86 lines
3.3 KiB
C++
86 lines
3.3 KiB
C++
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#include <experimental/filesystem>
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#include <experimental/optional>
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#include <string>
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#include "glog/logging.h"
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#include "transactions/type.hpp"
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#include "utils/datetime/timestamp.hpp"
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#include "utils/string.hpp"
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namespace durability {
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namespace fs = std::experimental::filesystem;
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/// Returns true if the given directory path exists or is succesfully created.
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bool EnsureDir(const fs::path &dir) {
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if (fs::exists(dir)) return true;
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std::error_code error_code; // Just for exception suppression.
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return fs::create_directories(dir, error_code);
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}
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/// Ensures the given durability directory exists and is ready for use. Creates
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/// the directory if it doesn't exist.
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void CheckDurabilityDir(const std::string &durability_dir) {
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namespace fs = std::experimental::filesystem;
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if (fs::exists(durability_dir)) {
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CHECK(fs::is_directory(durability_dir)) << "The durability directory path '"
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<< durability_dir
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<< "' is not a directory!";
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} else {
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bool success = EnsureDir(durability_dir);
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CHECK(success) << "Failed to create durability directory '"
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<< durability_dir << "'.";
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}
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}
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/// Returns the transaction id contained in the file name. If the filename is
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/// not a parseable WAL file name, nullopt is returned. If the filename
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/// represents the "current" WAL file, then the maximum possible transaction ID
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/// is returned because that's appropriate for the recovery logic (the current
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/// WAL does not yet have a maximum transaction ID and can't be discarded by
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/// the recovery regardless of the snapshot from which the transaction starts).
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std::experimental::optional<tx::transaction_id_t> TransactionIdFromWalFilename(
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const std::string &name) {
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auto nullopt = std::experimental::nullopt;
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// Get the max_transaction_id from the file name that has format
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// "XXXXX__max_transaction_<MAX_TRANS_ID>"
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auto file_name_split = utils::RSplit(name, "__", 1);
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if (file_name_split.size() != 2) {
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LOG(WARNING) << "Unable to parse WAL file name: " << name;
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return nullopt;
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}
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if (file_name_split[1] == "current")
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return std::numeric_limits<tx::transaction_id_t>::max();
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file_name_split = utils::RSplit(file_name_split[1], "_", 1);
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if (file_name_split.size() != 2) {
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LOG(WARNING) << "Unable to parse WAL file name: " << name;
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return nullopt;
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}
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auto &tx_id_str = file_name_split[1];
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try {
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return std::stoll(tx_id_str);
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} catch (std::invalid_argument &) {
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LOG(WARNING) << "Unable to parse WAL file name tx ID: " << tx_id_str;
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return nullopt;
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} catch (std::out_of_range &) {
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LOG(WARNING) << "WAL file name tx ID too large: " << tx_id_str;
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return nullopt;
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}
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}
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/// Generates a file path for a write-ahead log file. If given a transaction ID
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/// the file name will contain it. Otherwise the file path is for the "current"
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/// WAL file for which the max tx id is still unknown.
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fs::path WalFilenameForTransactionId(
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const std::experimental::filesystem::path &wal_dir,
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std::experimental::optional<tx::transaction_id_t> tx_id =
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std::experimental::nullopt) {
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auto file_name = Timestamp::now().to_iso8601();
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if (tx_id) {
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file_name += "__max_transaction_" + std::to_string(*tx_id);
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} else {
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file_name += "__current";
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}
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return wal_dir / file_name;
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}
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} // namespace durability
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