redis中 lua 環境的創建和初始化
redis 中,lua 環境的初始化,是從 redis.c/initServer()
函數中,調用 scriptingInit()
函數開始的。
關於 scriptingInit()
的描述
/* Initialize the scripting environment.
* It is possible to call this function to reset the scripting environment
* assuming that we call scriptingRelease() before.
* See scriptingReset() for more information. */
也就是說,這個函數是初始化lua環境的,當然,如果調用了 scriptingRelease()
在調用該函數,可以重置 lua 腳本環境。我們進入到函數中看一下代碼。
void scriptingInit(void) {
lua_State *lua = lua_open();
luaLoadLibraries(lua);
luaRemoveUnsupportedFunctions(lua);
/* Initialize a dictionary we use to map SHAs to scripts.
* This is useful for replication, as we need to replicate EVALSHA
* as EVAL, so we need to remember the associated script. */
server.lua_scripts = dictCreate(&shaScriptObjectDictType,NULL);
/* Register the redis commands table and fields */
lua_newtable(lua);
/* redis.call */
lua_pushstring(lua,"call");
lua_pushcfunction(lua,luaRedisCallCommand);
lua_settable(lua,-3);
/* redis.pcall */
lua_pushstring(lua,"pcall");
lua_pushcfunction(lua,luaRedisPCallCommand);
lua_settable(lua,-3);
/* redis.log and log levels. */
lua_pushstring(lua,"log");
lua_pushcfunction(lua,luaLogCommand);
lua_settable(lua,-3);
lua_pushstring(lua,"LOG_DEBUG");
lua_pushnumber(lua,REDIS_DEBUG);
lua_settable(lua,-3);
lua_pushstring(lua,"LOG_VERBOSE");
lua_pushnumber(lua,REDIS_VERBOSE);
lua_settable(lua,-3);
lua_pushstring(lua,"LOG_NOTICE");
lua_pushnumber(lua,REDIS_NOTICE);
lua_settable(lua,-3);
lua_pushstring(lua,"LOG_WARNING");
lua_pushnumber(lua,REDIS_WARNING);
lua_settable(lua,-3);
/* redis.sha1hex */
lua_pushstring(lua, "sha1hex");
lua_pushcfunction(lua, luaRedisSha1hexCommand);
lua_settable(lua, -3);
/* redis.error_reply and redis.status_reply */
lua_pushstring(lua, "error_reply");
lua_pushcfunction(lua, luaRedisErrorReplyCommand);
lua_settable(lua, -3);
lua_pushstring(lua, "status_reply");
lua_pushcfunction(lua, luaRedisStatusReplyCommand);
lua_settable(lua, -3);
/* Finally set the table as 'redis' global var. */
lua_setglobal(lua,"redis");
/* Replace math.random and math.randomseed with our implementations. */
lua_getglobal(lua,"math");
lua_pushstring(lua,"random");
lua_pushcfunction(lua,redis_math_random);
lua_settable(lua,-3);
lua_pushstring(lua,"randomseed");
lua_pushcfunction(lua,redis_math_randomseed);
lua_settable(lua,-3);
lua_setglobal(lua,"math");
/* Add a helper function that we use to sort the multi bulk output of non
* deterministic commands, when containing 'false' elements. */
{
char *compare_func = "function __redis__compare_helper(a,b)\n"
" if a == false then a = '' end\n"
" if b == false then b = '' end\n"
" return a<b\n"
"end\n";
luaL_loadbuffer(lua,compare_func,strlen(compare_func),"@cmp_func_def");
lua_pcall(lua,0,0,0);
}
/* Add a helper function we use for pcall error reporting.
* Note that when the error is in the C function we want to report the
* information about the caller, that's what makes sense from the point
* of view of the user debugging a script. */
{
char *errh_func = "local dbg = debug\n"
"function __redis__err__handler(err)\n"
" local i = dbg.getinfo(2,'nSl')\n"
" if i and i.what == 'C' then\n"
" i = dbg.getinfo(3,'nSl')\n"
" end\n"
" if i then\n"
" return i.source .. ':' .. i.currentline .. ': ' .. err\n"
" else\n"
" return err\n"
" end\n"
"end\n";
luaL_loadbuffer(lua,errh_func,strlen(errh_func),"@err_handler_def");
lua_pcall(lua,0,0,0);
}
/* Create the (non connected) client that we use to execute Redis commands
* inside the Lua interpreter.
* Note: there is no need to create it again when this function is called
* by scriptingReset(). */
if (server.lua_client == NULL) {
server.lua_client = createClient(-1);
server.lua_client->flags |= REDIS_LUA_CLIENT;
}
/* Lua beginners often don't use "local", this is likely to introduce
* subtle bugs in their code. To prevent problems we protect accesses
* to global variables. */
scriptingEnableGlobalsProtection(lua);
server.lua = lua;
}
1、 lua_open() 函數,創建一個lua環境
2、 luaLoadLibraries(lua)
,在新創建的lua環境中載入相應的庫,同時刪除庫中不需要的函數,防止從外部引入不安全的代碼 luaRemoveUnsupportedFunctions(lua)
,
void luaLoadLibraries(lua_State *lua) {
luaLoadLib(lua, "", luaopen_base);
luaLoadLib(lua, LUA_TABLIBNAME, luaopen_table);
luaLoadLib(lua, LUA_STRLIBNAME, luaopen_string);
luaLoadLib(lua, LUA_MATHLIBNAME, luaopen_math);
luaLoadLib(lua, LUA_DBLIBNAME, luaopen_debug);
luaLoadLib(lua, "cjson", luaopen_cjson);
luaLoadLib(lua, "struct", luaopen_struct);
luaLoadLib(lua, "cmsgpack", luaopen_cmsgpack);
luaLoadLib(lua, "bit", luaopen_bit);
#if 0 /* Stuff that we don't load currently, for sandboxing concerns. */
luaLoadLib(lua, LUA_LOADLIBNAME, luaopen_package);
luaLoadLib(lua, LUA_OSLIBNAME, luaopen_os);
#endif
}
/* Remove a functions that we don't want to expose to the Redis scripting
* environment. */
void luaRemoveUnsupportedFunctions(lua_State *lua) {
lua_pushnil(lua); //將空值入棧,此時棧頂元素爲空值
lua_setglobal(lua,"loadfile"); //出棧,取出棧頂元素,即空值,並將其作爲 loadfile 的值,也就相當於取消了 loadfile 這個函數的作用,置空了
}
3、 lua_newtable(lua)
創建一張空表,併入棧
4、 將 c 中的luaRedisCallCommand 函數壓入棧,作爲表的函數;將 c 中的luaRedisPCallCommand 函數入棧,作爲表的函數;將 c 中的luaLogCommand 函數入棧作爲表的函數;將表複製爲 redis,即創建 redis 全局 table。下面對其中一個註冊函數進行解釋
lua_newtable(lua);
/* redis.call */
lua_pushstring(lua,"call");
lua_pushcfunction(lua,luaRedisCallCommand);
lua_settable(lua,-3);
首先創建一個空表,入棧,此時棧頂元素爲 table。然後將字符串 “call” 入棧,再將 c 函數 luaRedisCallCommand 函數入棧
lua_settable(lua, -3)
意思是 t[k]=v,t 爲索引-3,棧中,-3 位元素 table,-1 爲 luaRedisCallCommand,-2 爲字符串call,v 表示棧頂元素,k表示棧頂元素的下一個元素,索引上面這個函數的意思就是
table["call"]=luaRedisCallCommand
就是將lua 中的call 函數註冊爲 c 中的 luaRedisCallCommand 函數,也可以記爲
table.call=luaRedisCallCommand
後面代碼意思都雷同,都是註冊 c 函數到 lua 中。
注意: lua_settable(lua_State *L, int index)
會將棧頂兩個元素彈出。
lua_setglobal(lua, "redis")
將表作爲 redis的值,即創建的表爲 redis 表,該表中包含以下函數:
- redis.call 函數和 redis.pcall 函數,用於執行 redis 命令
- redis.log 記錄日誌,日誌級別對應爲
redid.LOG_DEBUG
,redis.LOG_VERBOSE
,redis.LOG_NOTICE
,redis.LOG_WARNING
- redis.sha1hex,計算 SHA1 校驗和
redis.error_reply
和redis.status_reply
函數,返回 redis 錯誤信息
5、 用 c 中自制的隨機函數替換 Lua 中原有的隨機函數
6、 創建排序輔助函數, Lua 環境使用這個輔助函數來對一部分 redis 命令的結果進行排序,從而消除這些命令的不確定性。
function __redis__compare_helper(a,b)
if a == false
then
a = ''
end
if b == false
then
b = ''
end
return a<b
end
7、 創建 redis.pcall 函數的錯誤報告輔助函數,這個函數可以提供更加詳細發出錯信息,比如能夠在 c 函數的出錯信息中提供調用者的信息
local dbg = debug;
function __redis_err_handler(err)
local i = dbg.getinfo (2, 'sS1')
if i and i.what = 'C'
then
i = dgb.getinfo (3, 'nS1')
end
if i
then
return i.source .. ':' .. i.currentLine .. ':' .. err
else
return err
end
end
8、 對 lua 環境中的全局環境進行保護,防止用戶在執行 lua 腳本的過程中,將額外的全局變量添加到 Lua 環境中
9、 將完成修改的 lua 環境保存到服務器狀態的 lua 屬性中。
創建排序輔助函數 __redis__compare_helper
在 redis 中產生不同輸出的命令稱爲“帶有不確定性的命令”,比如:
- SINTER
- SUNION
- SDIFF
- SMEMBERS
- HKEYS
- HVALS
- KEYS
比如對 SMEMBERS
來說,在兩個值相同,但是順序不同的集合中,使用 SMEMBERS 得到的結果是不同的,輸出的值的順序不同。這樣的輸出就是不確定性,因爲它本身不會排序。而 lua 中創建的這個輔助排序函數,可以用來消除這種不確定性。當 lua 執行完一個帶有不確定性的命令時,程序會使用 __redis__compare_helper
作爲對比函數,自動調用 tables.sort 函數對命令進行一次排序,一次來保證相同的數據集總是產生相同的輸出。
那,到底是什麼一個代碼流程呢,因爲 redis.call 和 redis.pcall 在初始化的時候,已經使用 c 中的函數進行了註冊,所以當調用 redis.call 或者 redis.pcall 的時候實際喚醒調用的是 c 函數 luaRedisCallCommand 或者 luaRedisPCallCommand
int luaRedisCallCommand(lua_State *lua) {
return luaRedisGenericCommand(lua,1);
}
int luaRedisPCallCommand(lua_State *lua) {
return luaRedisGenericCommand(lua,0);
}
這兩個函數,都是調用的 luaRedisGenericCommand
函數,此時,在 luaGenericCommand
函數中,在滿足條件的情況下,調用 luaSortArray
函數。
if ((cmd->flags & REDIS_CMD_SORT_FOR_SCRIPT) &&
(reply[0] == '*' && reply[1] != '-')) {
luaSortArray(lua);
}
滿足上面條件的時候,才調用 luaSortArray
這個函數,函數定義如下所示
/* Sort the array currently in the stack. We do this to make the output
* of commands like KEYS or SMEMBERS something deterministic when called
* from Lua (to play well with AOf/replication).
*
* The array is sorted using table.sort itself, and assuming all the
* list elements are strings. */
void luaSortArray(lua_State *lua) {
/* Initial Stack: array */
lua_getglobal(lua,"table");
lua_pushstring(lua,"sort");
lua_gettable(lua,-2); /* Stack: array, table, table.sort */
lua_pushvalue(lua,-3); /* Stack: array, table, table.sort, array */
if (lua_pcall(lua,1,0,0)) {
/* Stack: array, table, error */
/* We are not interested in the error, we assume that the problem is
* that there are 'false' elements inside the array, so we try
* again with a slower function but able to handle this case, that
* is: table.sort(table, __redis__compare_helper) */
lua_pop(lua,1); /* Stack: array, table */
lua_pushstring(lua,"sort"); /* Stack: array, table, sort */
lua_gettable(lua,-2); /* Stack: array, table, table.sort */
lua_pushvalue(lua,-3); /* Stack: array, table, table.sort, array */
lua_getglobal(lua,"__redis__compare_helper"); //table.sort(list [,compare])
/* Stack: array, table, table.sort, array, __redis__compare_helper */
lua_call(lua,2,0);
}
/* Stack: array (sorted), table */
lua_pop(lua,1); /* Stack: array (sorted) */
}
將 table.sort 中的 comp 參數作爲 __redis_compare_helper
輔助排序函數進行排序
lua 環境協作組件
lua 服務器創建了兩個用於與 lua 環境進行寫作的組件,分別是負責執行 lua 腳本的 redis 命令的僞客戶端和保存 lua 腳本的 lua_scripts
字典。
typedef struct Server {
...
/* Scripting */
lua_State *lua; /* The Lua interpreter. We use just one for all clients */
redisClient *lua_client; /* The "fake client" to query Redis from Lua */
redisClient *lua_caller; /* The client running EVAL right now, or NULL */
dict *lua_scripts; /* A dictionary of SHA1 -> Lua scripts */
mstime_t lua_time_limit; /* Script timeout in milliseconds */
mstime_t lua_time_start; /* Start time of script, milliseconds time */
int lua_write_dirty; /* True if a write command was called during the
execution of the current script. */
int lua_random_dirty; /* True if a random command was called during the
execution of the current script. */
int lua_timedout; /* True if we reached the time limit for script
execution. */
int lua_kill; /* Kill the script if true. */
...
};
僞客戶端
redis 命令執行必須有相應的客戶端狀態,redis服務器專門爲 lua 環境創建了一個僞客戶端,server 中的 lua_client 成員就是 lua 的僞客戶端,當初始化 lua 環境時,對僞客戶端初始化如下(scriptingInit()):
/* Create the (non connected) client that we use to execute Redis commands
* inside the Lua interpreter.
* Note: there is no need to create it again when this function is called
* by scriptingReset(). */
if (server.lua_client == NULL) {
server.lua_client = createClient(-1);
server.lua_client->flags |= REDIS_LUA_CLIENT;
}
Lua 腳本使用 redis.call 或者 redis.pcall 執行 redis 命令的時候,步驟如下:
- Lua 環境將 redis.call 或者 redis.pcall 想要執行的命令傳給僞客戶端
- 僞客戶端將腳本想要執行的命令傳給命令執行器 (call)
- 命令執行器執行命令後,將結果返回給僞客戶端
- 僞客戶端接收到結果並將結果返回給 lua 環境
- lua 環境接收到結果之後,有將結果返回給 redis.call 或者 redis.pcall 函數
- 接收到結果的 redis.call 或者 redis.pcall 函數,將命令結果作爲函數返回值返回給腳本中的調用者。
以上步驟摘自 《Redis 設計與實現》 黃健宏著,機械工業出版社,20.1.1節 僞客戶端
使用客戶端執行lua腳本
./redis-cli -h ${IP} -p ${PORT} -a ${PASSWORD} --eval <lua script>
lua_scripts 字典
另一個lua環境協作組件是 lua_scripts
字典。這個字典的值,是 lua 對應的腳本,鍵是 lua 腳本的 SHA1 校驗和。這個可以在 scripting.c/luaCreateFunction()
函數中查看
{
int retval = dictAdd(server.lua_scripts,
sdsnewlen(funcname+2,40),body); //dict, key is sha1, value is script
redisAssertWithInfo(c,NULL,retval == DICT_OK);
incrRefCount(body);
}
funcname 就是 lua 腳本的SHA1校驗和,body 就是 lua 對應的腳本
EVAL 命令的實現
第一步:
當客戶端向服務器發送 EVAL 命令執行一段 lua 腳本的時候,服務器首先在 lua 環境中,爲傳入的腳本定義一個 lua 函數,函數名由 f_ 前綴加上腳本的 SHA1 校驗和,而函數體即爲腳本本身。
void evalGenericCommand(redisClient *c, int evalsha) {
lua_State *lua = server.lua;
char funcname[43];
long long numkeys;
int delhook = 0, err;
/* We want the same PRNG sequence at every call so that our PRNG is
* not affected by external state. */
redisSrand48(0);
/* We set this flag to zero to remember that so far no random command
* was called. This way we can allow the user to call commands like
* SRANDMEMBER or RANDOMKEY from Lua scripts as far as no write command
* is called (otherwise the replication and AOF would end with non
* deterministic sequences).
*
* Thanks to this flag we'll raise an error every time a write command
* is called after a random command was used. */
server.lua_random_dirty = 0;
server.lua_write_dirty = 0;
/* Get the number of arguments that are keys */
if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
return;
if (numkeys > (c->argc - 3)) {
addReplyError(c,"Number of keys can't be greater than number of args");
return;
} else if (numkeys < 0) {
addReplyError(c,"Number of keys can't be negative");
return;
}
/* We obtain the script SHA1, then check if this function is already
* defined into the Lua state */
funcname[0] = 'f';
funcname[1] = '_';
if (!evalsha) {
/* Hash the code if this is an EVAL call */
sha1hex(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
} else {
/* We already have the SHA if it is a EVALSHA */
int j;
char *sha = c->argv[1]->ptr;
/* Convert to lowercase. We don't use tolower since the function
* managed to always show up in the profiler output consuming
* a non trivial amount of time. */
for (j = 0; j < 40; j++)
funcname[j+2] = (sha[j] >= 'A' && sha[j] <= 'Z') ?
sha[j]+('a'-'A') : sha[j];
funcname[42] = '\0';
}
/* Push the pcall error handler function on the stack. */
lua_getglobal(lua, "__redis__err__handler");
/* Try to lookup the Lua function */
lua_getglobal(lua, funcname);
if (lua_isnil(lua,-1)) {
lua_pop(lua,1); /* remove the nil from the stack */
/* Function not defined... let's define it if we have the
* body of the function. If this is an EVALSHA call we can just
* return an error. */
if (evalsha) {
lua_pop(lua,1); /* remove the error handler from the stack. */
addReply(c, shared.noscripterr);
return;
}
if (luaCreateFunction(c,lua,funcname,c->argv[1]) == REDIS_ERR) {
lua_pop(lua,1); /* remove the error handler from the stack. */
/* The error is sent to the client by luaCreateFunction()
* itself when it returns REDIS_ERR. */
return;
}
/* Now the following is guaranteed to return non nil */
lua_getglobal(lua, funcname);
redisAssert(!lua_isnil(lua,-1));
}
...
}
首先解析參數,可以查看 EVAL 命令的語法
EVAL script numkeys key [key ...] arg [arg ...]
在 lua 環境創建對應的 lua 函數,保存在變量 funcname 中,
funcname[0] = 'f';
funcname[1] = '_';
表示函數名以 f_ 作爲前綴,使用 shahex1() 函數獲取腳本的 SHA1 校驗和,保存在 funcname 中,此時的 funcname 將作爲 lua 環境中腳本對應的函數名。使用 luaCreateFunction
函數在 lua 環境中創建該腳本的 lua 函數,同時將腳本即 lua 環境中對應的函數名加入到 lua_scripts
字典中。
/* Define a lua function with the specified function name and body.
* The function name musts be a 2 characters long string, since all the
* functions we defined in the Lua context are in the form:
*
* f_<hex sha1 sum>
*
* On success REDIS_OK is returned, and nothing is left on the Lua stack.
* On error REDIS_ERR is returned and an appropriate error is set in the
* client context. */
int luaCreateFunction(redisClient *c, lua_State *lua, char *funcname, robj *body) {
sds funcdef = sdsempty();
funcdef = sdscat(funcdef,"function "); //create lua function
funcdef = sdscatlen(funcdef,funcname,42);
funcdef = sdscatlen(funcdef,"() ",3);
funcdef = sdscatlen(funcdef,body->ptr,sdslen(body->ptr));
funcdef = sdscatlen(funcdef,"\nend",4);
if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"@user_script")) {
addReplyErrorFormat(c,"Error compiling script (new function): %s\n",
lua_tostring(lua,-1));
lua_pop(lua,1);
sdsfree(funcdef);
return REDIS_ERR;
}
sdsfree(funcdef);
if (lua_pcall(lua,0,0,0)) { //execute lua function
addReplyErrorFormat(c,"Error running script (new function): %s\n",
lua_tostring(lua,-1));
lua_pop(lua,1);
return REDIS_ERR;
}
/* We also save a SHA1 -> Original script map in a dictionary
* so that we can replicate / write in the AOF all the
* EVALSHA commands as EVAL using the original script. */
{
int retval = dictAdd(server.lua_scripts,
sdsnewlen(funcname+2,40),body); //dict, key is sha1, value is script
redisAssertWithInfo(c,NULL,retval == DICT_OK);
incrRefCount(body);
}
return REDIS_OK;
}
第二步:
執行腳本之前,服務器還需要做一些設置鉤子和傳入參數的準備工作
a、 將EVAL命令中傳入的參數和腳本參數分爲保存在 KEYS 和 ARGV 數組中,並作爲全局變量保存在 lua 環境中
/* Populate the argv and keys table accordingly to the arguments that
* EVAL received. */
luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys); // KEYS[1]=XX, KEYS[2]=XX
luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
b、 爲 lua 環境裝載超時吃力鉤子,當腳本運行時間超時時,客戶端通過 SCRIPT KILL 命令可以停止腳本,也可以通過 SHUTDOWN 命令停止服務器。
c、 執行腳本
d、 移除鉤子
e、 將執行腳本函數得到的結果保存到客戶端狀態的輸出緩衝去,等待服務器將結果返回給客戶端
if (err) {
addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
funcname, lua_tostring(lua,-1));
lua_pop(lua,2); /* Consume the Lua reply and remove error handler. */
} else {
/* On success convert the Lua return value into Redis protocol, and
* send it to * the client. */
luaReplyToRedisReply(c,lua); /* Convert and consume the reply. */
lua_pop(lua,1); /* Remove the error handler. */
}
EVALSHA 命令
每一個被 EVAL 命令執行過的腳本,在 lua 環境中都會有一個與腳本對應的 lua 函數,函數的名字由 f_ 前綴和腳本的 SHA1 校驗和組成。主要這個函數在 lua 環境中定義了,就會在 lua_scripts
中保存,那麼使用 EVALSHA 命令,即使不知道腳本本身,也可以直接使用腳本的校驗和來調用腳本對應的 lua 環境中的函數,這就是 EVALSHA 實現的原理
其他的腳本命令
這裏主要講下命令的作用
SCRIPT FLUSH,用於清楚服務器中和 Lua 腳本有關的信息,這個命令會釋放並重建 lua_scripts
字典,關閉現有的 lua 環境並重新創建一個新的 lua 環境
SCRIPT EXISTS,根據輸入的 SHA1 校驗和,檢查校驗和對應的腳本是否存在於服務器中。(注意:該命令允許一次傳入多個 SHA1 校驗和)
SCRIPT LOAD,首先在 lua 環境中爲腳本創建對應的 lua 函數,然後將腳本和 SHA1 校驗和保存在 lua_scripts
字典中
SCRIPT KILL,當服務器設置了參數 lua-time-limit
時,每次在執行 lua 腳本之前,都會設置一個超時鉤子,腳本運行時,一旦鉤子發現腳本運行時間已經超時,鉤子將定期檢查是否有 SCRIPT KILL 或者 SHUTDOWN 命令到達。如果超時腳本未執行任何寫操作,客戶端可以通過 SCRIPT KILL 命令停止腳本,並向執行腳本的客戶端返回一個錯誤信息。處理完之後,服務器將繼續執行。如果腳本已經執行過寫操作,那麼客戶端只能通過 SHUTDOWN 命令停止服務器,防止不合法的數據寫入服務器中。
/* ---------------------------------------------------------------------------
* SCRIPT command for script environment introspection and control
* ------------------------------------------------------------------------- */
void scriptCommand(redisClient *c) {
if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"flush")) {
scriptingReset();
addReply(c,shared.ok);
replicationScriptCacheFlush();
server.dirty++; /* Propagating this command is a good idea. */
} else if (c->argc >= 2 && !strcasecmp(c->argv[1]->ptr,"exists")) {
int j;
addReplyMultiBulkLen(c, c->argc-2);
for (j = 2; j < c->argc; j++) {
if (dictFind(server.lua_scripts,c->argv[j]->ptr))
addReply(c,shared.cone);
else
addReply(c,shared.czero);
}
} else if (c->argc == 3 && !strcasecmp(c->argv[1]->ptr,"load")) {
char funcname[43];
sds sha;
funcname[0] = 'f';
funcname[1] = '_';
sha1hex(funcname+2,c->argv[2]->ptr,sdslen(c->argv[2]->ptr));
sha = sdsnewlen(funcname+2,40);
if (dictFind(server.lua_scripts,sha) == NULL) {
if (luaCreateFunction(c,server.lua,funcname,c->argv[2])
== REDIS_ERR) {
sdsfree(sha);
return;
}
}
addReplyBulkCBuffer(c,funcname+2,40);
sdsfree(sha);
forceCommandPropagation(c,REDIS_PROPAGATE_REPL|REDIS_PROPAGATE_AOF);
} else if (c->argc == 2 && !strcasecmp(c->argv[1]->ptr,"kill")) {
if (server.lua_caller == NULL) {
addReplySds(c,sdsnew("-NOTBUSY No scripts in execution right now.\r\n"));
} else if (server.lua_write_dirty) {
addReplySds(c,sdsnew("-UNKILLABLE Sorry the script already executed write commands against the dataset. You can either wait the script termination or kill the server in a hard way using the SHUTDOWN NOSAVE command.\r\n"));
} else {
server.lua_kill = 1;
addReply(c,shared.ok);
}
} else {
addReplyError(c, "Unknown SCRIPT subcommand or wrong # of args.");
}
}
參考文獻:
1. Redis 設計與實現,黃健宏著,機械工業出版社
2. redis 3.0.7 版本的源代碼
3. lua manual 5.2