Freeze time sampling during command execution, and scripts (#10300)

Freeze time during execution of scripts and all other commands.
This means that a key is either expired or not, and doesn't change
state during a script execution. resolves #10182

This PR try to add a new `commandTimeSnapshot` function.
The function logic is extracted from `keyIsExpired`, but the related
calls to `fixed_time_expire` and `mstime()` are removed, see below.

In commands, we will avoid calling `mstime()` multiple times
and just use the one that sampled in call. The background is,
e.g. using `PEXPIRE 1` with valgrind sometimes result in the key
being deleted rather than expired. The reason is that both `PEXPIRE`
command and `checkAlreadyExpired` call `mstime()` separately.

There are other more important changes in this PR:
1. Eliminate `fixed_time_expire`, it is no longer needed. 
   When we want to sample time we should always use a time snapshot. 
   We will use `in_nested_call` instead to update the cached time in `call`.
2. Move the call for `updateCachedTime` from `serverCron` to `afterSleep`.
    Now `commandTimeSnapshot` will always return the sample time, the
    `lookupKeyReadWithFlags` call in `getNodeByQuery` will get a outdated
    cached time (because `processCommand` is out of the `call` context).
    We put the call to `updateCachedTime` in `aftersleep`.
3. Cache the time each time the module lock Redis.
    Call `updateCachedTime` in `moduleGILAfterLock`, affecting `RM_ThreadSafeContextLock`
    and `RM_ThreadSafeContextTryLock`

Currently the commandTimeSnapshot change affects the following TTL commands:
- SET EX / SET PX
- EXPIRE / PEXPIRE
- SETEX / PSETEX
- GETEX EX / GETEX PX
- TTL / PTTL
- EXPIRETIME / PEXPIRETIME
- RESTORE key TTL

And other commands just use the cached mstime (including TIME).

This is considered to be a breaking change since it can break a script
that uses a loop to wait for a key to expire.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/module.c b/src/module.c
index 19e60400f..6d9425baf 100644
--- a/src/module.c
+++ b/src/module.c
@@ -3838,7 +3838,7 @@ mstime_t RM_GetExpire(RedisModuleKey *key) {
     mstime_t expire = getExpire(key->db,key->key);
     if (expire == -1 || key->value == NULL)
         return REDISMODULE_NO_EXPIRE;
-    expire -= mstime();
+    expire -= commandTimeSnapshot();
     return expire >= 0 ? expire : 0;
 }
 
@@ -3855,7 +3855,7 @@ int RM_SetExpire(RedisModuleKey *key, mstime_t expire) {
     if (!(key->mode & REDISMODULE_WRITE) || key->value == NULL || (expire < 0 && expire != REDISMODULE_NO_EXPIRE))
         return REDISMODULE_ERR;
     if (expire != REDISMODULE_NO_EXPIRE) {
-        expire += mstime();
+        expire += commandTimeSnapshot();
         setExpire(key->ctx->client,key->db,key->key,expire);
     } else {
         removeExpire(key->db,key->key);
@@ -7752,6 +7752,7 @@ void moduleGILAfterLock() {
     /* Bump up the nesting level to prevent immediate propagation
      * of possible RM_Call from th thread */
     server.module_ctx_nesting++;
+    updateCachedTime(0);
 }
 
 /* Acquire the server lock before executing a thread safe API call.