Browse Source

separate header/impl for strman

master
Daniel Kolesa 4 months ago
parent
commit
6821260c37
  1. 6
      include/cubescript/cubescript.hh
  2. 1
      src/cs_state.cc
  3. 112
      src/cs_strman.cc
  4. 92
      src/cs_strman.hh
  5. 103
      src/cs_util.cc
  6. 79
      src/cs_util.hh
  7. 1
      src/lib_str.cc
  8. 1
      src/meson.build

6
include/cubescript/cubescript.hh

@ -298,10 +298,10 @@ LIBCUBESCRIPT_EXPORT bool cs_code_is_empty(cs_bcode *code);
struct LIBCUBESCRIPT_EXPORT cs_strref {
friend struct cs_value;
/* FIXME: eliminate this */
friend inline cs_strref cs_make_strref(char const *p, cs_shared_state &cs);
friend inline cs_strref cs_make_strref(char const *p, cs_shared_state *cs);
cs_strref() = delete;
cs_strref(cs_shared_state &cs, std::string_view str);
cs_strref(cs_shared_state *cs, std::string_view str);
cs_strref(cs_state &cs, std::string_view str);
cs_strref(cs_strref const &ref);
@ -327,7 +327,7 @@ struct LIBCUBESCRIPT_EXPORT cs_strref {
private:
/* for internal use only */
cs_strref(char const *p, cs_shared_state &cs);
cs_strref(char const *p, cs_shared_state *cs);
cs_shared_state *p_state;
char const *p_str;

1
src/cs_state.cc

@ -3,6 +3,7 @@
#include "cs_util.hh"
#include "cs_bcode.hh"
#include "cs_state.hh"
#include "cs_strman.hh"
namespace cscript {

112
src/cs_strman.cc

@ -0,0 +1,112 @@
#include <cubescript/cubescript.hh>
#include "cs_strman.hh"
namespace cscript {
struct cs_strref_state {
std::size_t length;
std::size_t refcount;
};
inline cs_strref_state *get_ref_state(char const *ptr) {
return const_cast<cs_strref_state *>(
reinterpret_cast<cs_strref_state const *>(ptr)
) - 1;
}
char const *cs_strman::add(std::string_view str) {
auto it = counts.find(str);
/* already present: just increment ref */
if (it != counts.end()) {
auto *st = it->second;
/* having a null pointer is the same as non-existence */
if (st) {
++st->refcount;
return reinterpret_cast<char const *>(st + 1);
}
}
/* not present: allocate brand new data */
auto ss = str.size();
auto strp = alloc_buf(ss);
/* write string data, it's already pre-terminated */
memcpy(strp, str.data(), ss);
/* store it */
counts.emplace(std::string_view{strp, ss}, get_ref_state(strp));
return strp;
}
char const *cs_strman::ref(char const *ptr) {
auto *ss = get_ref_state(ptr);
++ss->refcount;
return ptr;
}
char const *cs_strman::steal(char *ptr) {
auto *ss = get_ref_state(ptr);
auto sr = std::string_view{ptr, ss->length};
/* much like add(), but we already have memory */
auto it = counts.find(sr);
if (it != counts.end()) {
auto *st = it->second;
if (st) {
++st->refcount;
/* the buffer is superfluous now */
cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
return reinterpret_cast<char const *>(st + 1);
}
}
ss->refcount = 1;
counts.emplace(sr, ss);
return ptr;
}
void cs_strman::unref(char const *ptr) {
auto *ss = get_ref_state(ptr);
if (!--ss->refcount) {
/* refcount zero, so ditch it
* this path is a little slow...
*/
auto sr = std::string_view{ptr, ss->length};
auto it = counts.find(sr);
if (it == counts.end()) {
/* internal error: this should *never* happen */
throw cs_internal_error{"no refcount"};
}
/* we're freeing the key */
counts.erase(it);
/* dealloc */
cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
}
}
char const *cs_strman::find(std::string_view str) const {
auto it = counts.find(str);
if (it == counts.end()) {
return nullptr;
}
return reinterpret_cast<char const *>(it->second + 1);
}
std::string_view cs_strman::get(char const *ptr) const {
auto *ss = get_ref_state(ptr);
return std::string_view{ptr, ss->length};
}
char *cs_strman::alloc_buf(std::size_t len) const {
auto mem = cstate->alloc(nullptr, 0, len + sizeof(cs_strref_state) + 1);
if (!mem) {
throw cs_internal_error{"allocation failed"};
}
/* write length and initial refcount */
auto *sst = static_cast<cs_strref_state *>(mem);
sst->length = len;
sst->refcount = 1;
/* pre-terminate */
auto *strp = reinterpret_cast<char *>(sst + 1);
strp[len] = '\0';
/* now the user can fill it */
return strp;
};
} /* namespace cscript */

92
src/cs_strman.hh

@ -0,0 +1,92 @@
#ifndef LIBCUBESCRIPT_STRMAN_HH
#define LIBCUBESCRIPT_STRMAN_HH
#include <cubescript/cubescript.hh>
#include <unordered_map>
#include <string_view>
#include "cs_std.hh"
#include "cs_state.hh"
namespace cscript {
struct cs_strref_state;
/* string manager
*
* the purpose of this is to handle interning of strings; each string within
* a libcs state is represented (and allocated) exactly once, and reference
* counted; that both helps save resources, and potentially provide a means
* to reliably represent returned strings in places that is compatible with
* multiple threads and eliminate the chance of dangling pointers
*
* strings are allocated in a manner where the refcount and length are stored
* as a part of the string's memory, so it can be easily accessed using just
* the pointer to the string, but also this is transparent for usage
*
* this is not thread-safe yet, and later on it should be made that,
* for now we don't bother...
*/
struct cs_strman {
using allocator_type = cs_allocator<
std::pair<std::string_view const, cs_strref_state *>
>;
cs_strman() = delete;
cs_strman(cs_shared_state *cs): cstate{cs}, counts{allocator_type{cs}} {}
~cs_strman() {}
cs_strman(cs_strman const &) = delete;
cs_strman(cs_strman &&) = delete;
cs_strman &operator=(cs_strman const &) = delete;
cs_strman &operator=(cs_strman &&) = delete;
/* adds a string into the manager using any source, and returns a managed
* version; this is "slow" as it has to hash the string and potentially
* allocate fresh memory for it, but is perfectly safe at any time
*/
char const *add(std::string_view str);
/* this simply increments the reference count of an existing managed
* string, this is only safe when you know the pointer you are passing
* is already managed the system
*/
char const *ref(char const *ptr);
/* this will use the provided memory, assuming it is a fresh string that
* is yet to be added; the memory must be allocated with alloc_buf()
*/
char const *steal(char *ptr);
/* decrements the reference count and removes it from the system if
* that reaches zero; likewise, only safe with pointers that are managed
*/
void unref(char const *ptr);
/* just finds a managed pointer with the same contents
* as the input, if not found then a null pointer is returned
*/
char const *find(std::string_view str) const;
/* a quick helper to make a proper string view out of a ptr */
std::string_view get(char const *ptr) const;
/* this will allocate a buffer of the given length (plus one for
* terminating zero) so you can fill it; use steal() to write it
*/
char *alloc_buf(std::size_t len) const;
cs_shared_state *cstate;
std::unordered_map<
std::string_view, cs_strref_state *,
std::hash<std::string_view>,
std::equal_to<std::string_view>,
allocator_type
> counts;
};
} /* namespace cscript */
#endif

103
src/cs_util.cc

@ -1,6 +1,7 @@
#include <cubescript/cubescript.hh>
#include "cs_util.hh"
#include "cs_vm.hh"
#include "cs_strman.hh"
#include <cctype>
#include <cmath>
@ -182,108 +183,6 @@ done:
return ret;
}
/* string manager */
inline cs_strref_state *get_ref_state(char const *ptr) {
return const_cast<cs_strref_state *>(
reinterpret_cast<cs_strref_state const *>(ptr)
) - 1;
}
char const *cs_strman::add(std::string_view str) {
auto it = counts.find(str);
/* already present: just increment ref */
if (it != counts.end()) {
auto *st = it->second;
/* having a null pointer is the same as non-existence */
if (st) {
++st->refcount;
return reinterpret_cast<char const *>(st + 1);
}
}
/* not present: allocate brand new data */
auto ss = str.size();
auto strp = alloc_buf(ss);
/* write string data, it's already pre-terminated */
memcpy(strp, str.data(), ss);
/* store it */
counts.emplace(std::string_view{strp, ss}, get_ref_state(strp));
return strp;
}
char const *cs_strman::ref(char const *ptr) {
auto *ss = get_ref_state(ptr);
++ss->refcount;
return ptr;
}
char const *cs_strman::steal(char *ptr) {
auto *ss = get_ref_state(ptr);
auto sr = std::string_view{ptr, ss->length};
/* much like add(), but we already have memory */
auto it = counts.find(sr);
if (it != counts.end()) {
auto *st = it->second;
if (st) {
++st->refcount;
/* the buffer is superfluous now */
cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
return reinterpret_cast<char const *>(st + 1);
}
}
ss->refcount = 1;
counts.emplace(sr, ss);
return ptr;
}
void cs_strman::unref(char const *ptr) {
auto *ss = get_ref_state(ptr);
if (!--ss->refcount) {
/* refcount zero, so ditch it
* this path is a little slow...
*/
auto sr = std::string_view{ptr, ss->length};
auto it = counts.find(sr);
if (it == counts.end()) {
/* internal error: this should *never* happen */
throw cs_internal_error{"no refcount"};
}
/* we're freeing the key */
counts.erase(it);
/* dealloc */
cstate->alloc(ss, ss->length + sizeof(cs_strref_state) + 1, 0);
}
}
char const *cs_strman::find(std::string_view str) const {
auto it = counts.find(str);
if (it == counts.end()) {
return nullptr;
}
return reinterpret_cast<char const *>(it->second + 1);
}
std::string_view cs_strman::get(char const *ptr) const {
auto *ss = get_ref_state(ptr);
return std::string_view{ptr, ss->length};
}
char *cs_strman::alloc_buf(std::size_t len) const {
auto mem = cstate->alloc(nullptr, 0, len + sizeof(cs_strref_state) + 1);
if (!mem) {
throw cs_internal_error{"allocation failed"};
}
/* write length and initial refcount */
auto *sst = static_cast<cs_strref_state *>(mem);
sst->length = len;
sst->refcount = 1;
/* pre-terminate */
auto *strp = reinterpret_cast<char *>(sst + 1);
strp[len] = '\0';
/* now the user can fill it */
return strp;
};
/* strref */
cs_strref::cs_strref(cs_shared_state *cs, std::string_view str):

79
src/cs_util.hh

@ -25,85 +25,6 @@ inline cs_strref cs_make_strref(char const *p, cs_shared_state *cs) {
return cs_strref{p, cs};
}
/* string manager
*
* the purpose of this is to handle interning of strings; each string within
* a libcs state is represented (and allocated) exactly once, and reference
* counted; that both helps save resources, and potentially provide a means
* to reliably represent returned strings in places that is compatible with
* multiple threads and eliminate the chance of dangling pointers
*
* strings are allocated in a manner where the refcount and length are stored
* as a part of the string's memory, so it can be easily accessed using just
* the pointer to the string, but also this is transparent for usage
*
* this is not thread-safe yet, and later on it should be made that,
* for now we don't bother...
*/
struct cs_strref_state {
size_t length;
size_t refcount;
};
struct cs_strman {
using allocator_type = cs_allocator<
std::pair<std::string_view const, cs_strref_state *>
>;
cs_strman() = delete;
cs_strman(cs_shared_state *cs): cstate{cs}, counts{allocator_type{cs}} {}
~cs_strman() {}
cs_strman(cs_strman const &) = delete;
cs_strman(cs_strman &&) = delete;
cs_strman &operator=(cs_strman const &) = delete;
cs_strman &operator=(cs_strman &&) = delete;
/* adds a string into the manager using any source, and returns a managed
* version; this is "slow" as it has to hash the string and potentially
* allocate fresh memory for it, but is perfectly safe at any time
*/
char const *add(std::string_view str);
/* this simply increments the reference count of an existing managed
* string, this is only safe when you know the pointer you are passing
* is already managed the system
*/
char const *ref(char const *ptr);
/* this will use the provided memory, assuming it is a fresh string that
* is yet to be added; the memory must be allocated with alloc_buf()
*/
char const *steal(char *ptr);
/* decrements the reference count and removes it from the system if
* that reaches zero; likewise, only safe with pointers that are managed
*/
void unref(char const *ptr);
/* just finds a managed pointer with the same contents
* as the input, if not found then a null pointer is returned
*/
char const *find(std::string_view str) const;
/* a quick helper to make a proper string view out of a ptr */
std::string_view get(char const *ptr) const;
/* this will allocate a buffer of the given length (plus one for
* terminating zero) so you can fill it; use steal() to write it
*/
char *alloc_buf(std::size_t len) const;
cs_shared_state *cstate;
std::unordered_map<
std::string_view, cs_strref_state *,
std::hash<std::string_view>,
std::equal_to<std::string_view>,
allocator_type
> counts;
};
} /* namespace cscript */
#endif /* LIBCUBESCRIPT_CS_UTIL_HH */

1
src/lib_str.cc

@ -5,6 +5,7 @@
#include "cs_util.hh"
#include "cs_std.hh"
#include "cs_strman.hh"
namespace cscript {

1
src/meson.build

@ -9,6 +9,7 @@ libcubescript_src = [
'cs_gen.cc',
'cs_ident.cc',
'cs_state.cc',
'cs_strman.cc',
'cs_util.cc',
'cs_val.cc',
'cs_vm.cc',

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