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+/**
+ * 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