Skip to content

[refactor](cloud) improve FDB transaction approximate size calculation accuracy #60390

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
w41ter wants to merge 1 commit into
base: branch-4.0
Choose a base branch
from
+66 −12
Open

[refactor](cloud) improve FDB transaction approximate size calculation accuracy #60390

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
78 changes: 66 additions & 12 deletions cloud/src/meta-store/txn_kv.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -266,6 +266,53 @@ namespace doris::cloud::fdb {
// https://apple.github.io/foundationdb/known-limitations.html#design-limitations
constexpr size_t FDB_VALUE_BYTES_LIMIT = 100'000; // 100 KB

// FDB internal structure sizes for approximate size calculation
// See fdbclient/ReadYourWrites.actor.cpp for details
constexpr size_t FDB_SIZEOF_KEYRANGEREF = 32; // sizeof(KeyRangeRef)
constexpr size_t FDB_SIZEOF_MUTATIONREF = 56; // sizeof(MutationRef)

// Helper functions for calculating approximate size according to FDB's implementation
namespace {

// Calculate approximate size for read operation on single key
// Formula: 2*key + 1 + sizeof(KeyRangeRef)
// See fdbclient/ReadYourWrites.actor.cpp:329
inline constexpr size_t read_get_approximate_size(size_t key_size) {
return key_size * 2 + 1 + FDB_SIZEOF_KEYRANGEREF;
}

// Calculate approximate size for read operation on range
// Formula: begin + end + sizeof(KeyRangeRef)
// See fdbclient/ReadYourWrites.actor.cpp:245-280
inline constexpr size_t read_get_range_approximate_size(size_t begin_size, size_t end_size) {
return begin_size + end_size + FDB_SIZEOF_KEYRANGEREF;
}

// Calculate approximate size for write operation (set/atomic_op)
// Formula: key + val + sizeof(MutationRef) + sizeof(KeyRangeRef) + 2*key + 1
// See fdbclient/ReadYourWrites.actor.cpp:2267-2269
inline constexpr size_t write_set_approximate_size(size_t key_size, size_t val_size) {
size_t write_conflict = FDB_SIZEOF_KEYRANGEREF + key_size * 2 + 1;
return key_size + val_size + FDB_SIZEOF_MUTATIONREF + write_conflict;
}

// Calculate approximate size for clear operation on single key
// Formula: 2*key + 2*sizeof(KeyRangeRef)
// See fdbclient/ReadYourWrites.actor.cpp:2361-2362
inline constexpr size_t write_clear_approximate_size(size_t key_size) {
return key_size * 2 + FDB_SIZEOF_KEYRANGEREF * 2;
}

// Calculate approximate size for clear_range operation
// Formula: begin+end + sizeof(MutationRef) + sizeof(KeyRangeRef) + begin+end
// See fdbclient/ReadYourWrites.actor.cpp:2304-2306
inline constexpr size_t write_clear_range_approximate_size(size_t begin_size, size_t end_size) {
size_t write_conflict = FDB_SIZEOF_KEYRANGEREF + begin_size + end_size;
return begin_size + end_size + FDB_SIZEOF_MUTATIONREF + write_conflict;
}

} // anonymous namespace

// Ref https://apple.github.io/foundationdb/api-error-codes.html#developer-guide-error-codes.
constexpr fdb_error_t FDB_ERROR_CODE_TIMED_OUT = 1004;
constexpr fdb_error_t FDB_ERROR_CODE_TXN_TOO_OLD = 1007;
Expand Down Expand Up @@ -488,7 +535,7 @@ void Transaction::put(std::string_view key, std::string_view val) {

++num_put_keys_;
put_bytes_ += key.size() + val.size();
approximate_bytes_ += key.size() * 3 + val.size(); // See fdbclient/ReadYourWrites.actor.cpp
approximate_bytes_ += write_set_approximate_size(key.size(), val.size());

if (val.size() > FDB_VALUE_BYTES_LIMIT) {
LOG_WARNING("txn put with large value")
Expand Down Expand Up @@ -533,7 +580,9 @@ TxnErrorCode Transaction::get(std::string_view key, std::string* val, bool snaps
may_logging_single_version_reading(key);

StopWatch sw;
approximate_bytes_ += key.size() * 2; // See fdbclient/ReadYourWrites.actor.cpp for details
if (!snapshot) {
approximate_bytes_ += read_get_approximate_size(key.size());
}
auto* fut = fdb_transaction_get(txn_, (uint8_t*)key.data(), key.size(), snapshot);

g_bvar_txn_kv_get_count_normalized << 1;
Expand Down Expand Up @@ -577,7 +626,9 @@ TxnErrorCode Transaction::get(std::string_view begin, std::string_view end,
may_logging_single_version_reading(begin);

StopWatch sw;
approximate_bytes_ += begin.size() + end.size();
if (!opts.snapshot) {
approximate_bytes_ += read_get_range_approximate_size(begin.size(), end.size());
}
DORIS_CLOUD_DEFER {
g_bvar_txn_kv_range_get << sw.elapsed_us();
};
Expand Down Expand Up @@ -637,7 +688,7 @@ void Transaction::atomic_set_ver_key(std::string_view key_prefix, std::string_vi
g_bvar_txn_kv_atomic_set_ver_key << sw.elapsed_us();
++num_put_keys_;
put_bytes_ += key.size() + val.size();
approximate_bytes_ += key.size() * 3 + val.size();
approximate_bytes_ += write_set_approximate_size(key.size(), val.size());

if (val.size() > FDB_VALUE_BYTES_LIMIT) {
LOG_WARNING("atomic_set_ver_key with large value")
Expand Down Expand Up @@ -666,7 +717,7 @@ bool Transaction::atomic_set_ver_key(std::string_view key, uint32_t offset, std:
g_bvar_txn_kv_atomic_set_ver_key << sw.elapsed_us();
++num_put_keys_;
put_bytes_ += key_buf.size() + val.size();
approximate_bytes_ += key_buf.size() * 3 + val.size();
approximate_bytes_ += write_set_approximate_size(key_buf.size(), val.size());

if (val.size() > FDB_VALUE_BYTES_LIMIT) {
LOG_WARNING("atomic_set_ver_key with large value")
Expand Down Expand Up @@ -694,7 +745,7 @@ void Transaction::atomic_set_ver_value(std::string_view key, std::string_view va
g_bvar_txn_kv_atomic_set_ver_value << sw.elapsed_us();
++num_put_keys_;
put_bytes_ += key.size() + val.size();
approximate_bytes_ += key.size() * 3 + val.size();
approximate_bytes_ += write_set_approximate_size(key.size(), val.size());

if (val.size() > FDB_VALUE_BYTES_LIMIT) {
LOG_WARNING("atomic_set_ver_value with large value")
Expand All @@ -714,7 +765,7 @@ void Transaction::atomic_add(std::string_view key, int64_t to_add) {
g_bvar_txn_kv_atomic_add << sw.elapsed_us();
++num_put_keys_;
put_bytes_ += key.size() + 8;
approximate_bytes_ += key.size() * 3 + 8;
approximate_bytes_ += write_set_approximate_size(key.size(), 8);
}

bool Transaction::decode_atomic_int(std::string_view data, int64_t* val) {
Expand All @@ -736,7 +787,7 @@ void Transaction::remove(std::string_view key) {
g_bvar_txn_kv_remove << sw.elapsed_us();
++num_del_keys_;
delete_bytes_ += key.size();
approximate_bytes_ += key.size() * 4; // See fdbclient/ReadYourWrites.actor.cpp for details.
approximate_bytes_ += write_clear_approximate_size(key.size());
}

void Transaction::remove(std::string_view begin, std::string_view end) {
Expand All @@ -746,8 +797,7 @@ void Transaction::remove(std::string_view begin, std::string_view end) {
g_bvar_txn_kv_range_remove << sw.elapsed_us();
num_del_keys_ += 2;
delete_bytes_ += begin.size() + end.size();
approximate_bytes_ +=
(begin.size() + end.size()) * 2; // See fdbclient/ReadYourWrites.actor.cpp for details.
approximate_bytes_ += write_clear_range_approximate_size(begin.size(), end.size());
}

TxnErrorCode Transaction::commit() {
Expand Down Expand Up @@ -1143,7 +1193,9 @@ TxnErrorCode Transaction::batch_get(std::vector<std::optional<std::string>>* res
may_logging_single_version_reading(k);
futures.emplace_back(
fdb_transaction_get(txn_, (uint8_t*)k.data(), k.size(), opts.snapshot));
approximate_bytes_ += k.size() * 2;
if (!opts.snapshot) {
approximate_bytes_ += read_get_approximate_size(k.size());
}
}

size_t num_futures = futures.size();
Expand Down Expand Up @@ -1221,7 +1273,9 @@ TxnErrorCode Transaction::batch_scan(
snapshot, reverse);

futures.emplace_back(fut);
approximate_bytes_ += start.size() + end.size();
if (!opts.snapshot) {
approximate_bytes_ += read_get_range_approximate_size(start.size(), end.size());
}
}

size_t num_futures = futures.size();
Expand Down
Loading