Add CLIENT NO-TOUCH for clients to run commands without affecting LRU/LFU of keys (#11483)

When no-touch mode is enabled, the client will not touch LRU/LFU of the
keys it accesses, except when executing command `TOUCH`.
This allows inspecting or modifying the key-space without affecting their eviction.

Changes:
- A command `CLIENT NO-TOUCH ON|OFF` to switch on and off this mode.
- A client flag `#define CLIENT_NOTOUCH (1ULL<<45)`, which can be shown
  with `CLIENT INFO`, by the letter "T" in the "flags" field.
- Clear `NO-TOUCH` flag in `clearClientConnectionState`, which is used by `RESET`
  command and resetting temp clients used by modules.
- Also clear `NO-EVICT` flag in `clearClientConnectionState`, this might have been an
  oversight, spotted by @madolson.
- A test using `DEBUG OBJECT` command to verify that LRU stat is not touched when
  no-touch mode is on.
 

Co-authored-by: chentianjie <chentianjie@alibaba-inc.com>
Co-authored-by: Madelyn Olson <34459052+madolson@users.noreply.github.com>
Co-authored-by: sundb <sundbcn@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/server.h b/src/server.h
index 11629c718..7d8e65b36 100644
--- a/src/server.h
+++ b/src/server.h
@@ -390,6 +390,7 @@ extern int configOOMScoreAdjValuesDefaults[CONFIG_OOM_COUNT];
                                       memory eviction. */
 #define CLIENT_ALLOW_OOM (1ULL<<44) /* Client used by RM_Call is allowed to fully execute
                                        scripts even when in OOM */
+#define CLIENT_NO_TOUCH (1ULL<<45) /* This client will not touch LFU/LRU stats. */
 
 /* Client block type (btype field in client structure)
  * if CLIENT_BLOCKED flag is set. */