Robert Iakobashvili re-arranged the internal hash code to work with a custom

hash function for different hashes, and also expanded the default size for
the socket hash table used in multi handles to greatly enhance speed when
very many connections are added and the socket API is used.

CHANGES

@@ -6,6 +6,12 @@
 
                                   Changelog
 
+Daniel S (26 June 2007)
+- Robert Iakobashvili re-arranged the internal hash code to work with a custom
+  hash function for different hashes, and also expanded the default size for
+  the socket hash table used in multi handles to greatly enhance speed when
+  very many connections are added and the socket API is used.
+
 Daniel S (25 June 2007)
 - Adjusted how libcurl treats HTTP 1.1 responses without content-lenth or
   chunked encoding (that also lacks "Connection: close"). It now simply

RELEASE-NOTES

@@ -33,6 +33,6 @@ New curl mirrors:
 This release would not have looked like this without help, code, reports and
 advice from friends like these:
 
- 
+ Robert Iakobashvili
 
         Thanks! (and sorry if I forgot to mention someone)

lib/hash.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2006, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -33,20 +33,6 @@
 /* this must be the last include file */
 #include "memdebug.h"
 
-static unsigned long
-hash_str(const char *key, size_t key_length)
-{
-  char *end = (char *) key + key_length;
-  unsigned long h = 5381;
-
-  while (key < end) {
-    h += h << 5;
-    h ^= (unsigned long) *key++;
-  }
-
-  return h;
-}
-
 static void
 hash_element_dtor(void *user, void *element)
 {
@@ -63,10 +49,20 @@ hash_element_dtor(void *user, void *element)
 
 /* return 1 on error, 0 is fine */
 int
-Curl_hash_init(struct curl_hash *h, int slots, curl_hash_dtor dtor)
+Curl_hash_init(struct curl_hash *h,
+               int slots,
+               hash_function hfunc,
+               comp_function comparator,
+               curl_hash_dtor dtor)
 {
   int i;
 
+  if (!slots || !hfunc || !comparator ||!dtor) {
+    return 1; /* failure */
+  }
+
+  h->hash_func = hfunc;
+  h->comp_func = comparator;
   h->dtor = dtor;
   h->size = 0;
   h->slots = slots;
@@ -89,13 +85,20 @@ Curl_hash_init(struct curl_hash *h, int slots, curl_hash_dtor dtor)
 }
 
 struct curl_hash *
-Curl_hash_alloc(int slots, curl_hash_dtor dtor)
+Curl_hash_alloc(int slots,
+                hash_function hfunc,
+                comp_function comparator,
+                curl_hash_dtor dtor)
 {
   struct curl_hash *h;
 
+  if (!slots || !hfunc || !comparator ||!dtor) {
+    return NULL; /* failure */
+  }
+
   h = (struct curl_hash *) malloc(sizeof(struct curl_hash));
   if (h) {
-    if(Curl_hash_init(h, slots, dtor)) {
+    if(Curl_hash_init(h, slots, hfunc, comparator, dtor)) {
       /* failure */
       free(h);
       h = NULL;
@@ -105,26 +108,16 @@ Curl_hash_alloc(int slots, curl_hash_dtor dtor)
   return h;
 }
 
-static int
-hash_key_compare(char *key1, size_t key1_len, char *key2, size_t key2_len)
-{
-  if (key1_len == key2_len &&
-      *key1 == *key2 &&
-      memcmp(key1, key2, key1_len) == 0) {
-    return 1;
-  }
 
-  return 0;
-}
 
 static struct curl_hash_element *
-mk_hash_element(char *key, size_t key_len, const void *p)
+mk_hash_element(void *key, size_t key_len, const void *p)
 {
   struct curl_hash_element *he =
     (struct curl_hash_element *) malloc(sizeof(struct curl_hash_element));
 
   if(he) {
-    char *dup = malloc(key_len);
+    void *dup = malloc(key_len);
     if(dup) {
       /* copy the key */
       memcpy(dup, key, key_len);
@@ -142,22 +135,20 @@ mk_hash_element(char *key, size_t key_len, const void *p)
   return he;
 }
 
-#define find_slot(__h, __k, __k_len) (hash_str(__k, __k_len) % (__h)->slots)
-
-#define FETCH_LIST(x,y,z) x->table[find_slot(x, y, z)]
+#define FETCH_LIST(x,y,z) x->table[x->hash_func(y, z, x->slots)]
 
 /* Return the data in the hash. If there already was a match in the hash,
    that data is returned. */
 void *
-Curl_hash_add(struct curl_hash *h, char *key, size_t key_len, void *p)
+Curl_hash_add(struct curl_hash *h, void *key, size_t key_len, void *p)
 {
   struct curl_hash_element  *he;
   struct curl_llist_element *le;
-  struct curl_llist *l = FETCH_LIST(h, key, key_len);
+  struct curl_llist *l = FETCH_LIST (h, key, key_len);
 
   for (le = l->head; le; le = le->next) {
     he = (struct curl_hash_element *) le->ptr;
-    if (hash_key_compare(he->key, he->key_len, key, key_len)) {
+    if (h->comp_func(he->key, he->key_len, key, key_len)) {
       h->dtor(p);     /* remove the NEW entry */
       return he->ptr; /* return the EXISTING entry */
     }
@@ -183,7 +174,7 @@ Curl_hash_add(struct curl_hash *h, char *key, size_t key_len, void *p)
 }
 
 /* remove the identified hash entry, returns non-zero on failure */
-int Curl_hash_delete(struct curl_hash *h, char *key, size_t key_len)
+int Curl_hash_delete(struct curl_hash *h, void *key, size_t key_len)
 {
   struct curl_llist_element *le;
   struct curl_hash_element  *he;
@@ -191,7 +182,7 @@ int Curl_hash_delete(struct curl_hash *h, char *key, size_t key_len)
 
   for (le = l->head; le; le = le->next) {
     he = le->ptr;
-    if (hash_key_compare(he->key, he->key_len, key, key_len)) {
+    if (h->comp_func(he->key, he->key_len, key, key_len)) {
       Curl_llist_remove(l, le, (void *) h);
       return 0;
     }
@@ -200,7 +191,7 @@ int Curl_hash_delete(struct curl_hash *h, char *key, size_t key_len)
 }
 
 void *
-Curl_hash_pick(struct curl_hash *h, char *key, size_t key_len)
+Curl_hash_pick(struct curl_hash *h, void *key, size_t key_len)
 {
   struct curl_llist_element *le;
   struct curl_hash_element  *he;
@@ -208,7 +199,7 @@ Curl_hash_pick(struct curl_hash *h, char *key, size_t key_len)
 
   for (le = l->head; le; le = le->next) {
     he = le->ptr;
-    if (hash_key_compare(he->key, he->key_len, key, key_len)) {
+    if (h->comp_func(he->key, he->key_len, key, key_len)) {
       return he->ptr;
     }
   }
@@ -282,6 +273,34 @@ Curl_hash_destroy(struct curl_hash *h)
   free(h);
 }
 
+size_t Curl_hash_str(void* key, size_t key_length, size_t slots_num)
+{
+  char* key_str = (char *) key;
+  char *end = (char *) key_str + key_length;
+  unsigned long h = 5381;
+
+  while (key_str < end) {
+    h += h << 5;
+    h ^= (unsigned long) *key_str++;
+  }
+
+  return (h % slots_num);
+}
+
+size_t Curl_str_key_compare(void*k1, size_t key1_len, void*k2, size_t key2_len)
+{
+  char *key1 = (char *)k1;
+  char *key2 = (char *)k2;
+
+  if (key1_len == key2_len &&
+      *key1 == *key2 &&
+      memcmp(key1, key2, key1_len) == 0) {
+    return 1;
+  }
+
+  return 0;
+}
+
 #if 0 /* useful function for debugging hashes and their contents */
 void Curl_hash_print(struct curl_hash *h,
                      void (*func)(void *))

lib/hash.h

@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2005, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2007, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -29,10 +29,29 @@
 
 #include "llist.h"
 
+/* Hash function prototype */
+typedef size_t (*hash_function) (void* key,
+                                 size_t key_length,
+                                 size_t slots_num);
+
+/*
+   Comparator function prototype. Compares two keys.
+*/
+typedef size_t (*comp_function) (void* key1,
+                                 size_t key1_len,
+                                 void*key2,
+                                 size_t key2_len);
+
 typedef void (*curl_hash_dtor)(void *);
 
 struct curl_hash {
   struct curl_llist **table;
+
+  /* Hash function to be used for this hash table */
+  hash_function hash_func;
+
+  /* Comparator function to compare keys */
+  comp_function comp_func;
   curl_hash_dtor   dtor;
   int slots;
   size_t size;
@@ -45,11 +64,20 @@ struct curl_hash_element {
 };
 
 
-int Curl_hash_init(struct curl_hash *, int, curl_hash_dtor);
-struct curl_hash *Curl_hash_alloc(int, curl_hash_dtor);
-void *Curl_hash_add(struct curl_hash *, char *, size_t, void *);
-int Curl_hash_delete(struct curl_hash *h, char *key, size_t key_len);
-void *Curl_hash_pick(struct curl_hash *, char *, size_t);
+int Curl_hash_init(struct curl_hash *h,
+                   int slots,
+                   hash_function hfunc,
+                   comp_function comparator,
+                   curl_hash_dtor dtor);
+
+struct curl_hash *Curl_hash_alloc(int slots,
+                                  hash_function hfunc,
+                                  comp_function comparator,
+                                  curl_hash_dtor dtor);
+
+void *Curl_hash_add(struct curl_hash *h, void *key, size_t key_len, void *p);
+int Curl_hash_delete(struct curl_hash *h, void *key, size_t key_len);
+void *Curl_hash_pick(struct curl_hash *, void * key, size_t key_len);
 void Curl_hash_apply(struct curl_hash *h, void *user,
                      void (*cb)(void *user, void *ptr));
 int Curl_hash_count(struct curl_hash *h);
@@ -58,4 +86,8 @@ void Curl_hash_clean_with_criterium(struct curl_hash *h, void *user,
                                     int (*comp)(void *, void *));
 void Curl_hash_destroy(struct curl_hash *h);
 
+size_t Curl_hash_str(void* key, size_t key_length, size_t slots_num);
+size_t Curl_str_key_compare(void*k1, size_t key1_len, void*k2,
+                            size_t key2_len);
+
 #endif

lib/hostip.c

@@ -131,7 +131,8 @@ static void freednsentry(void *freethis);
 void Curl_global_host_cache_init(void)
 {
   if (!host_cache_initialized) {
-    Curl_hash_init(&hostname_cache, 7, freednsentry);
+    Curl_hash_init(&hostname_cache, 7, Curl_hash_str, Curl_str_key_compare,
+                   freednsentry);
     host_cache_initialized = 1;
   }
 }
@@ -537,7 +538,7 @@ static void freednsentry(void *freethis)
  */
 struct curl_hash *Curl_mk_dnscache(void)
 {
-  return Curl_hash_alloc(7, freednsentry);
+  return Curl_hash_alloc(7, Curl_hash_str, Curl_str_key_compare, freednsentry);
 }
 
 #ifdef CURLRES_ADDRINFO_COPY

lib/multi.c

@@ -50,6 +50,15 @@
 /* The last #include file should be: */
 #include "memdebug.h"
 
+/*
+  CURL_SOCKET_HASH_TABLE_SIZE should be a prime number. Increasing it from 97
+  to 911 takes on a 32-bit machine 4 x 804 = 3211 more bytes.  Still, every
+  CURL handle takes 45-50 K memory, therefore this 3K are not significant.
+*/
+#ifndef CURL_SOCKET_HASH_TABLE_SIZE
+#define CURL_SOCKET_HASH_TABLE_SIZE 911
+#endif
+
 struct Curl_message {
   /* the 'CURLMsg' is the part that is visible to the external user */
   struct CURLMsg extmsg;
@@ -305,6 +314,21 @@ static void sh_freeentry(void *freethis)
   free(p);
 }
 
+static size_t fd_key_compare(void*k1, size_t k1_len, void*k2, size_t k2_len)
+{
+  (void) k1_len; (void) k2_len;
+
+  return ((*((int* ) k1)) == (*((int* ) k2))) ? 1 : 0;
+}
+
+static size_t hash_fd(void* key, size_t key_length, size_t slots_num)
+{
+  int fd = * ((int* ) key);
+  (void) key_length;
+
+  return (fd % (int)slots_num);
+}
+
 /*
  * sh_init() creates a new socket hash and returns the handle for it.
  *
@@ -325,7 +349,8 @@ static void sh_freeentry(void *freethis)
  */
 static struct curl_hash *sh_init(void)
 {
-  return Curl_hash_alloc(97, sh_freeentry);
+  return Curl_hash_alloc(CURL_SOCKET_HASH_TABLE_SIZE, hash_fd, fd_key_compare,
+                         sh_freeentry);
 }
 
 CURLM *curl_multi_init(void)