937 lines
30 KiB
C
937 lines
30 KiB
C
/*
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******************************************************************************
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* Copyright (C) 1997-2004, International Business Machines
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* Corporation and others. All Rights Reserved.
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******************************************************************************
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* Date Name Description
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* 03/22/00 aliu Adapted from original C++ ICU Hashtable.
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* 07/06/01 aliu Modified to support int32_t keys on
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* platforms with sizeof(void*) < 32.
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******************************************************************************
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*/
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#include "uhash.h"
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#include "unicode/ustring.h"
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#include "cstring.h"
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#include "cmemory.h"
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#include "uassert.h"
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/* This hashtable is implemented as a double hash. All elements are
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* stored in a single array with no secondary storage for collision
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* resolution (no linked list, etc.). When there is a hash collision
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* (when two unequal keys have the same hashcode) we resolve this by
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* using a secondary hash. The secondary hash is an increment
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* computed as a hash function (a different one) of the primary
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* hashcode. This increment is added to the initial hash value to
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* obtain further slots assigned to the same hash code. For this to
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* work, the length of the array and the increment must be relatively
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* prime. The easiest way to achieve this is to have the length of
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* the array be prime, and the increment be any value from
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* 1..length-1.
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*
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* Hashcodes are 32-bit integers. We make sure all hashcodes are
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* non-negative by masking off the top bit. This has two effects: (1)
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* modulo arithmetic is simplified. If we allowed negative hashcodes,
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* then when we computed hashcode % length, we could get a negative
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* result, which we would then have to adjust back into range. It's
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* simpler to just make hashcodes non-negative. (2) It makes it easy
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* to check for empty vs. occupied slots in the table. We just mark
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* empty or deleted slots with a negative hashcode.
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*
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* The central function is _uhash_find(). This function looks for a
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* slot matching the given key and hashcode. If one is found, it
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* returns a pointer to that slot. If the table is full, and no match
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* is found, it returns NULL -- in theory. This would make the code
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* more complicated, since all callers of _uhash_find() would then
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* have to check for a NULL result. To keep this from happening, we
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* don't allow the table to fill. When there is only one
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* empty/deleted slot left, uhash_put() will refuse to increase the
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* count, and fail. This simplifies the code. In practice, one will
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* seldom encounter this using default UHashtables. However, if a
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* hashtable is set to a U_FIXED resize policy, or if memory is
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* exhausted, then the table may fill.
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*
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* High and low water ratios control rehashing. They establish levels
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* of fullness (from 0 to 1) outside of which the data array is
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* reallocated and repopulated. Setting the low water ratio to zero
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* means the table will never shrink. Setting the high water ratio to
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* one means the table will never grow. The ratios should be
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* coordinated with the ratio between successive elements of the
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* PRIMES table, so that when the primeIndex is incremented or
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* decremented during rehashing, it brings the ratio of count / length
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* back into the desired range (between low and high water ratios).
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*/
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/********************************************************************
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* PRIVATE Constants, Macros
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********************************************************************/
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/* This is a list of non-consecutive primes chosen such that
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* PRIMES[i+1] ~ 2*PRIMES[i]. (Currently, the ratio ranges from 1.81
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* to 2.18; the inverse ratio ranges from 0.459 to 0.552.) If this
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* ratio is changed, the low and high water ratios should also be
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* adjusted to suit.
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*
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* These prime numbers were also chosen so that they are the largest
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* prime number while being less than a power of two.
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*/
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static const int32_t PRIMES[] = {
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13, 31, 61, 127, 251, 509, 1021, 2039, 4093, 8191, 16381, 32749,
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65521, 131071, 262139, 524287, 1048573, 2097143, 4194301, 8388593,
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16777213, 33554393, 67108859, 134217689, 268435399, 536870909,
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1073741789, 2147483647 /*, 4294967291 */
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};
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#define PRIMES_LENGTH (sizeof(PRIMES) / sizeof(PRIMES[0]))
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/* These ratios are tuned to the PRIMES array such that a resize
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* places the table back into the zone of non-resizing. That is,
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* after a call to _uhash_rehash(), a subsequent call to
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* _uhash_rehash() should do nothing (should not churn). This is only
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* a potential problem with U_GROW_AND_SHRINK.
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*/
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static const float RESIZE_POLICY_RATIO_TABLE[6] = {
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/* low, high water ratio */
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0.0F, 0.5F, /* U_GROW: Grow on demand, do not shrink */
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0.1F, 0.5F, /* U_GROW_AND_SHRINK: Grow and shrink on demand */
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0.0F, 1.0F /* U_FIXED: Never change size */
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};
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/*
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Invariants for hashcode values:
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* DELETED < 0
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* EMPTY < 0
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* Real hashes >= 0
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Hashcodes may not start out this way, but internally they are
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adjusted so that they are always positive. We assume 32-bit
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hashcodes; adjust these constants for other hashcode sizes.
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*/
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#define HASH_DELETED ((int32_t) 0x80000000)
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#define HASH_EMPTY ((int32_t) HASH_DELETED + 1)
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#define IS_EMPTY_OR_DELETED(x) ((x) < 0)
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/* This macro expects a UHashTok.pointer as its keypointer and
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valuepointer parameters */
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#define HASH_DELETE_KEY_VALUE(hash, keypointer, valuepointer) \
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if (hash->keyDeleter != NULL && keypointer != NULL) { \
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(*hash->keyDeleter)(keypointer); \
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} \
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if (hash->valueDeleter != NULL && valuepointer != NULL) { \
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(*hash->valueDeleter)(valuepointer); \
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}
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/*
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* Constants for hinting whether a key or value is an integer
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* or a pointer. If a hint bit is zero, then the associated
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* token is assumed to be an integer.
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*/
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#define HINT_KEY_POINTER (1)
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#define HINT_VALUE_POINTER (2)
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/********************************************************************
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* Debugging
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********************************************************************/
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/********************************************************************
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* PRIVATE Prototypes
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********************************************************************/
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static UHashtable* _uhash_create(UHashFunction *keyHash, UKeyComparator *keyComp,
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int32_t primeIndex, UErrorCode *status);
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static void _uhash_allocate(UHashtable *hash, int32_t primeIndex,
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UErrorCode *status);
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static void _uhash_rehash(UHashtable *hash);
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static UHashElement* _uhash_find(const UHashtable *hash, UHashTok key,
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int32_t hashcode);
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static UHashTok _uhash_put(UHashtable *hash,
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UHashTok key,
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UHashTok value,
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int8_t hint,
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UErrorCode *status);
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static UHashTok _uhash_remove(UHashtable *hash,
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UHashTok key);
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static UHashTok _uhash_internalRemoveElement(UHashtable *hash, UHashElement* e);
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static UHashTok _uhash_setElement(UHashtable* hash, UHashElement* e,
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int32_t hashcode,
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UHashTok key, UHashTok value,
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int8_t hint);
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static void _uhash_internalSetResizePolicy(UHashtable *hash, enum UHashResizePolicy policy);
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/********************************************************************
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* PUBLIC API
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********************************************************************/
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U_CAPI UHashtable* U_EXPORT2
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uhash_open(UHashFunction *keyHash, UKeyComparator *keyComp,
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UErrorCode *status) {
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return _uhash_create(keyHash, keyComp, 3, status);
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}
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U_CAPI UHashtable* U_EXPORT2
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uhash_openSize(UHashFunction *keyHash, UKeyComparator *keyComp,
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int32_t size,
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UErrorCode *status) {
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/* Find the smallest index i for which PRIMES[i] >= size. */
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int32_t i = 0;
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while (i<(PRIMES_LENGTH-1) && PRIMES[i]<size) {
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++i;
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}
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return _uhash_create(keyHash, keyComp, i, status);
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}
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U_CAPI void U_EXPORT2
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uhash_close(UHashtable *hash) {
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U_ASSERT(hash != NULL);
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if (hash->elements != NULL) {
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if (hash->keyDeleter != NULL || hash->valueDeleter != NULL) {
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int32_t pos=-1;
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UHashElement *e;
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while ((e = (UHashElement*) uhash_nextElement(hash, &pos)) != NULL) {
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HASH_DELETE_KEY_VALUE(hash, e->key.pointer, e->value.pointer);
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}
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}
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uprv_free(hash->elements);
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hash->elements = NULL;
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}
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uprv_free(hash);
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}
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U_CAPI UHashFunction *U_EXPORT2
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uhash_setKeyHasher(UHashtable *hash, UHashFunction *fn) {
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UHashFunction *result = hash->keyHasher;
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hash->keyHasher = fn;
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return result;
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}
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U_CAPI UKeyComparator *U_EXPORT2
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uhash_setKeyComparator(UHashtable *hash, UKeyComparator *fn) {
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UKeyComparator *result = hash->keyComparator;
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hash->keyComparator = fn;
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return result;
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}
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U_CAPI UObjectDeleter *U_EXPORT2
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uhash_setKeyDeleter(UHashtable *hash, UObjectDeleter *fn) {
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UObjectDeleter *result = hash->keyDeleter;
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hash->keyDeleter = fn;
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return result;
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}
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U_CAPI UObjectDeleter *U_EXPORT2
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uhash_setValueDeleter(UHashtable *hash, UObjectDeleter *fn) {
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UObjectDeleter *result = hash->valueDeleter;
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hash->valueDeleter = fn;
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return result;
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}
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U_CAPI void U_EXPORT2
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uhash_setResizePolicy(UHashtable *hash, enum UHashResizePolicy policy) {
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_uhash_internalSetResizePolicy(hash, policy);
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hash->lowWaterMark = (int32_t)(hash->length * hash->lowWaterRatio);
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hash->highWaterMark = (int32_t)(hash->length * hash->highWaterRatio);
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_uhash_rehash(hash);
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}
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U_CAPI int32_t U_EXPORT2
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uhash_count(const UHashtable *hash) {
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return hash->count;
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}
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U_CAPI void* U_EXPORT2
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uhash_get(const UHashtable *hash,
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const void* key) {
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UHashTok keyholder;
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keyholder.pointer = (void*) key;
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return _uhash_find(hash, keyholder, hash->keyHasher(keyholder))->value.pointer;
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}
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U_CAPI void* U_EXPORT2
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uhash_iget(const UHashtable *hash,
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int32_t key) {
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UHashTok keyholder;
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keyholder.integer = key;
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return _uhash_find(hash, keyholder, hash->keyHasher(keyholder))->value.pointer;
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}
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U_CAPI int32_t U_EXPORT2
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uhash_geti(const UHashtable *hash,
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const void* key) {
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UHashTok keyholder;
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keyholder.pointer = (void*) key;
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return _uhash_find(hash, keyholder, hash->keyHasher(keyholder))->value.integer;
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}
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U_CAPI int32_t U_EXPORT2
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uhash_igeti(const UHashtable *hash,
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int32_t key) {
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UHashTok keyholder;
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keyholder.integer = key;
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return _uhash_find(hash, keyholder, hash->keyHasher(keyholder))->value.integer;
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}
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U_CAPI void* U_EXPORT2
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uhash_put(UHashtable *hash,
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void* key,
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void* value,
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UErrorCode *status) {
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UHashTok keyholder, valueholder;
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keyholder.pointer = key;
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valueholder.pointer = value;
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return _uhash_put(hash, keyholder, valueholder,
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HINT_KEY_POINTER | HINT_VALUE_POINTER,
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status).pointer;
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}
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U_CAPI void* U_EXPORT2
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uhash_iput(UHashtable *hash,
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int32_t key,
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void* value,
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UErrorCode *status) {
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UHashTok keyholder, valueholder;
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keyholder.integer = key;
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valueholder.pointer = value;
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return _uhash_put(hash, keyholder, valueholder,
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HINT_VALUE_POINTER,
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status).pointer;
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}
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U_CAPI int32_t U_EXPORT2
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uhash_puti(UHashtable *hash,
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void* key,
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int32_t value,
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UErrorCode *status) {
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UHashTok keyholder, valueholder;
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keyholder.pointer = key;
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valueholder.integer = value;
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return _uhash_put(hash, keyholder, valueholder,
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HINT_KEY_POINTER,
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status).integer;
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}
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U_CAPI int32_t U_EXPORT2
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uhash_iputi(UHashtable *hash,
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int32_t key,
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int32_t value,
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UErrorCode *status) {
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UHashTok keyholder, valueholder;
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keyholder.integer = key;
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valueholder.integer = value;
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return _uhash_put(hash, keyholder, valueholder,
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0, /* neither is a ptr */
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status).integer;
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}
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U_CAPI void* U_EXPORT2
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uhash_remove(UHashtable *hash,
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const void* key) {
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UHashTok keyholder;
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keyholder.pointer = (void*) key;
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return _uhash_remove(hash, keyholder).pointer;
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}
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U_CAPI void* U_EXPORT2
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uhash_iremove(UHashtable *hash,
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int32_t key) {
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UHashTok keyholder;
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keyholder.integer = key;
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return _uhash_remove(hash, keyholder).pointer;
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}
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U_CAPI int32_t U_EXPORT2
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uhash_removei(UHashtable *hash,
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const void* key) {
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UHashTok keyholder;
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keyholder.pointer = (void*) key;
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return _uhash_remove(hash, keyholder).integer;
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}
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U_CAPI int32_t U_EXPORT2
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uhash_iremovei(UHashtable *hash,
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int32_t key) {
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UHashTok keyholder;
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keyholder.integer = key;
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return _uhash_remove(hash, keyholder).integer;
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}
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U_CAPI void U_EXPORT2
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uhash_removeAll(UHashtable *hash) {
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int32_t pos = -1;
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const UHashElement *e;
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U_ASSERT(hash != NULL);
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if (hash->count != 0) {
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while ((e = uhash_nextElement(hash, &pos)) != NULL) {
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uhash_removeElement(hash, e);
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}
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}
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U_ASSERT(hash->count == 0);
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}
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U_CAPI const UHashElement* U_EXPORT2
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uhash_find(const UHashtable *hash, const void* key) {
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UHashTok keyholder;
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const UHashElement *e;
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keyholder.pointer = (void*) key;
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e = _uhash_find(hash, keyholder, hash->keyHasher(keyholder));
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return IS_EMPTY_OR_DELETED(e->hashcode) ? NULL : e;
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}
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U_CAPI const UHashElement* U_EXPORT2
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uhash_nextElement(const UHashtable *hash, int32_t *pos) {
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/* Walk through the array until we find an element that is not
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* EMPTY and not DELETED.
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*/
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int32_t i;
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U_ASSERT(hash != NULL);
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for (i = *pos + 1; i < hash->length; ++i) {
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if (!IS_EMPTY_OR_DELETED(hash->elements[i].hashcode)) {
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*pos = i;
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return &(hash->elements[i]);
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}
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}
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/* No more elements */
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return NULL;
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}
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U_CAPI void* U_EXPORT2
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uhash_removeElement(UHashtable *hash, const UHashElement* e) {
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U_ASSERT(hash != NULL);
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U_ASSERT(e != NULL);
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if (!IS_EMPTY_OR_DELETED(e->hashcode)) {
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return _uhash_internalRemoveElement(hash, (UHashElement*) e).pointer;
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}
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return NULL;
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}
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/********************************************************************
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* UHashTok convenience
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********************************************************************/
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/**
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* Return a UHashTok for an integer.
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*/
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/*U_CAPI UHashTok U_EXPORT2
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uhash_toki(int32_t i) {
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UHashTok tok;
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tok.integer = i;
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return tok;
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}*/
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/**
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* Return a UHashTok for a pointer.
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*/
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/*U_CAPI UHashTok U_EXPORT2
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uhash_tokp(void* p) {
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UHashTok tok;
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tok.pointer = p;
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return tok;
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}*/
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/********************************************************************
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* PUBLIC Key Hash Functions
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********************************************************************/
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/*
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Compute the hash by iterating sparsely over about 32 (up to 63)
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characters spaced evenly through the string. For each character,
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multiply the previous hash value by a prime number and add the new
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character in, like a linear congruential random number generator,
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producing a pseudorandom deterministic value well distributed over
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the output range. [LIU]
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*/
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#define STRING_HASH(TYPE, STR, STRLEN, DEREF) \
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int32_t hash = 0; \
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const TYPE *p = (const TYPE*) STR; \
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if (p != NULL) { \
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int32_t len = (int32_t)(STRLEN); \
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int32_t inc = ((len - 32) / 32) + 1; \
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const TYPE *limit = p + len; \
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while (p<limit) { \
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hash = (hash * 37) + DEREF; \
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p += inc; \
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} \
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} \
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return hash
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U_CAPI int32_t U_EXPORT2
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uhash_hashUChars(const UHashTok key) {
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STRING_HASH(UChar, key.pointer, u_strlen(p), *p);
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}
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/* Used by UnicodeString to compute its hashcode - Not public API. */
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U_CAPI int32_t U_EXPORT2
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uhash_hashUCharsN(const UChar *str, int32_t length) {
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STRING_HASH(UChar, str, length, *p);
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}
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U_CAPI int32_t U_EXPORT2
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uhash_hashChars(const UHashTok key) {
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STRING_HASH(uint8_t, key.pointer, uprv_strlen((char*)p), *p);
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}
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U_CAPI int32_t U_EXPORT2
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uhash_hashIChars(const UHashTok key) {
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STRING_HASH(uint8_t, key.pointer, uprv_strlen((char*)p), uprv_tolower(*p));
|
|
}
|
|
|
|
/********************************************************************
|
|
* PUBLIC Comparator Functions
|
|
********************************************************************/
|
|
|
|
U_CAPI UBool U_EXPORT2
|
|
uhash_compareUChars(const UHashTok key1, const UHashTok key2) {
|
|
const UChar *p1 = (const UChar*) key1.pointer;
|
|
const UChar *p2 = (const UChar*) key2.pointer;
|
|
if (p1 == p2) {
|
|
return TRUE;
|
|
}
|
|
if (p1 == NULL || p2 == NULL) {
|
|
return FALSE;
|
|
}
|
|
while (*p1 != 0 && *p1 == *p2) {
|
|
++p1;
|
|
++p2;
|
|
}
|
|
return (UBool)(*p1 == *p2);
|
|
}
|
|
|
|
U_CAPI UBool U_EXPORT2
|
|
uhash_compareChars(const UHashTok key1, const UHashTok key2) {
|
|
const char *p1 = (const char*) key1.pointer;
|
|
const char *p2 = (const char*) key2.pointer;
|
|
if (p1 == p2) {
|
|
return TRUE;
|
|
}
|
|
if (p1 == NULL || p2 == NULL) {
|
|
return FALSE;
|
|
}
|
|
while (*p1 != 0 && *p1 == *p2) {
|
|
++p1;
|
|
++p2;
|
|
}
|
|
return (UBool)(*p1 == *p2);
|
|
}
|
|
|
|
U_CAPI UBool U_EXPORT2
|
|
uhash_compareIChars(const UHashTok key1, const UHashTok key2) {
|
|
const char *p1 = (const char*) key1.pointer;
|
|
const char *p2 = (const char*) key2.pointer;
|
|
if (p1 == p2) {
|
|
return TRUE;
|
|
}
|
|
if (p1 == NULL || p2 == NULL) {
|
|
return FALSE;
|
|
}
|
|
while (*p1 != 0 && uprv_tolower(*p1) == uprv_tolower(*p2)) {
|
|
++p1;
|
|
++p2;
|
|
}
|
|
return (UBool)(*p1 == *p2);
|
|
}
|
|
|
|
/********************************************************************
|
|
* PUBLIC int32_t Support Functions
|
|
********************************************************************/
|
|
|
|
U_CAPI int32_t U_EXPORT2
|
|
uhash_hashLong(const UHashTok key) {
|
|
return key.integer;
|
|
}
|
|
|
|
U_CAPI UBool U_EXPORT2
|
|
uhash_compareLong(const UHashTok key1, const UHashTok key2) {
|
|
return (UBool)(key1.integer == key2.integer);
|
|
}
|
|
|
|
/********************************************************************
|
|
* PUBLIC Deleter Functions
|
|
********************************************************************/
|
|
|
|
U_CAPI void U_EXPORT2
|
|
uhash_freeBlock(void *obj) {
|
|
uprv_free(obj);
|
|
}
|
|
|
|
/********************************************************************
|
|
* PRIVATE Implementation
|
|
********************************************************************/
|
|
|
|
static UHashtable*
|
|
_uhash_create(UHashFunction *keyHash, UKeyComparator *keyComp,
|
|
int32_t primeIndex,
|
|
UErrorCode *status) {
|
|
UHashtable *result;
|
|
|
|
if (U_FAILURE(*status)) return NULL;
|
|
U_ASSERT(keyHash != NULL);
|
|
U_ASSERT(keyComp != NULL);
|
|
|
|
result = (UHashtable*) uprv_malloc(sizeof(UHashtable));
|
|
if (result == NULL) {
|
|
*status = U_MEMORY_ALLOCATION_ERROR;
|
|
return NULL;
|
|
}
|
|
|
|
result->keyHasher = keyHash;
|
|
result->keyComparator = keyComp;
|
|
result->keyDeleter = NULL;
|
|
result->valueDeleter = NULL;
|
|
_uhash_internalSetResizePolicy(result, U_GROW);
|
|
|
|
_uhash_allocate(result, primeIndex, status);
|
|
|
|
if (U_FAILURE(*status)) {
|
|
uprv_free(result);
|
|
return NULL;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Allocate internal data array of a size determined by the given
|
|
* prime index. If the index is out of range it is pinned into range.
|
|
* If the allocation fails the status is set to
|
|
* U_MEMORY_ALLOCATION_ERROR and all array storage is freed. In
|
|
* either case the previous array pointer is overwritten.
|
|
*
|
|
* Caller must ensure primeIndex is in range 0..PRIME_LENGTH-1.
|
|
*/
|
|
static void
|
|
_uhash_allocate(UHashtable *hash,
|
|
int32_t primeIndex,
|
|
UErrorCode *status) {
|
|
|
|
UHashElement *p, *limit;
|
|
UHashTok emptytok;
|
|
|
|
if (U_FAILURE(*status)) return;
|
|
|
|
U_ASSERT(primeIndex >= 0 && primeIndex < PRIMES_LENGTH);
|
|
|
|
hash->primeIndex = primeIndex;
|
|
hash->length = PRIMES[primeIndex];
|
|
|
|
p = hash->elements = (UHashElement*)
|
|
uprv_malloc(sizeof(UHashElement) * hash->length);
|
|
|
|
if (hash->elements == NULL) {
|
|
*status = U_MEMORY_ALLOCATION_ERROR;
|
|
return;
|
|
}
|
|
|
|
emptytok.pointer = NULL; /* Only one of these two is needed */
|
|
emptytok.integer = 0; /* but we don't know which one. */
|
|
|
|
limit = p + hash->length;
|
|
while (p < limit) {
|
|
p->key = emptytok;
|
|
p->value = emptytok;
|
|
p->hashcode = HASH_EMPTY;
|
|
++p;
|
|
}
|
|
|
|
hash->count = 0;
|
|
hash->lowWaterMark = (int32_t)(hash->length * hash->lowWaterRatio);
|
|
hash->highWaterMark = (int32_t)(hash->length * hash->highWaterRatio);
|
|
}
|
|
|
|
/**
|
|
* Attempt to grow or shrink the data arrays in order to make the
|
|
* count fit between the high and low water marks. hash_put() and
|
|
* hash_remove() call this method when the count exceeds the high or
|
|
* low water marks. This method may do nothing, if memory allocation
|
|
* fails, or if the count is already in range, or if the length is
|
|
* already at the low or high limit. In any case, upon return the
|
|
* arrays will be valid.
|
|
*/
|
|
static void
|
|
_uhash_rehash(UHashtable *hash) {
|
|
|
|
UHashElement *old = hash->elements;
|
|
int32_t oldLength = hash->length;
|
|
int32_t newPrimeIndex = hash->primeIndex;
|
|
int32_t i;
|
|
UErrorCode status = U_ZERO_ERROR;
|
|
|
|
if (hash->count > hash->highWaterMark) {
|
|
if (++newPrimeIndex >= PRIMES_LENGTH) {
|
|
return;
|
|
}
|
|
} else if (hash->count < hash->lowWaterMark) {
|
|
if (--newPrimeIndex < 0) {
|
|
return;
|
|
}
|
|
} else {
|
|
return;
|
|
}
|
|
|
|
_uhash_allocate(hash, newPrimeIndex, &status);
|
|
|
|
if (U_FAILURE(status)) {
|
|
hash->elements = old;
|
|
hash->length = oldLength;
|
|
return;
|
|
}
|
|
|
|
for (i = oldLength - 1; i >= 0; --i) {
|
|
if (!IS_EMPTY_OR_DELETED(old[i].hashcode)) {
|
|
UHashElement *e = _uhash_find(hash, old[i].key, old[i].hashcode);
|
|
U_ASSERT(e != NULL);
|
|
U_ASSERT(e->hashcode == HASH_EMPTY);
|
|
e->key = old[i].key;
|
|
e->value = old[i].value;
|
|
e->hashcode = old[i].hashcode;
|
|
++hash->count;
|
|
}
|
|
}
|
|
|
|
uprv_free(old);
|
|
}
|
|
|
|
/**
|
|
* Look for a key in the table, or if no such key exists, the first
|
|
* empty slot matching the given hashcode. Keys are compared using
|
|
* the keyComparator function.
|
|
*
|
|
* First find the start position, which is the hashcode modulo
|
|
* the length. Test it to see if it is:
|
|
*
|
|
* a. identical: First check the hash values for a quick check,
|
|
* then compare keys for equality using keyComparator.
|
|
* b. deleted
|
|
* c. empty
|
|
*
|
|
* Stop if it is identical or empty, otherwise continue by adding a
|
|
* "jump" value (moduloing by the length again to keep it within
|
|
* range) and retesting. For efficiency, there need enough empty
|
|
* values so that the searchs stop within a reasonable amount of time.
|
|
* This can be changed by changing the high/low water marks.
|
|
*
|
|
* In theory, this function can return NULL, if it is full (no empty
|
|
* or deleted slots) and if no matching key is found. In practice, we
|
|
* prevent this elsewhere (in uhash_put) by making sure the last slot
|
|
* in the table is never filled.
|
|
*
|
|
* The size of the table should be prime for this algorithm to work;
|
|
* otherwise we are not guaranteed that the jump value (the secondary
|
|
* hash) is relatively prime to the table length.
|
|
*/
|
|
static UHashElement*
|
|
_uhash_find(const UHashtable *hash, UHashTok key,
|
|
int32_t hashcode) {
|
|
|
|
int32_t firstDeleted = -1; /* assume invalid index */
|
|
int32_t theIndex, startIndex;
|
|
int32_t jump = 0; /* lazy evaluate */
|
|
int32_t tableHash;
|
|
|
|
hashcode &= 0x7FFFFFFF; /* must be positive */
|
|
startIndex = theIndex = (hashcode ^ 0x4000000) % hash->length;
|
|
|
|
do {
|
|
tableHash = hash->elements[theIndex].hashcode;
|
|
if (tableHash == hashcode) { /* quick check */
|
|
if ((*hash->keyComparator)(key, hash->elements[theIndex].key)) {
|
|
return &(hash->elements[theIndex]);
|
|
}
|
|
} else if (!IS_EMPTY_OR_DELETED(tableHash)) {
|
|
/* We have hit a slot which contains a key-value pair,
|
|
* but for which the hash code does not match. Keep
|
|
* looking.
|
|
*/
|
|
} else if (tableHash == HASH_EMPTY) { /* empty, end o' the line */
|
|
break;
|
|
} else if (firstDeleted < 0) { /* remember first deleted */
|
|
firstDeleted = theIndex;
|
|
}
|
|
if (jump == 0) { /* lazy compute jump */
|
|
/* The jump value must be relatively prime to the table
|
|
* length. As long as the length is prime, then any value
|
|
* 1..length-1 will be relatively prime to it.
|
|
*/
|
|
jump = (hashcode % (hash->length - 1)) + 1;
|
|
}
|
|
theIndex = (theIndex + jump) % hash->length;
|
|
} while (theIndex != startIndex);
|
|
|
|
if (firstDeleted >= 0) {
|
|
theIndex = firstDeleted; /* reset if had deleted slot */
|
|
} else if (tableHash != HASH_EMPTY) {
|
|
/* We get to this point if the hashtable is full (no empty or
|
|
* deleted slots), and we've failed to find a match. THIS
|
|
* WILL NEVER HAPPEN as long as uhash_put() makes sure that
|
|
* count is always < length.
|
|
*/
|
|
U_ASSERT(FALSE);
|
|
return NULL; /* Never happens if uhash_put() behaves */
|
|
}
|
|
return &(hash->elements[theIndex]);
|
|
}
|
|
|
|
static UHashTok
|
|
_uhash_put(UHashtable *hash,
|
|
UHashTok key,
|
|
UHashTok value,
|
|
int8_t hint,
|
|
UErrorCode *status) {
|
|
|
|
/* Put finds the position in the table for the new value. If the
|
|
* key is already in the table, it is deleted, if there is a
|
|
* non-NULL keyDeleter. Then the key, the hash and the value are
|
|
* all put at the position in their respective arrays.
|
|
*/
|
|
int32_t hashcode;
|
|
UHashElement* e;
|
|
UHashTok emptytok;
|
|
|
|
if (U_FAILURE(*status)) {
|
|
goto err;
|
|
}
|
|
U_ASSERT(hash != NULL);
|
|
/* Cannot always check pointer here or iSeries sees NULL every time. */
|
|
if ((hint & HINT_VALUE_POINTER) && value.pointer == NULL) {
|
|
/* Disallow storage of NULL values, since NULL is returned by
|
|
* get() to indicate an absent key. Storing NULL == removing.
|
|
*/
|
|
return _uhash_remove(hash, key);
|
|
}
|
|
if (hash->count > hash->highWaterMark) {
|
|
_uhash_rehash(hash);
|
|
}
|
|
|
|
hashcode = (*hash->keyHasher)(key);
|
|
e = _uhash_find(hash, key, hashcode);
|
|
U_ASSERT(e != NULL);
|
|
|
|
if (IS_EMPTY_OR_DELETED(e->hashcode)) {
|
|
/* Important: We must never actually fill the table up. If we
|
|
* do so, then _uhash_find() will return NULL, and we'll have
|
|
* to check for NULL after every call to _uhash_find(). To
|
|
* avoid this we make sure there is always at least one empty
|
|
* or deleted slot in the table. This only is a problem if we
|
|
* are out of memory and rehash isn't working.
|
|
*/
|
|
++hash->count;
|
|
if (hash->count == hash->length) {
|
|
/* Don't allow count to reach length */
|
|
--hash->count;
|
|
*status = U_MEMORY_ALLOCATION_ERROR;
|
|
goto err;
|
|
}
|
|
}
|
|
|
|
/* We must in all cases handle storage properly. If there was an
|
|
* old key, then it must be deleted (if the deleter != NULL).
|
|
* Make hashcodes stored in table positive.
|
|
*/
|
|
return _uhash_setElement(hash, e, hashcode & 0x7FFFFFFF, key, value, hint);
|
|
|
|
err:
|
|
/* If the deleters are non-NULL, this method adopts its key and/or
|
|
* value arguments, and we must be sure to delete the key and/or
|
|
* value in all cases, even upon failure.
|
|
*/
|
|
HASH_DELETE_KEY_VALUE(hash, key.pointer, value.pointer);
|
|
emptytok.pointer = NULL; emptytok.integer = 0;
|
|
return emptytok;
|
|
}
|
|
|
|
static UHashTok
|
|
_uhash_remove(UHashtable *hash,
|
|
UHashTok key) {
|
|
/* First find the position of the key in the table. If the object
|
|
* has not been removed already, remove it. If the user wanted
|
|
* keys deleted, then delete it also. We have to put a special
|
|
* hashcode in that position that means that something has been
|
|
* deleted, since when we do a find, we have to continue PAST any
|
|
* deleted values.
|
|
*/
|
|
UHashTok result;
|
|
UHashElement* e = _uhash_find(hash, key, hash->keyHasher(key));
|
|
U_ASSERT(e != NULL);
|
|
result.pointer = NULL; result.integer = 0;
|
|
if (!IS_EMPTY_OR_DELETED(e->hashcode)) {
|
|
result = _uhash_internalRemoveElement(hash, e);
|
|
if (hash->count < hash->lowWaterMark) {
|
|
_uhash_rehash(hash);
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
static UHashTok
|
|
_uhash_setElement(UHashtable *hash, UHashElement* e,
|
|
int32_t hashcode,
|
|
UHashTok key, UHashTok value, int8_t hint) {
|
|
|
|
UHashTok oldValue = e->value;
|
|
if (hash->keyDeleter != NULL && e->key.pointer != NULL &&
|
|
e->key.pointer != key.pointer) { /* Avoid double deletion */
|
|
(*hash->keyDeleter)(e->key.pointer);
|
|
}
|
|
if (hash->valueDeleter != NULL) {
|
|
if (oldValue.pointer != NULL &&
|
|
oldValue.pointer != value.pointer) { /* Avoid double deletion */
|
|
(*hash->valueDeleter)(oldValue.pointer);
|
|
}
|
|
oldValue.pointer = NULL;
|
|
}
|
|
/* Compilers should copy the UHashTok union correctly, but even if
|
|
* they do, memory heap tools (e.g. BoundsChecker) can get
|
|
* confused when a pointer is cloaked in a union and then copied.
|
|
* TO ALLEVIATE THIS, we use hints (based on what API the user is
|
|
* calling) to copy pointers when we know the user thinks
|
|
* something is a pointer. */
|
|
if (hint & HINT_KEY_POINTER) {
|
|
e->key.pointer = key.pointer;
|
|
} else {
|
|
e->key = key;
|
|
}
|
|
if (hint & HINT_VALUE_POINTER) {
|
|
e->value.pointer = value.pointer;
|
|
} else {
|
|
e->value = value;
|
|
}
|
|
e->hashcode = hashcode;
|
|
return oldValue;
|
|
}
|
|
|
|
/**
|
|
* Assumes that the given element is not empty or deleted.
|
|
*/
|
|
static UHashTok
|
|
_uhash_internalRemoveElement(UHashtable *hash, UHashElement* e) {
|
|
UHashTok empty;
|
|
U_ASSERT(!IS_EMPTY_OR_DELETED(e->hashcode));
|
|
--hash->count;
|
|
empty.pointer = NULL; empty.integer = 0;
|
|
return _uhash_setElement(hash, e, HASH_DELETED, empty, empty, 0);
|
|
}
|
|
|
|
static void
|
|
_uhash_internalSetResizePolicy(UHashtable *hash, enum UHashResizePolicy policy) {
|
|
U_ASSERT(hash != NULL);
|
|
U_ASSERT(((int32_t)policy) >= 0);
|
|
U_ASSERT(((int32_t)policy) < 3);
|
|
hash->lowWaterRatio = RESIZE_POLICY_RATIO_TABLE[policy * 2];
|
|
hash->highWaterRatio = RESIZE_POLICY_RATIO_TABLE[policy * 2 + 1];
|
|
}
|