[PATCH v2 15/19] tools/xenstore: switch hashtable to use the talloc framework

[Juergen Gross <jgross@xxxxxxxx>]

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@xxxxxxxx>
---
 tools/xenstore/hashtable.c        | 86 ++++++++++++-------------------
 tools/xenstore/hashtable.h        |  3 +-
 tools/xenstore/xenstored_core.c   |  5 +-
 tools/xenstore/xenstored_domain.c |  2 +-
 4 files changed, 39 insertions(+), 57 deletions(-)

diff --git a/tools/xenstore/hashtable.c b/tools/xenstore/hashtable.c
index 299549c51e..3b6745b692 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);
@@ -184,7 +171,7 @@ 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);
@@ -238,8 +225,8 @@ hashtable_remove(struct hashtable *h, void *k)
             h->entrycount--;
             v = e->v;
             if (h->flags & HASHTABLE_FREE_KEY)
-                free(e->k);
-            free(e);
+                talloc_free(e->k);
+            talloc_free(e);
             return v;
         }
         pE = &(e->next);
@@ -280,25 +267,20 @@ void
 hashtable_destroy(struct hashtable *h)
 {
     unsigned int i;
-    struct entry *e, *f;
+    struct entry *e;
     struct entry **table = h->table;
 
     for (i = 0; i < h->tablelength; i++)
     {
-        e = table[i];
-        while (NULL != e)
+        for (e = table[i]; e; e = e->next)
         {
-            f = e;
-            e = e->next;
             if (h->flags & HASHTABLE_FREE_KEY)
-                free(f->k);
+                talloc_free(e->k);
             if (h->flags & HASHTABLE_FREE_VALUE)
-                free(f->v);
-            free(f);
+                talloc_free(e->v);
         }
     }
-    free(h->table);
-    free(h);
+    talloc_free(h);
 }
 
 /*
diff --git a/tools/xenstore/hashtable.h b/tools/xenstore/hashtable.h
index 6d65431f96..becec73092 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 6c9d22b8a2..60433265ed 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -2419,11 +2419,10 @@ 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);
 }
 
@@ -2518,7 +2517,7 @@ 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 65e94e3822..4d735a5951 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -929,7 +929,7 @@ 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