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diff --git a/ctdb/common/db_hash.h b/ctdb/common/db_hash.h
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+/*
+   Using tdb as a hash table
+
+   Copyright (C) Amitay Isaacs  2015
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __CTDB_DB_HASH_H__
+#define __CTDB_DB_HASH_H__
+
+#include <talloc.h>
+#include <tdb.h>
+
+/**
+ * @file db_hash.h
+ *
+ * @brief Use tdb database as a hash table
+ *
+ * This uses in-memory tdb databases to create a fixed sized hash table.
+ */
+
+/**
+ * @brief Hash type to indicate the hashing function to use.
+ *
+ * DB_HASH_SIMPLE uses default hashing function
+ * DB_HASH_COMPLEX uses jenkins hashing function
+ */
+enum db_hash_type {
+	DB_HASH_SIMPLE,
+	DB_HASH_COMPLEX,
+};
+
+/**
+ * @brief Parser callback function called when fetching a record
+ *
+ * This function is called when fetching a record. This function should
+ * not modify key and data arguments.
+ *
+ * The function should return 0 on success and errno on error.
+ */
+typedef int (*db_hash_record_parser_fn)(uint8_t *keybuf, size_t keylen,
+					uint8_t *databuf, size_t datalen,
+					void *private_data);
+
+/**
+ * @brief Abstract structure representing tdb hash table
+ */
+struct db_hash_context;
+
+/**
+ * @brief Initialize tdb hash table
+ *
+ * This returns a new tdb hash table context which is a talloc context.  Freeing
+ * this context will free all the memory associated with the hash table.
+ *
+ * @param[in] mem_ctx Talloc memory context
+ * @param[in] name The name for the hash table
+ * @param[in] hash_size The size of the hash table
+ * @param[in] type The type of hashing function to use
+ * @param[out] result The new db_hash_context structure
+ * @return 0 on success, errno on failure
+ */
+int db_hash_init(TALLOC_CTX *mem_ctx, const char *name, int hash_size,
+		 enum db_hash_type type, struct db_hash_context **result);
+
+/**
+ * @brief Insert a record into the hash table
+ *
+ * The key and data can be any binary data.  Insert only if the record does not
+ * exist.  If the record already exists, return error.
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] keybuf The key buffer
+ * @param[in] keylen The key length
+ * @param[in] databuf The data buffer
+ * @param[in] datalen The data length
+ * @return 0 on success, errno on failure
+ */
+int db_hash_insert(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen,
+		   uint8_t *databuf, size_t datalen);
+
+/**
+ * @brief Add a record into the hash table
+ *
+ * The key and data can be any binary data.  If the record does not exist,
+ * insert the record.  If the record already exists, replace the record.
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] keybuf The key buffer
+ * @param[in] keylen The key length
+ * @param[in] databuf The data buffer
+ * @param[in] datalen The data length
+ * @return 0 on success, errno on failure
+ */
+int db_hash_add(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen,
+		uint8_t *databuf, size_t datalen); 
+/**
+ * @brief Delete a record from the hash table
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] keybuf The key buffer
+ * @param[in] keylen The key length
+ * @return 0 on success, errno on failure
+ */
+int db_hash_delete(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen);
+
+/**
+ * @brief Fetch a record from the hash table
+ *
+ * The key and data can be any binary data.
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] keybuf The key buffer
+ * @param[in] keylen The key length
+ * @param[in] parser Function called when the matching record is found
+ * @param[in] private_data Private data to parser function
+ * @return 0 on success, errno on failure
+ */
+int db_hash_fetch(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen,
+		  db_hash_record_parser_fn parser, void *private_data);
+
+/**
+ * @brief Check if a record exists in the hash table
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] keybuf The key buffer
+ * @param[in] keylen The key length
+ * @return 0 if the record exists, errno on failure
+ */
+int db_hash_exists(struct db_hash_context *dh, uint8_t *keybuf, size_t keylen);
+
+/**
+ * @brief Traverse the database without modification
+ *
+ * The parser function should return non-zero value to stop traverse.
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] parser Function called for each record
+ * @param[in] private_data Private data to parser function
+ * @param[out] count Number of records traversed
+ * @return 0 on success, errno on failure
+ */
+int db_hash_traverse(struct db_hash_context *dh,
+		     db_hash_record_parser_fn parser, void *private_data,
+		     int *count);
+
+/**
+ * @brief Traverse the database for modifications
+ *
+ * The parser function should return non-zero value to stop traverse.
+ *
+ * @param[in] dh The tdb hash table context
+ * @param[in] parser Function called for each record
+ * @param[in] private_data Private data to parser function
+ * @param[out] count Number of records traversed
+ * @return 0 on success, errno on failure
+ */
+int db_hash_traverse_update(struct db_hash_context *dh,
+			    db_hash_record_parser_fn parser,
+			    void *private_data, int *count);
+
+#endif /* __CTDB_DB_HASH_H__ */