Add dumpIncrementalCheckpoint utility (#6928)

ref #6827

dbms/src/Storages/Page/V3/CheckpointFile/CPFilesWriter.cpp

@@ -58,7 +58,7 @@ void CPFilesWriter::writePrefix(const CPFilesWriter::PrefixInfo & info)
     write_stage = WriteStage::WritingEdits;
 }
 
-bool CPFilesWriter::writeEditsAndApplyRemoteInfo(universal::PageEntriesEdit & edits)
+bool CPFilesWriter::writeEditsAndApplyCheckpointInfo(universal::PageEntriesEdit & edits)
 {
     RUNTIME_CHECK_MSG(write_stage == WriteStage::WritingEdits, "unexpected write stage {}", magic_enum::enum_name(write_stage));
 

dbms/src/Storages/Page/V3/CheckpointFile/CPFilesWriter.h

@@ -40,7 +40,7 @@ class CPFilesWriter : private boost::noncopyable
          * The list of lock files that will be always appended to the checkpoint file.
          *
          * Note: In addition to the specified lock files, the checkpoint file will also contain
-         * lock files from `writeEditsAndApplyRemoteInfo`.
+         * lock files from `writeEditsAndApplyCheckpointInfo`.
          */
         const std::unordered_set<String> & must_locked_files = {};
     };
@@ -71,7 +71,7 @@ class CPFilesWriter : private boost::noncopyable
      *
      * You must call `writeSuffix` finally, if you don't plan to write edits anymore.
      */
-    bool /* has_new_data */ writeEditsAndApplyRemoteInfo(universal::PageEntriesEdit & edit);
+    bool /* has_new_data */ writeEditsAndApplyCheckpointInfo(universal::PageEntriesEdit & edit);
 
     /**
      * This function must be called, and must be called last, after other `writeXxx`.

dbms/src/Storages/Page/V3/CheckpointFile/tests/gtest_file_read_write.cpp

@@ -29,7 +29,7 @@ class CheckpointFileTest : public DB::base::TiFlashStorageTestBasic
     void SetUp() override
     {
         dir = getTemporaryPath();
-        DB::tests::TiFlashTestEnv::tryRemovePath(dir);
+        dropDataOnDisk(dir);
         createIfNotExist(dir);
     }
 
@@ -99,7 +99,7 @@ try
     edits.appendRecord({.type = EditRecordType::DEL});
 
     ASSERT_THROW({
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     },
                  DB::Exception);
 }
@@ -124,7 +124,7 @@ try
     {
         auto edits = universal::PageEntriesEdit{};
         edits.appendRecord({.type = EditRecordType::VAR_DELETE, .page_id = "water"});
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     writer->writeSuffix();
     writer.reset();
@@ -180,15 +180,15 @@ try
     {
         auto edits = universal::PageEntriesEdit{};
         edits.appendRecord({.type = EditRecordType::VAR_DELETE, .page_id = "water"});
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     {
         auto edits = universal::PageEntriesEdit{};
         edits.appendRecord({.type = EditRecordType::VAR_ENTRY, .page_id = "abc", .entry = {.size = 29, .offset = 5}});
         edits.appendRecord({.type = EditRecordType::VAR_REF, .page_id = "foo", .ori_page_id = "abc"});
         edits.appendRecord({.type = EditRecordType::VAR_ENTRY, .page_id = "aaabbb", .entry = {.size = 22, .offset = 10}});
         edits.appendRecord({.type = EditRecordType::VAR_DELETE, .page_id = "rain"});
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     writer->writeSuffix();
     writer.reset();
@@ -290,7 +290,7 @@ try
         edits.appendRecord({.type = EditRecordType::VAR_REF, .page_id = "foo", .ori_page_id = "abc"});
         edits.appendRecord({.type = EditRecordType::VAR_ENTRY, .page_id = "aaabbb", .entry = {.size = 22, .offset = 10}});
         edits.appendRecord({.type = EditRecordType::VAR_DELETE, .page_id = "sun"});
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     writer->writeSuffix();
     writer.reset();
@@ -379,7 +379,7 @@ try
         .sequence = 5,
         .last_sequence = 3,
     });
-    writer->writeEditsAndApplyRemoteInfo(edits);
+    writer->writeEditsAndApplyCheckpointInfo(edits);
     writer->writeSuffix();
     writer.reset();
 
@@ -461,12 +461,12 @@ try
     });
     {
         auto edits = universal::PageEntriesEdit{};
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     {
         auto edits = universal::PageEntriesEdit{};
         edits.appendRecord({.type = EditRecordType::VAR_DELETE, .page_id = "snow"});
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     writer->writeSuffix();
     writer.reset();
@@ -562,7 +562,7 @@ try
             },
         });
         edits.appendRecord({.type = EditRecordType::VAR_ENTRY, .page_id = "aaabbb", .entry = {.size = 22, .offset = 10}});
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     writer->writeSuffix();
     writer.reset();
@@ -621,7 +621,7 @@ try
                 .page_id = fmt::format("record_{}", i),
                 .entry = {.size = 22, .offset = 10},
             });
-        writer->writeEditsAndApplyRemoteInfo(edits);
+        writer->writeEditsAndApplyCheckpointInfo(edits);
     }
     writer->writeSuffix();
     writer.reset();

dbms/src/Storages/Page/V3/PageDirectory.cpp

@@ -473,7 +473,7 @@ std::optional<PageEntryV3> VersionedPageEntries<Trait>::getLastEntry(std::option
     auto page_lock = acquireLock();
     if (type == EditRecordType::VAR_ENTRY)
     {
-        for (auto it_r = entries.rbegin(); it_r != entries.rend(); it_r++)
+        for (auto it_r = entries.rbegin(); it_r != entries.rend(); it_r++) // NOLINT(modernize-loop-convert)
         {
             if (seq.has_value() && it_r->first.sequence > seq.value())
                 continue;
@@ -486,6 +486,55 @@ std::optional<PageEntryV3> VersionedPageEntries<Trait>::getLastEntry(std::option
     return std::nullopt;
 }
 
+template <typename Trait>
+void VersionedPageEntries<Trait>::copyCheckpointInfoFromEdit(const typename PageEntriesEdit::EditRecord & edit)
+{
+    // We have a running PageStorage instance, and did a checkpoint dump. The checkpoint dump is encoded using
+    // PageEntriesEdit. During the checkpoint dump, this function is invoked so that we can write back where
+    // (the checkpoint info) each page's data was dumped.
+    // In this case, there is a living snapshot protecting the data.
+
+    // Pre-check: All ENTRY edit record must contain checkpoint info for copying.
+    RUNTIME_CHECK(edit.type == EditRecordType::VAR_ENTRY);
+    RUNTIME_CHECK(edit.entry.checkpoint_info.has_value());
+
+    auto page_lock = acquireLock();
+
+    if (type != EditRecordType::VAR_ENTRY)
+    {
+        // For example, Put X -> Delete X -> dumpSnapshotToEdit -> Full GC -> Delete X -> copyCheckpointInfoFromEdit.
+        // In this case, we have X=VAR_ENTRY in the `edit`, but will get X=VAR_DELETE in the page directory.
+        return;
+    }
+
+    // Due to GC movement, (sequence, epoch) may be changed to (sequence, epoch+x), so
+    // we search within [  (sequence, 0),  (sequence+1, 0)  ), and assign checkpoint info for all of it.
+    auto iter = MapUtils::findMutLess(entries, PageVersion(edit.version.sequence + 1));
+    if (iter == entries.end())
+    {
+        // The referenced version may be GCed so that we cannot find any matching entry.
+        return;
+    }
+
+    // TODO: Not sure if there is a full GC this may be false? Let's keep it here for now.
+    RUNTIME_CHECK(
+        iter->first.sequence == edit.version.sequence,
+        iter->first.sequence,
+        edit.version.sequence);
+
+    // Discard epoch, and only check sequence.
+    while (iter->first.sequence == edit.version.sequence)
+    {
+        // We will never meet the same Version mapping to one entry and one delete, so let's verify it is an entry.
+        RUNTIME_CHECK(iter->second.isEntry());
+        iter->second.entry.checkpoint_info = edit.entry.checkpoint_info;
+
+        if (iter == entries.begin())
+            break;
+        --iter;
+    }
+}
+
 // Returns true when **this id** is "visible" by `seq`.
 // If this page id is marked as deleted or not created, it is "not visible".
 // Note that not visible does not means this id can be GC.
@@ -1623,6 +1672,45 @@ bool PageDirectory<Trait>::tryDumpSnapshot(const ReadLimiterPtr & read_limiter,
     return done_any_io;
 }
 
+template <typename Trait>
+void PageDirectory<Trait>::copyCheckpointInfoFromEdit(PageEntriesEdit & edit)
+{
+    const auto & records = edit.getRecords();
+    if (records.empty())
+        return;
+
+    // Pre-check: All ENTRY edit record must contain checkpoint info.
+    // We do the pre-check before copying any remote info to avoid partial completion.
+    for (const auto & rec : records)
+    {
+        if (rec.type == EditRecordType::VAR_ENTRY)
+            RUNTIME_CHECK(rec.entry.checkpoint_info.has_value());
+    }
+
+    for (const auto & rec : records)
+    {
+        // Only VAR_ENTRY will contain checkpoint info.
+        if (rec.type != EditRecordType::VAR_ENTRY)
+            continue;
+
+        // TODO: Improve from O(nlogn) to O(n).
+
+        typename MVCCMapType::iterator iter;
+        {
+            std::shared_lock read_lock(table_rw_mutex);
+            iter = mvcc_table_directory.find(rec.page_id);
+            if (iter == mvcc_table_directory.end())
+                // There may be obsolete entries deleted.
+                // For example, if there is a `Put 1` with sequence 10, `Del 1` with sequence 11,
+                // and the snapshot sequence is 12, Page with id 1 may be deleted by the gc process.
+                continue;
+        }
+
+        auto & entries = iter->second;
+        entries->copyCheckpointInfoFromEdit(rec);
+    }
+}
+
 template <typename Trait>
 typename PageDirectory<Trait>::PageEntries PageDirectory<Trait>::gcInMemEntries(bool return_removed_entries)
 {

dbms/src/Storages/Page/V3/PageDirectory.h

@@ -45,6 +45,7 @@ extern const Metric PSMVCCNumSnapshots;
 
 namespace DB::PS::V3
 {
+
 class PageDirectorySnapshot : public DB::PageStorageSnapshot
 {
 public:
@@ -186,6 +187,8 @@ class VersionedPageEntries
 
     std::optional<PageEntryV3> getLastEntry(std::optional<UInt64> seq) const;
 
+    void copyCheckpointInfoFromEdit(const typename PageEntriesEdit::EditRecord & edit);
+
     bool isVisible(UInt64 seq) const;
 
     /**
@@ -353,6 +356,8 @@ class PageDirectory
     /// And we don't restore the entries in blob store, because this PageDirectory is just read only for its entries.
     bool tryDumpSnapshot(const ReadLimiterPtr & read_limiter = nullptr, const WriteLimiterPtr & write_limiter = nullptr, bool force = false);
 
+    void copyCheckpointInfoFromEdit(PageEntriesEdit & edit);
+
     // Perform a GC for in-memory entries and return the removed entries.
     // If `return_removed_entries` is false, then just return an empty set.
     PageEntries gcInMemEntries(bool return_removed_entries = true);

dbms/src/Storages/Page/V3/Universal/UniversalPageStorage.cpp

@@ -16,6 +16,8 @@
 #include <Common/TiFlashMetrics.h>
 #include <Storages/Page/V3/Blob/BlobConfig.h>
 #include <Storages/Page/V3/BlobStore.h>
+#include <Storages/Page/V3/CheckpointFile/CPFilesWriter.h>
+#include <Storages/Page/V3/CheckpointFile/CPWriteDataSource.h>
 #include <Storages/Page/V3/PageDirectoryFactory.h>
 #include <Storages/Page/V3/Universal/UniversalPageStorage.h>
 #include <Storages/Page/V3/Universal/UniversalWriteBatchImpl.h>
@@ -202,10 +204,86 @@ void UniversalPageStorage::registerUniversalExternalPagesCallbacks(const Univers
 {
     manager.registerExternalPagesCallbacks(callbacks);
 }
+
 void UniversalPageStorage::unregisterUniversalExternalPagesCallbacks(const String & prefix)
 {
     manager.unregisterExternalPagesCallbacks(prefix);
     // clean all external ids ptrs
     page_directory->unregisterNamespace(prefix);
 }
+
+UniversalPageStorage::DumpCheckpointResult
+UniversalPageStorage::dumpIncrementalCheckpoint(const UniversalPageStorage::DumpCheckpointOptions & options)
+{
+    std::scoped_lock lock(checkpoint_mu);
+
+    // Let's keep this snapshot until all finished, so that blob data will not be GCed.
+    auto snap = page_directory->createSnapshot(/*tracing_id*/ "dumpIncrementalCheckpoint");
+
+    if (snap->sequence == last_checkpoint_sequence)
+        return {};
+
+    auto edit_from_mem = page_directory->dumpSnapshotToEdit(snap);
+
+    // As a checkpoint, we write both entries (in manifest) and its data.
+    // Some entries' data may be already written by a previous checkpoint. These data will not be written again.
+
+    auto data_file_id = fmt::format(
+        fmt::runtime(options.data_file_id_pattern),
+        fmt::arg("sequence", snap->sequence),
+        fmt::arg("sub_file_index", 0));
+    auto data_file_path = fmt::format(
+        fmt::runtime(options.data_file_path_pattern),
+        fmt::arg("sequence", snap->sequence),
+        fmt::arg("sub_file_index", 0));
+
+    auto manifest_file_id = fmt::format(
+        fmt::runtime(options.manifest_file_id_pattern),
+        fmt::arg("sequence", snap->sequence));
+    auto manifest_file_path = fmt::format(
+        fmt::runtime(options.manifest_file_path_pattern),
+        fmt::arg("sequence", snap->sequence));
+
+    RUNTIME_CHECK(
+        data_file_path != manifest_file_path,
+        data_file_path,
+        manifest_file_path);
+
+    auto writer = PS::V3::CPFilesWriter::create({
+        .data_file_path = data_file_path,
+        .data_file_id = data_file_id,
+        .manifest_file_path = manifest_file_path,
+        .manifest_file_id = manifest_file_id,
+        .data_source = PS::V3::CPWriteDataSourceBlobStore::create(*blob_store),
+    });
+
+    writer->writePrefix({
+        .writer = options.writer_info,
+        .sequence = snap->sequence,
+        .last_sequence = last_checkpoint_sequence,
+    });
+    bool has_new_data = writer->writeEditsAndApplyCheckpointInfo(edit_from_mem);
+    writer->writeSuffix();
+    writer.reset();
+
+    SYNC_FOR("before_PageStorage::dumpIncrementalCheckpoint_copyInfo");
+
+    // TODO: Currently, even when has_new_data == false,
+    //   something will be written to DataFile (i.e., the file prefix).
+    //   This can be avoided, as its content is useless.
+    if (has_new_data)
+    {
+        // Copy back the checkpoint info to the current PageStorage.
+        // New checkpoint infos are attached in `writeEditsAndApplyCheckpointInfo`.
+        page_directory->copyCheckpointInfoFromEdit(edit_from_mem);
+    }
+
+    last_checkpoint_sequence = snap->sequence;
+
+    return DumpCheckpointResult{
+        .new_data_files = {{.id = data_file_id, .path = data_file_path}},
+        .new_manifest_files = {{.id = manifest_file_id, .path = manifest_file_path}},
+    };
+}
+
 } // namespace DB