}
+	}
+done:
+	for (i = 0; i < g_num_daemons; ++i) {
+		cconn_close(io_array + i);
+	}
+	if (some_unreachable) {
+		DEBUG("cconn_main_loop: some Ceph daemons were unreachable.");
+	}
+	else {
+		DEBUG("cconn_main_loop: reached all Ceph daemons :)");
+	}
+	return ret;
+}
+
+static int ceph_read(void)
+{
+	return cconn_main_loop(ASOK_REQ_DATA);
+}
+
+/******* lifecycle *******/
+static int ceph_init(void)
+{
+	int i, ret;
+	DEBUG("ceph_init");
+	ceph_daemons_print();
+
+	ret = cconn_main_loop(ASOK_REQ_VERSION);
+	if (ret)
+		return ret;
+	for (i = 0; i < g_num_daemons; ++i) {
+		struct ceph_daemon *d = g_daemons[i];
+		ret = plugin_register_data_set(&d->dset);
+		if (ret) {
+			ERROR("plugin_register_data_set(%s) failed!",
+			      d->dset.type);
+		}
+		else {
+			DEBUG("plugin_register_data_set(%s): "
+			      "d->dset.ds_num=%d",
+			      d->dset.type, d->dset.ds_num);
+		}
+	}
+	return 0;
+}
+
+static int ceph_shutdown(void)
+{
+	int i;
+	for (i = 0; i < g_num_daemons; ++i) {
+		ceph_daemon_free(g_daemons[i]);
+	}
+	sfree(g_daemons);
+	g_daemons = NULL;
+	g_num_daemons = 0;
+	DEBUG("finished ceph_shutdown");
+	return 0;
+}
+
+void module_register(void)
+{
+	plugin_register_complex_config("ceph", ceph_config);
+	plugin_register_init("ceph", ceph_init);
+	plugin_register_read("ceph", ceph_read);
+	plugin_register_shutdown("ceph", ceph_shutdown);
+}
-- 
1.7.2.5




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