[PATCH v3 13/17] tools/xenstore: switch hashtable to use the talloc framework

[Juergen Gross <jgross@suse.com>]

Instead of using malloc() and friends, let the hashtable implementation
use the talloc framework.

This is more consistent with the rest of xenstored and it allows to
track memory usage via "xenstore-control memreport".

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3:
- make key and value children of element (if flagged)
---
 tools/xenstore/hashtable.c        | 98 +++++++++++--------------------
 tools/xenstore/hashtable.h        |  3 +-
 tools/xenstore/xenstored_core.c   |  5 +-
 tools/xenstore/xenstored_domain.c |  2 +-
 4 files changed, 38 insertions(+), 70 deletions(-)

diff --git a/tools/xenstore/hashtable.c b/tools/xenstore/hashtable.c
index 6738719e47..6c2a0efeea 100644
--- a/tools/xenstore/hashtable.c
+++ b/tools/xenstore/hashtable.c
@@ -6,6 +6,8 @@
 #include <string.h>
 #include <math.h>
 #include <stdint.h>
+#include <stdarg.h>
+#include "talloc.h"
 
 struct entry
 {
@@ -50,7 +52,7 @@ indexFor(unsigned int tablelength, unsigned int hashvalue) {
 
 /*****************************************************************************/
 struct hashtable *
-create_hashtable(unsigned int minsize,
+create_hashtable(const void *ctx, unsigned int minsize,
                  unsigned int (*hashf) (void*),
                  int (*eqf) (void*,void*),
                  unsigned int flags)
@@ -66,10 +68,10 @@ create_hashtable(unsigned int minsize,
         if (primes[pindex] > minsize) { size = primes[pindex]; break; }
     }
 
-    h = (struct hashtable *)calloc(1, sizeof(struct hashtable));
+    h = talloc_zero(ctx, struct hashtable);
     if (NULL == h)
         goto err0;
-    h->table = (struct entry **)calloc(size, sizeof(struct entry *));
+    h->table = talloc_zero_array(h, struct entry *, size);
     if (NULL == h->table)
         goto err1;
 
@@ -83,7 +85,7 @@ create_hashtable(unsigned int minsize,
     return h;
 
 err1:
-   free(h);
+   talloc_free(h);
 err0:
    return NULL;
 }
@@ -115,47 +117,32 @@ hashtable_expand(struct hashtable *h)
     if (h->primeindex == (prime_table_length - 1)) return 0;
     newsize = primes[++(h->primeindex)];
 
-    newtable = (struct entry **)calloc(newsize, sizeof(struct entry*));
-    if (NULL != newtable)
+    newtable = talloc_realloc(h, h->table, struct entry *, newsize);
+    if (!newtable)
     {
-        /* This algorithm is not 'stable'. ie. it reverses the list
-         * when it transfers entries between the tables */
-        for (i = 0; i < h->tablelength; i++) {
-            while (NULL != (e = h->table[i])) {
-                h->table[i] = e->next;
-                index = indexFor(newsize,e->h);
+        h->primeindex--;
+        return 0;
+    }
+
+    h->table = newtable;
+    memset(newtable + h->tablelength, 0,
+           (newsize - h->tablelength) * sizeof(*newtable));
+    for (i = 0; i < h->tablelength; i++) {
+        for (pE = &(newtable[i]), e = *pE; e != NULL; e = *pE) {
+            index = indexFor(newsize, e->h);
+            if (index == i)
+            {
+                pE = &(e->next);
+            }
+            else
+            {
+                *pE = e->next;
                 e->next = newtable[index];
                 newtable[index] = e;
             }
         }
-        free(h->table);
-        h->table = newtable;
-    }
-    /* Plan B: realloc instead */
-    else 
-    {
-        newtable = (struct entry **)
-                   realloc(h->table, newsize * sizeof(struct entry *));
-        if (NULL == newtable) { (h->primeindex)--; return 0; }
-        h->table = newtable;
-        memset(newtable + h->tablelength, 0,
-               (newsize - h->tablelength) * sizeof(*newtable));
-        for (i = 0; i < h->tablelength; i++) {
-            for (pE = &(newtable[i]), e = *pE; e != NULL; e = *pE) {
-                index = indexFor(newsize,e->h);
-                if (index == i)
-                {
-                    pE = &(e->next);
-                }
-                else
-                {
-                    *pE = e->next;
-                    e->next = newtable[index];
-                    newtable[index] = e;
-                }
-            }
-        }
     }
+
     h->tablelength = newsize;
     h->loadlimit   = (unsigned int)
         (((uint64_t)newsize * max_load_factor) / 100);
@@ -184,12 +171,16 @@ hashtable_insert(struct hashtable *h, void *k, void *v)
          * element may be ok. Next time we insert, we'll try expanding again.*/
         hashtable_expand(h);
     }
-    e = (struct entry *)calloc(1, sizeof(struct entry));
+    e = talloc_zero(h, struct entry);
     if (NULL == e) { --(h->entrycount); return 0; } /*oom*/
     e->h = hash(h,k);
     index = indexFor(h->tablelength,e->h);
     e->k = k;
+    if (h->flags & HASHTABLE_FREE_KEY)
+        talloc_steal(e, k);
     e->v = v;
+    if (h->flags & HASHTABLE_FREE_VALUE)
+        talloc_steal(e, v);
     e->next = h->table[index];
     h->table[index] = e;
     return -1;
@@ -235,11 +226,7 @@ hashtable_remove(struct hashtable *h, void *k)
         {
             *pE = e->next;
             h->entrycount--;
-            if (h->flags & HASHTABLE_FREE_KEY)
-                free(e->k);
-            if (h->flags & HASHTABLE_FREE_VALUE)
-                free(e->v);
-            free(e);
+            talloc_free(e);
             return 1;
         }
         pE = &(e->next);
@@ -279,26 +266,7 @@ hashtable_iterate(struct hashtable *h,
 void
 hashtable_destroy(struct hashtable *h)
 {
-    unsigned int i;
-    struct entry *e, *f;
-    struct entry **table = h->table;
-
-    for (i = 0; i < h->tablelength; i++)
-    {
-        e = table[i];
-        while (NULL != e)
-        {
-            f = e;
-            e = e->next;
-            if (h->flags & HASHTABLE_FREE_KEY)
-                free(f->k);
-            if (h->flags & HASHTABLE_FREE_VALUE)
-                free(f->v);
-            free(f);
-        }
-    }
-    free(h->table);
-    free(h);
+    talloc_free(h);
 }
 
 /*
diff --git a/tools/xenstore/hashtable.h b/tools/xenstore/hashtable.h
index d6feb1b038..5d39c4e3a0 100644
--- a/tools/xenstore/hashtable.h
+++ b/tools/xenstore/hashtable.h
@@ -9,6 +9,7 @@ struct hashtable;
  * create_hashtable
    
  * @name                    create_hashtable
+ * @param   ctx             talloc context to use for allocations
  * @param   minsize         minimum initial size of hashtable
  * @param   hashfunction    function for hashing keys
  * @param   key_eq_fn       function for determining key equality
@@ -22,7 +23,7 @@ struct hashtable;
 #define HASHTABLE_FREE_KEY   (1U << 1)
 
 struct hashtable *
-create_hashtable(unsigned int minsize,
+create_hashtable(const void *ctx, unsigned int minsize,
                  unsigned int (*hashfunction) (void*),
                  int (*key_eq_fn) (void*,void*),
                  unsigned int flags
diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 3336e65c97..f27209dec8 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -2424,11 +2424,10 @@ static int keys_equal_fn(void *key1, void *key2)
 
 int remember_string(struct hashtable *hash, const char *str)
 {
-	char *k = malloc(strlen(str) + 1);
+	char *k = talloc_strdup(NULL, str);
 
 	if (!k)
 		return 0;
-	strcpy(k, str);
 	return hashtable_insert(hash, k, (void *)1);
 }
 
@@ -2523,7 +2522,7 @@ void check_store(void)
 	};
 
 	/* Don't free values (they are all void *1) */
-	reachable = create_hashtable(16, hash_from_key_fn, keys_equal_fn,
+	reachable = create_hashtable(NULL, 16, hash_from_key_fn, keys_equal_fn,
 				     HASHTABLE_FREE_KEY);
 	if (!reachable) {
 		log("check_store: ENOMEM");
diff --git a/tools/xenstore/xenstored_domain.c b/tools/xenstore/xenstored_domain.c
index 1723c9804a..3f20f03eb0 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -931,7 +931,7 @@ void domain_init(int evtfd)
 	int rc;
 
 	/* Start with a random rather low domain count for the hashtable. */
-	domhash = create_hashtable(8, domhash_fn, domeq_fn, 0);
+	domhash = create_hashtable(NULL, 8, domhash_fn, domeq_fn, 0);
 	if (!domhash)
 		barf_perror("Failed to allocate domain hashtable");
 
-- 
2.35.3