GH-3370: Remove synchronized from RemoteFileUtils (#3380)

* GH-3370: Remove synchronized from RemoteFileUtils

Fixes https://github.com/spring-projects/spring-integration/issues/3370

The `synchronized` on the `RemoteFileUtils.makeDirectories()` makes an application too
 slow, especially when we deal with different paths in different sessions

* Remove the `synchronized` from that method and rework `SftpSession.mkdir()`
to return `false` when "A file cannot be created if it already exists" exception
is thrown from the server.
Essentially make an `exists()` call to be sure that an exception is really related
to "file-already-exists" answer from the server

**Cherry-pick to 5.3.x, 5.2.x & 4.3.x**

* * Re-throw an exception in the `SftpSession.mkdir()`
when error code is not `4` or remote dir does not exist

* * Check `session.mkdir()` result in the
`RemoteFileUtils` to throw an `IOException` when `false`

* * Fix mock test to return `true` for `mkdir` instead of `null`

spring-integration-file/src/main/java/org/springframework/integration/file/remote/RemoteFileUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -28,6 +28,7 @@ import org.springframework.integration.file.remote.session.Session;
  * Utility methods for supporting remote file operations.
  *
  * @author Gary Russell
+ * @author Artem Bilan
  *
  * @since 3.0
  *
@@ -46,13 +47,11 @@ public final class RemoteFileUtils {
 	 * @param logger The logger.
 	 * @throws IOException Any IOException.
 	 */
-	public static synchronized <F> void makeDirectories(String path, Session<F> session, String remoteFileSeparator,
+	public static <F> void makeDirectories(String path, Session<F> session, String remoteFileSeparator,
 			Log logger) throws IOException {
 
 		if (!session.exists(path)) {
-
 			int nextSeparatorIndex = path.lastIndexOf(remoteFileSeparator);
-
 			if (nextSeparatorIndex > -1) {
 				List<String> pathsToCreate = new LinkedList<>();
 				while (nextSeparatorIndex > -1) {
@@ -71,13 +70,19 @@ public final class RemoteFileUtils {
 					if (logger.isDebugEnabled()) {
 						logger.debug("Creating '" + pathToCreate + "'");
 					}
-					session.mkdir(pathToCreate);
+					tryCreateRemoteDirectory(session, pathToCreate);
 				}
 			}
 			else {
-				session.mkdir(path);
+				tryCreateRemoteDirectory(session, path);
 			}
 		}
 	}
 
+	private static void tryCreateRemoteDirectory(Session<?> session, String path) throws IOException {
+		if (!session.mkdir(path)) {
+			throw new IOException("Could not create a remote directory: " + path);
+		}
+	}
+
 }

spring-integration-file/src/main/java/org/springframework/integration/file/remote/gateway/AbstractRemoteFileOutboundGateway.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -121,6 +121,7 @@ public abstract class AbstractRemoteFileOutboundGateway<F> extends AbstractReply
 			MessageSessionCallback<F, ?> messageSessionCallback) {
 
 		this(new RemoteFileTemplate<>(sessionFactory), messageSessionCallback);
+		remoteFileTemplateExplicitlySet(false);
 	}
 
 	/**
@@ -165,6 +166,7 @@ public abstract class AbstractRemoteFileOutboundGateway<F> extends AbstractReply
 			@Nullable String expression) {
 
 		this(new RemoteFileTemplate<>(sessionFactory), command, expression);
+		remoteFileTemplateExplicitlySet(false);
 	}
 
 	/**
@@ -516,6 +518,9 @@ public abstract class AbstractRemoteFileOutboundGateway<F> extends AbstractReply
 		}
 
 		populateBeanFactoryIntoComponentsIfAny();
+		if (!this.remoteFileTemplateExplicitlySet) {
+			this.remoteFileTemplate.afterPropertiesSet();
+		}
 	}
 
 	private void populateBeanFactoryIntoComponentsIfAny() {

spring-integration-file/src/test/java/org/springframework/integration/file/remote/gateway/RemoteFileOutboundGatewayTests.java

@@ -295,7 +295,7 @@ public class RemoteFileOutboundGatewayTests {
 		final List<String> madeDirs = new ArrayList<>();
 		doAnswer(invocation -> {
 			madeDirs.add(invocation.getArgument(0));
-			return null;
+			return true;
 		}).when(session).mkdir(anyString());
 		when(sessionFactory.getSession()).thenReturn(session);
 		Message<String> requestMessage = MessageBuilder.withPayload("foo")
@@ -939,7 +939,6 @@ public class RemoteFileOutboundGatewayTests {
 		Session<TestLsEntry> session = mock(Session.class);
 		TestRemoteFileOutboundGateway gw = new TestRemoteFileOutboundGateway(sessionFactory, "mput", "payload");
 		gw.setRemoteDirectoryExpression(new LiteralExpression("foo/"));
-		gw.setBeanFactory(mock(BeanFactory.class));
 		gw.afterPropertiesSet();
 		when(sessionFactory.getSession()).thenReturn(session);
 		final AtomicReference<String> written = new AtomicReference<>();

spring-integration-sftp/src/main/java/org/springframework/integration/sftp/session/SftpSession.java

@@ -252,8 +252,10 @@ public class SftpSession implements Session<LsEntry> {
 		try {
 			this.channel.mkdir(remoteDirectory);
 		}
-		catch (SftpException e) {
-			throw new NestedIOException("failed to create remote directory '" + remoteDirectory + "'.", e);
+		catch (SftpException ex) {
+			if (ex.id != ChannelSftp.SSH_FX_FAILURE || !exists(remoteDirectory)) {
+				throw new NestedIOException("failed to create remote directory '" + remoteDirectory + "'.", ex);
+			}
 		}
 		return true;
 	}

spring-integration-sftp/src/test/java/org/springframework/integration/sftp/outbound/SftpOutboundTests.java

@@ -219,7 +219,7 @@ public class SftpOutboundTests {
 		final List<String> madeDirs = new ArrayList<>();
 		doAnswer(invocation -> {
 			madeDirs.add(invocation.getArgument(0));
-			return null;
+			return true;
 		}).when(session).mkdir(anyString());
 		handler.handleMessage(new GenericMessage<>("qux"));
 		assertThat(madeDirs.size()).isEqualTo(3);