filter_lookup: stability/operational enhancements

- Removed unecessary FLB_FILTER_LOOKUP build flag now LookUp
is enabled by default like other filters (without flag).
- Fixed critical use-after-free bug in numeric value lookups.
- Added processed_records_total, matched_records_total and
skipped_records_total metrics to enable operational visibility
- Added unit tests to cover handling of different data types,
CSV loading/handling and metrics tests.

Tested with valgrind - no memory leaks. All unit tests pass.

Signed-off-by: Oleg Mukhin <[email protected]>

Author: olegmukhin

CMakeLists.txt

@@ -196,7 +196,6 @@ option(FLB_WASM_STACK_PROTECT  "Build with WASM runtime with strong stack protec
 option(FLB_ENFORCE_ALIGNMENT   "Enable limited platform specific aligned memory access" No)
 option(FLB_KAFKA               "Enable Kafka support"         Yes)
 option(FLB_ZIG                 "Enable zig integration"       Yes)
-option(FLB_FILTER_LOOKUP       "Enable filter lookup support" Yes)
 
 # Native Metrics Support (cmetrics)
 option(FLB_METRICS             "Enable metrics support"       Yes)

cmake/plugins_options.cmake

@@ -84,6 +84,7 @@ DEFINE_OPTION(FLB_FILTER_GEOIP2               "Enable geoip2 filter"
 DEFINE_OPTION(FLB_FILTER_GREP                 "Enable grep filter"                           ON)
 DEFINE_OPTION(FLB_FILTER_KUBERNETES           "Enable kubernetes filter"                     ON)
 DEFINE_OPTION(FLB_FILTER_LOG_TO_METRICS       "Enable log-derived metrics filter"            ON)
+DEFINE_OPTION(FLB_FILTER_LOOKUP              "Enable lookup filter"                         ON)
 DEFINE_OPTION(FLB_FILTER_LUA                  "Enable Lua scripting filter"                  ON)
 DEFINE_OPTION(FLB_FILTER_MODIFY               "Enable modify filter"                         ON)
 DEFINE_OPTION(FLB_FILTER_MULTILINE            "Enable multiline filter"                      ON)