mirror of
https://github.com/janet-lang/janet
synced 2024-06-28 08:03:16 +00:00
333ae7c4f8
This way we can support fewer build configurations. Also, remove all undefined behavior due to use of memcpy with NULL pointers. GCC was exploiting this to remove NULL checks in some builds.
246 lines
8.4 KiB
C
246 lines
8.4 KiB
C
/*
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* Copyright (c) 2020 Calvin Rose
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to
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* deal in the Software without restriction, including without limitation the
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* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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/* The symbol cache is an open hashtable with all active symbols in the program
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* stored in it. As the primary use of symbols is table lookups and equality
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* checks, all symbols are interned so that there is a single copy of it in the
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* whole program. Equality is then just a pointer check. */
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#ifndef JANET_AMALG
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#include "features.h"
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#include <janet.h>
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#include "state.h"
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#include "gc.h"
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#include "util.h"
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#include "symcache.h"
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#endif
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#include <string.h>
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/* Cache state */
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JANET_THREAD_LOCAL const uint8_t **janet_vm_cache = NULL;
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JANET_THREAD_LOCAL uint32_t janet_vm_cache_capacity = 0;
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JANET_THREAD_LOCAL uint32_t janet_vm_cache_count = 0;
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JANET_THREAD_LOCAL uint32_t janet_vm_cache_deleted = 0;
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/* Initialize the cache (allocate cache memory) */
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void janet_symcache_init() {
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janet_vm_cache_capacity = 1024;
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janet_vm_cache = calloc(1, (size_t) janet_vm_cache_capacity * sizeof(const uint8_t *));
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if (NULL == janet_vm_cache) {
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JANET_OUT_OF_MEMORY;
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}
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janet_vm_cache_count = 0;
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janet_vm_cache_deleted = 0;
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}
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/* Deinitialize the cache (free the cache memory) */
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void janet_symcache_deinit() {
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free((void *)janet_vm_cache);
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janet_vm_cache = NULL;
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janet_vm_cache_capacity = 0;
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janet_vm_cache_count = 0;
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janet_vm_cache_deleted = 0;
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}
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/* Mark an entry in the table as deleted. */
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static const uint8_t JANET_SYMCACHE_DELETED[1] = {0};
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/* Find an item in the cache and return its location.
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* If the item is not found, return the location
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* where one would put it. */
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static const uint8_t **janet_symcache_findmem(
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const uint8_t *str,
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int32_t len,
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int32_t hash,
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int *success) {
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uint32_t bounds[4];
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uint32_t i, j, index;
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const uint8_t **firstEmpty = NULL;
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/* We will search two ranges - index to the end,
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* and 0 to the index. */
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index = (uint32_t)hash & (janet_vm_cache_capacity - 1);
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bounds[0] = index;
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bounds[1] = janet_vm_cache_capacity;
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bounds[2] = 0;
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bounds[3] = index;
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for (j = 0; j < 4; j += 2)
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for (i = bounds[j]; i < bounds[j + 1]; ++i) {
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const uint8_t *test = janet_vm_cache[i];
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/* Check empty spots */
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if (NULL == test) {
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if (NULL == firstEmpty)
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firstEmpty = janet_vm_cache + i;
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goto notfound;
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}
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/* Check for marked deleted */
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if (JANET_SYMCACHE_DELETED == test) {
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if (firstEmpty == NULL)
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firstEmpty = janet_vm_cache + i;
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continue;
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}
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if (janet_string_equalconst(test, str, len, hash)) {
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/* Replace first deleted */
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*success = 1;
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if (firstEmpty != NULL) {
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*firstEmpty = test;
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janet_vm_cache[i] = JANET_SYMCACHE_DELETED;
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return firstEmpty;
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}
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return janet_vm_cache + i;
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}
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}
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notfound:
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*success = 0;
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return firstEmpty;
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}
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#define janet_symcache_find(str, success) \
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janet_symcache_findmem((str), janet_string_length(str), janet_string_hash(str), (success))
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/* Resize the cache. */
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static void janet_cache_resize(uint32_t newCapacity) {
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uint32_t i, oldCapacity;
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const uint8_t **oldCache = janet_vm_cache;
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const uint8_t **newCache = calloc(1, (size_t) newCapacity * sizeof(const uint8_t *));
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if (newCache == NULL) {
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JANET_OUT_OF_MEMORY;
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}
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oldCapacity = janet_vm_cache_capacity;
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janet_vm_cache = newCache;
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janet_vm_cache_capacity = newCapacity;
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janet_vm_cache_deleted = 0;
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/* Add all of the old cache entries back */
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for (i = 0; i < oldCapacity; ++i) {
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int status;
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const uint8_t **bucket;
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const uint8_t *x = oldCache[i];
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if (x != NULL && x != JANET_SYMCACHE_DELETED) {
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bucket = janet_symcache_find(x, &status);
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if (status || bucket == NULL) {
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/* there was a problem with the algorithm. */
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break;
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}
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*bucket = x;
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}
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}
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/* Free the old cache */
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free((void *)oldCache);
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}
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/* Add an item to the cache */
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static void janet_symcache_put(const uint8_t *x, const uint8_t **bucket) {
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if ((janet_vm_cache_count + janet_vm_cache_deleted) * 2 > janet_vm_cache_capacity) {
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int status;
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janet_cache_resize(janet_tablen((2 * janet_vm_cache_count + 1)));
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bucket = janet_symcache_find(x, &status);
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}
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/* Add x to the cache */
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janet_vm_cache_count++;
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*bucket = x;
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}
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/* Remove a symbol from the symcache */
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void janet_symbol_deinit(const uint8_t *sym) {
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int status = 0;
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const uint8_t **bucket = janet_symcache_find(sym, &status);
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if (status) {
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janet_vm_cache_count--;
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janet_vm_cache_deleted++;
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*bucket = JANET_SYMCACHE_DELETED;
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}
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}
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/* Create a symbol from a byte string */
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const uint8_t *janet_symbol(const uint8_t *str, int32_t len) {
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int32_t hash = janet_string_calchash(str, len);
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uint8_t *newstr;
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int success = 0;
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const uint8_t **bucket = janet_symcache_findmem(str, len, hash, &success);
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if (success)
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return *bucket;
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JanetStringHead *head = janet_gcalloc(JANET_MEMORY_SYMBOL, sizeof(JanetStringHead) + (size_t) len + 1);
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head->hash = hash;
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head->length = len;
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newstr = (uint8_t *)(head->data);
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safe_memcpy(newstr, str, len);
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newstr[len] = 0;
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janet_symcache_put((const uint8_t *)newstr, bucket);
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return newstr;
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}
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/* Get a symbol from a cstring */
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const uint8_t *janet_csymbol(const char *cstr) {
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return janet_symbol((const uint8_t *)cstr, (int32_t) strlen(cstr));
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}
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/* Store counter for genysm to avoid quadratic behavior */
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JANET_THREAD_LOCAL uint8_t gensym_counter[8] = {'_', '0', '0', '0', '0', '0', '0', 0};
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/* Increment the gensym buffer */
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static void inc_gensym(void) {
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for (int i = sizeof(gensym_counter) - 2; i; i--) {
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if (gensym_counter[i] == '9') {
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gensym_counter[i] = 'a';
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break;
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} else if (gensym_counter[i] == 'z') {
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gensym_counter[i] = 'A';
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break;
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} else if (gensym_counter[i] == 'Z') {
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gensym_counter[i] = '0';
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} else {
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gensym_counter[i]++;
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break;
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}
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}
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}
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/* Generate a unique symbol. This is used in the library function gensym. The
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* symbol will be of the format _XXXXXX, where X is a base64 digit, and
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* prefix is the argument passed. No prefix for speed. */
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const uint8_t *janet_symbol_gen(void) {
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const uint8_t **bucket = NULL;
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uint8_t *sym;
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int32_t hash = 0;
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int status;
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/* Leave spaces for 6 base 64 digits and two dashes. That means 64^6 possible suffixes, which
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* is enough for resolving collisions. */
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do {
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hash = janet_string_calchash(
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gensym_counter,
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sizeof(gensym_counter) - 1);
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bucket = janet_symcache_findmem(
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gensym_counter,
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sizeof(gensym_counter) - 1,
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hash,
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&status);
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} while (status && (inc_gensym(), 1));
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JanetStringHead *head = janet_gcalloc(JANET_MEMORY_SYMBOL, sizeof(JanetStringHead) + sizeof(gensym_counter));
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head->length = sizeof(gensym_counter) - 1;
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head->hash = hash;
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sym = (uint8_t *)(head->data);
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memcpy(sym, gensym_counter, sizeof(gensym_counter));
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janet_symcache_put((const uint8_t *)sym, bucket);
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return (const uint8_t *)sym;
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}
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