/*-
 * #%L
 * HAPI FHIR Storage api
 * %%
 * Copyright (C) 2014 - 2025 Smile CDR, Inc.
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
package ca.uhn.fhir.jpa.dao.tx;

import ca.uhn.fhir.i18n.Msg;
import ca.uhn.fhir.interceptor.api.HookParams;
import ca.uhn.fhir.interceptor.api.IInterceptorBroadcaster;
import ca.uhn.fhir.interceptor.api.Pointcut;
import ca.uhn.fhir.interceptor.model.RequestPartitionId;
import ca.uhn.fhir.jpa.api.model.ResourceVersionConflictResolutionStrategy;
import ca.uhn.fhir.jpa.dao.DaoFailureUtil;
import ca.uhn.fhir.jpa.model.config.PartitionSettings;
import ca.uhn.fhir.jpa.partition.IRequestPartitionHelperSvc;
import ca.uhn.fhir.rest.api.server.RequestDetails;
import ca.uhn.fhir.rest.api.server.storage.TransactionDetails;
import ca.uhn.fhir.rest.server.exceptions.BaseServerResponseException;
import ca.uhn.fhir.rest.server.exceptions.InternalErrorException;
import ca.uhn.fhir.rest.server.exceptions.ResourceVersionConflictException;
import ca.uhn.fhir.rest.server.servlet.ServletRequestDetails;
import ca.uhn.fhir.rest.server.util.CompositeInterceptorBroadcaster;
import ca.uhn.fhir.util.ICallable;
import ca.uhn.fhir.util.SleepUtil;
import com.google.common.annotations.VisibleForTesting;
import jakarta.annotation.Nonnull;
import jakarta.annotation.Nullable;
import jakarta.persistence.PessimisticLockException;
import org.apache.commons.lang3.Validate;
import org.apache.commons.lang3.exception.ExceptionUtils;
import org.hibernate.exception.ConstraintViolationException;
import org.hl7.fhir.instance.model.api.IBaseOperationOutcome;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.DataIntegrityViolationException;
import org.springframework.dao.PessimisticLockingFailureException;
import org.springframework.orm.ObjectOptimisticLockingFailureException;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.annotation.Isolation;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.support.TransactionCallback;
import org.springframework.transaction.support.TransactionCallbackWithoutResult;
import org.springframework.transaction.support.TransactionOperations;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.transaction.support.TransactionTemplate;

import java.util.List;
import java.util.Objects;
import java.util.concurrent.Callable;
import java.util.stream.Stream;

/**
 * @see IHapiTransactionService for an explanation of this class
 */
public class HapiTransactionService implements IHapiTransactionService {

        public static final String XACT_USERDATA_KEY_RESOLVED_TAG_DEFINITIONS =
                        HapiTransactionService.class.getName() + "_RESOLVED_TAG_DEFINITIONS";
        public static final String XACT_USERDATA_KEY_EXISTING_SEARCH_PARAMS =
                        HapiTransactionService.class.getName() + "_EXISTING_SEARCH_PARAMS";
        private static final Logger ourLog = LoggerFactory.getLogger(HapiTransactionService.class);
        private static final ThreadLocal<RequestPartitionId> ourRequestPartitionThreadLocal = new ThreadLocal<>();
        private static final ThreadLocal<HapiTransactionService> ourExistingTransaction = new ThreadLocal<>();

        /**
         * Default value for {@link #setTransactionPropagationWhenChangingPartitions(Propagation)}
         *
         * @since 7.6.0
         */
        public static final Propagation DEFAULT_TRANSACTION_PROPAGATION_WHEN_CHANGING_PARTITIONS = Propagation.REQUIRED;

        @Autowired
        protected IInterceptorBroadcaster myInterceptorBroadcaster;

        @Autowired
        protected PlatformTransactionManager myTransactionManager;

        @Autowired
        protected IRequestPartitionHelperSvc myRequestPartitionHelperSvc;

        @Autowired
        protected PartitionSettings myPartitionSettings;

        private Propagation myTransactionPropagationWhenChangingPartitions =
                        DEFAULT_TRANSACTION_PROPAGATION_WHEN_CHANGING_PARTITIONS;

        private SleepUtil mySleepUtil = new SleepUtil();

        @VisibleForTesting
        public void setInterceptorBroadcaster(IInterceptorBroadcaster theInterceptorBroadcaster) {
                myInterceptorBroadcaster = theInterceptorBroadcaster;
        }

        @VisibleForTesting
        public void setSleepUtil(SleepUtil theSleepUtil) {
                mySleepUtil = theSleepUtil;
        }

        @Override
        public IExecutionBuilder withRequest(@Nullable RequestDetails theRequestDetails) {
                return buildExecutionBuilder(theRequestDetails);
        }

        @Override
        public IExecutionBuilder withSystemRequest() {
                return buildExecutionBuilder(null);
        }

        protected IExecutionBuilder buildExecutionBuilder(@Nullable RequestDetails theRequestDetails) {
                return new ExecutionBuilder(theRequestDetails);
        }

        /**
         * @deprecated Use {@link #withRequest(RequestDetails)} with fluent call instead
         */
        @Deprecated
        public <T> T execute(
                        @Nullable RequestDetails theRequestDetails,
                        @Nullable TransactionDetails theTransactionDetails,
                        @Nonnull TransactionCallback<T> theCallback) {
                return execute(theRequestDetails, theTransactionDetails, theCallback, null);
        }

        /**
         * @deprecated Use {@link #withRequest(RequestDetails)} with fluent call instead
         */
        @Deprecated
        public void execute(
                        @Nullable RequestDetails theRequestDetails,
                        @Nullable TransactionDetails theTransactionDetails,
                        @Nonnull Propagation thePropagation,
                        @Nonnull Isolation theIsolation,
                        @Nonnull Runnable theCallback) {
                TransactionCallbackWithoutResult callback = new TransactionCallbackWithoutResult() {
                        @Override
                        protected void doInTransactionWithoutResult(@Nonnull TransactionStatus status) {
                                theCallback.run();
                        }
                };
                execute(theRequestDetails, theTransactionDetails, callback, null, thePropagation, theIsolation);
        }

        /**
         * @deprecated Use {@link #withRequest(RequestDetails)} with fluent call instead
         */
        @Deprecated
        @Override
        public <T> T withRequest(
                        @Nullable RequestDetails theRequestDetails,
                        @Nullable TransactionDetails theTransactionDetails,
                        @Nonnull Propagation thePropagation,
                        @Nonnull Isolation theIsolation,
                        @Nonnull ICallable<T> theCallback) {

                TransactionCallback<T> callback = tx -> theCallback.call();
                return execute(theRequestDetails, theTransactionDetails, callback, null, thePropagation, theIsolation);
        }

        /**
         * @deprecated Use {@link #withRequest(RequestDetails)} with fluent call instead
         */
        @Deprecated
        public <T> T execute(
                        @Nullable RequestDetails theRequestDetails,
                        @Nullable TransactionDetails theTransactionDetails,
                        @Nonnull TransactionCallback<T> theCallback,
                        @Nullable Runnable theOnRollback) {
                return execute(theRequestDetails, theTransactionDetails, theCallback, theOnRollback, null, null);
        }

        /**
         * @deprecated Use {@link #withRequest(RequestDetails)} with fluent call instead
         */
        @Deprecated
        @SuppressWarnings({"ConstantConditions", "removal"})
        public <T> T execute(
                        @Nullable RequestDetails theRequestDetails,
                        @Nullable TransactionDetails theTransactionDetails,
                        @Nonnull TransactionCallback<T> theCallback,
                        @Nullable Runnable theOnRollback,
                        @Nullable Propagation thePropagation,
                        @Nullable Isolation theIsolation) {
                return withRequest(theRequestDetails)
                                .withTransactionDetails(theTransactionDetails)
                                .withPropagation(thePropagation)
                                .withIsolation(theIsolation)
                                .onRollback(theOnRollback)
                                .execute(theCallback);
        }

        /**
         * @deprecated Use {@link #withRequest(RequestDetails)} with fluent call instead
         */
        @SuppressWarnings("removal")
        @Deprecated
        public <T> T execute(
                        @Nullable RequestDetails theRequestDetails,
                        @Nullable TransactionDetails theTransactionDetails,
                        @Nonnull TransactionCallback<T> theCallback,
                        @Nullable Runnable theOnRollback,
                        @Nonnull Propagation thePropagation,
                        @Nonnull Isolation theIsolation,
                        RequestPartitionId theRequestPartitionId) {
                return withRequest(theRequestDetails)
                                .withTransactionDetails(theTransactionDetails)
                                .withPropagation(thePropagation)
                                .withIsolation(theIsolation)
                                .withRequestPartitionId(theRequestPartitionId)
                                .onRollback(theOnRollback)
                                .execute(theCallback);
        }

        public boolean isCustomIsolationSupported() {
                return false;
        }

        @VisibleForTesting
        public void setRequestPartitionSvcForUnitTest(IRequestPartitionHelperSvc theRequestPartitionHelperSvc) {
                myRequestPartitionHelperSvc = theRequestPartitionHelperSvc;
        }

        public PlatformTransactionManager getTransactionManager() {
                return myTransactionManager;
        }

        @VisibleForTesting
        public void setTransactionManager(PlatformTransactionManager theTransactionManager) {
                myTransactionManager = theTransactionManager;
        }

        @VisibleForTesting
        public void setPartitionSettingsForUnitTest(PartitionSettings thePartitionSettings) {
                myPartitionSettings = thePartitionSettings;
        }

        @Nullable
        protected <T> T doExecute(ExecutionBuilder theExecutionBuilder, TransactionCallback<T> theCallback) {
                RequestPartitionId effectiveRequestPartitionId = theExecutionBuilder.getEffectiveRequestPartitionId();
                final RequestPartitionId requestPartitionId;
                if (effectiveRequestPartitionId != null
                                && myPartitionSettings.isDefaultPartition(effectiveRequestPartitionId)) {
                        requestPartitionId = myPartitionSettings.getDefaultRequestPartitionId();
                } else {
                        requestPartitionId = effectiveRequestPartitionId;
                }

                RequestPartitionId previousRequestPartitionId = null;
                if (requestPartitionId != null) {
                        previousRequestPartitionId = ourRequestPartitionThreadLocal.get();
                        ourRequestPartitionThreadLocal.set(requestPartitionId);
                }

                ourLog.trace("Starting doExecute for RequestPartitionId {}", requestPartitionId);
                if (isCompatiblePartition(previousRequestPartitionId, requestPartitionId)) {
                        if (ourExistingTransaction.get() == this && canReuseExistingTransaction(theExecutionBuilder)) {
                                /*
                                 * If we're already in an active transaction, and it's for the right partition,
                                 * and it's not a read-only transaction, we don't need to open a new transaction
                                 * so let's just add a method to the stack trace that makes this obvious.
                                 */
                                return executeInExistingTransaction(theCallback);
                        }
                }

                HapiTransactionService previousExistingTransaction = ourExistingTransaction.get();
                try {
                        ourExistingTransaction.set(this);

                        if (isRequiresNewTransactionWhenChangingPartitions()) {
                                return executeInNewTransactionForPartitionChange(
                                                theExecutionBuilder, theCallback, requestPartitionId, previousRequestPartitionId);
                        } else {
                                return doExecuteInTransaction(
                                                theExecutionBuilder, theCallback, requestPartitionId, previousRequestPartitionId);
                        }
                } finally {
                        ourExistingTransaction.set(previousExistingTransaction);
                }
        }

        protected boolean isRequiresNewTransactionWhenChangingPartitions() {
                return myTransactionPropagationWhenChangingPartitions == Propagation.REQUIRES_NEW;
        }

        @Override
        public boolean isCompatiblePartition(
                        RequestPartitionId theRequestPartitionId, RequestPartitionId theOtherRequestPartitionId) {
                return !myPartitionSettings.isPartitioningEnabled()
                                || !isRequiresNewTransactionWhenChangingPartitions()
                                || Objects.equals(theRequestPartitionId, theOtherRequestPartitionId);
        }

        @Nullable
        private <T> T executeInNewTransactionForPartitionChange(
                        ExecutionBuilder theExecutionBuilder,
                        TransactionCallback<T> theCallback,
                        RequestPartitionId requestPartitionId,
                        RequestPartitionId previousRequestPartitionId) {
                ourLog.trace("executeInNewTransactionForPartitionChange");
                theExecutionBuilder.myPropagation = myTransactionPropagationWhenChangingPartitions;
                return doExecuteInTransaction(theExecutionBuilder, theCallback, requestPartitionId, previousRequestPartitionId);
        }

        private boolean isThrowableOrItsSubclassPresent(Throwable theThrowable, Class<? extends Throwable> theClass) {
                return ExceptionUtils.indexOfType(theThrowable, theClass) != -1;
        }

        private boolean isThrowablePresent(Throwable theThrowable, Class<? extends Throwable> theClass) {
                return ExceptionUtils.indexOfThrowable(theThrowable, theClass) != -1;
        }

        private boolean isRetriable(Throwable theThrowable) {
                return isThrowablePresent(theThrowable, ResourceVersionConflictException.class)
                                || isThrowablePresent(theThrowable, DataIntegrityViolationException.class)
                                || isThrowablePresent(theThrowable, ConstraintViolationException.class)
                                || isThrowablePresent(theThrowable, ObjectOptimisticLockingFailureException.class)
                                // calling isThrowableOrItsSubclassPresent instead of isThrowablePresent for
                                // PessimisticLockingFailureException, because we want to retry on its subclasses as well,  especially
                                // CannotAcquireLockException, which is thrown in some deadlock situations which we want to retry
                                || isThrowableOrItsSubclassPresent(theThrowable, PessimisticLockingFailureException.class)
                                || isThrowableOrItsSubclassPresent(theThrowable, PessimisticLockException.class);
        }

        @Nullable
        private <T> T doExecuteInTransaction(
                        ExecutionBuilder theExecutionBuilder,
                        TransactionCallback<T> theCallback,
                        RequestPartitionId requestPartitionId,
                        RequestPartitionId previousRequestPartitionId) {
                ourLog.trace("doExecuteInTransaction");
                try {
                        // retry loop
                        for (int i = 0; ; i++) {
                                try {

                                        return doExecuteCallback(theExecutionBuilder, theCallback);

                                } catch (Exception e) {
                                        int retriesRemaining = 0;
                                        int maxRetries = 0;
                                        boolean exceptionIsRetriable = isRetriable(e);
                                        if (exceptionIsRetriable) {
                                                maxRetries = calculateMaxRetries(theExecutionBuilder.myRequestDetails, e);
                                                retriesRemaining = maxRetries - i;
                                        }

                                        // we roll back on all exceptions.
                                        theExecutionBuilder.rollbackTransactionProcessingChanges(retriesRemaining > 0);

                                        if (!exceptionIsRetriable) {
                                                ourLog.debug("Unexpected transaction exception. Will not be retried.", e);
                                                throw e;
                                        } else {
                                                // We have several exceptions that we consider retriable, call all of them "version conflicts"
                                                ourLog.debug("Version conflict detected", e);

                                                // should we retry?
                                                if (retriesRemaining > 0) {
                                                        // We are retrying.
                                                        sleepForRetry(i);
                                                } else {
                                                        throwResourceVersionConflictException(i, maxRetries, e);
                                                }
                                        }
                                }
                        }
                } finally {
                        if (requestPartitionId != null) {
                                ourRequestPartitionThreadLocal.set(previousRequestPartitionId);
                        }
                }
        }

        private static void throwResourceVersionConflictException(
                        int theAttemptIndex, int theMaxRetries, Exception theCause) {
                IBaseOperationOutcome oo = null;
                if (theCause instanceof ResourceVersionConflictException) {
                        oo = ((ResourceVersionConflictException) theCause).getOperationOutcome();
                }

                if (theAttemptIndex > 0) {
                        // log if we tried to retry, but still failed
                        String msg = "Max retries (" + theMaxRetries + ") exceeded for version conflict: " + theCause.getMessage();
                        ourLog.info(msg);
                        throw new ResourceVersionConflictException(Msg.code(549) + msg, theCause, oo);
                }

                throw new ResourceVersionConflictException(Msg.code(550) + theCause.getMessage(), theCause, oo);
        }

        /**
         * Sleep a bit more each time, with 0 sleep on first retry and some random dither.
         * @param theAttemptIndex 0-index for the first attempt, 1 for second, etc.
         */
        private void sleepForRetry(int theAttemptIndex) {
                double sleepAmount = (250.0d * theAttemptIndex) * Math.random();
                long sleepAmountLong = (long) sleepAmount;
                ourLog.info(
                                "About to start a transaction retry due to conflict or constraint error. Sleeping {}ms first.",
                                sleepAmountLong);
                mySleepUtil.sleepAtLeast(sleepAmountLong, false);
        }

        public void setTransactionPropagationWhenChangingPartitions(
                        Propagation theTransactionPropagationWhenChangingPartitions) {
                Objects.requireNonNull(theTransactionPropagationWhenChangingPartitions);
                myTransactionPropagationWhenChangingPartitions = theTransactionPropagationWhenChangingPartitions;
        }

        @Nullable
        protected <T> T doExecuteCallback(ExecutionBuilder theExecutionBuilder, TransactionCallback<T> theCallback) {
                try {
                        TransactionTemplate txTemplate = new TransactionTemplate(myTransactionManager);

                        if (theExecutionBuilder.myPropagation != null) {
                                txTemplate.setPropagationBehavior(theExecutionBuilder.myPropagation.value());
                        }

                        if (isCustomIsolationSupported()
                                        && theExecutionBuilder.myIsolation != null
                                        && theExecutionBuilder.myIsolation != Isolation.DEFAULT) {
                                txTemplate.setIsolationLevel(theExecutionBuilder.myIsolation.value());
                        }

                        if (theExecutionBuilder.myReadOnly) {
                                txTemplate.setReadOnly(true);
                        }

                        return txTemplate.execute(theCallback);
                } catch (MyException e) {
                        if (e.getCause() instanceof RuntimeException) {
                                throw (RuntimeException) e.getCause();
                        } else {
                                throw new InternalErrorException(Msg.code(551) + e);
                        }
                }
        }

        private int calculateMaxRetries(RequestDetails theRequestDetails, Exception e) {
                int maxRetries = 0;

                /*
                 * If two client threads both concurrently try to add the same tag that isn't
                 * known to the system already, they'll both try to create a row in HFJ_TAG_DEF,
                 * which is the tag definition table. In that case, a constraint error will be
                 * thrown by one of the client threads, so we auto-retry in order to avoid
                 * annoying spurious failures for the client.
                 */
                if (DaoFailureUtil.isTagStorageFailure(e)) {
                        maxRetries = 3;
                }

                // Our default policy is no-retry.
                // But we often register UserRequestRetryVersionConflictsInterceptor, which supports a retry header
                // and retry settings on RequestDetails.
                if (maxRetries == 0) {
                        IInterceptorBroadcaster compositeBroadcaster = CompositeInterceptorBroadcaster.newCompositeBroadcaster(
                                        this.myInterceptorBroadcaster, theRequestDetails);
                        if (compositeBroadcaster.hasHooks(Pointcut.STORAGE_VERSION_CONFLICT)) {
                                HookParams params = new HookParams()
                                                .add(RequestDetails.class, theRequestDetails)
                                                .addIfMatchesType(ServletRequestDetails.class, theRequestDetails);
                                ResourceVersionConflictResolutionStrategy conflictResolutionStrategy =
                                                (ResourceVersionConflictResolutionStrategy) compositeBroadcaster.callHooksAndReturnObject(
                                                                Pointcut.STORAGE_VERSION_CONFLICT, params);
                                if (conflictResolutionStrategy != null && conflictResolutionStrategy.isRetry()) {
                                        maxRetries = conflictResolutionStrategy.getMaxRetries();
                                }
                        }
                }
                return maxRetries;
        }

        protected class ExecutionBuilder implements IExecutionBuilder, TransactionOperations, Cloneable {
                private final RequestDetails myRequestDetails;
                private Isolation myIsolation;
                private Propagation myPropagation;
                private boolean myReadOnly;
                private TransactionDetails myTransactionDetails;
                private Runnable myOnRollback;
                protected RequestPartitionId myRequestPartitionId;

                protected ExecutionBuilder(RequestDetails theRequestDetails) {
                        myRequestDetails = theRequestDetails;
                }

                @Override
                public ExecutionBuilder withIsolation(Isolation theIsolation) {
                        assert myIsolation == null;
                        myIsolation = theIsolation;
                        return this;
                }

                @Override
                public ExecutionBuilder withTransactionDetails(TransactionDetails theTransactionDetails) {
                        assert myTransactionDetails == null;
                        myTransactionDetails = theTransactionDetails;
                        return this;
                }

                @Override
                public ExecutionBuilder withPropagation(Propagation thePropagation) {
                        assert myPropagation == null;
                        myPropagation = thePropagation;
                        return this;
                }

                @Override
                public ExecutionBuilder withRequestPartitionId(RequestPartitionId theRequestPartitionId) {
                        assert myRequestPartitionId == null;
                        myRequestPartitionId = theRequestPartitionId;
                        return this;
                }

                @Override
                public ExecutionBuilder readOnly() {
                        myReadOnly = true;
                        return this;
                }

                @SuppressWarnings("removal")
                @Override
                public ExecutionBuilder onRollback(Runnable theOnRollback) {
                        assert myOnRollback == null;
                        myOnRollback = theOnRollback;
                        return this;
                }

                @Override
                public void execute(Runnable theTask) {
                        TransactionCallback<Void> task = tx -> {
                                theTask.run();
                                return null;
                        };
                        execute(task);
                }

                @Override
                public <T> T execute(Callable<T> theTask) {
                        TransactionCallback<T> callback = tx -> invokeCallableAndHandleAnyException(theTask);
                        return execute(callback);
                }

                @Override
                public <T> T execute(@Nonnull TransactionCallback<T> callback) {
                        return doExecute(this, callback);
                }

                @Override
                public <T> T read(IExecutionCallable<T> theCallback) {
                        return execute(() -> theCallback.call(myRequestPartitionId));
                }

                @Override
                public <T> Stream<T> search(IExecutionCallable<Stream<T>> theCallback) {
                        return execute(() -> theCallback.call(myRequestPartitionId));
                }

                @Override
                public <T> List<T> searchList(IExecutionCallable<List<T>> theCallback) {
                        return execute(() -> theCallback.call(myRequestPartitionId));
                }

                @VisibleForTesting
                public RequestPartitionId getRequestPartitionIdForTesting() {
                        return myRequestPartitionId;
                }

                @VisibleForTesting
                public RequestDetails getRequestDetailsForTesting() {
                        return myRequestDetails;
                }

                public Propagation getPropagation() {
                        return myPropagation;
                }

                @Nullable
                protected RequestPartitionId getEffectiveRequestPartitionId() {
                        final RequestPartitionId requestPartitionId;
                        if (myRequestPartitionId != null) {
                                requestPartitionId = myRequestPartitionId;
                        } else if (myRequestDetails != null) {
                                requestPartitionId = myRequestPartitionHelperSvc.determineGenericPartitionForRequest(myRequestDetails);
                        } else {
                                requestPartitionId = null;
                        }
                        return requestPartitionId;
                }

                /**
                 * This method is called when a transaction has failed, and we need to rollback any changes made to the
                 * state of our objects in RAM.
                 * <p>
                 * This is used to undo any changes made during transaction resolution, such as conditional references,
                 * placeholders, etc.
                 *
                 * @param theWillRetry Should be <code>true</code> if the transaction is about to be automatically retried
                 *                     by the transaction service.
                 */
                void rollbackTransactionProcessingChanges(boolean theWillRetry) {
                        if (myOnRollback != null) {
                                myOnRollback.run();
                        }

                        if (myTransactionDetails != null) {
                                /*
                                 * Loop through the rollback undo actions in reverse order so we leave things in the correct
                                 * initial state. E.g., the resource ID may get modified twice if a resource is being modified
                                 * within a FHIR transaction: first the TransactionProcessor sets a new ID and adds a rollback
                                 * item, and then the Resource DAO touches the ID a second time and adds a second rollback item.
                                 */
                                List<Runnable> rollbackUndoActions = myTransactionDetails.getRollbackUndoActions();
                                for (int i = rollbackUndoActions.size() - 1; i >= 0; i--) {
                                        Runnable rollbackUndoAction = rollbackUndoActions.get(i);
                                        rollbackUndoAction.run();
                                }

                                /*
                                 * If we're about to retry the transaction, we shouldn't clear the rollback undo actions
                                 * because we need to re-execute them if the transaction fails a second time.
                                 */
                                if (!theWillRetry) {
                                        myTransactionDetails.clearRollbackUndoActions();
                                }

                                myTransactionDetails.clearResolvedItems();
                                myTransactionDetails.clearUserData(XACT_USERDATA_KEY_RESOLVED_TAG_DEFINITIONS);
                                myTransactionDetails.clearUserData(XACT_USERDATA_KEY_EXISTING_SEARCH_PARAMS);
                        }
                }
        }

        /**
         * This is just an unchecked exception so that we can catch checked exceptions inside TransactionTemplate
         * and rethrow them outside of it
         */
        static class MyException extends RuntimeException {

                public MyException(Throwable theThrowable) {
                        super(theThrowable);
                }
        }

        /**
         * Returns true if we already have an active transaction associated with the current thread, AND
         * either it's non-read-only or we only need a read-only transaction, AND
         * the newly requested transaction has a propagation of REQUIRED
         */
        private static boolean canReuseExistingTransaction(ExecutionBuilder theExecutionBuilder) {
                return TransactionSynchronizationManager.isActualTransactionActive()
                                && (!TransactionSynchronizationManager.isCurrentTransactionReadOnly() || theExecutionBuilder.myReadOnly)
                                && (theExecutionBuilder.myPropagation == null
                                                || theExecutionBuilder.myPropagation
                                                                == DEFAULT_TRANSACTION_PROPAGATION_WHEN_CHANGING_PARTITIONS);
        }

        @Nullable
        private static <T> T executeInExistingTransaction(@Nonnull TransactionCallback<T> theCallback) {
                ourLog.trace("executeInExistingTransaction");
                // TODO we could probably track the TransactionStatus we need as a thread local like we do our partition id.
                return theCallback.doInTransaction(null);
        }

        /**
         * Invokes {@link Callable#call()} and rethrows any exceptions thrown by that method.
         * If the exception extends {@link BaseServerResponseException} it is rethrown unmodified.
         * Otherwise, it's wrapped in a {@link InternalErrorException}.
         */
        public static <T> T invokeCallableAndHandleAnyException(Callable<T> theTask) {
                try {
                        return theTask.call();
                } catch (BaseServerResponseException e) {
                        throw e;
                } catch (Exception e) {
                        throw new InternalErrorException(Msg.code(2223) + e.getMessage(), e);
                }
        }

        public static <T> T executeWithDefaultPartitionInContext(@Nonnull ICallable<T> theCallback) {
                RequestPartitionId previousRequestPartitionId = ourRequestPartitionThreadLocal.get();
                ourRequestPartitionThreadLocal.set(RequestPartitionId.defaultPartition());
                try {
                        return theCallback.call();
                } finally {
                        ourRequestPartitionThreadLocal.set(previousRequestPartitionId);
                }
        }

        public static RequestPartitionId getRequestPartitionAssociatedWithThread() {
                return ourRequestPartitionThreadLocal.get();
        }

        /**
         * Throws an {@link IllegalArgumentException} if a transaction is active
         */
        public static void noTransactionAllowed() {
                Validate.isTrue(
                                !TransactionSynchronizationManager.isActualTransactionActive(),
                                "Transaction must not be active but found an active transaction");
        }

        /**
         * Throws an {@link IllegalArgumentException} if no transaction is active
         */
        public static void requireTransaction() {
                Validate.isTrue(
                                TransactionSynchronizationManager.isActualTransactionActive(),
                                "Transaction required here but no active transaction found");
        }
}