Strange replication behavior with Lua and RM_Replicate() #4466
Description
This in itself may be two issues:
RM_Replicate()opens aMULTIcall which is never actually closed- Commands executed within Lua scripts never actually get replicated unless another (builtin??) command is also invoked within it.
I've solved the first issue - I realized that RM_Replicate ended up calling propagate() which shouldn't be used in conjunction with alsoPropagate(). I'm still trying to figure out the second one.
Here's a Python script which demonstrates the issue:
#!/usr/bin/env python
from redis.client import StrictRedis
MASTER_PORT=7777
SLAVE_PORT=8888
rr_master = StrictRedis(port=MASTER_PORT)
rr_slave = StrictRedis(port=SLAVE_PORT)
rr_slave.execute_command('SLAVEOF', 'localhost', str(MASTER_PORT))
rr_master.execute_command('MY.CMDV')
rr_master.execute_command('MY.CMD')
rr_master.execute_command('EVAL', r'''
redis.call("MY.CMDV", "fooScript");
redis.call("MY.CMD", "barScript");
print("Hello!!!");
''', '0')This is assuming a very dumb module called 'MY':
#include "redismodule.h"
static int DummyCommand(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
RedisModule_Replicate(ctx, "MY.CMD", "v", argv, argc);
return RedisModule_ReplyWithSimpleString(ctx, "OK");
}
static int DummyCommandVerbatim(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
RedisModule_ReplicateVerbatim(ctx);
return RedisModule_ReplyWithSimpleString(ctx, "OK");
}
int RedisModule_OnLoad(RedisModuleCtx *ctx, RedisModuleString **argv, int argc) {
if (RedisModule_Init(ctx, "MY", 1, REDISMODULE_APIVER_1) != REDISMODULE_OK) {
return REDISMODULE_ERR;
}
if (RedisModule_CreateCommand(ctx, "MY.CMD", DummyCommand, "write deny-oom", 1, 1, 1) != REDISMODULE_OK) {
return REDISMODULE_ERR;
}
if (RedisModule_CreateCommand(ctx, "MY.CMDV", DummyCommandVerbatim, "write deny-oom", 1, 1, 1) != REDISMODULE_OK) {
return REDISMODULE_ERR;
}
return REDISMODULE_OK;
}MONITOR output on slave (after running the commands a few times)
1511374285.851288 [0 [::1]:7777] "PING"
1511374288.673754 [0 [::1]:7777] "SELECT" "0"
1511374288.673766 [0 [::1]:7777] "MY.CMDV"
1511374288.673877 [0 [::1]:7777] "MULTI"
1511374288.673888 [0 [::1]:7777] "MY.CMD" "MY.CMD"
1511374288.673896 [0 [::1]:7777] "EXEC"
1511374288.674053 [0 [::1]:7777] "MULTI"
1511374291.619535 [0 [::1]:7777] "MULTI"
1511374291.619545 [0 [::1]:7777] "MY.CMDV"
1511374291.619549 [0 [::1]:7777] "MY.CMD" "MY.CMD"
1511374291.619557 [0 [::1]:7777] "EXEC"
1511374291.619677 [0 [::1]:7777] "MULTI"
Making use of alsoPropagate rather than propagate:
1511374434.392146 [0 [::1]:7777] "MY.CMDV"
1511374434.392324 [0 [::1]:7777] "MULTI"
1511374434.392333 [0 [::1]:7777] "MY.CMD" "MY.CMD"
1511374434.392341 [0 [::1]:7777] "EXEC"
I'm wondering if perhaps Lua is also mixing the two APIs.