Consider all compaction input files to compute the oldest ancestor time (#6279)

Summary:
Look at all compaction input files to compute the oldest ancestor time.

In https://github.com/facebook/rocksdb/issues/5992 we changed how creation_time (aka oldest-ancestor-time) table property of compaction output files is computed from max(creation-time-of-all-compaction-inputs) to min(creation-time-of-all-inputs). This exposed a bug where, during compaction, the creation_time:s of only the L0 compaction inputs were being looked at, and all other input levels were being ignored. This PR fixes the issue.
Some TTL compactions when using Level-Style compactions might not have run due to this bug.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6279

Test Plan: Enhanced the unit tests to validate that the correct time is propagated to the compaction outputs.

Differential Revision: D19337812

Pulled By: sagar0

fbshipit-source-id: edf8a72f11e405e93032ff5f45590816debe0bb4

HISTORY.md

@@ -7,6 +7,7 @@
 * A new `OptimisticTransactionDBOptions` Option that allows users to configure occ validation policy. The default policy changes from kValidateSerial to kValidateParallel to reduce mutex contention.
 
 ### Bug Fixes
+* Fixed a bug where non-L0 compaction input files were not considered to compute the `creation_time` of new compaction outputs.
 * Fix a bug that can cause unnecessary bg thread to be scheduled(#6104).
 * Fix a bug in which a snapshot read could be affected by a DeleteRange after the snapshot (#6062).
 * Fix crash caused by concurrent CF iterations and drops(#6147).

db/compaction/compaction.cc

@@ -545,11 +545,13 @@ bool Compaction::ShouldFormSubcompactions() const {
 
 uint64_t Compaction::MinInputFileOldestAncesterTime() const {
   uint64_t min_oldest_ancester_time = port::kMaxUint64;
-  for (const auto& file : inputs_[0].files) {
+  for (const auto& level_files : inputs_) {
-    uint64_t oldest_ancester_time = file->TryGetOldestAncesterTime();
+    for (const auto& file : level_files.files) {
-    if (oldest_ancester_time != 0) {
+      uint64_t oldest_ancester_time = file->TryGetOldestAncesterTime();
-      min_oldest_ancester_time =
+      if (oldest_ancester_time != 0) {
-          std::min(min_oldest_ancester_time, oldest_ancester_time);
+        min_oldest_ancester_time =
+            std::min(min_oldest_ancester_time, oldest_ancester_time);
+      }
     }
   }
   return min_oldest_ancester_time;

db/db_compaction_test.cc

@@ -3607,6 +3607,15 @@ TEST_F(DBCompactionTest, LevelTtlCascadingCompactions) {
         ASSERT_OK(Put(Key(i), RandomString(&rnd, kValueSize)));
       }
       Flush();
+      // Get the first file's creation time. This will be the oldest file in the
+      // DB. Compactions inolving this file's descendents should keep getting
+      // this time.
+      std::vector<std::vector<FileMetaData>> level_to_files;
+      dbfull()->TEST_GetFilesMetaData(dbfull()->DefaultColumnFamily(),
+                                      &level_to_files);
+      uint64_t oldest_time = level_to_files[0][0].oldest_ancester_time;
+      // Add 1 hour and do another flush.
+      env_->addon_time_.fetch_add(1 * 60 * 60);
       for (int i = 101; i <= 200; ++i) {
         ASSERT_OK(Put(Key(i), RandomString(&rnd, kValueSize)));
       }
@@ -3614,11 +3623,13 @@ TEST_F(DBCompactionTest, LevelTtlCascadingCompactions) {
       MoveFilesToLevel(6);
       ASSERT_EQ("0,0,0,0,0,0,2", FilesPerLevel());
 
+      env_->addon_time_.fetch_add(1 * 60 * 60);
       // Add two L4 files with key ranges: [1 .. 50], [51 .. 150].
       for (int i = 1; i <= 50; ++i) {
         ASSERT_OK(Put(Key(i), RandomString(&rnd, kValueSize)));
       }
       Flush();
+      env_->addon_time_.fetch_add(1 * 60 * 60);
       for (int i = 51; i <= 150; ++i) {
         ASSERT_OK(Put(Key(i), RandomString(&rnd, kValueSize)));
       }
@@ -3626,6 +3637,7 @@ TEST_F(DBCompactionTest, LevelTtlCascadingCompactions) {
       MoveFilesToLevel(4);
       ASSERT_EQ("0,0,0,0,2,0,2", FilesPerLevel());
 
+      env_->addon_time_.fetch_add(1 * 60 * 60);
       // Add one L1 file with key range: [26, 75].
       for (int i = 26; i <= 75; ++i) {
         ASSERT_OK(Put(Key(i), RandomString(&rnd, kValueSize)));
@@ -3667,6 +3679,10 @@ TEST_F(DBCompactionTest, LevelTtlCascadingCompactions) {
       ASSERT_EQ("1,0,0,0,0,0,1", FilesPerLevel());
       ASSERT_EQ(5, ttl_compactions);
 
+      dbfull()->TEST_GetFilesMetaData(dbfull()->DefaultColumnFamily(),
+                                      &level_to_files);
+      ASSERT_EQ(oldest_time, level_to_files[6][0].oldest_ancester_time);
+
       env_->addon_time_.fetch_add(25 * 60 * 60);
       ASSERT_OK(Put(Key(2), "1"));
       if (if_restart) {