aoqi@0: /*
aoqi@0:  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_UTILITIES_RESOURCEHASH_HPP
aoqi@0: #define SHARE_VM_UTILITIES_RESOURCEHASH_HPP
aoqi@0: 
aoqi@0: #include "memory/allocation.hpp"
aoqi@0: #include "utilities/top.hpp"
aoqi@0: 
aoqi@0: template<typename K> struct ResourceHashtableFns {
aoqi@0:     typedef unsigned (*hash_fn)(K const&);
aoqi@0:     typedef bool (*equals_fn)(K const&, K const&);
aoqi@0: };
aoqi@0: 
aoqi@0: template<typename K> unsigned primitive_hash(const K& k) {
aoqi@0:   unsigned hash = (unsigned)((uintptr_t)k);
aoqi@0:   return hash ^ (hash > 3); // just in case we're dealing with aligned ptrs
aoqi@0: }
aoqi@0: 
aoqi@0: template<typename K> bool primitive_equals(const K& k0, const K& k1) {
aoqi@0:   return k0 == k1;
aoqi@0: }
aoqi@0: 
aoqi@0: template<
aoqi@0:     typename K, typename V,
aoqi@0:     // xlC does not compile this:
aoqi@0:     // http://stackoverflow.com/questions/8532961/template-argument-of-type-that-is-defined-by-inner-typedef-from-other-template-c
aoqi@0:     //typename ResourceHashtableFns<K>::hash_fn   HASH   = primitive_hash<K>,
aoqi@0:     //typename ResourceHashtableFns<K>::equals_fn EQUALS = primitive_equals<K>,
aoqi@0:     unsigned (*HASH)  (K const&)           = primitive_hash<K>,
aoqi@0:     bool     (*EQUALS)(K const&, K const&) = primitive_equals<K>,
aoqi@0:     unsigned SIZE = 256
aoqi@0:     >
aoqi@0: class ResourceHashtable : public ResourceObj {
aoqi@0:  private:
aoqi@0: 
aoqi@0:   class Node : public ResourceObj {
aoqi@0:    public:
aoqi@0:     unsigned _hash;
aoqi@0:     K _key;
aoqi@0:     V _value;
aoqi@0:     Node* _next;
aoqi@0: 
aoqi@0:     Node(unsigned hash, K const& key, V const& value) :
aoqi@0:         _hash(hash), _key(key), _value(value), _next(NULL) {}
aoqi@0:   };
aoqi@0: 
aoqi@0:   Node* _table[SIZE];
aoqi@0: 
aoqi@0:   // Returns a pointer to where the node where the value would reside if
aoqi@0:   // it's in the table.
aoqi@0:   Node** lookup_node(unsigned hash, K const& key) {
aoqi@0:     unsigned index = hash % SIZE;
aoqi@0:     Node** ptr = &_table[index];
aoqi@0:     while (*ptr != NULL) {
aoqi@0:       Node* node = *ptr;
aoqi@0:       if (node->_hash == hash && EQUALS(key, node->_key)) {
aoqi@0:         break;
aoqi@0:       }
aoqi@0:       ptr = &(node->_next);
aoqi@0:     }
aoqi@0:     return ptr;
aoqi@0:   }
aoqi@0: 
aoqi@0:   Node const** lookup_node(unsigned hash, K const& key) const {
aoqi@0:     return const_cast<Node const**>(
aoqi@0:         const_cast<ResourceHashtable*>(this)->lookup_node(hash, key));
aoqi@0:   }
aoqi@0: 
aoqi@0:  public:
aoqi@0:   ResourceHashtable() { memset(_table, 0, SIZE * sizeof(Node*)); }
aoqi@0: 
aoqi@0:   bool contains(K const& key) const {
aoqi@0:     return get(key) != NULL;
aoqi@0:   }
aoqi@0: 
aoqi@0:   V* get(K const& key) const {
aoqi@0:     unsigned hv = HASH(key);
aoqi@0:     Node const** ptr = lookup_node(hv, key);
aoqi@0:     if (*ptr != NULL) {
aoqi@0:       return const_cast<V*>(&(*ptr)->_value);
aoqi@0:     } else {
aoqi@0:       return NULL;
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   // Inserts or replaces a value in the table
aoqi@0:   void put(K const& key, V const& value) {
aoqi@0:     unsigned hv = HASH(key);
aoqi@0:     Node** ptr = lookup_node(hv, key);
aoqi@0:     if (*ptr != NULL) {
aoqi@0:       (*ptr)->_value = value;
aoqi@0:     } else {
aoqi@0:       *ptr = new Node(hv, key, value);
aoqi@0:     }
aoqi@0:   }
aoqi@0: 
aoqi@0:   // ITER contains bool do_entry(K const&, V const&), which will be
aoqi@0:   // called for each entry in the table.  If do_entry() returns false,
aoqi@0:   // the iteration is cancelled.
aoqi@0:   template<class ITER>
aoqi@0:   void iterate(ITER* iter) const {
aoqi@0:     Node* const* bucket = _table;
aoqi@0:     while (bucket < &_table[SIZE]) {
aoqi@0:       Node* node = *bucket;
aoqi@0:       while (node != NULL) {
aoqi@0:         bool cont = iter->do_entry(node->_key, node->_value);
aoqi@0:         if (!cont) { return; }
aoqi@0:         node = node->_next;
aoqi@0:       }
aoqi@0:       ++bucket;
aoqi@0:     }
aoqi@0:   }
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: #endif // SHARE_VM_UTILITIES_RESOURCEHASH_HPP