Merge #137554

137554: changefeedccl: move resolved span frontiers into separate package r=asg0451 a=andyyang890

This patch renames `schemaChangeFrontier` to `resolvedSpanFrontier`
to reflect that not all resolved span boundaries correspond to schema
changes (e.g. initial-scan-only, end time reached). Its private fields
are also now properly encapsulated and new derived struct types for each
processor type have been created to handle the processor-specific
boundary handling logic. The field and method used for tracking whether
a changefeed is considered idle has been extracted from the frontier
struct because it is not related to span progress or boundaries.
Finally, the frontier data structures have been moved to a separate
`resolvedspan` package to provide better abstraction of its internal
implementation.

Epic: None

Release note: None

Co-authored-by: Andy Yang <[email protected]>

pkg/BUILD.bazel

@@ -34,6 +34,7 @@ ALL_TESTS = [
     "//pkg/ccl/changefeedccl/checkpoint:checkpoint_test",
     "//pkg/ccl/changefeedccl/kvevent:kvevent_test",
     "//pkg/ccl/changefeedccl/kvfeed:kvfeed_test",
+    "//pkg/ccl/changefeedccl/resolvedspan:resolvedspan_test",
     "//pkg/ccl/changefeedccl/schemafeed:schemafeed_test",
     "//pkg/ccl/changefeedccl:changefeedccl_test",
     "//pkg/ccl/cliccl:cliccl_test",
@@ -880,6 +881,8 @@ GO_TARGETS = [
     "//pkg/ccl/changefeedccl/kvfeed:kvfeed",
     "//pkg/ccl/changefeedccl/kvfeed:kvfeed_test",
     "//pkg/ccl/changefeedccl/mocks:mocks",
+    "//pkg/ccl/changefeedccl/resolvedspan:resolvedspan",
+    "//pkg/ccl/changefeedccl/resolvedspan:resolvedspan_test",
     "//pkg/ccl/changefeedccl/schemafeed/schematestutils:schematestutils",
     "//pkg/ccl/changefeedccl/schemafeed:schemafeed",
     "//pkg/ccl/changefeedccl/schemafeed:schemafeed_test",

pkg/ccl/changefeedccl/BUILD.bazel

@@ -25,7 +25,6 @@ go_library(
         "parquet.go",
         "parquet_sink_cloudstorage.go",
         "protected_timestamps.go",
-        "resolved_span_frontier.go",
         "retry.go",
         "scheduled_changefeed.go",
         "schema_registry.go",
@@ -61,6 +60,7 @@ go_library(
         "//pkg/ccl/changefeedccl/checkpoint",
         "//pkg/ccl/changefeedccl/kvevent",
         "//pkg/ccl/changefeedccl/kvfeed",
+        "//pkg/ccl/changefeedccl/resolvedspan",
         "//pkg/ccl/changefeedccl/schemafeed",
         "//pkg/ccl/changefeedccl/timers",
         "//pkg/ccl/kvccl/kvfollowerreadsccl",