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/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [https://neo4j.com]
*
* 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.
*/
package org.neo4j.driver.async;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CompletionStage;
import java.util.concurrent.Executor;
import java.util.function.Function;
import org.neo4j.driver.AccessMode;
import org.neo4j.driver.BaseSession;
import org.neo4j.driver.Bookmark;
import org.neo4j.driver.Query;
import org.neo4j.driver.Result;
import org.neo4j.driver.Transaction;
import org.neo4j.driver.TransactionConfig;
import org.neo4j.driver.Values;
/**
* Provides a context of work for database interactions.
*
* An AsyncSession hosts a series of {@linkplain AsyncTransaction transactions}
* carried out against a database. Within the database, all queries are
* carried out within a transaction. Within application code, however, it is
* not always necessary to explicitly {@link #beginTransactionAsync() begin a
* transaction}. If a query is {@link #runAsync} directly against a {@link
* AsyncSession}, the server will automatically BEGIN and
* COMMIT that query within its own transaction. This type
* of transaction is known as an autocommit transaction.
*
* Unmanaged transactions allow multiple queries to be committed as part of
* a single atomic operation and can be rolled back if necessary. They can also
* be used to ensure causal consistency, meaning that an application
* can run a series of queries on different members of a cluster, while
* ensuring that each query sees the state of graph at least as up-to-date as
* the graph seen by the previous query. For more on causal consistency, see
* the Neo4j clustering manual.
*
* Typically, a session will acquire a TCP connection to execute query or
* transaction. Such a connection will be acquired from a connection pool
* and released back there when query result is consumed or transaction is
* committed or rolled back. One connection can therefore be adopted by many
* sessions, although by only one at a time. Application code should never need
* to deal directly with connection management.
*
* A session inherits its destination address and permissions from its
* underlying connection. This means that for a single query/transaction one
* session may only ever target one machine within a cluster and does not
* support re-authentication. To achieve otherwise requires creation of a
* separate session.
*
* Similarly, multiple sessions should be used when working with concurrency;
* session implementations are not thread safe.
*
* @since 4.0
*/
public interface AsyncSession extends BaseSession, AsyncQueryRunner {
/**
* Begin a new unmanaged {@linkplain Transaction transaction}. At
* most one transaction may exist in a session at any point in time. To
* maintain multiple concurrent transactions, use multiple concurrent
* sessions.
*
* This operation is asynchronous and returns a {@link CompletionStage}. This stage is completed with a new
* {@link Transaction} object when begin operation is successful.
* It is completed exceptionally if transaction can't be started.
*
* Returned stage can be completed by an IO thread which should never block.
* Otherwise IO operations on this and potentially other network connections might deadlock.
* Please do not chain blocking operations like {@link CompletableFuture#get()} on the returned stage.
* Consider using asynchronous calls throughout the chain or offloading blocking operation to a different {@link Executor}.
* This can be done using methods with "Async" suffix like
* {@link CompletionStage#thenApplyAsync(Function)} or {@link CompletionStage#thenApplyAsync(Function, Executor)}.
*
* @return a {@link CompletionStage completion stage} that represents the asynchronous begin of a transaction.
*/
CompletionStage beginTransactionAsync();
/**
* Begin a new unmanaged {@linkplain AsyncTransaction transaction} with the specified {@link TransactionConfig configuration}.
* At most one transaction may exist in a session at any point in time.
* To maintain multiple concurrent transactions, use multiple concurrent sessions.
*
* This operation is asynchronous and returns a {@link CompletionStage}. This stage is completed with a new
* {@link AsyncTransaction} object when begin operation is successful. It is completed exceptionally if
* transaction can't be started.
*
* Returned stage can be completed by an IO thread which should never block.
* Otherwise IO operations on this and potentially other network connections might deadlock.
* Please do not chain blocking operations like {@link CompletableFuture#get()} on the returned stage.
* Consider using asynchronous calls throughout the chain or offloading blocking operation to a different {@link Executor}.
* This can be done using methods with "Async" suffix like
* {@link CompletionStage#thenApplyAsync(Function)} or {@link CompletionStage#thenApplyAsync(Function, Executor)}.
*
* @param config configuration for the new transaction.
* @return a {@link CompletionStage completion stage} that represents the asynchronous begin of a transaction.
*/
CompletionStage beginTransactionAsync(TransactionConfig config);
/**
* Execute given unit of asynchronous work in a {@link AccessMode#READ read} asynchronous transaction.
*
* Transaction will automatically be committed unless given unit of work fails or
* {@link AsyncTransaction#commitAsync() async transaction commit} fails.
* It will also not be committed if explicitly rolled back via {@link AsyncTransaction#rollbackAsync()}.
*
* Returned stage and given {@link AsyncTransactionWork} can be completed/executed by an IO thread which should never block.
* Otherwise IO operations on this and potentially other network connections might deadlock.
* Please do not chain blocking operations like {@link CompletableFuture#get()} on the returned stage and do not use them inside the
* {@link AsyncTransactionWork}.
* Consider using asynchronous calls throughout the chain or offloading blocking operation to a different {@link Executor}.
* This can be done using methods with "Async" suffix like
* {@link CompletionStage#thenApplyAsync(Function)} or {@link CompletionStage#thenApplyAsync(Function, Executor)}.
*
* @param work the {@link AsyncTransactionWork} to be applied to a new read transaction. Operation executed by the
* given work must be asynchronous.
* @param the return type of the given unit of work.
* @return a {@link CompletionStage completion stage} completed with the same result as returned by the given
* unit of work. Stage can be completed exceptionally if given work or commit fails.
* @deprecated superseded by {@link #executeReadAsync(AsyncTransactionCallback)}.
*/
@Deprecated
CompletionStage readTransactionAsync(AsyncTransactionWork> work);
/**
* Execute a unit of work as a single, managed transaction with {@link AccessMode#READ read} access mode and retry behaviour. The transaction allows for one
* or more statements to be run.
*
* The driver will attempt committing the transaction when the provided unit of work completes successfully. Any exception emitted by the unit of work will
* result in a rollback attempt and abortion of execution unless exception is considered to be valid for retry attempt by the driver.
*
* The provided unit of work should not return {@link Result} object as it won't be valid outside the scope of the transaction.
*
* It is prohibited to block the thread completing the returned {@link CompletionStage}. Please avoid blocking operations or hand processing over to a
* different thread.
*
* @param callback the callback representing the unit of work.
* @param the return type of the given unit of work.
* @return a completion stage that completes successfully with the result of the unit of work on success or completes exceptionally otherwise.
*/
default CompletionStage executeReadAsync(AsyncTransactionCallback> callback) {
return executeReadAsync(callback, TransactionConfig.empty());
}
/**
* Execute given unit of asynchronous work in a {@link AccessMode#READ read} asynchronous transaction with
* the specified {@link TransactionConfig configuration}.
*
* Transaction will automatically be committed unless given unit of work fails or
* {@link AsyncTransaction#commitAsync() async transaction commit} fails.
* It will also not be committed if explicitly rolled back via {@link AsyncTransaction#rollbackAsync()}.
*
* Returned stage and given {@link AsyncTransactionWork} can be completed/executed by an IO thread which should never block.
* Otherwise IO operations on this and potentially other network connections might deadlock.
* Please do not chain blocking operations like {@link CompletableFuture#get()} on the returned stage and do not use them inside the
* {@link AsyncTransactionWork}.
* Consider using asynchronous calls throughout the chain or offloading blocking operation to a different {@link Executor}.
* This can be done using methods with "Async" suffix like
* {@link CompletionStage#thenApplyAsync(Function)} or {@link CompletionStage#thenApplyAsync(Function, Executor)}.
*
* @param work the {@link AsyncTransactionWork} to be applied to a new read transaction. Operation executed by the
* given work must be asynchronous.
* @param config configuration for all transactions started to execute the unit of work.
* @param the return type of the given unit of work.
* @return a {@link CompletionStage completion stage} completed with the same result as returned by the given
* unit of work. Stage can be completed exceptionally if given work or commit fails.
* @deprecated superseded by {@link #executeReadAsync(AsyncTransactionCallback, TransactionConfig)}.
*/
@Deprecated
CompletionStage readTransactionAsync(
AsyncTransactionWork> work, TransactionConfig config);
/**
* Execute a unit of work as a single, managed transaction with {@link AccessMode#READ read} access mode and retry behaviour. The transaction allows for one or more statements to be run.
*
* The driver will attempt committing the transaction when the provided unit of work completes successfully. Any exception emitted by the unit of work
* will result in a rollback attempt and abortion of execution unless exception is considered to be valid for retry attempt by the driver.
*
* The provided unit of work should not return {@link Result} object as it won't be valid outside the scope of the transaction.
*
* It is prohibited to block the thread completing the returned {@link CompletionStage}. Please avoid blocking operations or hand processing over to a
* different thread.
*
* @param callback the callback representing the unit of work.
* @param config configuration for all transactions started to execute the unit of work.
* @param the return type of the given unit of work.
* @return a completion stage that completes successfully with the result of the unit of work on success or completes exceptionally otherwise.
*/
CompletionStage executeReadAsync(
AsyncTransactionCallback> callback, TransactionConfig config);
/**
* Execute given unit of asynchronous work in a {@link AccessMode#WRITE write} asynchronous transaction.
*
* Transaction will automatically be committed unless given unit of work fails or
* {@link AsyncTransaction#commitAsync() async transaction commit} fails. It will also not be committed if explicitly
* rolled back via {@link AsyncTransaction#rollbackAsync()}.
*
* Returned stage and given {@link AsyncTransactionWork} can be completed/executed by an IO thread which should never block.
* Otherwise IO operations on this and potentially other network connections might deadlock.
* Please do not chain blocking operations like {@link CompletableFuture#get()} on the returned stage and do not use them inside the
* {@link AsyncTransactionWork}.
* Consider using asynchronous calls throughout the chain or offloading blocking operation to a different {@link Executor}.
* This can be done using methods with "Async" suffix like
* {@link CompletionStage#thenApplyAsync(Function)} or {@link CompletionStage#thenApplyAsync(Function, Executor)}.
*
* @param work the {@link AsyncTransactionWork} to be applied to a new write transaction. Operation executed by the
* given work must be asynchronous.
* @param the return type of the given unit of work.
* @return a {@link CompletionStage completion stage} completed with the same result as returned by the given
* unit of work. Stage can be completed exceptionally if given work or commit fails.
* @deprecated superseded by {@link #executeWriteAsync(AsyncTransactionCallback)}.
*/
@Deprecated
CompletionStage writeTransactionAsync(AsyncTransactionWork> work);
/**
* Execute a unit of work as a single, managed transaction with {@link AccessMode#WRITE write} access mode and retry behaviour. The transaction allows for
* one or more statements to be run.
*
* The driver will attempt committing the transaction when the provided unit of work completes successfully. Any exception emitted by the unit of work will
* result in a rollback attempt and abortion of execution unless exception is considered to be valid for retry attempt by the driver.
*
* The provided unit of work should not return {@link Result} object as it won't be valid outside the scope of the transaction.
*
* It is prohibited to block the thread completing the returned {@link CompletionStage}. Please avoid blocking operations or hand processing over to a
* different thread.
*
* @param callback the callback representing the unit of work.
* @param the return type of the given unit of work.
* @return a completion stage that completes successfully with the result of the unit of work on success or completes exceptionally otherwise.
*/
default CompletionStage executeWriteAsync(AsyncTransactionCallback> callback) {
return executeWriteAsync(callback, TransactionConfig.empty());
}
/**
* Execute given unit of asynchronous work in a {@link AccessMode#WRITE write} asynchronous transaction with
* the specified {@link TransactionConfig configuration}.
*
* Transaction will automatically be committed unless given unit of work fails or
* {@link AsyncTransaction#commitAsync() async transaction commit} fails. It will also not be committed if explicitly
* rolled back via {@link AsyncTransaction#rollbackAsync()}.
*
* Returned stage and given {@link AsyncTransactionWork} can be completed/executed by an IO thread which should never block.
* Otherwise IO operations on this and potentially other network connections might deadlock.
* Please do not chain blocking operations like {@link CompletableFuture#get()} on the returned stage and do not use them inside the
* {@link AsyncTransactionWork}.
* Consider using asynchronous calls throughout the chain or offloading blocking operation to a different {@link Executor}.
* This can be done using methods with "Async" suffix like
* {@link CompletionStage#thenApplyAsync(Function)} or {@link CompletionStage#thenApplyAsync(Function, Executor)}.
*
* @param work the {@link AsyncTransactionWork} to be applied to a new write transaction. Operation executed by the
* given work must be asynchronous.
* @param config configuration for all transactions started to execute the unit of work.
* @param the return type of the given unit of work.
* @return a {@link CompletionStage completion stage} completed with the same result as returned by the given
* unit of work. Stage can be completed exceptionally if given work or commit fails.
* @deprecated superseded by {@link #executeWriteAsync(AsyncTransactionCallback, TransactionConfig)}.
*/
@Deprecated
CompletionStage writeTransactionAsync(
AsyncTransactionWork> work, TransactionConfig config);
/**
* Execute a unit of work as a single, managed transaction with {@link AccessMode#WRITE write} access mode and retry behaviour. The transaction allows for one or more statements to be run.
*
* The driver will attempt committing the transaction when the provided unit of work completes successfully. Any exception emitted by the unit of work
* will result in a rollback attempt and abortion of execution unless exception is considered to be valid for retry attempt by the driver.
*
* The provided unit of work should not return {@link Result} object as it won't be valid outside the scope of the transaction.
*
* It is prohibited to block the thread completing the returned {@link CompletionStage}. Please avoid blocking operations or hand processing over to a
* different thread.
*
* @param callback the callback representing the unit of work.
* @param config configuration for all transactions started to execute the unit of work.
* @param the return type of the given unit of work.
* @return a completion stage that completes successfully with the result of the unit of work on success or completes exceptionally otherwise.
*/
CompletionStage executeWriteAsync(
AsyncTransactionCallback> callback, TransactionConfig config);
/**
* Run a query asynchronously in an auto-commit transaction with the specified {@link TransactionConfig configuration} and return a
* {@link CompletionStage} with a result cursor.
*
* It is not allowed to chain blocking operations on the returned {@link CompletionStage}. See class javadoc in {@link AsyncQueryRunner} for
* more information.
*
* @param query text of a Neo4j query.
* @param config configuration for the new transaction.
* @return new {@link CompletionStage} that gets completed with a result cursor when query execution is successful.
* Stage can be completed exceptionally when error happens, e.g. connection can't be acquired from the pool.
*/
CompletionStage runAsync(String query, TransactionConfig config);
/**
* Run a query asynchronously in an auto-commit transaction with the specified {@link TransactionConfig configuration} and return a
* {@link CompletionStage} with a result cursor.
*
* This method takes a set of parameters that will be injected into the
* query by Neo4j. Using parameters is highly encouraged, it helps avoid
* dangerous cypher injection attacks and improves database performance as
* Neo4j can re-use query plans more often.
*
* This version of runAsync takes a {@link Map} of parameters. The values in the map
* must be values that can be converted to Neo4j types. See {@link Values#parameters(Object...)} for
* a list of allowed types.
*
Example
*
* {@code
* Map metadata = new HashMap<>();
* metadata.put("type", "update name");
*
* TransactionConfig config = TransactionConfig.builder()
* .withTimeout(Duration.ofSeconds(3))
* .withMetadata(metadata)
* .build();
*
* Map parameters = new HashMap();
* parameters.put("myNameParam", "Bob");
*
* CompletionStage cursorStage = session.runAsync(
* "MATCH (n) WHERE n.name = $myNameParam RETURN (n)",
* parameters,
* config);
* }
*
* It is not allowed to chain blocking operations on the returned {@link CompletionStage}. See class javadoc in {@link AsyncQueryRunner} for
* more information.
*
* @param query text of a Neo4j query.
* @param parameters input data for the query.
* @param config configuration for the new transaction.
* @return new {@link CompletionStage} that gets completed with a result cursor when query execution is successful.
* Stage can be completed exceptionally when error happens, e.g. connection can't be acquired from the pool.
*/
CompletionStage runAsync(String query, Map parameters, TransactionConfig config);
/**
* Run a query asynchronously in an auto-commit transaction with the specified {@link TransactionConfig configuration} and return a
* {@link CompletionStage} with a result cursor.
* Example
*
* {@code
* Map metadata = new HashMap<>();
* metadata.put("type", "update name");
*
* TransactionConfig config = TransactionConfig.builder()
* .withTimeout(Duration.ofSeconds(3))
* .withMetadata(metadata)
* .build();
*
* Query query = new Query( "MATCH (n) WHERE n.name = $myNameParam RETURN n.age" );
* CompletionStage cursorStage = session.runAsync(query, config);
* }
*
* It is not allowed to chain blocking operations on the returned {@link CompletionStage}. See class javadoc in {@link AsyncQueryRunner} for
* more information.
*
* @param query a Neo4j query.
* @param config configuration for the new transaction.
* @return new {@link CompletionStage} that gets completed with a result cursor when query execution is successful.
* Stage can be completed exceptionally when error happens, e.g. connection can't be acquired from the pool.
*/
CompletionStage runAsync(Query query, TransactionConfig config);
/**
* Return the last bookmark of this session.
*
* When no new bookmark is received, the initial bookmarks are returned as a composite {@link Bookmark} containing all initial bookmarks. This may happen
* when no work has been done using the session. If no initial bookmarks have been provided, an empty {@link Bookmark} is returned.
*
* @return the last bookmark.
*/
@Deprecated
Bookmark lastBookmark();
/**
* Return a set of last bookmarks.
*
* When no new bookmark is received, the initial bookmarks are returned. This may happen when no work has been done using the session. Multivalued {@link
* Bookmark} instances will be mapped to distinct {@link Bookmark} instances. If no initial bookmarks have been provided, an empty set is returned.
*
* @return the immutable set of last bookmarks.
*/
Set lastBookmarks();
/**
* Signal that you are done using this session. In the default driver usage, closing and accessing sessions is
* very low cost.
*
* This operation is asynchronous and returns a {@link CompletionStage}. Stage is completed when all outstanding
* queries in the session have completed, meaning any writes you performed are guaranteed to be durably stored.
* It might be completed exceptionally when there are unconsumed errors from previous queries or transactions.
*
* @return a {@link CompletionStage completion stage} that represents the asynchronous close.
*/
CompletionStage closeAsync();
}