102 lines
4 KiB
C
102 lines
4 KiB
C
/**
|
|
@file
|
|
|
|
A reliable hashtable implementation. The implementation makes
|
|
use of nested top actions, and is reentrant. Currently, all keys
|
|
and values must be of the same length, although this restriction
|
|
will eventually be removed.
|
|
|
|
The implementation uses a linear hash function, allowing the
|
|
bucket list to be resized dynamically. Because the bucket list is
|
|
built on top of arrayList, all operations are O(1), assuming the
|
|
hash function behaves correctly. Currently, linkedListNTA
|
|
implements the bucket lists.
|
|
|
|
@see nestedTopAction.h, linkedListNTA.h, arrayList.h
|
|
|
|
@ingroup OPERATIONS
|
|
|
|
$id$
|
|
|
|
*/
|
|
|
|
#ifndef __LINEAR_HASH_NTA_H
|
|
#define __LINEAR_HASH_NTA_H
|
|
/** Currently, only used in the type field of the iterators. */
|
|
#define FIXED_LENGTH_HASH 0
|
|
#define VARIABLE_LENGTH_HASH 1
|
|
|
|
/** Pass this into the keySize and/or valueSize parameter of the
|
|
constructor below if the hashtable should support variable length
|
|
keys and/or values, respectively. */
|
|
#define VARIABLE_LENGTH -1
|
|
|
|
typedef struct {
|
|
recordid hashHeader;
|
|
recordid bucket;
|
|
int numBuckets;
|
|
int keySize;
|
|
int valueSize;
|
|
lladd_linkedList_iterator * it;
|
|
lladd_pagedList_iterator * pit;
|
|
} lladd_hash_iterator;
|
|
|
|
compensated_function recordid ThashCreate(int xid, int keySize, int valSize);
|
|
compensated_function void ThashDelete(int xid, recordid hash);
|
|
/* @return 1 if the key was defined, 0 otherwise. */
|
|
compensated_function int ThashInsert(int xid, recordid hash, const byte* key, int keySize, const byte* value, int valueSize);
|
|
/* @return 1 if the key was defined, 0 otherwise. */
|
|
compensated_function int ThashRemove(int xid, recordid hash, const byte* key, int keySize);
|
|
|
|
/** @return size of the value associated with key, or -1 if key not found.
|
|
(a return value of zero means the key is associated with an
|
|
empty value.) */
|
|
compensated_function int ThashLookup(int xid, recordid hash, const byte* key, int keySize, byte ** value);
|
|
/**
|
|
Allocate a new hash iterator. This API is designed to eventually be
|
|
overloaded, and is subject to change. If the iterator is run to completion,
|
|
it is automatically freed. Otherwise, it should be manually freed with free().
|
|
@param xid transaction id
|
|
@param hash the recordid returned by ThashAlloc
|
|
@param keySize the same as the value passed into ThashAlloc.
|
|
@param valueSize the same as the value passed into ThashAlloc
|
|
*/
|
|
lladd_hash_iterator * ThashIterator(int xid, recordid hash, int keySize, int valueSize);
|
|
/**
|
|
Obtain the next value in the hash table.
|
|
|
|
@return 1 if another value exists; 0 if the iterator is done, and has been deallocated.
|
|
@param keySize Currently, keySize and valueSize must
|
|
be set to the correct sizes when ThashNext is called. Once hashtables with
|
|
variable sized entries are supported, this restriction will be relaxed or removed
|
|
entirely.
|
|
@param key a pointer to an uninitialized pointer value. If another entry is
|
|
encountered, then the uninitialized pointer value will be set to point
|
|
to a malloc()'ed region of memory that contains the value's key. This
|
|
region of memory should be manually free()'ed by the application. LLADD
|
|
normally leaves memory management to the application. However, once
|
|
hashes with variable size entries are supported, it would be extremely
|
|
difficult for the application to malloc an appropriate buffer for the
|
|
iterator, so this function call does not obey normal LLADD calling
|
|
semantics.
|
|
@param value analagous to value.
|
|
@param valueSize analagous to keySize
|
|
*/
|
|
int ThashNext(int xid, lladd_hash_iterator * it, byte ** key, int * keySize, byte** value, int * valueSize);
|
|
|
|
|
|
/** Free the hash iterator and its associated resources. */
|
|
void ThashDone(int xid, lladd_hash_iterator * it);
|
|
|
|
Operation getLinearHashInsert();
|
|
Operation getLinearHashRemove();
|
|
|
|
void LinearHashNTAInit();
|
|
|
|
|
|
//Support 16 entries by default.
|
|
#define HASH_INIT_BITS 4
|
|
#define HASH_FILL_FACTOR 0.7
|
|
|
|
#endif // __LINEAR_HASH_NTA_H
|
|
|