libglusterfs, glusterfsd: add shortname resolution + optname hinting support to VOLUME SET

Trie code used for hinting is contributed by Avati.

Signed-off-by: Csaba Henk <csaba@lowlife.hu>
Signed-off-by: Anand V. Avati <avati@dev.gluster.com>

BUG: 1750 (clean up volgen)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=1750

6 files changed, 777 insertions, 33 deletions

diff --git a/libglusterfs/src/Makefile.am b/libglusterfs/src/Makefile.am
index 71a088d98..619ccf158 100644
--- a/libglusterfs/src/Makefile.am
+++ b/libglusterfs/src/Makefile.am
@@ -6,9 +6,9 @@ libglusterfs_la_LIBADD = @LEXLIB@
 
 lib_LTLIBRARIES = libglusterfs.la
 
-libglusterfs_la_SOURCES = dict.c graph.lex.c y.tab.c xlator.c logging.c  hashfn.c defaults.c common-utils.c timer.c inode.c call-stub.c compat.c fd.c compat-errno.c event.c mem-pool.c gf-dirent.c syscall.c iobuf.c globals.c statedump.c stack.c checksum.c $(CONTRIBDIR)/md5/md5.c $(CONTRIBDIR)/rbtree/rb.c rbthash.c latency.c graph.c $(CONTRIBDIR)/uuid/clear.c $(CONTRIBDIR)/uuid/copy.c $(CONTRIBDIR)/uuid/gen_uuid.c $(CONTRIBDIR)/uuid/pack.c $(CONTRIBDIR)/uuid/tst_uuid.c $(CONTRIBDIR)/uuid/parse.c $(CONTRIBDIR)/uuid/unparse.c $(CONTRIBDIR)/uuid/uuid_time.c $(CONTRIBDIR)/uuid/compare.c $(CONTRIBDIR)/uuid/isnull.c $(CONTRIBDIR)/uuid/unpack.c syncop.c graph-print.c
+libglusterfs_la_SOURCES = dict.c graph.lex.c y.tab.c xlator.c logging.c  hashfn.c defaults.c common-utils.c timer.c inode.c call-stub.c compat.c fd.c compat-errno.c event.c mem-pool.c gf-dirent.c syscall.c iobuf.c globals.c statedump.c stack.c checksum.c $(CONTRIBDIR)/md5/md5.c $(CONTRIBDIR)/rbtree/rb.c rbthash.c latency.c graph.c $(CONTRIBDIR)/uuid/clear.c $(CONTRIBDIR)/uuid/copy.c $(CONTRIBDIR)/uuid/gen_uuid.c $(CONTRIBDIR)/uuid/pack.c $(CONTRIBDIR)/uuid/tst_uuid.c $(CONTRIBDIR)/uuid/parse.c $(CONTRIBDIR)/uuid/unparse.c $(CONTRIBDIR)/uuid/uuid_time.c $(CONTRIBDIR)/uuid/compare.c $(CONTRIBDIR)/uuid/isnull.c $(CONTRIBDIR)/uuid/unpack.c syncop.c graph-print.c trie.c
 
-noinst_HEADERS = common-utils.h defaults.h dict.h glusterfs.h hashfn.h logging.h  xlator.h  stack.h timer.h list.h inode.h call-stub.h compat.h fd.h revision.h compat-errno.h event.h mem-pool.h byte-order.h gf-dirent.h locking.h syscall.h iobuf.h globals.h statedump.h checksum.h $(CONTRIBDIR)/md5/md5.h $(CONTRIBDIR)/rbtree/rb.h rbthash.h iatt.h latency.h mem-types.h $(CONTRIBDIR)/uuid/uuidd.h $(CONTRIBDIR)/uuid/uuid.h $(CONTRIBDIR)/uuid/uuidP.h $(CONTRIBDIR)/uuid/uuid_types.h syncop.h graph-utils.h graph-mem-types.h
+noinst_HEADERS = common-utils.h defaults.h dict.h glusterfs.h hashfn.h logging.h  xlator.h  stack.h timer.h list.h inode.h call-stub.h compat.h fd.h revision.h compat-errno.h event.h mem-pool.h byte-order.h gf-dirent.h locking.h syscall.h iobuf.h globals.h statedump.h checksum.h $(CONTRIBDIR)/md5/md5.h $(CONTRIBDIR)/rbtree/rb.h rbthash.h iatt.h latency.h mem-types.h $(CONTRIBDIR)/uuid/uuidd.h $(CONTRIBDIR)/uuid/uuid.h $(CONTRIBDIR)/uuid/uuidP.h $(CONTRIBDIR)/uuid/uuid_types.h syncop.h graph-utils.h graph-mem-types.h trie.h trie-mem-types.h
 
 EXTRA_DIST = graph.l graph.y
 
diff --git a/libglusterfs/src/trie-mem-types.h b/libglusterfs/src/trie-mem-types.h
new file mode 100644
index 000000000..2b21f67e1
--- /dev/null
+++ b/libglusterfs/src/trie-mem-types.h
@@ -0,0 +1,34 @@
+/*
+   Copyright (c) 2010 Gluster, Inc. <http://www.gluster.com>
+   This file is part of GlusterFS.
+
+   GlusterFS is free software; you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published
+   by the Free Software Foundation; either version 3 of the License,
+   or (at your option) any later version.
+
+   GlusterFS 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
+   Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __TRIE_MEM_TYPES_H__
+#define __TRIE_MEM_TYPES_H__
+
+#include "mem-types.h"
+
+#define GF_MEM_TYPE_START (gf_common_mt_end + 1)
+
+enum gf_trie_mem_types_ {
+        gf_trie_mt_trie = GF_MEM_TYPE_START,
+        gf_trie_mt_data,
+        gf_trie_mt_node,
+        gf_trie_mt_buf,
+        gf_trie_mt_end,
+};
+#endif
diff --git a/libglusterfs/src/trie.c b/libglusterfs/src/trie.c
new file mode 100644
index 000000000..2501e71a5
--- /dev/null
+++ b/libglusterfs/src/trie.c
@@ -0,0 +1,397 @@
+/*
+  Copyright (c) 2010 Gluster, Inc. <http://www.gluster.com>
+  This file is part of GlusterFS.
+
+  GlusterFS is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published
+  by the Free Software Foundation; either version 3 of the License,
+  or (at your option) any later version.
+
+  GlusterFS 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
+  Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see
+  <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <ctype.h>
+
+#include "common-utils.h"
+#include "trie-mem-types.h"
+#include "trie.h"
+
+#define DISTANCE_EDIT 1
+#define DISTANCE_INS  1
+#define DISTANCE_DEL  1
+
+
+struct trienode {
+        char             id;
+        char             eow;
+        int              depth;
+        void            *data;
+        struct trie     *trie;
+        struct trienode *parent;
+        struct trienode *subnodes[255];
+};
+
+struct trie {
+        struct trienode   root;
+        int               nodecnt;
+        size_t            len;
+};
+
+
+trie_t *
+trie_new ()
+{
+        trie_t *trie = NULL;
+
+        trie = GF_CALLOC (1, sizeof (*trie),  gf_trie_mt_trie);
+        if (!trie)
+                return NULL;
+
+        trie->root.trie = trie;
+
+        return trie;
+}
+
+
+static trienode_t *
+trie_subnode (trienode_t *node, int id)
+{
+        trienode_t *subnode = NULL;
+
+        subnode = node->subnodes[id];
+        if (!subnode) {
+                subnode = GF_CALLOC (1, sizeof (*subnode), gf_trie_mt_node);
+                if (!subnode)
+                        return NULL;
+
+                subnode->id        = id;
+                subnode->depth     = node->depth + 1;
+                node->subnodes[id] = subnode;
+                subnode->parent    = node;
+                subnode->trie      = node->trie;
+                node->trie->nodecnt++;
+        }
+
+        return subnode;
+}
+
+
+int
+trie_add (trie_t *trie, const char *dword)
+{
+        trienode_t *node = NULL;
+        int              i = 0;
+        char             id = 0;
+        trienode_t *subnode = NULL;
+
+        node = &trie->root;
+
+        for (i = 0; i < strlen (dword); i++) {
+                id = dword[i];
+
+                subnode = trie_subnode (node, id);
+                if (!subnode)
+                        return -1;
+                node = subnode;
+        }
+
+        node->eow = 1;
+
+        return 0;
+}
+
+static void
+trienode_free (trienode_t *node)
+{
+        trienode_t *trav = NULL;
+        int              i = 0;
+
+        for (i = 0; i < 255; i++) {
+                trav = node->subnodes[i];
+
+                if (trav)
+                        trienode_free (trav);
+        }
+
+        if (node->data)
+                GF_FREE (node->data);
+        GF_FREE (node);
+}
+
+
+void
+trie_destroy (trie_t *trie)
+{
+        trienode_free ((trienode_t *)trie);
+}
+
+
+void
+trie_destroy_bynode (trienode_t *node)
+{
+        trie_destroy (node->trie);
+}
+
+
+static int
+trienode_walk (trienode_t *node, int (*fn)(trienode_t *node, void *data),
+               void *data, int eowonly)
+{
+        trienode_t *trav = NULL;
+        int              i = 0;
+        int              cret = 0;
+        int              ret = 0;
+
+        if (!eowonly || node->eow)
+                ret = fn (node, data);
+
+        if (ret)
+                goto out;
+
+        for (i = 0; i < 255; i++) {
+                trav = node->subnodes[i];
+                if (!trav)
+                        continue;
+
+                cret = trienode_walk (trav, fn, data, eowonly);
+                if (cret < 0) {
+                        ret = cret;
+                        goto out;
+                }
+                ret += cret;
+        }
+
+out:
+        return ret;
+}
+
+
+static int
+trie_walk (trie_t *trie, int (*fn)(trienode_t *node, void *data),
+           void *data, int eowonly)
+{
+        return trienode_walk (&trie->root, fn, data, eowonly);
+}
+
+
+static void
+print_node (trienode_t *node, char **buf)
+{
+        if (!node->parent)
+                return;
+
+        if (node->parent) {
+                print_node (node->parent, buf);
+                *(*buf)++ = node->id;
+        }
+}
+
+
+int
+trienode_get_word (trienode_t *node, char **bufp)
+{
+        char *buf = NULL;
+
+        buf = GF_CALLOC (1, node->depth + 1, gf_trie_mt_buf);
+        if (!buf)
+                return -1;
+        *bufp = buf;
+
+        print_node (node, &buf);
+
+        return 0;
+}
+
+
+static int
+calc_dist (trienode_t *node, void *data)
+{
+        const char *word = NULL;
+        int         i = 0;
+        int        *row = NULL;
+        int        *uprow = NULL;
+        int         distu = 0;
+        int         distl = 0;
+        int         distul = 0;
+
+        word = data;
+
+        node->data = GF_CALLOC (node->trie->len, sizeof (int), gf_trie_mt_data);
+        if (!node->data)
+                return -1;
+        row = node->data;
+
+        if (!node->parent) {
+                for (i = 0; i < node->trie->len; i++)
+                        row[i] = i+1;
+
+                return 0;
+        }
+
+        uprow = node->parent->data;
+
+        distu = node->depth;          /* up node */
+        distul = node->parent->depth; /* up-left node */
+
+        for (i = 0; i < node->trie->len; i++) {
+                distl = uprow[i];     /* left node */
+
+                if (word[i] == node->id)
+                        row[i] = distul;
+                else
+                        row[i] = min ((distul + DISTANCE_EDIT),
+                                      min ((distu + DISTANCE_DEL),
+                                           (distl + DISTANCE_INS)));
+
+                distu  = row[i];
+                distul = distl;
+        }
+
+        return 0;
+}
+
+
+int
+trienode_get_dist (trienode_t *node)
+{
+        int *row = NULL;
+
+        row = node->data;
+
+        return row[node->trie->len - 1];
+}
+
+
+struct trienodevec_w {
+        struct trienodevec *vec;
+        const char *word;
+};
+
+
+static void
+trienodevec_clear (struct trienodevec *nodevec)
+{
+        memset(nodevec->nodes, 0, sizeof (*nodevec->nodes) * nodevec->cnt);
+}
+
+
+static int
+collect_closest (trienode_t *node, void *data)
+{
+        struct trienodevec_w *nodevec_w = NULL;
+        struct trienodevec *nodevec = NULL;
+        int dist = 0;
+        int i = 0;
+
+        nodevec_w = data;
+        nodevec = nodevec_w->vec;
+
+        if (calc_dist (node, (void *)nodevec_w->word))
+                return -1;
+
+        if (!node->eow || !nodevec->cnt)
+                return 0;
+
+        dist = trienode_get_dist (node);
+
+        /*
+         * I thought that when descending further after some dictionary word dw,
+         * if we see that child's distance is bigger than it was for dw, then we
+         * can prune this branch, as it can contain only worse nodes.
+         *
+         * This conjecture fails, see eg:
+         *
+         * d("AB", "B") = 1;
+         * d("AB", "BA") = 2;
+         * d("AB", "BAB") = 1;
+         *
+         * -- if both "B" and "BAB" are in dict., then pruning at "BA" * would
+         * miss "BAB".
+         *
+         * (example courtesy of Richard Bann <richardbann at gmail.com>)
+
+        if (node->parent->eow && dist > trienode_get_dist (node->parent))
+                return 1;
+
+         */
+
+        if (nodevec->nodes[0] &&
+            dist < trienode_get_dist (nodevec->nodes[0])) {
+                /* improving over the findings so far */
+                trienodevec_clear (nodevec);
+                nodevec->nodes[0] = node;
+        } else if (!nodevec->nodes[0] ||
+                   dist == trienode_get_dist (nodevec->nodes[0])) {
+                /* as good as the best so far, add if there is free space */
+                for (i = 0; i < nodevec->cnt; i++) {
+                        if (!nodevec->nodes[i]) {
+                                nodevec->nodes[i] = node;
+                                break;
+                        }
+                }
+        }
+
+        return 0;
+}
+
+
+int
+trie_measure (trie_t *trie, const char *word, trienode_t **nodes,
+              int nodecnt)
+{
+        struct trienodevec nodevec = {0,};
+
+        nodevec.nodes = nodes;
+        nodevec.cnt = nodecnt;
+
+        return trie_measure_vec (trie, word, &nodevec);
+}
+
+
+int
+trie_measure_vec (trie_t *trie, const char *word, struct trienodevec *nodevec)
+{
+        struct trienodevec_w nodevec_w = {0,};
+        int ret = 0;
+
+        trie->len = strlen (word);
+
+        trienodevec_clear (nodevec);
+        nodevec_w.vec = nodevec;
+        nodevec_w.word = word;
+
+        ret = trie_walk (trie, collect_closest, &nodevec_w, 0);
+        if (ret > 0)
+                ret = 0;
+
+        return ret;
+}
+
+
+static int
+trienode_reset (trienode_t *node, void *data)
+{
+        if (node->data)
+                GF_FREE (node->data);
+
+        return 0;
+}
+
+
+void
+trie_reset_search (trie_t *trie)
+{
+        trie->len = 0;
+
+        trie_walk (trie, trienode_reset, NULL, 0);
+}
diff --git a/libglusterfs/src/trie.h b/libglusterfs/src/trie.h
new file mode 100644
index 000000000..a670c2a27
--- /dev/null
+++ b/libglusterfs/src/trie.h
@@ -0,0 +1,60 @@
+/*
+  Copyright (c) 2007-2010 Gluster, Inc. <http://www.gluster.com>
+  This file is part of GlusterFS.
+
+  GlusterFS is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Affero General Public License as published
+  by the Free Software Foundation; either version 3 of the License,
+  or (at your option) any later version.
+
+  GlusterFS 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
+  Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License
+  along with this program.  If not, see
+  <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _TRIE_H_
+#define _TRIE_H_
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+struct trienode;
+typedef struct trienode trienode_t;
+
+struct trie;
+typedef struct trie trie_t;
+
+struct trienodevec {
+        trienode_t **nodes;
+        unsigned cnt;
+};
+
+
+trie_t *trie_new ();
+
+int trie_add (trie_t *trie, const char *word);
+
+void trie_destroy (trie_t *trie);
+
+void trie_destroy_bynode (trienode_t *node);
+
+int trie_measure (trie_t *trie, const char *word, trienode_t **nodes,
+                  int nodecnt);
+
+int trie_measure_vec (trie_t *trie, const char *word,
+                      struct trienodevec *nodevec);
+
+void trie_reset_search (trie_t *trie);
+
+int trienode_get_dist (trienode_t *node);
+
+int trienode_get_word (trienode_t *node, char **buf);
+
+#endif
diff --git a/xlators/mgmt/glusterd/src/glusterd-op-sm.c b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
index d19caddc6..e57acf1d2 100644
--- a/xlators/mgmt/glusterd/src/glusterd-op-sm.c
+++ b/xlators/mgmt/glusterd/src/glusterd-op-sm.c
@@ -1123,6 +1123,7 @@ glusterd_op_stage_set_volume (gd1_mgmt_stage_op_req *req, char **op_errstr)
         char                                    *volname       = NULL;
  	int                                      exists        = 0;
  	char					*key	       = NULL;
+        char                                    *key_fixed     = NULL;
         char                                    *value         = NULL;
  	char					 str[100]      = {0, };
  	int					 count	       = 0;
@@ -1204,13 +1205,20 @@ glusterd_op_stage_set_volume (gd1_mgmt_stage_op_req *req, char **op_errstr)
                         break;
 
 		
-		exists = glusterd_check_option_exists (key, NULL);
-
-		if (exists != 1) {
+		exists = glusterd_check_option_exists (key, &key_fixed);
+                if (exists == -1) {
+                        ret = -1;
+                        goto out;
+                }
+		if (!exists) {
                 	gf_log ("", GF_LOG_ERROR, "Option with name: %s "
                         	"does not exist", key);
-                        snprintf (errstr, 2048, "option : %s does not exist",
-                                  key);
+                        ret = snprintf (errstr, 2048,
+                                       "option : %s does not exist",
+                                       key);
+                        if (key_fixed)
+                                snprintf (errstr + ret, 2048 - ret,
+                                          "\nDid you mean %s?", key_fixed);
                         *op_errstr = gf_strdup (errstr);
 
 			ret = -1;
@@ -1227,6 +1235,8 @@ glusterd_op_stage_set_volume (gd1_mgmt_stage_op_req *req, char **op_errstr)
                         goto out;
                 }
 
+                if (key_fixed)
+                        key = key_fixed;
                 ret = dict_set_str (val_dict, key, value);
 
                 if (ret) {
@@ -1236,7 +1246,10 @@ glusterd_op_stage_set_volume (gd1_mgmt_stage_op_req *req, char **op_errstr)
                         goto out;
                 }
 
-
+                if (key_fixed) {
+                        GF_FREE (key_fixed);
+                        key_fixed = NULL;
+                }
 	}
 
         *op_errstr = NULL;
@@ -1258,6 +1271,9 @@ out:
         if (val_dict)
                 dict_unref (val_dict);
 
+        if (key_fixed)
+                GF_FREE (key_fixed);
+
         if (ret) {
                 if (!(*op_errstr)) {
                         *op_errstr = gf_strdup ("Error, Validation Failed");
@@ -1269,7 +1285,7 @@ out:
                         gf_log ("glsuterd", GF_LOG_DEBUG,
                         "Error, Cannot Validate option");
         }
-return ret;
+        return ret;
 }
 
 static int
@@ -3196,6 +3212,7 @@ glusterd_op_set_volume (gd1_mgmt_stage_op_req *req)
         glusterd_conf_t                         *priv = NULL;
 	int					 count = 1;
 	char					*key = NULL;
+	char					*key_fixed = NULL;
 	char					*value = NULL;
 	char					 str[50] = {0, };
         GF_ASSERT (req);
@@ -3234,7 +3251,15 @@ glusterd_op_set_volume (gd1_mgmt_stage_op_req *req)
 
 		sprintf (str, "key%d", count);
 		ret = dict_get_str (dict, str, &key);
-
+                if (!ret) {
+                        ret = glusterd_check_option_exists (key, &key_fixed);
+                        GF_ASSERT (ret);
+                        if (ret == -1) {
+                                key_fixed = NULL;
+                                goto out;
+                        }
+                        ret = 0;
+                }
 
 		if (ret)
 			break;
@@ -3250,9 +3275,11 @@ glusterd_op_set_volume (gd1_mgmt_stage_op_req *req)
         	}
 
                 value = gf_strdup (value);
-                if (value)
+                if (value) {
+                        if (key_fixed)
+                                key = key_fixed;
 		        ret = dict_set_dynstr (volinfo->dict, key, value);
-                else
+                } else
                         ret = -1;
 
 		if (ret) {
@@ -3261,6 +3288,11 @@ glusterd_op_set_volume (gd1_mgmt_stage_op_req *req)
 			ret = -1;
 			goto out;
         	}
+
+                if (key_fixed) {
+                        GF_FREE (key_fixed);
+                        key_fixed = NULL;
+                }
 	}
 
 	if ( count == 1 ) {
@@ -3294,6 +3326,8 @@ glusterd_op_set_volume (gd1_mgmt_stage_op_req *req)
 out:
         if (dict)
                 dict_unref (dict);
+        if (key_fixed)
+                GF_FREE (key_fixed);
         gf_log ("", GF_LOG_DEBUG, "returning %d", ret);
         return ret;
 }
diff --git a/xlators/mgmt/glusterd/src/glusterd-volgen.c b/xlators/mgmt/glusterd/src/glusterd-volgen.c
index 42e2f6377..16f4b92e5 100644
--- a/xlators/mgmt/glusterd/src/glusterd-volgen.c
+++ b/xlators/mgmt/glusterd/src/glusterd-volgen.c
@@ -31,6 +31,7 @@
 #include "logging.h"
 #include "dict.h"
 #include "graph-utils.h"
+#include "trie.h"
 #include "glusterd-mem-types.h"
 #include "cli1.h"
 #include "glusterd-volgen.h"
@@ -336,6 +337,193 @@ first_of (glusterfs_graph_t *graph)
 
 /**************************
  *
+ * Trie glue
+ *
+ *************************/
+
+
+static int
+volopt_selector (int lvl, char **patt, void *param,
+                     int (*optcbk)(char *word, void *param))
+{
+        struct volopt_map_entry *vme = NULL;
+        char *w = NULL;
+        int i = 0;
+        int len = 0;
+        int ret = 0;
+        char *dot = NULL;
+
+        for (vme = glusterd_volopt_map; vme->key; vme++) {
+                w = vme->key;
+
+                for (i = 0; i < lvl; i++) {
+                        if (patt[i]) {
+                                w = strtail (w, patt[i]);
+                                GF_ASSERT (!w || *w);
+                                if (!w || *w != '.')
+                                        goto next;
+                        } else {
+                                w = strchr (w, '.');
+                                GF_ASSERT (w);
+                        }
+                        w++;
+                }
+
+                dot = strchr (w, '.');
+                if (dot) {
+                        len = dot - w;
+                        w = gf_strdup (w);
+                        if (!w)
+                                return -1;
+                        w[len] = '\0';
+                }
+                ret = optcbk (w, param);
+                if (dot)
+                        GF_FREE (w);
+                if (ret)
+                        return -1;
+ next:
+                continue;
+        }
+
+        return 0;
+}
+
+static int
+volopt_trie_cbk (char *word, void *param)
+{
+        return trie_add ((trie_t *)param, word);
+}
+
+static int
+process_nodevec (struct trienodevec *nodevec, char **hint)
+{
+        int ret = 0;
+        char *hint1 = NULL;
+        char *hint2 = NULL;
+        char *hintinfx = "";
+        trienode_t **nodes = nodevec->nodes;
+
+        if (!nodes[0]) {
+                *hint = NULL;
+                return 0;
+        }
+
+#if 0
+        /* Limit as in git */
+        if (trienode_get_dist (nodes[0]) >= 6) {
+                *hint = NULL;
+                return 0;
+        }
+#endif
+
+        if (trienode_get_word (nodes[0], &hint1))
+                return -1;
+
+        if (nodevec->cnt < 2 || !nodes[1]) {
+                *hint = hint1;
+                return 0;
+        }
+
+        if (trienode_get_word (nodes[1], &hint2))
+                return -1;
+
+        if (*hint)
+                hintinfx = *hint;
+        ret = gf_asprintf (hint, "%s or %s%s", hint1, hintinfx, hint2);
+        if (ret > 0)
+                ret = 0;
+        return ret;
+}
+
+static int
+volopt_trie_section (int lvl, char **patt, char *word, char **hint, int hints)
+{
+        trienode_t *nodes[] = { NULL, NULL };
+        struct trienodevec nodevec = { nodes, 2};
+        trie_t *trie = NULL;
+        int ret = 0;
+
+        trie = trie_new ();
+        if (!trie)
+                return -1;
+
+        if (volopt_selector (lvl, patt, trie, &volopt_trie_cbk)) {
+                trie_destroy (trie);
+
+                return -1;
+        }
+
+        GF_ASSERT (hints <= 2);
+        nodevec.cnt = hints;
+        ret = trie_measure_vec (trie, word, &nodevec);
+        if (ret || !nodevec.nodes[0])
+                trie_destroy (trie);
+
+        ret = process_nodevec (&nodevec, hint);
+        trie_destroy (trie);
+
+        return ret;
+}
+
+static int
+volopt_trie (char *key, char **hint)
+{
+        char *patt[] = { NULL };
+        char *fullhint = NULL;
+        char *dot = NULL;
+        char *dom = NULL;
+        int   len = 0;
+        int   ret = 0;
+
+        *hint = NULL;
+
+        dot = strchr (key, '.');
+        if (!dot)
+                return volopt_trie_section (1, patt, key, hint, 2);
+
+        len = dot - key;
+        dom = gf_strdup (key);
+        if (!dom)
+                return -1;
+        dom[len] = '\0';
+
+        ret = volopt_trie_section (0, NULL, dom, patt, 1);
+        GF_FREE (dom);
+        if (ret) {
+                patt[0] = NULL;
+                goto out;
+        }
+        if (!patt[0])
+                goto out;
+
+        *hint = "...";
+        ret = volopt_trie_section (1, patt, dot + 1, hint, 2);
+        if (ret)
+                goto out;
+        if (*hint) {
+                ret = gf_asprintf (&fullhint, "%s.%s", patt[0], *hint);
+                GF_FREE (*hint);
+                if (ret >= 0) {
+                        ret = 0;
+                        *hint = fullhint;
+                }
+        }
+
+ out:
+        if (patt[0])
+                GF_FREE (patt[0]);
+        if (ret)
+                *hint = NULL;
+
+        return ret;
+}
+
+
+
+
+/**************************
+ *
  * Volume generation engine
  *
  **************************/
@@ -502,23 +690,35 @@ glusterd_volinfo_get (glusterd_volinfo_t *volinfo, char *key, char **value)
         return 0;
 }
 
-static char *
-option_complete (char *key)
+static int
+option_complete (char *key, char **completion)
 {
         struct volopt_map_entry *vme = NULL;
-        char *completion = NULL;
 
+        *completion = NULL;
         for (vme = glusterd_volopt_map; vme->key; vme++) {
                 if (strcmp (strchr (vme->key, '.') + 1, key) != 0)
                         continue;
 
-                if (completion)
-                        return NULL;
-                else
-                        completion = vme->key;
+                if (*completion && strcmp (*completion, vme->key) != 0) {
+                        /* cancel on non-unique match */
+                        *completion = NULL;
+
+                        return 0;
+                } else
+                        *completion = vme->key;
         }
 
-        return completion;
+        if (*completion) {
+                /* For sake of unified API we want
+                 * have the completion to be a to-be-freed
+                 * string.
+                 */
+                *completion = gf_strdup (*completion);
+                return -!*completion;
+        }
+
+        return 0;
 }
 
 int
@@ -535,9 +735,17 @@ glusterd_check_option_exists (char *key, char **completion)
 
         if (!strchr (key, '.')) {
                 if (completion) {
-                        *completion = option_complete (key);
+                        ret = option_complete (key, completion);
+                        if (ret) {
+                                gf_log ("", GF_LOG_ERROR, "Out of memory");
+                                return -1;
+                        }
 
-                        return !!*completion;
+                        ret = !!*completion;
+                        if (ret)
+                                return ret;
+                        else
+                                goto trie;
                 } else
                         return 0;
         }
@@ -549,8 +757,6 @@ glusterd_check_option_exists (char *key, char **completion)
                         break;
                 }
         }
-
-        return ret;
 #else
         vme.key = key;
 
@@ -563,22 +769,35 @@ glusterd_check_option_exists (char *key, char **completion)
          * have to update the fnmatch in this comment also :P ]]
          */
         dict = get_new_dict ();
-        if (!dict || dict_set_str (dict, key, ""))
-                goto oom;
+        if (!dict || dict_set_str (dict, key, "")) {
+                gf_log ("", GF_LOG_ERROR, "Out of memory");
+
+                return -1;
+        }
 
         ret = volgen_graph_set_options_generic (NULL, dict, &vme,
                                                 &optget_option_handler);
         dict_destroy (dict);
-        if (ret)
-                goto oom;
-
-        return !!vme.value;
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR, "Out of memory");
 
- oom:
-        gf_log ("", GF_LOG_ERROR, "Out of memory");
+                return -1;
+        }
 
-        return -1;
+        ret = !!vme.value;
 #endif
+
+        if (ret || !completion)
+                return ret;
+
+ trie:
+        ret = volopt_trie (key, completion);
+        if (ret) {
+                gf_log ("", GF_LOG_ERROR,
+                        "Some error occured during keyword hinting");
+        }
+
+        return ret;
 }
 
 static int