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Diffstat (limited to 'src/mongo/db/concurrency/exception_util.h')
| -rw-r--r-- | src/mongo/db/concurrency/exception_util.h | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/src/mongo/db/concurrency/exception_util.h b/src/mongo/db/concurrency/exception_util.h new file mode 100644 index 00000000000..9aac97b9d70 --- /dev/null +++ b/src/mongo/db/concurrency/exception_util.h @@ -0,0 +1,135 @@ +/** + * Copyright (C) 2022-present MongoDB, Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the Server Side Public License, version 1, + * as published by MongoDB, Inc. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * Server Side Public License for more details. + * + * You should have received a copy of the Server Side Public License + * along with this program. If not, see + * <http://www.mongodb.com/licensing/server-side-public-license>. + * + * As a special exception, the copyright holders give permission to link the + * code of portions of this program with the OpenSSL library under certain + * conditions as described in each individual source file and distribute + * linked combinations including the program with the OpenSSL library. You + * must comply with the Server Side Public License in all respects for + * all of the code used other than as permitted herein. If you modify file(s) + * with this exception, you may extend this exception to your version of the + * file(s), but you are not obligated to do so. If you do not wish to do so, + * delete this exception statement from your version. If you delete this + * exception statement from all source files in the program, then also delete + * it in the license file. + */ + +#pragma once + +#include "mongo/base/string_data.h" +#include "mongo/db/concurrency/temporarily_unavailable_exception.h" +#include "mongo/db/concurrency/write_conflict_exception.h" +#include "mongo/db/curop.h" +#include "mongo/db/operation_context.h" +#include "mongo/util/assert_util.h" +#include "mongo/util/fail_point.h" + +namespace mongo { + +extern FailPoint skipWriteConflictRetries; + +/** + * Will log a message if sensible and will do an exponential backoff to make sure + * we don't hammer the same doc over and over. + * @param attempt - what attempt is this, 1 based + * @param operation - e.g. "update" + */ +void logWriteConflictAndBackoff(int attempt, StringData operation, StringData ns); + +void handleTemporarilyUnavailableException(OperationContext* opCtx, + int attempts, + StringData opStr, + StringData ns, + const TemporarilyUnavailableException& e); + +/** + * Handle a TemporarilyUnavailableException inside a multi-document transaction. + */ +void handleTemporarilyUnavailableExceptionInTransaction(OperationContext* opCtx, + StringData opStr, + StringData ns, + const TemporarilyUnavailableException& e); + +void handleTransactionTooLargeForCacheException(OperationContext* opCtx, + int* writeConflictAttempts, + StringData opStr, + StringData ns, + const TransactionTooLargeForCacheException& e); + +/** + * A `TransactionTooLargeForCache` is thrown if it has been determined that it is unlikely to + * ever complete the operation because the configured cache is insufficient to hold all the + * transaction state. This helps to avoid retrying, maybe indefinitely, a transaction which would + * never be able to complete. + */ +[[noreturn]] inline void throwTransactionTooLargeForCache(StringData context) { + iasserted({ErrorCodes::TransactionTooLargeForCache, context}); +} + +/** + * Runs the argument function f as many times as needed for f to complete or throw an exception + * other than WriteConflictException or TemporarilyUnavailableException. For each time f throws an + * one of these exceptions, logs the error, waits a spell, cleans up, and then tries f again. + * Imposes no upper limit on the number of times to re-try f after a WriteConflictException, so any + * required timeout behavior must be enforced within f. When retrying a + * TemporarilyUnavailableException, f is called a finite number of times before we eventually let + * the error escape. + * + * If we are already in a WriteUnitOfWork, we assume that we are being called within a + * WriteConflictException retry loop up the call stack. Hence, this retry loop is reduced to an + * invocation of the argument function f without any exception handling and retry logic. + */ +template <typename F> +auto writeConflictRetry(OperationContext* opCtx, StringData opStr, StringData ns, F&& f) { + invariant(opCtx); + invariant(opCtx->lockState()); + invariant(opCtx->recoveryUnit()); + + // This failpoint disables exception handling for write conflicts. Only allow this exception to + // escape user operations. Do not allow exceptions to escape internal threads, which may rely on + // this exception handler to avoid crashing. + bool userSkipWriteConflictRetry = MONGO_unlikely(skipWriteConflictRetries.shouldFail()) && + opCtx->getClient()->isFromUserConnection(); + if (opCtx->lockState()->inAWriteUnitOfWork() || userSkipWriteConflictRetry) { + try { + return f(); + } catch (TemporarilyUnavailableException const& e) { + if (opCtx->inMultiDocumentTransaction()) { + handleTemporarilyUnavailableExceptionInTransaction(opCtx, opStr, ns, e); + } + throw; + } + } + + int writeConflictAttempts = 0; + int attemptsTempUnavailable = 0; + while (true) { + try { + return f(); + } catch (WriteConflictException const&) { + CurOp::get(opCtx)->debug().additiveMetrics.incrementWriteConflicts(1); + logWriteConflictAndBackoff(writeConflictAttempts, opStr, ns); + ++writeConflictAttempts; + opCtx->recoveryUnit()->abandonSnapshot(); + } catch (TemporarilyUnavailableException const& e) { + handleTemporarilyUnavailableException(opCtx, ++attemptsTempUnavailable, opStr, ns, e); + } catch (TransactionTooLargeForCacheException const& e) { + handleTransactionTooLargeForCacheException(opCtx, &writeConflictAttempts, opStr, ns, e); + } + } +} + +} // namespace mongo |
