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lua_bloom_filter.c
291 lines (242 loc) · 6.89 KB
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lua_bloom_filter.c
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/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
/** @brief Lua bloom_filter implementation @file */
#include <limits.h>
#include <math.h>
#include <string.h>
#include "lauxlib.h"
#include "lua.h"
#include "xxhash.h"
#ifdef LUA_SANDBOX
#include "luasandbox_output.h"
#include "luasandbox_serialize.h"
#endif
static const char* mozsvc_bloom_filter = "mozsvc.bloom_filter";
typedef struct bloom_filter
{
size_t items;
size_t bytes;
size_t bits;
size_t cnt;
unsigned int hashes;
double probability;
unsigned char data[];
} bloom_filter;
static int bloom_filter_new(lua_State* lua)
{
int n = lua_gettop(lua);
luaL_argcheck(lua, n == 2, 0, "incorrect number of arguments");
int items = luaL_checkint(lua, 1);
luaL_argcheck(lua, 1 < items, 1, "items must be > 1");
double probability = luaL_checknumber(lua, 2);
luaL_argcheck(lua, 0 < probability && 1 > probability, 2, "probability must be between 0 and 1");
size_t bits = (size_t)ceil(items * log(probability) / log(1 / pow(2, log(2))));
size_t bytes = (size_t)ceil((double)bits / CHAR_BIT);
unsigned int hashes = (unsigned int)round(log(2) * bits / items);
size_t nbytes = sizeof(bloom_filter) + bytes;
bloom_filter* bf = (bloom_filter*)lua_newuserdata(lua, nbytes);
bf->items = items;
bf->bits = bits;
bf->bytes = bytes;
bf->hashes = hashes;
bf->probability = probability;
bf->cnt = 0;
memset(bf->data, 0, bf->bytes);
luaL_getmetatable(lua, mozsvc_bloom_filter);
lua_setmetatable(lua, -2);
return 1;
}
static bloom_filter* check_bloom_filter(lua_State* lua, int args)
{
void* ud = luaL_checkudata(lua, 1, mozsvc_bloom_filter);
luaL_argcheck(lua, ud != NULL, 1, "invalid userdata type");
luaL_argcheck(lua, args == lua_gettop(lua), 0,
"incorrect number of arguments");
return (bloom_filter*)ud;
}
static int bloom_filter_add(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 2);
size_t len = 0;
double val = 0;
void* key = NULL;
switch (lua_type(lua, 2)) {
case LUA_TSTRING:
key = (void*)lua_tolstring(lua, 2, &len);
break;
case LUA_TNUMBER:
val = lua_tonumber(lua, 2);
len = sizeof(double);
key = &val;
break;
default:
luaL_argerror(lua, 2, "must be a string or number");
break;
}
unsigned int bit = 0;
int added = 0;
for (unsigned int i = 0; i < bf->hashes; ++i) {
bit = XXH32(key, (int)len, i) % bf->bits;
if (!(bf->data[bit / CHAR_BIT] & 1 << (bit % CHAR_BIT))) {
bf->data[bit / CHAR_BIT] |= 1 << (bit % CHAR_BIT);
added = 1;
}
}
if (added) {
++bf->cnt;
}
lua_pushboolean(lua, added);
return 1;
}
static int bloom_filter_query(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 2);
size_t len = 0;
double val = 0;
void* key = NULL;
switch (lua_type(lua, 2)) {
case LUA_TSTRING:
key = (void*)lua_tolstring(lua, 2, &len);
break;
case LUA_TNUMBER:
val = lua_tonumber(lua, 2);
len = sizeof(double);
key = &val;
break;
default:
luaL_argerror(lua, 2, "must be a string or number");
break;
}
unsigned int bit = 0;
int found = 1;
for (unsigned int i = 0; i < bf->hashes && found; ++i) {
bit = XXH32(key, (int)len, i) % bf->bits;
found = bf->data[bit / CHAR_BIT] & 1 << (bit % CHAR_BIT);
}
lua_pushboolean(lua, found);
return 1;
}
static int bloom_filter_count(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 1);
lua_pushnumber(lua, (lua_Number)bf->cnt);
return 1;
}
static int bloom_filter_probability(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 1);
lua_pushnumber(lua, (lua_Number)bf->probability);
return 1;
}
static int bloom_filter_items(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 1);
lua_pushnumber(lua, (lua_Number)bf->items);
return 1;
}
static int bloom_filter_bytes(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 1);
lua_pushnumber(lua, (lua_Number)bf->bytes);
return 1;
}
static int bloom_filter_tostring(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 1);
lua_pushlstring(lua, (const char*)bf->data, bf->bytes);
return 1;
}
static int bloom_filter_clear(lua_State* lua)
{
bloom_filter* bf = check_bloom_filter(lua, 1);
memset(bf->data, 0, bf->bytes);
bf->cnt = 0;
return 0;
}
static int bloom_filter_fromstring(lua_State* lua)
{
size_t len = 0;
const char* values = NULL;
bloom_filter* bf = NULL;
if (lua_gettop(lua) == 2) { // todo remove conditional check after migration
bf = check_bloom_filter(lua, 2);
values = luaL_checklstring(lua, 2, &len);
} else {
bf = check_bloom_filter(lua, 3);
bf->cnt = (size_t)luaL_checknumber(lua, 2);
values = luaL_checklstring(lua, 3, &len);
}
if (len != bf->bytes) {
luaL_error(lua, "fromstring() bytes found: %d, expected %d", len, bf->bytes);
}
memcpy(bf->data, values, len);
return 0;
}
static int bloom_filter_version(lua_State* lua)
{
lua_pushstring(lua, DIST_VERSION);
return 1;
}
#ifdef LUA_SANDBOX
static int
serialize_bloom_filter(lua_State *lua) {
lsb_output_buffer* ob = lua_touserdata(lua, -1);
const char *key = lua_touserdata(lua, -2);
bloom_filter* bf = lua_touserdata(lua, -3);
if (!(ob && key && bf)) {
return 1;
}
if (lsb_outputf(ob,
"if %s == nil then %s = bloom_filter.new(%u, %g) end\n",
key,
key,
(unsigned)bf->items,
bf->probability)) {
return 1;
}
if (lsb_outputf(ob, "%s:fromstring(%u, \"", key, (unsigned)bf->cnt)) {
return 1;
}
if (lsb_serialize_binary(ob, bf->data, bf->bytes)) return 1;
if (lsb_outputs(ob, "\")\n", 3)) {
return 1;
}
return 0;
}
#endif
static const struct luaL_reg bloom_filterlib_f[] =
{
{ "new", bloom_filter_new }
, { "version", bloom_filter_version }
, { NULL, NULL }
};
static const struct luaL_reg bloom_filterlib_m[] =
{
{ "add", bloom_filter_add }
, { "query", bloom_filter_query }
, { "clear", bloom_filter_clear }
, { "count", bloom_filter_count }
, { "fromstring", bloom_filter_fromstring } // used for data restoration
, { "tostring", bloom_filter_tostring }
, { "items", bloom_filter_items }
, { "probability", bloom_filter_probability }
, { "bytes", bloom_filter_bytes }
, { NULL, NULL }
};
int luaopen_bloom_filter(lua_State* lua)
{
#ifdef LUA_SANDBOX
lua_newtable(lua);
lsb_add_serialize_function(lua, serialize_bloom_filter);
lua_replace(lua, LUA_ENVIRONINDEX);
#endif
luaL_newmetatable(lua, mozsvc_bloom_filter);
lua_pushvalue(lua, -1);
lua_setfield(lua, -2, "__index");
luaL_register(lua, NULL, bloom_filterlib_m);
luaL_register(lua, "bloom_filter", bloom_filterlib_f);
return 1;
}