add fair semaphore

Author: sanderegg

packages/service-library/src/servicelib/redis/_semaphore_lua.py

@@ -26,10 +26,19 @@ def _load_script(script_name: str) -> str:
         return script_file.read_text(encoding="utf-8").strip()
 
 
+# TODO: old
 ACQUIRE_SEMAPHORE_SCRIPT: Final[str] = _load_script("acquire_semaphore")
 RELEASE_SEMAPHORE_SCRIPT: Final[str] = _load_script("release_semaphore")
 RENEW_SEMAPHORE_SCRIPT: Final[str] = _load_script("renew_semaphore")
 COUNT_SEMAPHORE_SCRIPT: Final[str] = _load_script("count_semaphore")
 
-SCRIPT_BAD_EXIT_CODE: Final[int] = 255
+# fair semaphore scripts (token pool based)
+ACQUIRE_FAIR_SEMAPHORE_V2_SCRIPT: Final[str] = _load_script("acquire_fair_semaphore_v2")
+RELEASE_FAIR_SEMAPHORE_V2_SCRIPT: Final[str] = _load_script("release_fair_semaphore_v2")
+CLEANUP_FAIR_SEMAPHORE_V2_SCRIPT: Final[str] = _load_script("cleanup_fair_semaphore_v2")
+RENEW_FAIR_SEMAPHORE_V2_SCRIPT: Final[str] = _load_script("renew_fair_semaphore_v2")
+COUNT_FAIR_SEMAPHORE_V2_SCRIPT: Final[str] = _load_script("count_fair_semaphore_v2")
+
+
 SCRIPT_OK_EXIT_CODE: Final[int] = 0
+SCRIPT_BAD_EXIT_CODE: Final[int] = 255