chore(ci): modernize Codecov config for the coverage initiative [DNM]

.codecov.yml

@@ -15,68 +15,132 @@
 
 # For more configuration details:
 # https://docs.codecov.io/docs/codecov-yaml
-
-# Check if this file is valid by running in bash:
+#
+# Validate this file:
 # curl -X POST --data-binary @.codecov.yml https://codecov.io/validate
 
+codecov:
+  # Wait for the parallel test jobs to finish uploading before evaluating status
+  # and posting the PR comment, so a partial upload does not report a false drop.
+  notify:
+    wait_for_ci: true
+
 coverage:
   precision: 2
   round: down
   range: "50...100"
+  status:
+    # Statuses are informational for now: they surface the delta on each PR but do
+    # not fail the build. Flip a component to blocking (drop `informational`, set a
+    # `target`/`threshold`) once its coverage has climbed, so the initiative does
+    # not gate unrelated PRs mid-flight.
+    project:
+      default:
+        informational: true
+    patch:
+      default:
+        informational: true
 
-# Ignoring Paths
-# --------------
-# which folders/files to ignore
+# Generated code (Avro/Thrift/Protobuf/ANTLR) is produced at build time, has no
+# source in git, and is therefore already absent from the Codecov report; it needs
+# no entry here. The paths below are non-generated code that should not count.
 ignore:
-  - "hudi-common/src/main/java/org/apache/hudi/avro/model/*"
+  # Generated Avro model classes (kept for safety in case sources are ever committed).
+  - "hudi-common/src/main/java/org/apache/hudi/avro/model/**"
+  # Example and quickstart applications are illustrative, not production.
+  - "hudi-examples/**"
+  # Integration-test harness (test DAGs, fixtures, generators), not production behavior.
+  - "hudi-integ-test/**"
+  # Packaging and bundle shims: assembly config, no testable logic.
+  - "packaging/**"
+  # Vendored copy of Spark's HadoopFSUtils; owned upstream, not Hudi logic.
+  - "hudi-spark-datasource/hudi-spark-common/src/main/scala/org/apache/spark/HoodieHadoopFSUtils.scala"
+  # Metaserver is an incubating component with no shipped coverage. Remove this line
+  # if it is taken into scope for the coverage initiative.
+  - "hudi-platform-service/**"
+  # Standalone main()-style tools and legacy JSON/payload helpers carried over from the
+  # previous config; these are exercised by integration tests, not unit tests. Kept
+  # excluded for consistency (entries for since-deleted classes have been dropped).
   - "hudi-common/src/main/java/org/apache/hudi/avro/MercifulJsonConverter.java"
-  - "hudi-common/src/main/java/org/apache/hudi/common/HoodieJsonPayload"
+  - "hudi-common/src/main/java/org/apache/hudi/common/HoodieJsonPayload.java"
   - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HoodieCleaner.java"
   - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HoodieCompactionAdminTool.java"
   - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HoodieCompactor.java"
-  - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HoodieSnapshotCopier.java"
   - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HoodieWithTimelineServer.java"
-  - "hudi-utilities/src/main/java/org/apache/hudi/utilities/UpgradePayloadFromUberToApache.java"
   - "hudi-utilities/src/main/java/org/apache/hudi/utilities/perf/TimelineServerPerf.java"
-  - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HDFSParquetImporter.java"
   - "hudi-utilities/src/main/java/org/apache/hudi/utilities/HiveIncrementalPuller.java"
-  - "hudi-utilities/src/main/java/org/apache/hudi/utilities/adhoc/UpgradePayloadFromUberToApache.java"
-  - "hudi-client/src/main/java/org/apache/hudi/metrics/JmxMetricsReporter.java"
-  - "hudi-client/src/main/java/org/apache/hudi/metrics/JmxReporterServer.java"
-  - "hudi-client/src/main/java/org/apache/hudi/metrics/MetricsGraphiteReporter.java"
-  - "hudi-hadoop-mr/src/main/java/com/uber/hoodie/hadoop/HoodieInputFormat.java"
-  - "hudi-hadoop-mr/src/main/java/com/uber/hoodie/hadoop/realtime/HoodieRealtimeInputFormat.java"
 
-comment: false
+# Post a coverage summary on every PR so reviewers can see the per-component and
+# per-patch delta (used to enforce the coverage-quality bar for the initiative).
+comment:
+  layout: "condensed_header, diff, components, flags, files"
+  behavior: default
+  require_changes: false
+
+# Carry the last known coverage forward for a flag when its CI job is skipped by the
+# path filter on a given PR, so a partial run does not zero out that flag's coverage.
+# Flags uploaded by .github/workflows/bot.yml: spark-client-hadoop-common, utilities,
+# common-and-other-modules, spark-java-tests, spark-scala-tests, hadoop-mr-java-client,
+# integration-tests.
+flag_management:
+  default_rules:
+    carryforward: true
 
-flags:
-  hudicli:
-    paths:
-      - hudi-cli/src/main/
-  hudiclient:
-    paths:
-      - hudi-client/src/main/
-  hudicommon:
-    paths:
-      - hudi-common/src/main/
-  hudiexamples:
-    paths:
-      - hudi-examples/src/main/
-  hudihadoopmr:
-    paths:
-      - hudi-hadoop-mr/src/main/
-  hudihivesync:
-    paths:
-      - hudi-hive-sync/src/main/
-  hudiintegtest:
-    paths:
-      - hudi-integ-test/src/main/
-  hudispark:
-    paths:
-      - hudi-spark/src/main/
-  huditimelineservice:
-    paths:
-      - hudi-timeline-service/src/main/
-  hudiutilities:
-    paths:
-      - hudi-utilities/src/main/
+# Per-ownership-area coverage, so each coverage subtask can read its own number on
+# every PR. Paths align with the module layout and the ENG-44401 subtask breakdown.
+component_management:
+  individual_components:
+    - component_id: hudi-common
+      name: hudi-common
+      paths:
+        - "hudi-common/**"
+    - component_id: hudi-client
+      name: hudi-client
+      paths:
+        - "hudi-client/hudi-client-common/**"
+        - "hudi-client/hudi-spark-client/**"
+        - "hudi-client/hudi-java-client/**"
+    - component_id: hudi-flink
+      name: hudi-flink
+      paths:
+        - "hudi-flink-datasource/**"
+        - "hudi-client/hudi-flink-client/**"
+    - component_id: hudi-spark-datasource
+      name: hudi-spark-datasource
+      paths:
+        - "hudi-spark-datasource/**"
+    - component_id: hudi-utilities
+      name: hudi-utilities
+      paths:
+        - "hudi-utilities/**"
+    - component_id: hudi-cli
+      name: hudi-cli
+      paths:
+        - "hudi-cli/**"
+    - component_id: hudi-hadoop
+      name: hudi-hadoop
+      paths:
+        - "hudi-hadoop-common/**"
+        - "hudi-hadoop-mr/**"
+    - component_id: hudi-sync
+      name: hudi-sync
+      paths:
+        - "hudi-sync/**"
+    - component_id: hudi-io
+      name: hudi-io
+      paths:
+        - "hudi-io/**"
+    - component_id: hudi-timeline-service
+      name: hudi-timeline-service
+      paths:
+        - "hudi-timeline-service/**"
+    - component_id: hudi-cloud
+      name: hudi-cloud
+      paths:
+        - "hudi-aws/**"
+        - "hudi-gcp/**"
+        - "hudi-azure/**"
+    - component_id: hudi-kafka-connect
+      name: hudi-kafka-connect
+      paths:
+        - "hudi-kafka-connect/**"

hudi-common/src/main/java/org/apache/hudi/common/util/Base64CodecUtil.java

@@ -29,6 +29,8 @@
  */
 public final class Base64CodecUtil {
 
+  // DNM: temporary no-op comment to trigger CI so the updated Codecov config uploads a report. Revert before merge.
+
   /**
    * Decodes data from the input string into using the encoding scheme.
    *

scripts/jacoco/README.md

@@ -107,4 +107,37 @@ Published Artifacts
 - `merge_jacoco_exec_files.sh`: merges multiple JaCoCo execution data files in multiple modules.
 - `merge_jacoco_job_files.sh`: merges multiple JaCoCo execution data files from multiple Azure pipeline jobs.
 - `generate_jacoco_coverage_report.sh`: generates the JaCoCo code coverage report by taking the execution data file,
-  source files and class files.
+  source files and class files.
+
+## Per-PR coverage on Codecov
+
+In addition to the aggregated Azure report described above, coverage is uploaded to
+[Codecov](https://app.codecov.io/gh/apache/hudi) on every pull request and every commit to master.
+This is the canonical per-PR view.
+
+- Each test job in `.github/workflows/bot.yml` runs with the JaCoCo agent, builds a merged report
+  via `scripts/jacoco/generate_merged_coverage_report.sh`, and uploads `jacoco-report.xml` to
+  Codecov under a flag (`spark-java-tests`, `spark-scala-tests`, `utilities`,
+  `common-and-other-modules`, `spark-client-hadoop-common`, `hadoop-mr-java-client`,
+  `integration-tests`).
+- `.codecov.yml` configures reporting: `ignore` drops non-production code (examples, packaging,
+  the integration-test harness, an incubating module); `component_management` reports coverage per
+  ownership area (hudi-common, hudi-client, hudi-spark-datasource, hudi-flink, ...); and
+  `flag_management` carries a flag's coverage forward when its job is skipped by the path filter,
+  so a partial run does not report a false drop.
+- Generated code (Thrift, Protobuf, ANTLR) has no source committed to git, so it never appears
+  in the Codecov report and needs no exclusion. The one committed generated path, the Avro model
+  classes, is still ignored defensively in `.codecov.yml`.
+- Codecov posts a summary comment on each PR with the project, per-component, and per-patch
+  coverage delta. Statuses are informational (they do not fail the build); to gate a component
+  against regression later, remove `informational` and set a `target`/`threshold` for it.
+
+To read coverage for a single module locally, run its tests with the JaCoCo agent and open the
+generated `target/site/jacoco*/index.html`, for example:
+
+```bash
+mvn test -pl hudi-common -Punit-tests -Djacoco.skip=false
+```
+
+Instruction coverage is the headline metric; branch coverage (also in the report) shows whether
+both sides of each conditional are exercised, which is what catches untested error and config paths.