void scriptCommand(rliteClient *c) {
if (c->argc == 2 && !strcasecmp(c->argv[1],"flush")) {
scriptingReset();
c->reply = createStatusObject(RLITE_STR_OK);
} else if (c->argc >= 2 && !strcasecmp(c->argv[1],"exists")) {
int j;
c->reply = createArrayObject(c->argc - 2);
for (j = 2; j < c->argc; j++) {
c->reply->element[j - 2] = createLongLongObject(getScript(c, c->argv[j], NULL, NULL) == RL_OK ? 1 : 0);
}
} else if (c->argc == 3 && !strcasecmp(c->argv[1],"load")) {
char sha[41];
sha1hex(sha,c->argv[2],c->argvlen[2]);
setScript(c, c->argv[2], c->argvlen[2]);
c->reply = createStringObject(sha,40);
} else if (c->argc == 2 && !strcasecmp(c->argv[1],"kill")) {
if (lua_caller == NULL) {
c->reply = createCStringObject("NOTBUSY No scripts in execution right now.\r\n");
} else if (lua_write_dirty) {
c->reply = createCStringObject("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 {
lua_kill = 1;
c->reply = createStatusObject(RLITE_STR_OK);
}
} else {
c->reply = createErrorObject("ERR Unknown SCRIPT subcommand or wrong # of args.");
}
}
static int setScript(rliteClient *c, char *script, long scriptlen) {
int retval;
char hash[40];
sha1hex(hash, script, scriptlen);
RL_CALL(rl_select_internal, RL_OK, c->context->db, RLITE_INTERNAL_DB_LUA);
RL_CALL(rl_set, RL_OK, c->context->db, (unsigned char *)hash, 40, (unsigned char *)script, scriptlen, 0, 0);
cleanup:
rl_select_internal(c->context->db, RLITE_INTERNAL_DB_NO);
return retval;
}
/* This adds redis.sha1hex(string) to Lua scripts using the same hashing
* function used for sha1ing lua scripts. */
int luaRedisSha1hexCommand(lua_State *lua) {
int argc = lua_gettop(lua);
char digest[41];
size_t len;
char *s;
if (argc != 1) {
luaPushError(lua, "wrong number of arguments");
return 1;
}
s = (char*)lua_tolstring(lua,1,&len);
sha1hex(digest,s,len);
lua_pushstring(lua,digest);
return 1;
}
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.");
}
}
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;
}
/* 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;
for (j = 0; j < 40; j++)
funcname[j+2] = tolower(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));
}
/* Populate the argv and keys table accordingly to the arguments that
* EVAL received. */
luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
/* Select the right DB in the context of the Lua client */
selectDb(server.lua_client,c->db->id);
/* Set a hook in order to be able to stop the script execution if it
* is running for too much time.
* We set the hook only if the time limit is enabled as the hook will
* make the Lua script execution slower. */
server.lua_caller = c;
server.lua_time_start = mstime();
server.lua_kill = 0;
if (server.lua_time_limit > 0 && server.masterhost == NULL) {
lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
delhook = 1;
}
/* At this point whether this script was never seen before or if it was
* already defined, we can call it. We have zero arguments and expect
* a single return value. */
err = lua_pcall(lua,0,1,-2);
/* Perform some cleanup that we need to do both on error and success. */
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
if (server.lua_timedout) {
server.lua_timedout = 0;
/* Restore the readable handler that was unregistered when the
* script timeout was detected. */
aeCreateFileEvent(server.el,c->fd,AE_READABLE,
readQueryFromClient,c);
}
server.lua_caller = NULL;
selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
lua_gc(lua,LUA_GCSTEP,1);
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 should be propagated to Slave and AOF file as full EVAL, unless
* we are sure that the script was already in the context of all the
* attached slaves *and* the current AOF file if enabled.
*
* To do so we use a cache of SHA1s of scripts that we already propagated
* as full EVAL, that's called the Replication Script Cache.
*
* For repliation, everytime a new slave attaches to the master, we need to
* flush our cache of scripts that can be replicated as EVALSHA, while
* for AOF we need to do so every time we rewrite the AOF file. */
if (evalsha) {
if (!replicationScriptCacheExists(c->argv[1]->ptr)) {
/* This script is not in our script cache, replicate it as
* EVAL, then add it into the script cache, as from now on
* slaves and AOF know about it. */
robj *script = dictFetchValue(server.lua_scripts,c->argv[1]->ptr);
replicationScriptCacheAdd(c->argv[1]->ptr);
redisAssertWithInfo(c,NULL,script != NULL);
rewriteClientCommandArgument(c,0,
resetRefCount(createStringObject("EVAL",4)));
rewriteClientCommandArgument(c,1,script);
forceCommandPropagation(c,REDIS_PROPAGATE_REPL|REDIS_PROPAGATE_AOF);
}
}
}
void evalGenericCommand(redisClient *c, int evalsha) {
lua_State *lua = server.lua;
char funcname[43];
long long numkeys;
int delhook = 0, err;
// 随机数的种子，在产生哈希值的时候会用到
/* 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;
// 检查参数的有效性
/* 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;
}
// 函数名以 f_ 开头
/* We obtain the script SHA1, then check if this function is already
* defined into the Lua state */
funcname[0] = 'f';
funcname[1] = '_';
// 如果没有哈希值，需要计算 lua 脚本的哈希值
if (!evalsha) {
// 计算哈希值，会放入到 SHA1 -> lua_script 哈希表中
// c->argv[1]->ptr 是用户指定的 lua 脚本
// sha1hex() 产生的哈希值存在 funcname 中
/* Hash the code if this is an EVAL call */
sha1hex(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
} else {
// 用户自己指定了哈希值
/* We already have the SHA if it is a EVALSHA */
int j;
char *sha = c->argv[1]->ptr;
for (j = 0; j < 40; j++)
funcname[j+2] = tolower(sha[j]);
funcname[42] = '\0';
}
// 将错误处理函数入栈
// lua_getglobal() 会将读取指定的全局变量，且将其入栈
/* Push the pcall error handler function on the stack. */
lua_getglobal(lua, "__redis__err__handler");
/* Try to lookup the Lua function */
// 在 lua 中查找是否注册了此函数。这一句尝试将 funcname 入栈
lua_getglobal(lua, funcname);
if (lua_isnil(lua,-1)) { // funcname 在 lua 中不存在
// 将 nil 出栈
lua_pop(lua,1); /* remove the nil from the stack */
// 已经确定 funcname 在 lua 中没有定义，需要创建
/* 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;
}
// 创建 lua 函数 funcname
// c->argv[1] 指向用户指定的 lua 脚本
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;
}
// 现在 lua 中已经有 funcname 这个全局变量了，将其读取并入栈，
// 准备调用
/* Now the following is guaranteed to return non nil */
lua_getglobal(lua, funcname);
redisAssert(!lua_isnil(lua,-1));
}
// 设置参数，包括键和值
/* Populate the argv and keys table accordingly to the arguments that
* EVAL received. */
luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
// 选择数据集，lua_client 有专用的数据集
/* Select the right DB in the context of the Lua client */
selectDb(server.lua_client,c->db->id);
// 设置超时回调函数，以在 lua 脚本执行过长时间的时候停止脚本的运行
/* Set a hook in order to be able to stop the script execution if it
* is running for too much time.
* We set the hook only if the time limit is enabled as the hook will
* make the Lua script execution slower. */
server.lua_caller = c;
server.lua_time_start = ustime()/1000;
server.lua_kill = 0;
if (server.lua_time_limit > 0 && server.masterhost == NULL) {
// 当 lua 解释器执行了 100000，luaMaskCountHook() 会被调用
lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
delhook = 1;
}
// 现在，我们确定函数已经注册成功了.可以直接调用 lua 脚本
/* At this point whether this script was never seen before or if it was
* already defined, we can call it. We have zero arguments and expect
* a single return value. */
err = lua_pcall(lua,0,1,-2);
// 删除超时回调函数
/* Perform some cleanup that we need to do both on error and success. */
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
// 如果已经超时了，说明 lua 脚本已在超时后背 SCRPIT KILL 终结了
// 恢复监听发送 lua 脚本命令的客户端
if (server.lua_timedout) {
server.lua_timedout = 0;
/* Restore the readable handler that was unregistered when the
* script timeout was detected. */
aeCreateFileEvent(server.el,c->fd,AE_READABLE,
readQueryFromClient,c);
}
// lua_caller 置空
server.lua_caller = NULL;
// 执行 lua 脚本用的是 lua 脚本执行专用的数据集。现在恢复原有的数据集
selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
// Garbage collection 垃圾回收
lua_gc(lua,LUA_GCSTEP,1);
// 处理执行 lua 脚本的错误
if (err) {
// 告知客户端
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. */
// 成功了
} 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. */
}
// 将 lua 脚本发布到主从复制上，并写入 AOF 文件
/* EVALSHA should be propagated to Slave and AOF file as full EVAL, unless
* we are sure that the script was already in the context of all the
* attached slaves *and* the current AOF file if enabled.
*
* To do so we use a cache of SHA1s of scripts that we already propagated
* as full EVAL, that's called the Replication Script Cache.
*
* For repliation, everytime a new slave attaches to the master, we need to
* flush our cache of scripts that can be replicated as EVALSHA, while
* for AOF we need to do so every time we rewrite the AOF file. */
if (evalsha) {
if (!replicationScriptCacheExists(c->argv[1]->ptr)) {
/* This script is not in our script cache, replicate it as
* EVAL, then add it into the script cache, as from now on
* slaves and AOF know about it. */
// 从 server.lua_scripts 获取 lua 脚本
// c->argv[1]->ptr 是 SHA1
robj *script = dictFetchValue(server.lua_scripts,c->argv[1]->ptr);
// 添加到主从复制专用的脚本缓存中
replicationScriptCacheAdd(c->argv[1]->ptr);
redisAssertWithInfo(c,NULL,script != NULL);
// 重写命令
// 参数 1 为：EVAL
// 参数 2 为：lua_script
// 如此一来在执行 AOF 持久化和主从复制的时候，lua 脚本就能得到传播
rewriteClientCommandArgument(c,0,
resetRefCount(createStringObject("EVAL",4)));
rewriteClientCommandArgument(c,1,script);
}
}
}
void evalGenericCommand(rliteClient *c, int evalsha) {
scriptingInit();
lua_client->context = c->context;
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. */
rliteSrand48(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. */
lua_random_dirty = 0;
lua_write_dirty = 0;
/* Get the number of arguments that are keys */
if (getLongLongFromObjectOrReply(c,c->argv[2],c->argvlen[2],&numkeys,NULL) != RLITE_OK)
return;
if (numkeys > (c->argc - 3)) {
c->reply = createErrorObject("Number of keys can't be greater than number of args");
return;
} else if (numkeys < 0) {
c->reply = createErrorObject("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],c->argvlen[1]);
} else {
/* We already have the SHA if it is a EVALSHA */
int j;
char *sha = c->argv[1];
/* 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';
char *body;
long bodylen;
int retval = getScript(c, funcname + 2, &body, &bodylen);
if (retval != RL_OK) {
c->reply = createErrorObject(RLITE_NOSCRIPTERR);
return;
}
luaCreateFunction(c, lua, funcname, body, bodylen);
rl_free(body);
}
/* Push the pcall error handler function on the stack. */
lua_getglobal(lua, "__rlite__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. */
c->reply = createErrorObject(RLITE_NOSCRIPTERR);
return;
}
if (luaCreateFunction(c,lua,funcname,c->argv[1], c->argvlen[1]) == RLITE_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 RLITE_ERR. */
return;
}
/* Now the following is guaranteed to return non nil */
lua_getglobal(lua, funcname);
if (lua_isnil(lua,-1)) {
// TODO: panic
return;
}
}
/* Populate the argv and keys table accordingly to the arguments that
* EVAL received. */
luaSetGlobalArray(lua,"KEYS",c->argv+3,c->argvlen+3,numkeys);
luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argvlen+3+numkeys,c->argc-3-numkeys);
/* Set a hook in order to be able to stop the script execution if it
* is running for too much time.
* We set the hook only if the time limit is enabled as the hook will
* make the Lua script execution slower. */
lua_caller = c;
lua_time_start = rl_mstime();
lua_kill = 0;
if (lua_time_limit > 0) {
lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
delhook = 1;
}
/* At this point whether this script was never seen before or if it was
* already defined, we can call it. We have zero arguments and expect
* a single return value. */
err = lua_pcall(lua,0,1,-2);
/* Perform some cleanup that we need to do both on error and success. */
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
if (lua_timedout) {
lua_timedout = 0;
/* Restore the readable handler that was unregistered when the
* script timeout was detected. */
}
lua_caller = NULL;
/* Call the Lua garbage collector from time to time to avoid a
* full cycle performed by Lua, which adds too latency.
*
* The call is performed every LUA_GC_CYCLE_PERIOD executed commands
* (and for LUA_GC_CYCLE_PERIOD collection steps) because calling it
* for every command uses too much CPU. */
#define LUA_GC_CYCLE_PERIOD 50
{
static long gc_count = 0;
gc_count++;
if (gc_count == LUA_GC_CYCLE_PERIOD) {
lua_gc(lua,LUA_GCSTEP,LUA_GC_CYCLE_PERIOD);
gc_count = 0;
}
}
if (err) {
char err[1024];
snprintf(err, 1024, "Error running script (call to %s): %s\n",
funcname, lua_tostring(lua,-1));
c->reply = createErrorObject(err);
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. */
}
}
void evalGenericCommand(redisClient *c, int evalsha)
{
lua_State *lua = server.lua;
char funcname[43];
long long numkeys;
int delhook = 0;
/* We want the same PRNG sequence at every call so that our PRNG is
* not affected by external state.
*
* 在每次执行 EVAL 时重置随机 seed ，从而保证可以生成相同的随机序列。
*/
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.
*
* 用两个变量，对命令进行检查
* 确保在调用随机命令之后，再调用写命令将出现错误
*/
server.lua_random_dirty = 0;
server.lua_write_dirty = 0;
/* Get the number of arguments that are keys */
// 获取输入键的数量
if (getLongLongFromObjectOrReply(c,c->argv[2],&numkeys,NULL) != REDIS_OK)
return;
// 对键的正确性做一个快速检查
if (numkeys > (c->argc - 3))
{
addReplyError(c,"Number of keys can't be greater than number of args");
return;
}
/* We obtain the script SHA1, then check if this function is already
* defined into the Lua state */
// 组合出函数的名字，例如 f_282297a0228f48cd3fc6a55de6316f31422f5d17
funcname[0] = 'f';
funcname[1] = '_';
if (!evalsha)
{
/* Hash the code if this is an EVAL call */
// 如果执行的是 EVAL 命令，那么计算脚本的 SHA1 校验和
sha1hex(funcname+2,c->argv[1]->ptr,sdslen(c->argv[1]->ptr));
}
else
{
// 如果执行的是 EVALSHA 命令，直接使用传入的 SHA1 值
/* We already have the SHA if it is a EVALSHA */
int j;
char *sha = c->argv[1]->ptr;
for (j = 0; j < 40; j++)
funcname[j+2] = tolower(sha[j]);
funcname[42] = '\0';
}
/* Try to lookup the Lua function */
// 按名查找函数
lua_getglobal(lua, funcname);
if (lua_isnil(lua,1))
{
// 没找到脚本相应的脚本
lua_pop(lua,1); /* remove the nil from the stack */
/* Function not defined... let's define it if we have the
* body of the funciton. If this is an EVALSHA call we can just
* return an error. */
if (evalsha)
{
// 如果执行的是 EVALSHA ，返回脚本未找到错误
addReply(c, shared.noscripterr);
return;
}
// 如果执行的是 EVAL ，那么创建并执行新函数，然后将代码添加到脚本字典中
if (luaCreateFunction(c,lua,funcname,c->argv[1]) == REDIS_ERR) return;
/* Now the following is guaranteed to return non nil */
lua_getglobal(lua, funcname);
redisAssert(!lua_isnil(lua,1));
}
/* Populate the argv and keys table accordingly to the arguments that
* EVAL received. */
// 设置 KEYS 和 ARGV 全局变量到 Lua 环境
luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
/* Select the right DB in the context of the Lua client */
// 为 Lua 所属的（伪）客户端设置数据库
selectDb(server.lua_client,c->db->id);
/* Set an hook in order to be able to stop the script execution if it
* is running for too much time.
*
* 设置一个钩子，用于在运行时间过长时停止脚本的运作。
*
* We set the hook only if the time limit is enabled as the hook will
* make the Lua script execution slower.
*
* 只在开启了时间限制选项时使用钩子，因为它会拖慢脚本的运行速度。
*/
// 调用客户端
server.lua_caller = c;
// 脚本开始时间
server.lua_time_start = ustime()/1000;
// 是否杀死脚本
server.lua_kill = 0;
// 只在开启时间限制时使用钩子
if (server.lua_time_limit > 0 && server.masterhost == NULL)
{
lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
delhook = 1;
}
/* At this point whatever this script was never seen before or if it was
* already defined, we can call it. We have zero arguments and expect
* a single return value. */
// 执行脚本（所属的函数）
if (lua_pcall(lua,0,1,0))
{
// 以下是脚本执行出错的代码。。。
// 删除钩子
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
// 脚本执行已超时
if (server.lua_timedout)
{
// 清除超时 FLAG
server.lua_timedout = 0;
/* Restore the readable handler that was unregistered when the
* script timeout was detected. */
// 将超时钩子里删除的读事件重新加上
aeCreateFileEvent(server.el,c->fd,AE_READABLE,
readQueryFromClient,c);
}
// 清空调用者
server.lua_caller = NULL;
// 更新目标数据库
selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
funcname, lua_tostring(lua,-1));
// 弹出函数
lua_pop(lua,1);
// 执行完整的废料回首循环（full garbage-collection cycle）
lua_gc(lua,LUA_GCCOLLECT,0);
// 返回
return;
}
// 以下是脚本执行成功时执行的代码。。。
// 删除钩子
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
// 清空超时 FLAG
server.lua_timedout = 0;
// 清空调用者
server.lua_caller = NULL;
// 更新 DB
selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
// 将 Lua 回复转换成 Redis 回复
luaReplyToRedisReply(c,lua);
// 执行 1 步渐进式 GC
lua_gc(lua,LUA_GCSTEP,1);
/* If we have slaves attached we want to replicate this command as
* EVAL instead of EVALSHA. We do this also in the AOF as currently there
* is no easy way to propagate a command in a different way in the AOF
* and in the replication link.
*
* 如果有附属节点，那么使用 EVAL 而不是 EVALSHA 来传播脚本
* 因为目前还没有代码可以检测脚本是否已经传送到附属节点中
*
* IMPROVEMENT POSSIBLE:
* 1) Replicate this command as EVALSHA in the AOF.
* 2) Remember what slave already received a given script, and replicate
* the EVALSHA against this slaves when possible.
*/
// 如果执行的是 EVALSHA 命令
if (evalsha)
{
// 取出脚本代码体（body）
robj *script = dictFetchValue(server.lua_scripts,c->argv[1]->ptr);
redisAssertWithInfo(c,NULL,script != NULL);
// 重写客户端命令为 EVAL
rewriteClientCommandArgument(c,0,
resetRefCount(createStringObject("EVAL",4)));
rewriteClientCommandArgument(c,1,script);
}
}
void evalGenericCommand(redisClient *c, int evalsha) {
lua_State *lua = server.lua;
char funcname[43];
long long numkeys;
int delhook = 0;
/* 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;
}
/* 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;
for (j = 0; j < 40; j++)
funcname[j+2] = tolower(sha[j]);
funcname[42] = '\0';
}
/* 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 funciton. If this is an EVALSHA call we can just
* return an error. */
if (evalsha) {
addReply(c, shared.noscripterr);
return;
}
if (luaCreateFunction(c,lua,funcname,c->argv[1]) == REDIS_ERR) return;
/* Now the following is guaranteed to return non nil */
lua_getglobal(lua, funcname);
redisAssert(!lua_isnil(lua,1));
}
/* Populate the argv and keys table accordingly to the arguments that
* EVAL received. */
luaSetGlobalArray(lua,"KEYS",c->argv+3,numkeys);
luaSetGlobalArray(lua,"ARGV",c->argv+3+numkeys,c->argc-3-numkeys);
/* Select the right DB in the context of the Lua client */
selectDb(server.lua_client,c->db->id);
/* Set an hook in order to be able to stop the script execution if it
* is running for too much time.
* We set the hook only if the time limit is enabled as the hook will
* make the Lua script execution slower. */
server.lua_caller = c;
server.lua_time_start = ustime()/1000;
server.lua_kill = 0;
if (server.lua_time_limit > 0 && server.masterhost == NULL) {
lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
delhook = 1;
}
/* At this point whatever this script was never seen before or if it was
* already defined, we can call it. We have zero arguments and expect
* a single return value. */
if (lua_pcall(lua,0,1,0)) {
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
if (server.lua_timedout) {
server.lua_timedout = 0;
/* Restore the readable handler that was unregistered when the
* script timeout was detected. */
aeCreateFileEvent(server.el,c->fd,AE_READABLE,
readQueryFromClient,c);
}
server.lua_caller = NULL;
selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
addReplyErrorFormat(c,"Error running script (call to %s): %s\n",
funcname, lua_tostring(lua,-1));
lua_pop(lua,1);
lua_gc(lua,LUA_GCCOLLECT,0);
return;
}
if (delhook) lua_sethook(lua,luaMaskCountHook,0,0); /* Disable hook */
server.lua_timedout = 0;
server.lua_caller = NULL;
selectDb(c,server.lua_client->db->id); /* set DB ID from Lua client */
luaReplyToRedisReply(c,lua);
lua_gc(lua,LUA_GCSTEP,1);
/* If we have slaves attached we want to replicate this command as
* EVAL instead of EVALSHA. We do this also in the AOF as currently there
* is no easy way to propagate a command in a different way in the AOF
* and in the replication link.
*
* IMPROVEMENT POSSIBLE:
* 1) Replicate this command as EVALSHA in the AOF.
* 2) Remember what slave already received a given script, and replicate
* the EVALSHA against this slaves when possible.
*/
if (evalsha) {
robj *script = dictFetchValue(server.lua_scripts,c->argv[1]->ptr);
redisAssertWithInfo(c,NULL,script != NULL);
rewriteClientCommandArgument(c,0,
resetRefCount(createStringObject("EVAL",4)));
rewriteClientCommandArgument(c,1,script);
}
}