Random command like SPOP with count is replicated as
some SREM operations, and store them in also_propagate
array to propagate after the call, but this would break
atomicity.

To keep the command's atomicity, wrap also_propagate
array with MULTI/EXEC.

RM_Call() will now use EBADF and ENONET in addition to EINVAL in order
to provide more information about errors (i.e. when return value is
NULL).

trimming talk about RESP protocol from API docs (should be independent to that anyway)

This is a light-weight replace function, useful for use cases such as
realloc()ing an existing value, etc.  Using RM_ModuleTypeSetValue() in
such cases is wasteful and complex as it attempts to delete the old
value, call its destructor, etc.

- Adding RM_ScanKey
- Adding tests for RM_ScanKey
- Refactoring RM_Scan API

Changes in RM_Scan
- cleanup in docs and coding convention
- Moving out of experimantal Api
- Adding ctx to scan callback
- Dont use cursor of -1 as an indication of done (can be a valid cursor)
- Set errno when returning 0 for various reasons
- Rename Cursor to ScanCursor
- Test filters key that are not strings, and opens a key if NULL

The implementation expose the following new functions:
1. RedisModule_CursorCreate - allow to create a new cursor object for
keys scanning
2. RedisModule_CursorRestart - restart an existing cursor to restart the
scan
3. RedisModule_CursorDestroy - destroy an existing cursor
4. RedisModule_Scan - scan keys

The RedisModule_Scan function gets a cursor object, a callback and void*
(used as user private data).
The callback will be called for each key in the database proving the key
name and the value as RedisModuleKey.

- the API name was odd, separated to two apis one for LRU and one for LFU
- the LRU idle time was in 1 second resolution, which might be ok for RDB
  and RESTORE, but i think modules may need higher resolution
- adding tests for LFU and for handling maxmemory policy mismatch

Fixes GitHub issue #6492
Added stream support in RM_KeyType and RM_ValueLength.
Also moduleDelKeyIfEmpty was updated, even though it has
no effect now (It will be relevant when stream type direct
API will be coded - i.e. RM_StreamAdd)

The exposed functions:
1. RedisModule_GetUsedMemoryPercentage - return the used memory
2. RedisModue_MallocSize - return for a given pointer, the amount of memory allocated for this pointer

Add two new functions that leverage the RedisModuleDataType mechanism
for RDB serialization/deserialization and make it possible to use it
to/from arbitrary strings:

* RM_SaveDataTypeToString()
* RM_LoadDataTypeFromString()

New API:

- RedisModule_StringToLongDouble
- RedisModule_CreateStringFromLongDouble
- RedisModule_ReplyWithLongDouble

rename RM_ServerInfoGetFieldNumerical RM_ServerInfoGetFieldSigned
move string2ull to util.c
fix leak in RM_GetServerInfo when duplicate info fields exist

looks like each platform implements long double differently (different bit count)
so we can't save them as binary, and we also want to avoid creating a new RDB
format version, so we save these are hex strings using "%La".

This commit includes a change in the arguments of ld2string to support this.
as well as tests for coverage and short reads.

coded by @guybe7

- Add RM_GetServerInfo and friends
- Add auto memory for new opaque struct
- Add tests for new APIs

other minor fixes:
- add const in various char pointers
- requested_section in modulesCollectInfo was actually not sds but char*
- extract new string2d out of getDoubleFromObject for code reuse

Add module API for

See #6525, this likely creates a NULL deference if the client was
terminated by Redis between the creation of the blocked client and the
creation of the thread safe context.

Using the is_key_ready() callback plus the reply callback later, creates
different issues AFAIK:

1. More complex API.
2. We need to call the reply callback() ASAP if the is_key_ready()
interface returned success, however the internals do not work in that
way, so when the reply callback is called the setup could be different.
To fix that, there is to break the current design that handles the
unblocked clients asyncrhonously, and run the list ASAP.

Now we handle propagation when we free the context.

* replication hooks: role change, master link status, replica online/offline
* persistence hooks: saving, loading, loading progress
* misc hooks: cron loop, shutdown, module loaded/unloaded
* change the way hooks test work, and add tests for all of the above

startLoading() now gets flag indicating what is loaded.
stopLoading() now gets an indication of success or failure.
adding startSaving() and stopSaving() with similar args and role.

Some commands would want to open a key without touching it's LRU/LFU
similarly to the OBJECT or DEBUG command do.

Other commands may want to implement logic similar to what RESTORE
does (and in the future MIGRATE) and get/set the LRU or LFU.

Adding a test for coverage for RM_Call in a new "misc" unit
to be used for various short simple tests

also solves compilation warnings in redismodule.h and fork.c

Also, add an API for getting server.notify_keyspace_events

Other (unrelated) changes:
Add RM_GetKeynameFromModuleKey

This commit also fixes an uninitialized module struct member (that luckily never got released)

Introduce ReplyWithVerbatimString, ReplyWithEmptyArray, ReplyWithNullArray and ReplyWithEmptyString to redis module API

As we know if a module exports module-side data types,
unload it is not allowed. This rule is the same with
blocked clients in module, because we use background
threads to implement module blocked clients, and it's
not safe to unload a module if there are background
threads running. So it's necessary to check if any
blocked clients running in this module when unload it.

Moreover, after that we can ensure that if no modules,
then no module blocked clients even module unloaded.
So, we can call moduleHandleBlockedClients only when
we have installed modules.