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Make it able to ignore WAL related VersionEdits in older versions #7873

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56 changes: 52 additions & 4 deletions db/version_edit.cc
Original file line number Diff line number Diff line change
Expand Up @@ -226,13 +226,17 @@ bool VersionEdit::EncodeTo(std::string* dst) const {
}

for (const auto& wal_addition : wal_additions_) {
PutVarint32(dst, kWalAddition);
wal_addition.EncodeTo(dst);
PutVarint32(dst, kNewWalAddition);
std::string encoded;
wal_addition.EncodeTo(&encoded);
PutLengthPrefixedSlice(dst, encoded);
}

if (!wal_deletion_.IsEmpty()) {
PutVarint32(dst, kWalDeletion);
wal_deletion_.EncodeTo(dst);
PutVarint32(dst, kNewWalDeletion);
std::string encoded;
wal_deletion_.EncodeTo(&encoded);
PutLengthPrefixedSlice(dst, encoded);
}

// 0 is default and does not need to be explicitly written
Expand Down Expand Up @@ -375,6 +379,11 @@ const char* VersionEdit::DecodeNewFile4From(Slice* input) {

Status VersionEdit::DecodeFrom(const Slice& src) {
Clear();
#ifndef NDEBUG
bool ignore_ignorable_tags = false;
TEST_SYNC_POINT_CALLBACK("VersionEdit::EncodeTo:IgnoreIgnorableTags",
&ignore_ignorable_tags);
#endif
Slice input = src;
const char* msg = nullptr;
uint32_t tag = 0;
Expand All @@ -385,6 +394,11 @@ Status VersionEdit::DecodeFrom(const Slice& src) {
Slice str;
InternalKey key;
while (msg == nullptr && GetVarint32(&input, &tag)) {
#ifndef NDEBUG
if (ignore_ignorable_tags && tag > kTagSafeIgnoreMask) {
tag = kTagSafeIgnoreMask;
}
#endif
switch (tag) {
case kDbId:
if (GetLengthPrefixedSlice(&input, &str)) {
Expand Down Expand Up @@ -575,6 +589,23 @@ Status VersionEdit::DecodeFrom(const Slice& src) {
break;
}

case kNewWalAddition: {
Slice encoded;
if (!GetLengthPrefixedSlice(&input, &encoded)) {
msg = "WalAddition not prefixed by length";
break;
}

WalAddition wal_addition;
const Status s = wal_addition.DecodeFrom(&encoded);
if (!s.ok()) {
return s;
}

wal_additions_.emplace_back(std::move(wal_addition));
break;
}

case kWalDeletion: {
WalDeletion wal_deletion;
const Status s = wal_deletion.DecodeFrom(&input);
Expand All @@ -586,6 +617,23 @@ Status VersionEdit::DecodeFrom(const Slice& src) {
break;
}

case kNewWalDeletion: {
Slice encoded;
if (!GetLengthPrefixedSlice(&input, &encoded)) {
msg = "WalDeletion not prefixed by length";
break;
}

WalDeletion wal_deletion;
const Status s = wal_deletion.DecodeFrom(&encoded);
if (!s.ok()) {
return s;
}

wal_deletion_ = std::move(wal_deletion);
break;
}

case kColumnFamily:
if (!GetVarint32(&input, &column_family_)) {
if (!msg) {
Expand Down
2 changes: 2 additions & 0 deletions db/version_edit.h
Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,8 @@ enum Tag : uint32_t {
kWalAddition,
kWalDeletion,
kFullHistoryTsLow,
kNewWalAddition,
kNewWalDeletion,
};

enum NewFileCustomTag : uint32_t {
Expand Down
102 changes: 88 additions & 14 deletions db/version_edit_test.cc
Original file line number Diff line number Diff line change
Expand Up @@ -324,14 +324,22 @@ TEST_F(VersionEditTest, AddWalEncodeDecode) {
TestEncodeDecode(edit);
}

static std::string PrefixEncodedWalAdditionWithLength(
const std::string& encoded) {
std::string ret;
PutVarint32(&ret, Tag::kNewWalAddition);
PutLengthPrefixedSlice(&ret, encoded);
return ret;
}

TEST_F(VersionEditTest, AddWalDecodeBadLogNumber) {
std::string encoded;
PutVarint32(&encoded, Tag::kWalAddition);

{
// No log number.
std::string encoded_edit = PrefixEncodedWalAdditionWithLength(encoded);
VersionEdit edit;
Status s = edit.DecodeFrom(encoded);
Status s = edit.DecodeFrom(encoded_edit);
ASSERT_TRUE(s.IsCorruption());
ASSERT_TRUE(s.ToString().find("Error decoding WAL log number") !=
std::string::npos)
Expand All @@ -345,8 +353,10 @@ TEST_F(VersionEditTest, AddWalDecodeBadLogNumber) {
unsigned char* ptr = reinterpret_cast<unsigned char*>(&c);
*ptr = 128;
encoded.append(1, c);

std::string encoded_edit = PrefixEncodedWalAdditionWithLength(encoded);
VersionEdit edit;
Status s = edit.DecodeFrom(encoded);
Status s = edit.DecodeFrom(encoded_edit);
ASSERT_TRUE(s.IsCorruption());
ASSERT_TRUE(s.ToString().find("Error decoding WAL log number") !=
std::string::npos)
Expand All @@ -358,39 +368,45 @@ TEST_F(VersionEditTest, AddWalDecodeBadTag) {
constexpr WalNumber kLogNumber = 100;
constexpr uint64_t kSizeInBytes = 100;

std::string encoded_without_tag;
PutVarint32(&encoded_without_tag, Tag::kWalAddition);
PutVarint64(&encoded_without_tag, kLogNumber);
std::string encoded;
PutVarint64(&encoded, kLogNumber);

{
// No tag.
std::string encoded_edit = PrefixEncodedWalAdditionWithLength(encoded);
VersionEdit edit;
Status s = edit.DecodeFrom(encoded_without_tag);
Status s = edit.DecodeFrom(encoded_edit);
ASSERT_TRUE(s.IsCorruption());
ASSERT_TRUE(s.ToString().find("Error decoding tag") != std::string::npos)
<< s.ToString();
}

{
// Only has size tag, no terminate tag.
std::string encoded_with_size = encoded_without_tag;
std::string encoded_with_size = encoded;
PutVarint32(&encoded_with_size,
static_cast<uint32_t>(WalAdditionTag::kSyncedSize));
PutVarint64(&encoded_with_size, kSizeInBytes);

std::string encoded_edit =
PrefixEncodedWalAdditionWithLength(encoded_with_size);
VersionEdit edit;
Status s = edit.DecodeFrom(encoded_with_size);
Status s = edit.DecodeFrom(encoded_edit);
ASSERT_TRUE(s.IsCorruption());
ASSERT_TRUE(s.ToString().find("Error decoding tag") != std::string::npos)
<< s.ToString();
}

{
// Only has terminate tag.
std::string encoded_with_terminate = encoded_without_tag;
std::string encoded_with_terminate = encoded;
PutVarint32(&encoded_with_terminate,
static_cast<uint32_t>(WalAdditionTag::kTerminate));

std::string encoded_edit =
PrefixEncodedWalAdditionWithLength(encoded_with_terminate);
VersionEdit edit;
ASSERT_OK(edit.DecodeFrom(encoded_with_terminate));
ASSERT_OK(edit.DecodeFrom(encoded_edit));
auto& wal_addition = edit.GetWalAdditions()[0];
ASSERT_EQ(wal_addition.GetLogNumber(), kLogNumber);
ASSERT_FALSE(wal_addition.GetMetadata().HasSyncedSize());
Expand All @@ -401,15 +417,15 @@ TEST_F(VersionEditTest, AddWalDecodeNoSize) {
constexpr WalNumber kLogNumber = 100;

std::string encoded;
PutVarint32(&encoded, Tag::kWalAddition);
PutVarint64(&encoded, kLogNumber);
PutVarint32(&encoded, static_cast<uint32_t>(WalAdditionTag::kSyncedSize));
// No real size after the size tag.

{
// Without terminate tag.
std::string encoded_edit = PrefixEncodedWalAdditionWithLength(encoded);
VersionEdit edit;
Status s = edit.DecodeFrom(encoded);
Status s = edit.DecodeFrom(encoded_edit);
ASSERT_TRUE(s.IsCorruption());
ASSERT_TRUE(s.ToString().find("Error decoding WAL file size") !=
std::string::npos)
Expand All @@ -419,8 +435,10 @@ TEST_F(VersionEditTest, AddWalDecodeNoSize) {
{
// With terminate tag.
PutVarint32(&encoded, static_cast<uint32_t>(WalAdditionTag::kTerminate));

std::string encoded_edit = PrefixEncodedWalAdditionWithLength(encoded);
VersionEdit edit;
Status s = edit.DecodeFrom(encoded);
Status s = edit.DecodeFrom(encoded_edit);
ASSERT_TRUE(s.IsCorruption());
// The terminate tag is misunderstood as the size.
ASSERT_TRUE(s.ToString().find("Error decoding tag") != std::string::npos)
Expand Down Expand Up @@ -515,6 +533,62 @@ TEST_F(VersionEditTest, FullHistoryTsLow) {
TestEncodeDecode(edit);
}

// Tests that if RocksDB is downgraded, the new types of VersionEdits
// that have a tag larger than kTagSafeIgnoreMask can be safely ignored.
TEST_F(VersionEditTest, IgnorableTags) {
SyncPoint::GetInstance()->SetCallBack(
"VersionEdit::EncodeTo:IgnoreIgnorableTags", [&](void* arg) {
bool* ignore = static_cast<bool*>(arg);
*ignore = true;
});
SyncPoint::GetInstance()->EnableProcessing();

constexpr uint64_t kPrevLogNumber = 100;
constexpr uint64_t kLogNumber = 200;
constexpr uint64_t kNextFileNumber = 300;
constexpr uint64_t kColumnFamilyId = 400;

VersionEdit edit;
// Add some ignorable entries.
for (int i = 0; i < 2; i++) {
edit.AddWal(i + 1, WalMetadata(i + 2));
}
edit.SetDBId("db_id");
// Add unignorable entries.
edit.SetPrevLogNumber(kPrevLogNumber);
edit.SetLogNumber(kLogNumber);
// Add more ignorable entries.
edit.DeleteWalsBefore(100);
// Add unignorable entry.
edit.SetNextFile(kNextFileNumber);
// Add more ignorable entries.
edit.SetFullHistoryTsLow("ts");
// Add unignorable entry.
edit.SetColumnFamily(kColumnFamilyId);

std::string encoded;
ASSERT_TRUE(edit.EncodeTo(&encoded));

VersionEdit decoded;
ASSERT_OK(decoded.DecodeFrom(encoded));

// Check that all ignorable entries are ignored.
ASSERT_FALSE(decoded.HasDbId());
ASSERT_FALSE(decoded.HasFullHistoryTsLow());
ASSERT_FALSE(decoded.IsWalAddition());
ASSERT_FALSE(decoded.IsWalDeletion());
ASSERT_TRUE(decoded.GetWalAdditions().empty());
ASSERT_TRUE(decoded.GetWalDeletion().IsEmpty());

// Check that unignorable entries are still present.
ASSERT_EQ(edit.GetPrevLogNumber(), kPrevLogNumber);
ASSERT_EQ(edit.GetLogNumber(), kLogNumber);
ASSERT_EQ(edit.GetNextFile(), kNextFileNumber);
ASSERT_EQ(edit.GetColumnFamily(), kColumnFamilyId);

SyncPoint::GetInstance()->DisableProcessing();
}

} // namespace ROCKSDB_NAMESPACE

int main(int argc, char** argv) {
Expand Down