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+/*
+ * util/storage/slabhash.h - hashtable consisting of several smaller tables.
+ *
+ * Copyright (c) 2007, NLnet Labs. All rights reserved.
+ *
+ * This software is open source.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of the NLNET LABS nor the names of its contributors may
+ * be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * \file
+ *
+ * Hash table that consists of smaller hash tables.
+ * It cannot grow, but that gives it the ability to have multiple
+ * locks. Also this means there are multiple LRU lists.
+ */
+
+#ifndef UTIL_STORAGE_SLABHASH_H
+#define UTIL_STORAGE_SLABHASH_H
+#include "util/storage/lruhash.h"
+
+/** default number of slabs */
+#define HASH_DEFAULT_SLABS 4
+
+/**
+ * Hash table formed from several smaller ones.
+ * This results in a partitioned lruhash table, a 'slashtable'.
+ * None of the data inside the slabhash may be altered.
+ * Therefore, no locks are needed to access the structure.
+ */
+struct slabhash {
+ /** the size of the array - must be power of 2 */
+ size_t size;
+ /** size bitmask - uses high bits. */
+ uint32_t mask;
+ /** shift right this many bits to get index into array. */
+ unsigned int shift;
+ /** lookup array of hash tables */
+ struct lruhash** array;
+};
+
+/**
+ * Create new slabbed hash table.
+ * @param numtables: number of hash tables to use, other parameters used to
+ * initialize these smaller hashtables.
+ * @param start_size: size of hashtable array at start, must be power of 2.
+ * @param maxmem: maximum amount of memory this table is allowed to use.
+ * so every table gets maxmem/numtables to use for itself.
+ * @param sizefunc: calculates memory usage of entries.
+ * @param compfunc: compares entries, 0 on equality.
+ * @param delkeyfunc: deletes key.
+ * @param deldatafunc: deletes data.
+ * @param arg: user argument that is passed to user function calls.
+ * @return: new hash table or NULL on malloc failure.
+ */
+struct slabhash* slabhash_create(size_t numtables, size_t start_size,
+ size_t maxmem, lruhash_sizefunc_t sizefunc,
+ lruhash_compfunc_t compfunc, lruhash_delkeyfunc_t delkeyfunc,
+ lruhash_deldatafunc_t deldatafunc, void* arg);
+
+/**
+ * Delete hash table. Entries are all deleted.
+ * @param table: to delete.
+ */
+void slabhash_delete(struct slabhash* table);
+
+/**
+ * Clear hash table. Entries are all deleted.
+ * @param table: to make empty.
+ */
+void slabhash_clear(struct slabhash* table);
+
+/**
+ * Insert a new element into the hashtable, uses lruhash_insert.
+ * If key is already present data pointer in that entry is updated.
+ *
+ * @param table: hash table.
+ * @param hash: hash value. User calculates the hash.
+ * @param entry: identifies the entry.
+ * If key already present, this entry->key is deleted immediately.
+ * But entry->data is set to NULL before deletion, and put into
+ * the existing entry. The data is then freed.
+ * @param data: the data.
+ * @param cb_override: if not NULL overrides the cb_arg for deletfunc.
+ */
+void slabhash_insert(struct slabhash* table, hashvalue_t hash,
+ struct lruhash_entry* entry, void* data, void* cb_override);
+
+/**
+ * Lookup an entry in the hashtable. Uses lruhash_lookup.
+ * At the end of the function you hold a (read/write)lock on the entry.
+ * The LRU is updated for the entry (if found).
+ * @param table: hash table.
+ * @param hash: hash of key.
+ * @param key: what to look for, compared against entries in overflow chain.
+ * the hash value must be set, and must work with compare function.
+ * @param wr: set to true if you desire a writelock on the entry.
+ * with a writelock you can update the data part.
+ * @return: pointer to the entry or NULL. The entry is locked.
+ * The user must unlock the entry when done.
+ */
+struct lruhash_entry* slabhash_lookup(struct slabhash* table,
+ hashvalue_t hash, void* key, int wr);
+
+/**
+ * Remove entry from hashtable. Does nothing if not found in hashtable.
+ * Delfunc is called for the entry. Uses lruhash_remove.
+ * @param table: hash table.
+ * @param hash: hash of key.
+ * @param key: what to look for.
+ */
+void slabhash_remove(struct slabhash* table, hashvalue_t hash, void* key);
+
+/**
+ * Output debug info to the log as to state of the hash table.
+ * @param table: hash table.
+ * @param id: string printed with table to identify the hash table.
+ * @param extended: set to true to print statistics on overflow bin lengths.
+ */
+void slabhash_status(struct slabhash* table, const char* id, int extended);
+
+/**
+ * Retrieve slab hash total size.
+ * @param table: hash table.
+ * @return size configured as max.
+ */
+size_t slabhash_get_size(struct slabhash* table);
+
+/**
+ * Retrieve slab hash current memory use.
+ * @param table: hash table.
+ * @return memory in use.
+ */
+size_t slabhash_get_mem(struct slabhash* table);
+
+/**
+ * Get lruhash table for a given hash value
+ * @param table: slabbed hash table.
+ * @param hash: hash value.
+ * @return the lru hash table.
+ */
+struct lruhash* slabhash_gettable(struct slabhash* table, hashvalue_t hash);
+
+/**
+ * Set markdel function
+ * @param table: slabbed hash table.
+ * @param md: markdel function ptr.
+ */
+void slabhash_setmarkdel(struct slabhash* table, lruhash_markdelfunc_t md);
+
+/**
+ * Traverse a slabhash.
+ * @param table: slabbed hash table.
+ * @param wr: if true, writelock is obtained, otherwise readlock.
+ * @param func: function to call for every element.
+ * @param arg: user argument to function.
+ */
+void slabhash_traverse(struct slabhash* table, int wr,
+ void (*func)(struct lruhash_entry*, void*), void* arg);
+
+/* --- test representation --- */
+/** test structure contains test key */
+struct slabhash_testkey {
+ /** the key id */
+ int id;
+ /** the entry */
+ struct lruhash_entry entry;
+};
+/** test structure contains test data */
+struct slabhash_testdata {
+ /** data value */
+ int data;
+};
+
+/** test sizefunc for lruhash */
+size_t test_slabhash_sizefunc(void*, void*);
+/** test comparefunc for lruhash */
+int test_slabhash_compfunc(void*, void*);
+/** test delkey for lruhash */
+void test_slabhash_delkey(void*, void*);
+/** test deldata for lruhash */
+void test_slabhash_deldata(void*, void*);
+/* --- end test representation --- */
+
+#endif /* UTIL_STORAGE_SLABHASH_H */