| /* |
| ******************************************************************************* |
| * Copyright (C) 1997-2000, International Business Machines |
| * Corporation and others. All Rights Reserved. |
| ******************************************************************************* |
| * Date Name Description |
| * 03/22/00 aliu Adapted from original C++ ICU Hashtable. |
| ******************************************************************************* |
| */ |
| |
| #include "uhash.h" |
| #include "unicode/ustring.h" |
| #include "cstring.h" |
| #include "cmemory.h" |
| |
| /* This hashtable is implemented as a double hash. All elements are |
| * stored in a single array with no secondary storage for collision |
| * resolution (no linked list, etc.). When there is a hash collision |
| * (when two unequal keys have the same hashcode) we resolve this by |
| * using a secondary hash. The secondary hash is an increment |
| * computed as a hash function (a different one) of the primary |
| * hashcode. This increment is added to the initial hash value to |
| * obtain further slots assigned to the same hash code. For this to |
| * work, the length of the array and the increment must be relatively |
| * prime. The easiest way to achieve this is to have the length of |
| * the array be prime, and the increment be any value from |
| * 1..length-1. |
| * |
| * Hashcodes are 32-bit integers. We make sure all hashcodes are |
| * non-negative by masking off the top bit. This has two effects: (1) |
| * modulo arithmetic is simplified. If we allowed negative hashcodes, |
| * then when we computed hashcode % length, we could get a negative |
| * result, which we would then have to adjust back into range. It's |
| * simpler to just make hashcodes non-negative. (2) It makes it easy |
| * to check for empty vs. occupied slots in the table. We just mark |
| * empty or deleted slots with a negative hashcode. |
| * |
| * The central function is _uhash_find(). This function looks for a |
| * slot matching the given key and hashcode. If one is found, it |
| * returns a pointer to that slot. If the table is full, and no match |
| * is found, it returns NULL -- in theory. This would make the code |
| * more complicated, since all callers of _uhash_find() would then |
| * have to check for a NULL result. To keep this from happening, we |
| * don't allow the table to fill. When there is only one |
| * empty/deleted slot left, uhash_put() will refuse to increase the |
| * count, and fail. This simplifies the code. In practice, one will |
| * seldom encounter this using default UHashtables. However, if a |
| * hashtable is set to a U_FIXED resize policy, or if memory is |
| * exhausted, then the table may fill. |
| * |
| * High and low water ratios control rehashing. They establish levels |
| * of fullness (from 0 to 1) outside of which the data array is |
| * reallocated and repopulated. Setting the low water ratio to zero |
| * means the table will never shrink. Setting the high water ratio to |
| * one means the table will never grow. The ratios should be |
| * coordinated with the ratio between successive elements of the |
| * PRIMES table, so that when the primeIndex is incremented or |
| * decremented during rehashing, it brings the ratio of count / length |
| * back into the desired range (between low and high water ratios). |
| */ |
| |
| /******************************************************************** |
| * PRIVATE Constants, Macros |
| ********************************************************************/ |
| |
| /* This is a list of non-consecutive primes chosen such that |
| * PRIMES[i+1] ~ 2*PRIMES[i]. (Currently, the ratio ranges from 1.81 |
| * to 2.18; the inverse ratio ranges from 0.459 to 0.552.) If this |
| * ratio is changed, the low and high water ratios should also be |
| * adjusted to suit. |
| */ |
| static int32_t PRIMES[] = { |
| 17, 37, 67, 131, 257, 521, 1031, 2053, 4099, 8209, 16411, 32771, |
| 65537, 131101, 262147, 524309, 1048583, 2097169, 4194319, 8388617, |
| 16777259, 33554467, 67108879, 134217757, 268435459, 536870923, |
| 1073741827, 2147483647 |
| }; |
| |
| #define PRIMES_LENGTH (sizeof(PRIMES) / sizeof(PRIMES[0])) |
| |
| /* These ratios are tuned to the PRIMES array such that a resize |
| * places the table back into the zone of non-resizing. That is, |
| * after a call to _uhash_rehash(), a subsequent call to |
| * _uhash_rehash() should do nothing (should not churn). This is only |
| * a potential problem with U_GROW_AND_SHRINK. |
| */ |
| static const float RESIZE_POLICY_RATIO_TABLE[6] = { |
| /* low, high water ratio */ |
| 0.0F, 0.5F, /* U_GROW: Grow on demand, do not shrink */ |
| 0.1F, 0.5F, /* U_GROW_AND_SHRINK: Grow and shrink on demand */ |
| 0.0F, 1.0F /* U_FIXED: Never change size */ |
| }; |
| |
| /* |
| Invariants for hashcode values: |
| |
| * DELETED < 0 |
| * EMPTY < 0 |
| * Real hashes >= 0 |
| |
| Hashcodes may not start out this way, but internally they are |
| adjusted so that they are always positive. We assume 32-bit |
| hashcodes; adjust these constants for other hashcode sizes. |
| */ |
| #define HASH_DELETED ((int32_t) 0x80000000) |
| #define HASH_EMPTY ((int32_t) HASH_DELETED + 1) |
| |
| #define IS_EMPTY_OR_DELETED(x) ((x) < 0) |
| |
| #define HASH_DELETE_KEY_VALUE(hash, key, value) \ |
| if (hash->keyDeleter != NULL && key != NULL) { \ |
| (*hash->keyDeleter)(key); \ |
| } \ |
| if (hash->valueDeleter != NULL && value != NULL) { \ |
| (*hash->valueDeleter)(value); \ |
| } |
| |
| /******************************************************************** |
| * Debugging |
| ********************************************************************/ |
| |
| /* Enable this section to compile in runtime assertion checking. */ |
| |
| /* #define HASH_DEBUG */ |
| #ifdef HASH_DEBUG |
| |
| #include <stdio.h> |
| |
| #define assert(exp) (void)( (exp) || (_assert(#exp, __FILE__, __LINE__), 0) ) |
| |
| static void _assert(const char* exp, const char* file, int line) { |
| printf("ERROR: assert(%s) failed: %s, line %d\n", |
| exp, file, line); |
| } |
| |
| #else |
| |
| #define assert(exp) |
| |
| #endif |
| |
| /******************************************************************** |
| * PRIVATE Prototypes |
| ********************************************************************/ |
| |
| static UHashtable* _uhash_create(UHashFunction keyHash, UKeyComparator keyComp, |
| int32_t primeIndex, UErrorCode *status); |
| |
| static void _uhash_allocate(UHashtable *hash, int32_t primeIndex, |
| UErrorCode *status); |
| |
| static void _uhash_rehash(UHashtable *hash); |
| |
| static UHashElement* _uhash_find(const UHashtable *hash, const void* key, |
| int32_t hashcode); |
| |
| static void* _uhash_internalRemoveElement(UHashtable *hash, UHashElement* e); |
| |
| static void* _uhash_setElement(UHashtable* hash, UHashElement* e, |
| int32_t hashcode, void* key, void* value); |
| |
| static void _uhash_internalSetResizePolicy(UHashtable *hash, enum UHashResizePolicy policy); |
| |
| /******************************************************************** |
| * PUBLIC API |
| ********************************************************************/ |
| |
| U_CAPI UHashtable* |
| uhash_open(UHashFunction keyHash, UKeyComparator keyComp, |
| UErrorCode *status) { |
| |
| return _uhash_create(keyHash, keyComp, 3, status); |
| } |
| |
| U_CAPI UHashtable* |
| uhash_openSize(UHashFunction keyHash, UKeyComparator keyComp, |
| int32_t size, |
| UErrorCode *status) { |
| |
| /* Find the smallest index i for which PRIMES[i] >= size. */ |
| int32_t i = 0; |
| while (i<(PRIMES_LENGTH-1) && PRIMES[i]<size) { |
| ++i; |
| } |
| |
| return _uhash_create(keyHash, keyComp, i, status); |
| } |
| |
| U_CAPI void |
| uhash_close(UHashtable *hash) { |
| assert(hash != NULL); |
| if (hash->elements != NULL) { |
| if (hash->keyDeleter != NULL || hash->valueDeleter != NULL) { |
| int32_t pos=-1; |
| UHashElement *e; |
| while ((e = (UHashElement*) uhash_nextElement(hash, &pos)) != NULL) { |
| HASH_DELETE_KEY_VALUE(hash, e->key, e->value); |
| } |
| } |
| uprv_free(hash->elements); |
| hash->elements = NULL; |
| } |
| uprv_free(hash); |
| } |
| |
| U_CAPI UHashFunction |
| uhash_setKeyHasher(UHashtable *hash, UHashFunction fn) { |
| UHashFunction result = hash->keyHasher; |
| hash->keyHasher = fn; |
| return result; |
| } |
| |
| U_CAPI UKeyComparator |
| uhash_setKeyComparator(UHashtable *hash, UKeyComparator fn) { |
| UKeyComparator result = hash->keyComparator; |
| hash->keyComparator = fn; |
| return result; |
| } |
| |
| U_CAPI UObjectDeleter |
| uhash_setKeyDeleter(UHashtable *hash, UObjectDeleter fn) { |
| UObjectDeleter result = hash->keyDeleter; |
| hash->keyDeleter = fn; |
| return result; |
| } |
| |
| U_CAPI UObjectDeleter |
| uhash_setValueDeleter(UHashtable *hash, UObjectDeleter fn) { |
| UObjectDeleter result = hash->valueDeleter; |
| hash->valueDeleter = fn; |
| return result; |
| } |
| |
| U_CAPI void |
| uhash_setResizePolicy(UHashtable *hash, enum UHashResizePolicy policy) { |
| _uhash_internalSetResizePolicy(hash, policy); |
| hash->lowWaterMark = (int32_t)(hash->length * hash->lowWaterRatio); |
| hash->highWaterMark = (int32_t)(hash->length * hash->highWaterRatio); |
| _uhash_rehash(hash); |
| } |
| |
| U_CAPI int32_t |
| uhash_count(const UHashtable *hash) { |
| return hash->count; |
| } |
| |
| U_CAPI void* |
| uhash_get(const UHashtable *hash, |
| const void* key) { |
| return _uhash_find(hash, key, hash->keyHasher(key))->value; |
| } |
| |
| U_CAPI void* |
| uhash_put(UHashtable *hash, |
| void* key, |
| void* value, |
| 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; |
| |
| if (U_FAILURE(*status)) { |
| goto err; |
| } |
| assert(hash != NULL); |
| if (value == 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); |
| 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); |
| |
| 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, value); |
| return NULL; |
| } |
| |
| U_CAPI void* |
| uhash_remove(UHashtable *hash, |
| const void* 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. |
| */ |
| void* result = NULL; |
| UHashElement* e = _uhash_find(hash, key, hash->keyHasher(key)); |
| assert(e != NULL); |
| if (!IS_EMPTY_OR_DELETED(e->hashcode)) { |
| result = _uhash_internalRemoveElement(hash, e); |
| if (hash->count < hash->lowWaterMark) { |
| _uhash_rehash(hash); |
| } |
| } |
| return result; |
| } |
| |
| U_CAPI void |
| uhash_removeAll(UHashtable *hash) { |
| int32_t pos = -1; |
| const UHashElement *e; |
| assert(hash != NULL); |
| if (hash->count != 0) { |
| while ((e = uhash_nextElement(hash, &pos)) != NULL) { |
| uhash_removeElement(hash, e); |
| } |
| } |
| assert(hash->count == 0); |
| } |
| |
| U_CAPI const UHashElement* |
| uhash_nextElement(const UHashtable *hash, int32_t *pos) { |
| /* Walk through the array until we find an element that is not |
| * EMPTY and not DELETED. |
| */ |
| int32_t i; |
| assert(hash != NULL); |
| for (i = *pos + 1; i < hash->length; ++i) { |
| if (!IS_EMPTY_OR_DELETED(hash->elements[i].hashcode)) { |
| *pos = i; |
| return &(hash->elements[i]); |
| } |
| } |
| |
| /* No more elements */ |
| return NULL; |
| } |
| |
| U_CAPI void* |
| uhash_removeElement(UHashtable *hash, const UHashElement* e) { |
| assert(hash != NULL); |
| assert(e != NULL); |
| if (!IS_EMPTY_OR_DELETED(e->hashcode)) { |
| return _uhash_internalRemoveElement(hash, (UHashElement*) e); |
| } |
| return NULL; |
| } |
| |
| /******************************************************************** |
| * PUBLIC Key Hash Functions |
| ********************************************************************/ |
| |
| /* |
| Compute the hash by iterating sparsely over about 32 (up to 63) |
| characters spaced evenly through the string. For each character, |
| multiply the previous hash value by a prime number and add the new |
| character in, like a linear congruential random number generator, |
| producing a pseudorandom deterministic value well distributed over |
| the output range. [LIU] |
| */ |
| |
| #define STRING_HASH(TYPE, STRLEN, DEREF) \ |
| int32_t hash = 0; \ |
| if (key != NULL) { \ |
| const TYPE *p = (const TYPE*) key; \ |
| int32_t len = STRLEN; \ |
| int32_t inc = ((len - 32) / 32) + 1; \ |
| const TYPE *limit = p + len; \ |
| while (p<limit) { \ |
| hash = (hash * 37) + DEREF; \ |
| p += inc; \ |
| } \ |
| } \ |
| return hash |
| |
| U_CAPI int32_t |
| uhash_hashUChars(const void *key) { |
| STRING_HASH(UChar, u_strlen(p), *p); |
| } |
| |
| /* Used by UnicodeString to compute its hashcode - Not public API. */ |
| U_CAPI int32_t |
| uhash_hashUCharsN(const UChar *key, int32_t length) { |
| STRING_HASH(UChar, length, *p); |
| } |
| |
| U_CAPI int32_t |
| uhash_hashChars(const void *key) { |
| STRING_HASH(uint8_t, uprv_strlen((char*)p), *p); |
| } |
| |
| U_CAPI int32_t |
| uhash_hashIChars(const void *key) { |
| STRING_HASH(uint8_t, uprv_strlen((char*)p), uprv_tolower(*p)); |
| } |
| |
| /******************************************************************** |
| * PUBLIC Comparator Functions |
| ********************************************************************/ |
| |
| U_CAPI UBool |
| uhash_compareUChars(const void *key1, const void *key2) { |
| const UChar *p1 = (const UChar*) key1; |
| const UChar *p2 = (const UChar*) key2; |
| if (p1 == p2) { |
| return TRUE; |
| } |
| if (p1 == NULL || p2 == NULL) { |
| return FALSE; |
| } |
| while (*p1 != 0 && *p1 == *p2) { |
| ++p1; |
| ++p2; |
| } |
| return (*p1 == *p2); |
| } |
| |
| U_CAPI UBool |
| uhash_compareChars(const void *key1, const void *key2) { |
| const char *p1 = (const char*) key1; |
| const char *p2 = (const char*) key2; |
| if (p1 == p2) { |
| return TRUE; |
| } |
| if (p1 == NULL || p2 == NULL) { |
| return FALSE; |
| } |
| while (*p1 != 0 && *p1 == *p2) { |
| ++p1; |
| ++p2; |
| } |
| return (*p1 == *p2); |
| } |
| |
| U_CAPI UBool |
| uhash_compareIChars(const void *key1, const void *key2) { |
| const char *p1 = (const char*) key1; |
| const char *p2 = (const char*) key2; |
| if (p1 == p2) { |
| return TRUE; |
| } |
| if (p1 == NULL || p2 == NULL) { |
| return FALSE; |
| } |
| while (*p1 != 0 && uprv_tolower(*p1) == uprv_tolower(*p2)) { |
| ++p1; |
| ++p2; |
| } |
| return (*p1 == *p2); |
| } |
| |
| /******************************************************************** |
| * PUBLIC int32_t Support Functions |
| ********************************************************************/ |
| |
| U_CAPI int32_t |
| uhash_hashLong(const void *key) { |
| return (int32_t) key; |
| } |
| |
| U_CAPI UBool |
| uhash_compareLong(const void *key1, const void *key2) { |
| return key1 == key2; |
| } |
| |
| /******************************************************************** |
| * PUBLIC Deleter Functions |
| ********************************************************************/ |
| |
| U_CAPI void |
| 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; |
| assert(keyHash != NULL); |
| 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; |
| |
| if (U_FAILURE(*status)) return; |
| |
| 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; |
| } |
| |
| limit = p + hash->length; |
| while (p < limit) { |
| p->key = NULL; |
| p->value = NULL; |
| 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); |
| assert(e != NULL); |
| 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, const void* 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. |
| */ |
| assert(FALSE); |
| return NULL; /* Never happens if uhash_put() behaves */ |
| } |
| return &(hash->elements[theIndex]); |
| } |
| |
| static void* |
| _uhash_setElement(UHashtable *hash, UHashElement* e, |
| int32_t hashcode, void* key, void* value) { |
| |
| void* oldKey = e->key; |
| void* oldValue = e->value; |
| if (hash->keyDeleter != NULL && oldKey != NULL && |
| oldKey != key) { /* Avoid double deletion */ |
| (*hash->keyDeleter)(oldKey); |
| } |
| if (oldValue == value) { /* Avoid double deletion */ |
| oldValue = NULL; |
| } |
| if (hash->valueDeleter != NULL && oldValue != NULL) { |
| (*hash->valueDeleter)(oldValue); |
| oldValue = NULL; |
| } |
| e->key = key; |
| e->value = value; |
| e->hashcode = hashcode; |
| return oldValue; |
| } |
| |
| /** |
| * Assumes that the given element is not empty or deleted. |
| */ |
| static void* |
| _uhash_internalRemoveElement(UHashtable *hash, UHashElement* e) { |
| assert(!IS_EMPTY_OR_DELETED(e->hashcode)); |
| --hash->count; |
| return _uhash_setElement(hash, e, HASH_DELETED, NULL, NULL); |
| } |
| |
| static void |
| _uhash_internalSetResizePolicy(UHashtable *hash, enum UHashResizePolicy policy) { |
| assert(hash == 0); |
| assert(((int32_t)policy) >= 0); |
| assert(((int32_t)policy) < 3); |
| hash->lowWaterRatio = RESIZE_POLICY_RATIO_TABLE[policy * 2]; |
| hash->highWaterRatio = RESIZE_POLICY_RATIO_TABLE[policy * 2 + 1]; |
| } |
