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#include "std.h"
#include "lpc_incl.h"
#include "stralloc.h"
#include "hash.h"
#include "comm.h"
/* used temporarily by SVALUE_STRLEN() */
int svalue_strlen_size;
#ifdef NOISY_DEBUG
void bp (void) {
}
#endif
/*
this code is not the same as the original code. I cleaned it up to
use structs to: 1) make it easier to check the driver for memory leaks
(using MallocDebug on a NeXT) and 2) because it looks cleaner this way.
--Truilkan@TMI 92/04/19
modified to make calls to strlen() unnecessary and to remove superfluous
calls to findblock(). -- Truilkan@TMI, 1992/08/05
*/
/*
* stralloc.c - string management.
*
* All strings are stored in an extensible hash table, with reference counts.
* free_string decreases the reference count; if it gets to zero, the string
* will be deallocated. add_string increases the ref count if it finds a
* matching string, or allocates it if it cant. There is no way to allocate
* a string of a particular size to fill later (hash wont work!), so you'll
* have to copy things from a static (or malloced and later freed) buffer -
* that is, if you want to avoid space leaks...
*
* Current overhead:
* sizeof(block_t) per string (string pointer, next pointer, and a short
* for refs). Strings are nearly all fairly short, so this is a significant
* overhead - there is also the 4 byte malloc overhead and the fact that
* malloc generally allocates blocks which are a power of 2 (should write my
* own best-fit malloc specialised to strings); then again, GNU malloc
* is bug free...
*/
/*
* there is also generic hash table management code, but strings can be shared
* (that was the point of this code), will be unique in the table,
* require a reference count, and are malloced, copied and freed at
* will by the string manager. Besides, I wrote this code first :-).
* Look at htable.c for the other code. It uses the Hash() function
* defined here, and requires hashed objects to have a pointer to the
* next element in the chain (which you specify when you call the functions).
*/
#ifdef STRING_STATS
int num_distinct_strings = 0;
int bytes_distinct_strings = 0;
int overhead_bytes = 0;
int allocd_strings = 0;
int allocd_bytes = 0;
int search_len = 0;
int num_str_searches = 0;
#endif
#define StrHash(s) (whashstr((s), 20) & (htable_size_minus_one))
#define hfindblock(s, h) sfindblock(s, h = StrHash(s))
#define findblock(s) sfindblock(s, StrHash(s))
INLINE_STATIC block_t *sfindblock (const char *, int);
/*
* hash table - list of pointers to heads of string chains.
* Each string in chain has a pointer to the next string and a
* reference count (char *, int) stored just before the start of the string.
* HTABLE_SIZE is in config.h, and should be a prime, probably between
* 1000 and 5000.
*/
static block_t **base_table = (block_t **) 0;
static int htable_size;
static int htable_size_minus_one;
INLINE_STATIC block_t *alloc_new_string (const char *, int);
void init_strings()
{
int x, y;
/* ensure that htable size is a power of 2 */
y = HTABLE_SIZE;
for (htable_size = 1; htable_size < y; htable_size *= 2)
;
htable_size_minus_one = htable_size - 1;
base_table = CALLOCATE(htable_size, block_t *,
TAG_STR_TBL, "init_strings");
#ifdef STRING_STATS
overhead_bytes += (sizeof(block_t *) * htable_size);
#endif
for (x = 0; x < htable_size; x++) {
base_table[x] = 0;
}
}
/*
* Looks for a string in the table. If it finds it, returns a pointer to
* the start of the string part, and moves the entry for the string to
* the head of the pointer chain. One thing (blech!) - puts the previous
* pointer on the hash chain into fs_prev.
*/
INLINE_STATIC block_t *
sfindblock (const char * s, int h)
{
block_t *curr, *prev;
curr = base_table[h];
prev = NULL;
#ifdef STRING_STATS
num_str_searches++;
#endif
while (curr) {
#ifdef STRING_STATS
search_len++;
#endif
if (*(STRING(curr)) == *s && !strcmp(STRING(curr), s)) { /* found it */
if (prev) { /* not at head of list */
NEXT(prev) = NEXT(curr);
NEXT(curr) = base_table[h];
base_table[h] = curr;
}
return (curr); /* pointer to string */
}
prev = curr;
curr = NEXT(curr);
}
return ((block_t *) 0); /* not found */
}
char *
findstring (const char * s)
{
block_t *b;
if ((b = findblock(s))) {
return STRING(b);
} else {
return (NULL);
}
}
/* alloc_new_string: Make a space for a string. */
INLINE_STATIC block_t *
alloc_new_string (const char * string, int h)
{
block_t *b;
int len = strlen(string);
int size;
if (len > max_string_length) {
len = max_string_length;
}
size = sizeof(block_t) + len + 1;
b = (block_t *) DXALLOC(size, TAG_SHARED_STRING, "alloc_new_string");
strncpy(STRING(b), string, len);
STRING(b)[len] = '\0'; /* strncpy doesn't put on \0 if 'from' too
* long */
SIZE(b) = (len > USHRT_MAX ? USHRT_MAX : len);
REFS(b) = 1;
NEXT(b) = base_table[h];
base_table[h] = b;
ADD_NEW_STRING(SIZE(b), sizeof(block_t));
ADD_STRING(SIZE(b));
return (b);
}
char *
make_shared_string (const char * str)
{
block_t *b;
int h;
b = hfindblock(str, h); /* hfindblock macro sets h = StrHash(s) */
if (!b) {
b = alloc_new_string(str, h);
} else {
if (REFS(b))
REFS(b)++;
ADD_STRING(SIZE(b));
}
NDBG(b);
return (STRING(b));
}
/*
ref_string: Fatal to call this function on a string that isn't shared.
*/
const char *
ref_string (const char * str)
{
block_t *b;
b = BLOCK(str);
#ifdef DEBUG
if (b != findblock(str)) {
fatal("stralloc.c: called ref_string on non-shared string: %s.\n", str);
}
#endif /* defined(DEBUG) */
if (REFS(b))
REFS(b)++;
NDBG(b);
ADD_STRING(SIZE(b));
return str;
}
/* free_string: fatal to call free_string on a non-shared string */
/*
* free_string - reduce the ref count on a string. Various sanity
* checks applied.
*/
void
free_string (const char * str)
{
block_t **prev, *b;
int h;
b = BLOCK(str);
DEBUG_CHECK1(b != findblock(str),"stralloc.c: free_string called on non-shared string: %s.\n", str);
/*
* if a string has been ref'd USHRT_MAX times then we assume that its used
* often enough to justify never freeing it.
*/
if (!REFS(b))
return;
REFS(b)--;
SUB_STRING(SIZE(b));
NDBG(b);
if (REFS(b) > 0)
return;
h = StrHash(str);
prev = base_table + h;
while ((b = *prev)) {
if (STRING(b) == str) {
*prev = NEXT(b);
break;
}
prev = &(NEXT(b));
}
DEBUG_CHECK1(!b, "free_string: not found in string table! (\"%s\")\n", str);
SUB_NEW_STRING(SIZE(b), sizeof(block_t));
FREE(b);
CHECK_STRING_STATS;
}
void
deallocate_string (char * str)
{
int h;
block_t *b, **prev;
h = StrHash(str);
prev = base_table + h;
while ((b = *prev)) {
if (STRING(b) == str) {
*prev = NEXT(b);
break;
}
prev = &(NEXT(b));
}
DEBUG_CHECK1(!b,"stralloc.c: deallocate_string called on non-shared string: %s.\n", str);
FREE(b);
}
int
add_string_status (outbuffer_t * out, int verbose)
{
#ifdef STRING_STATS
if (verbose == 1) {
outbuf_add(out, "All strings:\n");
outbuf_add(out, "-------------------------\t Strings Bytes\n");
}
if (verbose != -1)
outbuf_addv(out, "All strings:\t\t\t%8d %8d + %d overhead\n",
num_distinct_strings, bytes_distinct_strings, overhead_bytes);
if (verbose == 1) {
outbuf_addv(out, "Total asked for\t\t\t%8d %8d\n",
allocd_strings, allocd_bytes);
outbuf_addv(out, "Space actually required/total string bytes %d%%\n",
(bytes_distinct_strings + overhead_bytes) * 100 / allocd_bytes);
outbuf_addv(out, "Searches: %d Average search length: %6.3f\n",
num_str_searches, (double) search_len / num_str_searches);
}
return (bytes_distinct_strings + overhead_bytes);
#else
if (verbose)
outbuf_add(out, "<String statistics disabled, no information available>\n");
return 0;
#endif
}
#ifdef DEBUGMALLOC_EXTENSIONS
#define DME 0,
#else
#define DME
#endif
/* This stuff needs a bit more work, otherwise FREE_MSTR() will crash on this
malloc_block_t the_null_string_blocks[2] = { { DME 0, 1 }, { DME 0, 0 } };
char *the_null_string = (char *)&the_null_string_blocks[1];
*/
#ifdef DEBUGMALLOC
char *int_new_string (int size, char * tag)
#else
char *int_new_string (int size)
#endif
{
malloc_block_t *mbt;
#if 0
if (!size) {
the_null_string_blocks[0].ref++;
ADD_NEW_STRING(0, sizeof(malloc_block_t));
return the_null_string;
}
#endif
mbt = (malloc_block_t *)DXALLOC(size + sizeof(malloc_block_t) + 1, TAG_MALLOC_STRING, tag);
if (size < USHRT_MAX) {
mbt->size = size;
ADD_NEW_STRING(size, sizeof(malloc_block_t));
} else {
mbt->size = USHRT_MAX;
ADD_NEW_STRING(USHRT_MAX, sizeof(malloc_block_t));
}
mbt->ref = 1;
ADD_STRING(mbt->size);
CHECK_STRING_STATS;
return (char *)(mbt + 1);
}
char *extend_string (const char * str, int len) {
malloc_block_t *mbt;
#ifdef STRING_STATS
int oldsize = MSTR_SIZE(str);
#endif
mbt = (malloc_block_t *)DREALLOC(MSTR_BLOCK(str), len + sizeof(malloc_block_t) + 1, TAG_MALLOC_STRING, "extend_string");
if (len < USHRT_MAX) {
mbt->size = len;
} else {
mbt->size = USHRT_MAX;
}
ADD_STRING_SIZE(mbt->size - oldsize);
CHECK_STRING_STATS;
return (char *)(mbt + 1);
}
#ifdef DEBUGMALLOC
char *int_alloc_cstring (const char * str, char * tag)
#else
char *int_alloc_cstring (const char * str)
#endif
{
char *ret;
ret = (char *)DXALLOC(strlen(str) + 1, TAG_STRING, tag);
strcpy(ret, str);
return ret;
}
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