prosody
735b8f4a6d7e
util-src/table.c

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util-src/table.c @ 11661:735b8f4a6d7e

net.http: Send entire HTTP request header as one write When opportunistic writes are enabled this reduces the number of syscalls and TCP packets sent on the wire. Experiments with TCP Fast Open made this even more obvious. That table trick probably wasn't as efficient. Lua generates bytecode for a table with zero array slots and space for two entries in the hash part, plus code to set [2] and [4]. I didn't verify but I suspect it would have had to resize the table when setting [1] and [3], although probably only once. Concatenating the strings directly in Lua is easier to read and involves no extra table or function call.
author Kim Alvefur <zash@zash.se>
date Thu, 08 Jul 2021 18:21:59 +0200
parent 7969:1c6a07606309
child 12402:8deb401a21f6
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7c4cf87f4dff util.table, Makefile: New C module that allows pre-allocation of tables to improve performance and decrease memory fragmentation
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1 #include <lua.h>
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2 #include <lauxlib.h>
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3
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4 static int Lcreate_table(lua_State *L) {
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5 lua_createtable(L, luaL_checkinteger(L, 1), luaL_checkinteger(L, 2));
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6 return 1;
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7 }
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8
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9 static int Lpack(lua_State *L) {
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10 unsigned int n_args = lua_gettop(L);
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11 lua_createtable(L, n_args, 1);
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12 lua_insert(L, 1);
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14 for(int arg = n_args; arg >= 1; arg--) {
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15 lua_rawseti(L, 1, arg);
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16 }
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18 lua_pushinteger(L, n_args);
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19 lua_setfield(L, -2, "n");
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20 return 1;
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21 }
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23 int luaopen_util_table(lua_State *L) {
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24 #if (LUA_VERSION_NUM > 501)
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25 luaL_checkversion(L);
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26 #endif
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27 lua_createtable(L, 0, 2);
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28 lua_pushcfunction(L, Lcreate_table);
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29 lua_setfield(L, -2, "create");
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30 lua_pushcfunction(L, Lpack);
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31 lua_setfield(L, -2, "pack");
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32 return 1;
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33 }