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    `lookupKeyReadWithFlags` call in `getNodeByQuery` will get a outdated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, 0 insertions, 9 deletions

diff --git a/src/blocked.c b/src/blocked.c
index 65b584213..c4aded0c5 100644
--- a/src/blocked.c
+++ b/src/blocked.c
@@ -642,14 +642,6 @@ void handleClientsBlockedOnKeys(void) {
              * we can safely call signalKeyAsReady() against this key. */
             dictDelete(rl->db->ready_keys,rl->key);
 
-            /* Even if we are not inside call(), increment the call depth
-             * in order to make sure that keys are expired against a fixed
-             * reference time, and not against the wallclock time. This
-             * way we can lookup an object multiple times (BLMOVE does
-             * that) without the risk of it being freed in the second
-             * lookup, invalidating the first one.
-             * See https://github.com/redis/redis/pull/6554. */
-            server.fixed_time_expire++;
             updateCachedTime(0);
 
             /* Serve clients blocked on the key. */
@@ -681,7 +673,6 @@ void handleClientsBlockedOnKeys(void) {
                 if (server.also_propagate.numops > 0)
                     propagatePendingCommands();
             }
-            server.fixed_time_expire--;
 
             /* Free this item. */
             decrRefCount(rl->key);