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Use charpool to back string_pool

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string_pool (string interning) was using STL strings with lots of extra
constructions, when all we need is a const char array. We can use
charpool for that and get all the benefits there of tightly-packed heap
allocations.
This commit is contained in:
dmiller
2022-09-12 16:59:36 +00:00
parent cc5cd5f2c6
commit 7ec32df7ea
3 changed files with 63 additions and 45 deletions
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53
charpool.cc
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@@ -72,8 +72,8 @@
static char *charpool[16];
static int currentcharpool;
static int currentcharpoolsz;
static char *nextchar;
static size_t currentcharpoolsz;
static size_t nexti;
/* Allocated blocks are allocated to multiples of ALIGN_ON. This is the
definition used by the malloc in Glibc 2.7, which says that it "suffices for
@@ -87,7 +87,8 @@ static int cp_init(void) {
/* Create our char pool */
currentcharpool = 0;
currentcharpoolsz = 16384;
nextchar = charpool[0] = (char *) safe_malloc(currentcharpoolsz);
nexti = 0;
charpool[0] = (char *) safe_malloc(currentcharpoolsz);
charpool_initialized = 1;
return 0;
}
@@ -109,8 +110,8 @@ static inline void cp_grow(void) {
}
currentcharpoolsz <<= 1;
nextchar = charpool[currentcharpool] = (char *)
safe_malloc(currentcharpoolsz);
nexti = 0;
charpool[currentcharpool] = (char *) safe_malloc(currentcharpoolsz);
}
void *cp_alloc(int sz) {
@@ -122,9 +123,9 @@ void *cp_alloc(int sz) {
if ((modulus = sz % ALIGN_ON))
sz += ALIGN_ON - modulus;
if ((nextchar - charpool[currentcharpool]) + sz <= currentcharpoolsz) {
p = nextchar;
nextchar += sz;
if (nexti + sz <= currentcharpoolsz) {
p = charpool[currentcharpool] + nexti;
nexti += sz;
return p;
}
/* Doh! We've got to make room */
@@ -134,32 +135,12 @@ void *cp_alloc(int sz) {
}
char *cp_strdup(const char *src) {
const char *p;
char *q;
/* end points to the first illegal char */
char *end;
int modulus;
cp_init();
end = charpool[currentcharpool] + currentcharpoolsz;
q = nextchar;
p = src;
while((nextchar < end) && *p) {
*nextchar++ = *p++;
}
if (nextchar < end) {
/* Goody, we have space */
*nextchar++ = '\0';
if ((modulus = (nextchar - q) % ALIGN_ON))
nextchar += ALIGN_ON - modulus;
return q;
}
/* Doh! We ran out -- need to allocate more */
cp_grow();
return cp_strdup(src);
const char *cp_strndup(const char *src, int len) {
char *dst = (char *) cp_alloc(len + 1); // Additional byte for null terminator
dst[len] = '\0';
return (const char *) memcpy(dst, src, len);
}
const char *cp_strdup(const char *src) {
return cp_strndup(src, strlen(src));
}