jchash.c

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "php_jchash.h"
#include "ext/standard/php_var.h"
#include "ext/standard/crc32.h"

ZEND_DECLARE_MODULE_GLOBALS(jchash)

ZEND_BEGIN_ARG_INFO_EX(arginfo_jchash, 0, 0, 1)
  ZEND_ARG_INFO(0, key)
  ZEND_ARG_INFO(0, num_buckets)
ZEND_END_ARG_INFO()

static const zend_function_entry jchash_functions[] = {
  PHP_FE(jchash,  arginfo_jchash)
  PHP_FE_END
};

zend_module_entry jchash_module_entry = {
	STANDARD_MODULE_HEADER,
	"jchash",
	jchash_functions,
	PHP_MINIT(jchash),
	PHP_MSHUTDOWN(jchash),
	NULL,
	PHP_RSHUTDOWN(jchash),
	PHP_MINFO(jchash),
	PHP_JCHASH_VERSION,
	STANDARD_MODULE_PROPERTIES
};

#ifdef COMPILE_DL_JCHASH
#ifdef ZTS
ZEND_TSRMLS_CACHE_DEFINE()
#endif
ZEND_GET_MODULE(jchash)
#endif

#define JCHASH_HASH_ADD_NEW(ht, num_idx, str_idx, val) \
      (str_idx) \
      ? zend_hash_add_new(ht, str_idx, val) \
      : zend_hash_index_add_new(ht, num_idx, val)

#define JCHASH_HASH_UPDATE(ht, num_idx, str_idx, val) \
      (str_idx) \
      ? zend_hash_update(ht, str_idx, val) \
      : zend_hash_index_update(ht, num_idx, val)

#define JCHASH_HASH_FIND(ht, num_idx, str_idx) \
      (str_idx) \
      ? zend_hash_find(ht, str_idx) \
      : zend_hash_index_find(ht, num_idx)

PHP_INI_BEGIN()
    // STD_PHP_INI_ENTRY("jchash.default",   "unsafe_raw", PHP_INI_SYSTEM|PHP_INI_PERDIR, UpdateDefaultFilter, default_filter, zend_filter_globals, filter_globals)
    // PHP_INI_ENTRY("jchash.default_flags", NULL,     PHP_INI_SYSTEM|PHP_INI_PERDIR, OnUpdateFlags)
PHP_INI_END()

PHP_MINIT_FUNCTION(jchash)
{
    REGISTER_INI_ENTRIES();
    return SUCCESS;
}

PHP_MSHUTDOWN_FUNCTION(jchash)
{
    UNREGISTER_INI_ENTRIES();
    return SUCCESS;
}

PHP_RSHUTDOWN_FUNCTION(jchash)
{
    return SUCCESS;
}

PHP_MINFO_FUNCTION(jchash)
{
    php_info_print_table_start();
    php_info_print_table_row(2, "Version", PHP_JCHASH_VERSION);
    php_info_print_table_end();
    DISPLAY_INI_ENTRIES();
}

uint32_t JumpConsistentHash(uint64_t key, uint32_t num_buckets)
{
    // php_printf("key: %lu, num_buckets: %lu\n", key, num_buckets);
    uint32_t b = -1, j = 0;
    while (j < num_buckets) {
        b = j;
        key = key * 2862933555777941757ULL + 1;
        j = (b + 1) * ((double)(1LL << 31)) / ((double)((key >> 33) + 1));
    }
    return b;
}

PHP_FUNCTION(jchash)
{
    zval *zvalkey;
    zend_long num_buckets;
    if (zend_parse_parameters(ZEND_NUM_ARGS(), "zl", &zvalkey, &num_buckets) == FAILURE) {
        return;
    }

    zend_long key;
    zend_string *str;
    if (Z_TYPE_P(zvalkey) == IS_STRING) {

        str = Z_STR_P(zvalkey);
        char *p = str->val;
        size_t nr = str->len;
        uint32_t crcinit = 0;
        register uint32_t crc;
        crc = crcinit^0xFFFFFFFF;
        for (; nr--; ++p) {
          crc = ((crc >> 8) & 0x00FFFFFF) ^ crc32tab[(crc ^ (*p)) & 0xFF ];
        }
        key = crc^0xFFFFFFFF;

    } else if (Z_TYPE_P(zvalkey) == IS_LONG) {
        key = Z_LVAL_P(zvalkey);
    } else {
        php_error_docref(NULL, E_ERROR, "Unsupported type of key");
    }

    // php_printf("key: %lu, num_buckets: %lu\n", key, num_buckets);

    uint64_t b = JumpConsistentHash(key, num_buckets);
    ZVAL_LONG(return_value, b);
}