feat(update): add MergingSnapshotUpdate

[gty404]

Summary

Implements MergingSnapshotUpdate — the abstract base class for merge-based snapshot operations (MergeAppend, OverwriteFiles, RowDelta, etc.), consistent with Java's MergingSnapshotProducer.

Core Implementation

• Filter → write → merge pipeline in Apply()
• Conflict detection helpers
• AddDataFile, DeleteDataFile, AddDeleteFile, DeleteDeleteFile, AddManifest, AppendManifest primitive API

Supporting Changes

• Add ReplacedManifestsCount() to ManifestFilterManager and ManifestMergeManager
• Fix SnapshotSummaryBuilder: manifest count fields (manifests-created, manifests-kept, manifests-replaced) are now always emitted together — matching Java's SnapshotProducer.buildManifestCountSummary
• Fix SnapshotUpdate::DeleteFile: removed static from capturing lambda (caused use-after-free heap corruption)

Tests

• manifest_filter_manager_test.cc: 27 tests
• merging_snapshot_update_test.cc: 34 tests aligned with Java's TestSnapshotSummary, TestMergeAppend, TestRowDelta

All 378 tests pass.

[github-actions]

Cpp-Linter Report ⚠️

Some files did not pass the configured checks!

clang-tidy (v22.1.6) reports: 31 concern(s)

• src/iceberg/test/manifest_filter_manager_test.cc:454:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "DropDeleteFilesOlderThan_KeepsNewerEntries" according to Googletest FAQ

    454 | TEST_F(ManifestFilterManagerTest, DropDeleteFilesOlderThan_KeepsNewerEntries) {
        |                                   ^

• src/iceberg/test/manifest_filter_manager_test.cc:512:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "RemoveDanglingDeletesFor_FiltersDanglingDV" according to Googletest FAQ

    512 | TEST_F(ManifestFilterManagerTest, RemoveDanglingDeletesFor_FiltersDanglingDV) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:181:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddsDataFiles_InitiallyFalse" according to Googletest FAQ

    181 | TEST_F(MergingSnapshotUpdateTest, AddsDataFiles_InitiallyFalse) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:188:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddsDataFiles_TrueAfterAdd" according to Googletest FAQ

    188 | TEST_F(MergingSnapshotUpdateTest, AddsDataFiles_TrueAfterAdd) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:195:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddsDeleteFiles_TrueAfterAdd" according to Googletest FAQ

    195 | TEST_F(MergingSnapshotUpdateTest, AddsDeleteFiles_TrueAfterAdd) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:203:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "DeletesDataFiles_TrueAfterRegisterDelete" according to Googletest FAQ

    203 | TEST_F(MergingSnapshotUpdateTest, DeletesDataFiles_TrueAfterRegisterDelete) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:296:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "CleanUncommitted_ClearsCaches" according to Googletest FAQ

    296 | TEST_F(MergingSnapshotUpdateTest, CleanUncommitted_ClearsCaches) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:309:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "CommitDeleteFile_SummaryHasAddedDeleteFiles" according to Googletest FAQ

    309 | TEST_F(MergingSnapshotUpdateTest, CommitDeleteFile_SummaryHasAddedDeleteFiles) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:326:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "CommitDeletesDeleteFile_SummaryHasRemovedDeleteFiles" according to Googletest FAQ

    326 | TEST_F(MergingSnapshotUpdateTest, CommitDeletesDeleteFile_SummaryHasRemovedDeleteFiles) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:352:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "DuplicateDataFile_OnlyCountedOnce" according to Googletest FAQ

    352 | TEST_F(MergingSnapshotUpdateTest, DuplicateDataFile_OnlyCountedOnce) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:398:37: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "ValidateNewDeleteFile_V1Rejected" according to Googletest FAQ

    398 | TEST_F(MergingSnapshotUpdateV1Test, ValidateNewDeleteFile_V1Rejected) {
        |                                     ^

• src/iceberg/test/merging_snapshot_update_test.cc:404:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "ValidateNewDeleteFile_V2RejectsDeletionVector" according to Googletest FAQ

    404 | TEST_F(MergingSnapshotUpdateTest, ValidateNewDeleteFile_V2RejectsDeletionVector) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:413:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "ValidateNewDeleteFile_V2AllowsEqualityDelete" according to Googletest FAQ

    413 | TEST_F(MergingSnapshotUpdateTest, ValidateNewDeleteFile_V2AllowsEqualityDelete) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:425:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddManifest_RejectsDeleteManifest" according to Googletest FAQ

    425 | TEST_F(MergingSnapshotUpdateTest, AddManifest_RejectsDeleteManifest) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:436:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddManifest_RejectsManifestWithExistingFiles" according to Googletest FAQ

    436 | TEST_F(MergingSnapshotUpdateTest, AddManifest_RejectsManifestWithExistingFiles) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:448:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddManifest_RejectsManifestWithDeletedFiles" according to Googletest FAQ

    448 | TEST_F(MergingSnapshotUpdateTest, AddManifest_RejectsManifestWithDeletedFiles) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:459:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddManifest_RejectsManifestWithAssignedSnapshotId" according to Googletest FAQ

    459 | TEST_F(MergingSnapshotUpdateTest, AddManifest_RejectsManifestWithAssignedSnapshotId) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:469:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AddManifest_RejectsManifestWithFirstRowId" according to Googletest FAQ

    469 | TEST_F(MergingSnapshotUpdateTest, AddManifest_RejectsManifestWithFirstRowId) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:484:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AppendManifest_EmptyTable" according to Googletest FAQ

    484 | TEST_F(MergingSnapshotUpdateTest, AppendManifest_EmptyTable) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:504:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AppendManifest_WithDataFiles" according to Googletest FAQ

    504 | TEST_F(MergingSnapshotUpdateTest, AppendManifest_WithDataFiles) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:527:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AppendManifest_MergeWithMinCountOne" according to Googletest FAQ

    527 | TEST_F(MergingSnapshotUpdateTest, AppendManifest_MergeWithMinCountOne) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:551:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "AppendManifest_DoNotMergeMinCount" according to Googletest FAQ

    551 | TEST_F(MergingSnapshotUpdateTest, AppendManifest_DoNotMergeMinCount) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:585:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "ManifestMerge_MergesIntoOne" according to Googletest FAQ

    585 | TEST_F(MergingSnapshotUpdateTest, ManifestMerge_MergesIntoOne) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:609:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "ManifestMerge_DoesNotMergeWhenBelowMinCount" according to Googletest FAQ

    609 | TEST_F(MergingSnapshotUpdateTest, ManifestMerge_DoesNotMergeWhenBelowMinCount) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:625:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "ManifestMerge_DoesNotMergeWhenSizeTargetTooSmall" according to Googletest FAQ

    625 | TEST_F(MergingSnapshotUpdateTest, ManifestMerge_DoesNotMergeWhenSizeTargetTooSmall) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:649:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "Summary_ManifestCountsOnFirstCommit" according to Googletest FAQ

    649 | TEST_F(MergingSnapshotUpdateTest, Summary_ManifestCountsOnFirstCommit) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:661:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "Summary_ManifestCountsOnSecondCommitNoMerge" according to Googletest FAQ

    661 | TEST_F(MergingSnapshotUpdateTest, Summary_ManifestCountsOnSecondCommitNoMerge) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:676:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "Summary_ManifestCountsAfterMerge" according to Googletest FAQ

    676 | TEST_F(MergingSnapshotUpdateTest, Summary_ManifestCountsAfterMerge) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:696:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "Summary_ManifestCountsAfterDelete" according to Googletest FAQ

    696 | TEST_F(MergingSnapshotUpdateTest, Summary_ManifestCountsAfterDelete) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:721:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "DataSpec_ThrowsWithMultipleSpecs" according to Googletest FAQ

    721 | TEST_F(MergingSnapshotUpdateTest, DataSpec_ThrowsWithMultipleSpecs) {
        |                                   ^

• src/iceberg/test/merging_snapshot_update_test.cc:729:35: warning: [google-readability-avoid-underscore-in-googletest-name]

  avoid using "_" in test name "DataSpec_ThrowsWhenEmpty" according to Googletest FAQ

    729 | TEST_F(MergingSnapshotUpdateTest, DataSpec_ThrowsWhenEmpty) {
        |                                   ^

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