org.springframework.transaction.reactive.TransactionSynchronizationManager Maven / Gradle / Ivy
/*
* Copyright 2002-2023 the original author or authors.
*
* 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
*
* https://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.
*/
package org.springframework.transaction.reactive;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import reactor.core.publisher.Mono;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.lang.Nullable;
import org.springframework.transaction.NoTransactionException;
import org.springframework.util.Assert;
/**
* Central delegate that manages resources and transaction synchronizations per
* subscriber context. To be used by resource management code but not by typical
* application code.
*
* Supports one resource per key without overwriting, that is, a resource needs
* to be removed before a new one can be set for the same key.
* Supports a list of transaction synchronizations if synchronization is active.
*
*
Resource management code should check for context-bound resources, e.g.
* database connections, via {@code getResource}. Such code is normally not
* supposed to bind resources to units of work, as this is the responsibility
* of transaction managers. A further option is to lazily bind on first use if
* transaction synchronization is active, for performing transactions that span
* an arbitrary number of resources.
*
*
Transaction synchronization must be activated and deactivated by a transaction
* manager via {@link #initSynchronization()} and {@link #clearSynchronization()}.
* This is automatically supported by {@link AbstractReactiveTransactionManager},
* and thus by all standard Spring transaction managers.
*
*
Resource management code should only register synchronizations when this
* manager is active, which can be checked via {@link #isSynchronizationActive};
* it should perform immediate resource cleanup else. If transaction synchronization
* isn't active, there is either no current transaction, or the transaction manager
* doesn't support transaction synchronization.
*
*
Synchronization is for example used to always return the same resources within
* a transaction, e.g. a database connection for any given connection factory.
*
* @author Mark Paluch
* @author Juergen Hoeller
* @since 5.2
* @see #isSynchronizationActive
* @see #registerSynchronization
* @see TransactionSynchronization
*/
public class TransactionSynchronizationManager {
private final TransactionContext transactionContext;
public TransactionSynchronizationManager(TransactionContext transactionContext) {
Assert.notNull(transactionContext, "TransactionContext must not be null");
this.transactionContext = transactionContext;
}
/**
* Get the {@link TransactionSynchronizationManager} that is associated with
* the current transaction context.
*
Mainly intended for code that wants to bind resources or synchronizations.
* @throws NoTransactionException if the transaction info cannot be found —
* for example, because the method was invoked outside a managed transaction
*/
public static Mono forCurrentTransaction() {
return TransactionContextManager.currentContext().map(TransactionSynchronizationManager::new);
}
/**
* Check if there is a resource for the given key bound to the current context.
* @param key the key to check (usually the resource factory)
* @return if there is a value bound to the current context
*/
public boolean hasResource(Object key) {
Object actualKey = TransactionSynchronizationUtils.unwrapResourceIfNecessary(key);
Object value = doGetResource(actualKey);
return (value != null);
}
/**
* Retrieve a resource for the given key that is bound to the current context.
* @param key the key to check (usually the resource factory)
* @return a value bound to the current context (usually the active
* resource object), or {@code null} if none
*/
@Nullable
public Object getResource(Object key) {
Object actualKey = TransactionSynchronizationUtils.unwrapResourceIfNecessary(key);
return doGetResource(actualKey);
}
/**
* Actually check the value of the resource that is bound for the given key.
*/
@Nullable
private Object doGetResource(Object actualKey) {
return this.transactionContext.getResources().get(actualKey);
}
/**
* Bind the given resource for the given key to the current context.
* @param key the key to bind the value to (usually the resource factory)
* @param value the value to bind (usually the active resource object)
* @throws IllegalStateException if there is already a value bound to the context
*/
public void bindResource(Object key, Object value) throws IllegalStateException {
Object actualKey = TransactionSynchronizationUtils.unwrapResourceIfNecessary(key);
Assert.notNull(value, "Value must not be null");
Map map = this.transactionContext.getResources();
Object oldValue = map.put(actualKey, value);
if (oldValue != null) {
throw new IllegalStateException(
"Already value [" + oldValue + "] for key [" + actualKey + "] bound to context");
}
}
/**
* Unbind a resource for the given key from the current context.
* @param key the key to unbind (usually the resource factory)
* @return the previously bound value (usually the active resource object)
* @throws IllegalStateException if there is no value bound to the context
*/
public Object unbindResource(Object key) throws IllegalStateException {
Object actualKey = TransactionSynchronizationUtils.unwrapResourceIfNecessary(key);
Object value = doUnbindResource(actualKey);
if (value == null) {
throw new IllegalStateException("No value for key [" + actualKey + "] bound to context");
}
return value;
}
/**
* Unbind a resource for the given key from the current context.
* @param key the key to unbind (usually the resource factory)
* @return the previously bound value, or {@code null} if none bound
*/
@Nullable
public Object unbindResourceIfPossible(Object key) {
Object actualKey = TransactionSynchronizationUtils.unwrapResourceIfNecessary(key);
return doUnbindResource(actualKey);
}
/**
* Actually remove the value of the resource that is bound for the given key.
*/
@Nullable
private Object doUnbindResource(Object actualKey) {
Map map = this.transactionContext.getResources();
return map.remove(actualKey);
}
//-------------------------------------------------------------------------
// Management of transaction synchronizations
//-------------------------------------------------------------------------
/**
* Return if transaction synchronization is active for the current context.
* Can be called before register to avoid unnecessary instance creation.
* @see #registerSynchronization
*/
public boolean isSynchronizationActive() {
return (this.transactionContext.getSynchronizations() != null);
}
/**
* Activate transaction synchronization for the current context.
* Called by a transaction manager on transaction begin.
* @throws IllegalStateException if synchronization is already active
*/
public void initSynchronization() throws IllegalStateException {
if (isSynchronizationActive()) {
throw new IllegalStateException("Cannot activate transaction synchronization - already active");
}
this.transactionContext.setSynchronizations(new LinkedHashSet<>());
}
/**
* Register a new transaction synchronization for the current context.
* Typically called by resource management code.
* Note that synchronizations can implement the
* {@link org.springframework.core.Ordered} interface.
* They will be executed in an order according to their order value (if any).
* @param synchronization the synchronization object to register
* @throws IllegalStateException if transaction synchronization is not active
* @see org.springframework.core.Ordered
*/
public void registerSynchronization(TransactionSynchronization synchronization)
throws IllegalStateException {
Assert.notNull(synchronization, "TransactionSynchronization must not be null");
Set synchs = this.transactionContext.getSynchronizations();
if (synchs == null) {
throw new IllegalStateException("Transaction synchronization is not active");
}
synchs.add(synchronization);
}
/**
* Return an unmodifiable snapshot list of all registered synchronizations
* for the current context.
* @return unmodifiable List of TransactionSynchronization instances
* @throws IllegalStateException if synchronization is not active
* @see TransactionSynchronization
*/
public List getSynchronizations() throws IllegalStateException {
Set synchs = this.transactionContext.getSynchronizations();
if (synchs == null) {
throw new IllegalStateException("Transaction synchronization is not active");
}
// Return unmodifiable snapshot, to avoid ConcurrentModificationExceptions
// while iterating and invoking synchronization callbacks that in turn
// might register further synchronizations.
if (synchs.isEmpty()) {
return Collections.emptyList();
}
else {
// Sort lazily here, not in registerSynchronization.
List sortedSynchs = new ArrayList<>(synchs);
AnnotationAwareOrderComparator.sort(sortedSynchs);
return Collections.unmodifiableList(sortedSynchs);
}
}
/**
* Deactivate transaction synchronization for the current context.
* Called by the transaction manager on transaction cleanup.
* @throws IllegalStateException if synchronization is not active
*/
public void clearSynchronization() throws IllegalStateException {
if (!isSynchronizationActive()) {
throw new IllegalStateException("Cannot deactivate transaction synchronization - not active");
}
this.transactionContext.setSynchronizations(null);
}
//-------------------------------------------------------------------------
// Exposure of transaction characteristics
//-------------------------------------------------------------------------
/**
* Expose the name of the current transaction, if any.
* Called by the transaction manager on transaction begin and on cleanup.
* @param name the name of the transaction, or {@code null} to reset it
* @see org.springframework.transaction.TransactionDefinition#getName()
*/
public void setCurrentTransactionName(@Nullable String name) {
this.transactionContext.setCurrentTransactionName(name);
}
/**
* Return the name of the current transaction, or {@code null} if none set.
* To be called by resource management code for optimizations per use case,
* for example to optimize fetch strategies for specific named transactions.
* @see org.springframework.transaction.TransactionDefinition#getName()
*/
@Nullable
public String getCurrentTransactionName() {
return this.transactionContext.getCurrentTransactionName();
}
/**
* Expose a read-only flag for the current transaction.
* Called by the transaction manager on transaction begin and on cleanup.
* @param readOnly {@code true} to mark the current transaction
* as read-only; {@code false} to reset such a read-only marker
* @see org.springframework.transaction.TransactionDefinition#isReadOnly()
*/
public void setCurrentTransactionReadOnly(boolean readOnly) {
this.transactionContext.setCurrentTransactionReadOnly(readOnly);
}
/**
* Return whether the current transaction is marked as read-only.
* To be called by resource management code when preparing a newly
* created resource.
* Note that transaction synchronizations receive the read-only flag
* as argument for the {@code beforeCommit} callback, to be able
* to suppress change detection on commit. The present method is meant
* to be used for earlier read-only checks.
* @see org.springframework.transaction.TransactionDefinition#isReadOnly()
* @see TransactionSynchronization#beforeCommit(boolean)
*/
public boolean isCurrentTransactionReadOnly() {
return this.transactionContext.isCurrentTransactionReadOnly();
}
/**
* Expose an isolation level for the current transaction.
* Called by the transaction manager on transaction begin and on cleanup.
* @param isolationLevel the isolation level to expose, according to the
* R2DBC Connection constants (equivalent to the corresponding Spring
* TransactionDefinition constants), or {@code null} to reset it
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_UNCOMMITTED
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_COMMITTED
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_REPEATABLE_READ
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_SERIALIZABLE
* @see org.springframework.transaction.TransactionDefinition#getIsolationLevel()
*/
public void setCurrentTransactionIsolationLevel(@Nullable Integer isolationLevel) {
this.transactionContext.setCurrentTransactionIsolationLevel(isolationLevel);
}
/**
* Return the isolation level for the current transaction, if any.
* To be called by resource management code when preparing a newly
* created resource (for example, a R2DBC Connection).
* @return the currently exposed isolation level, according to the
* R2DBC Connection constants (equivalent to the corresponding Spring
* TransactionDefinition constants), or {@code null} if none
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_UNCOMMITTED
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_READ_COMMITTED
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_REPEATABLE_READ
* @see org.springframework.transaction.TransactionDefinition#ISOLATION_SERIALIZABLE
* @see org.springframework.transaction.TransactionDefinition#getIsolationLevel()
*/
@Nullable
public Integer getCurrentTransactionIsolationLevel() {
return this.transactionContext.getCurrentTransactionIsolationLevel();
}
/**
* Expose whether there currently is an actual transaction active.
* Called by the transaction manager on transaction begin and on cleanup.
* @param active {@code true} to mark the current context as being associated
* with an actual transaction; {@code false} to reset that marker
*/
public void setActualTransactionActive(boolean active) {
this.transactionContext.setActualTransactionActive(active);
}
/**
* Return whether there currently is an actual transaction active.
* This indicates whether the current context is associated with an actual
* transaction rather than just with active transaction synchronization.
*
To be called by resource management code that wants to discriminate
* between active transaction synchronization (with or without backing
* resource transaction; also on PROPAGATION_SUPPORTS) and an actual
* transaction being active (with backing resource transaction;
* on PROPAGATION_REQUIRED, PROPAGATION_REQUIRES_NEW, etc).
* @see #isSynchronizationActive()
*/
public boolean isActualTransactionActive() {
return this.transactionContext.isActualTransactionActive();
}
/**
* Clear the entire transaction synchronization state:
* registered synchronizations as well as the various transaction characteristics.
* @see #clearSynchronization()
* @see #setCurrentTransactionName
* @see #setCurrentTransactionReadOnly
* @see #setCurrentTransactionIsolationLevel
* @see #setActualTransactionActive
*/
public void clear() {
this.transactionContext.clear();
}
}