Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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.apache.nifi.processors.standard; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.util.ArrayList; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; import java.util.concurrent.BlockingQueue; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.TimeUnit; import org.apache.commons.lang3.StringUtils; import org.apache.nifi.annotation.lifecycle.OnStopped; import org.apache.nifi.components.AllowableValue; import org.apache.nifi.components.PropertyDescriptor; import org.apache.nifi.flowfile.FlowFile; import org.apache.nifi.flowfile.attributes.CoreAttributes; import org.apache.nifi.processor.AbstractProcessor; import org.apache.nifi.processor.ProcessContext; import org.apache.nifi.processor.ProcessSession; import org.apache.nifi.processor.Relationship; import org.apache.nifi.processor.exception.ProcessException; import org.apache.nifi.processor.io.OutputStreamCallback; import org.apache.nifi.processor.util.StandardValidators; import org.apache.nifi.processors.standard.util.FileTransfer; import org.apache.nifi.processors.standard.util.PermissionDeniedException; import org.apache.nifi.stream.io.StreamUtils; import org.apache.nifi.util.StopWatch; import org.apache.nifi.util.Tuple; /** * A base class for FetchSFTP, FetchFTP processors. * * Note that implementations of this class should never use the @SupportsBatching annotation! Doing so * could result in data loss! */ public abstract class FetchFileTransfer extends AbstractProcessor { static final AllowableValue COMPLETION_NONE = new AllowableValue("None", "None", "Leave the file as-is"); static final AllowableValue COMPLETION_MOVE = new AllowableValue("Move File", "Move File", "Move the file to the directory specified by the <Move Destination Directory> property"); static final AllowableValue COMPLETION_DELETE = new AllowableValue("Delete File", "Delete File", "Deletes the original file from the remote system"); static final PropertyDescriptor HOSTNAME = new PropertyDescriptor.Builder().name("Hostname") .description("The fully-qualified hostname or IP address of the host to fetch the data from") .addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true).required(true) .build(); static final PropertyDescriptor UNDEFAULTED_PORT = new PropertyDescriptor.Builder().name("Port") .description("The port to connect to on the remote host to fetch the data from") .addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true).required(true) .build(); public static final PropertyDescriptor USERNAME = new PropertyDescriptor.Builder().name("Username") .description("Username").addValidator(StandardValidators.NON_EMPTY_VALIDATOR) .expressionLanguageSupported(true).required(true).build(); public static final PropertyDescriptor REMOTE_FILENAME = new PropertyDescriptor.Builder().name("Remote File") .description("The fully qualified filename on the remote system").required(true) .addValidator(StandardValidators.NON_EMPTY_VALIDATOR).expressionLanguageSupported(true).build(); static final PropertyDescriptor COMPLETION_STRATEGY = new PropertyDescriptor.Builder() .name("Completion Strategy") .description( "Specifies what to do with the original file on the server once it has been pulled into NiFi. If the Completion Strategy fails, a warning will be " + "logged but the data will still be transferred.") .expressionLanguageSupported(false).allowableValues(COMPLETION_NONE, COMPLETION_MOVE, COMPLETION_DELETE) .defaultValue(COMPLETION_NONE.getValue()).required(true).build(); static final PropertyDescriptor MOVE_DESTINATION_DIR = new PropertyDescriptor.Builder() .name("Move Destination Directory") .description( "The directory on the remote server to the move the original file to once it has been ingested into NiFi. " + "This property is ignored unless the Completion Strategy is set to \"Move File\". The specified directory must already exist on" + "the remote system, or the rename will fail.") .expressionLanguageSupported(true).addValidator(StandardValidators.NON_EMPTY_VALIDATOR).required(false) .build(); public static final Relationship REL_SUCCESS = new Relationship.Builder().name("success") .description("All FlowFiles that are received are routed to success").build(); static final Relationship REL_COMMS_FAILURE = new Relationship.Builder().name("comms.failure").description( "Any FlowFile that could not be fetched from the remote server due to a communications failure will be transferred to this Relationship.") .build(); static final Relationship REL_NOT_FOUND = new Relationship.Builder().name("not.found").description( "Any FlowFile for which we receive a 'Not Found' message from the remote server will be transferred to this Relationship.") .build(); static final Relationship REL_PERMISSION_DENIED = new Relationship.Builder().name("permission.denied") .description( "Any FlowFile that could not be fetched from the remote server due to insufficient permissions will be transferred to this Relationship.") .build(); private final Map<Tuple<String, Integer>, BlockingQueue<FileTransferIdleWrapper>> fileTransferMap = new HashMap<>(); private final long IDLE_CONNECTION_MILLIS = TimeUnit.SECONDS.toMillis(10L); // amount of time to wait before closing an idle connection private volatile long lastClearTime = System.currentTimeMillis(); @Override public Set<Relationship> getRelationships() { final Set<Relationship> relationships = new HashSet<>(); relationships.add(REL_SUCCESS); relationships.add(REL_NOT_FOUND); relationships.add(REL_PERMISSION_DENIED); relationships.add(REL_COMMS_FAILURE); return relationships; } /** * Close connections that are idle or optionally close all connections. * Connections are considered "idle" if they have not been used in 10 seconds. * * @param closeNonIdleConnections if <code>true</code> will close all connection; if <code>false</code> will close only idle connections */ private void closeConnections(final boolean closeNonIdleConnections) { for (final Map.Entry<Tuple<String, Integer>, BlockingQueue<FileTransferIdleWrapper>> entry : fileTransferMap .entrySet()) { final BlockingQueue<FileTransferIdleWrapper> wrapperQueue = entry.getValue(); final List<FileTransferIdleWrapper> putBack = new ArrayList<>(); FileTransferIdleWrapper wrapper; while ((wrapper = wrapperQueue.poll()) != null) { final long lastUsed = wrapper.getLastUsed(); final long nanosSinceLastUse = System.nanoTime() - lastUsed; if (!closeNonIdleConnections && TimeUnit.NANOSECONDS.toMillis(nanosSinceLastUse) < IDLE_CONNECTION_MILLIS) { putBack.add(wrapper); } else { try { wrapper.getFileTransfer().close(); } catch (final IOException ioe) { getLogger().warn("Failed to close Idle Connection due to {}", new Object[] { ioe }, ioe); } } } for (final FileTransferIdleWrapper toPutBack : putBack) { wrapperQueue.offer(toPutBack); } } } @OnStopped public void cleanup() { // close all connections closeConnections(true); } @Override protected List<PropertyDescriptor> getSupportedPropertyDescriptors() { final List<PropertyDescriptor> properties = new ArrayList<>(); properties.add(HOSTNAME); properties.add(UNDEFAULTED_PORT); properties.add(REMOTE_FILENAME); properties.add(COMPLETION_STRATEGY); properties.add(MOVE_DESTINATION_DIR); return properties; } @Override public void onTrigger(final ProcessContext context, final ProcessSession session) throws ProcessException { FlowFile flowFile = session.get(); if (flowFile == null) { return; } final StopWatch stopWatch = new StopWatch(true); final String host = context.getProperty(HOSTNAME).evaluateAttributeExpressions(flowFile).getValue(); final int port = context.getProperty(UNDEFAULTED_PORT).evaluateAttributeExpressions(flowFile).asInteger(); final String filename = context.getProperty(REMOTE_FILENAME).evaluateAttributeExpressions(flowFile) .getValue(); // Try to get a FileTransfer object from our cache. BlockingQueue<FileTransferIdleWrapper> transferQueue; synchronized (fileTransferMap) { final Tuple<String, Integer> tuple = new Tuple<>(host, port); transferQueue = fileTransferMap.get(tuple); if (transferQueue == null) { transferQueue = new LinkedBlockingQueue<>(); fileTransferMap.put(tuple, transferQueue); } // periodically close idle connections if (System.currentTimeMillis() - lastClearTime > IDLE_CONNECTION_MILLIS) { closeConnections(false); lastClearTime = System.currentTimeMillis(); } } // we have a queue of FileTransfer Objects. Get one from the queue or create a new one. FileTransfer transfer; FileTransferIdleWrapper transferWrapper = transferQueue.poll(); if (transferWrapper == null) { transfer = createFileTransfer(context); } else { transfer = transferWrapper.getFileTransfer(); } // Pull data from remote system. final InputStream in; try { in = transfer.getInputStream(filename, flowFile); flowFile = session.write(flowFile, new OutputStreamCallback() { @Override public void process(final OutputStream out) throws IOException { StreamUtils.copy(in, out); transfer.flush(); } }); transferQueue.offer(new FileTransferIdleWrapper(transfer, System.nanoTime())); } catch (final FileNotFoundException e) { getLogger().error( "Failed to fetch content for {} from filename {} on remote host {} because the file could not be found on the remote system; routing to {}", new Object[] { flowFile, filename, host, REL_NOT_FOUND.getName() }); session.transfer(session.penalize(flowFile), REL_NOT_FOUND); session.getProvenanceReporter().route(flowFile, REL_NOT_FOUND); return; } catch (final PermissionDeniedException e) { getLogger().error( "Failed to fetch content for {} from filename {} on remote host {} due to insufficient permissions; routing to {}", new Object[] { flowFile, filename, host, REL_PERMISSION_DENIED.getName() }); session.transfer(session.penalize(flowFile), REL_PERMISSION_DENIED); session.getProvenanceReporter().route(flowFile, REL_PERMISSION_DENIED); return; } catch (final ProcessException | IOException e) { try { transfer.close(); } catch (final IOException e1) { getLogger().warn("Failed to close connection to {}:{} due to {}", new Object[] { host, port, e.toString() }, e); } getLogger().error( "Failed to fetch content for {} from filename {} on remote host {}:{} due to {}; routing to comms.failure", new Object[] { flowFile, filename, host, port, e.toString() }, e); session.transfer(session.penalize(flowFile), REL_COMMS_FAILURE); return; } // Add FlowFile attributes final String protocolName = transfer.getProtocolName(); final Map<String, String> attributes = new HashMap<>(); attributes.put(protocolName + ".remote.host", host); attributes.put(protocolName + ".remote.port", String.valueOf(port)); attributes.put(protocolName + ".remote.filename", filename); if (filename.contains("/")) { final String path = StringUtils.substringBeforeLast(filename, "/"); final String filenameOnly = StringUtils.substringAfterLast(filename, "/"); attributes.put(CoreAttributes.PATH.key(), path); attributes.put(CoreAttributes.FILENAME.key(), filenameOnly); } else { attributes.put(CoreAttributes.FILENAME.key(), filename); } flowFile = session.putAllAttributes(flowFile, attributes); // emit provenance event and transfer FlowFile session.getProvenanceReporter().fetch(flowFile, protocolName + "://" + host + ":" + port + "/" + filename, stopWatch.getElapsed(TimeUnit.MILLISECONDS)); session.transfer(flowFile, REL_SUCCESS); // it is critical that we commit the session before moving/deleting the remote file. Otherwise, we could have a situation where // we ingest the data, delete/move the remote file, and then NiFi dies/is shut down before the session is committed. This would // result in data loss! If we commit the session first, we are safe. session.commit(); final String completionStrategy = context.getProperty(COMPLETION_STRATEGY).getValue(); if (COMPLETION_DELETE.getValue().equalsIgnoreCase(completionStrategy)) { try { transfer.deleteFile(null, filename); } catch (final FileNotFoundException e) { // file doesn't exist -- effectively the same as removing it. Move on. } catch (final IOException ioe) { getLogger().warn( "Successfully fetched the content for {} from {}:{}{} but failed to remove the remote file due to {}", new Object[] { flowFile, host, port, filename, ioe }, ioe); } } else if (COMPLETION_MOVE.getValue().equalsIgnoreCase(completionStrategy)) { String targetDir = context.getProperty(MOVE_DESTINATION_DIR).evaluateAttributeExpressions(flowFile) .getValue(); if (!targetDir.endsWith("/")) { targetDir = targetDir + "/"; } final String simpleFilename = StringUtils.substringAfterLast(filename, "/"); final String target = targetDir + simpleFilename; try { transfer.rename(filename, target); } catch (final IOException ioe) { getLogger().warn( "Successfully fetched the content for {} from {}:{}{} but failed to rename the remote file due to {}", new Object[] { flowFile, host, port, filename, ioe }, ioe); } } } /** * Creates a new instance of a FileTransfer that can be used to pull files from a remote system. * * @param context the ProcessContext to use in order to obtain configured properties * @return a FileTransfer that can be used to pull files from a remote system */ protected abstract FileTransfer createFileTransfer(ProcessContext context); /** * Wrapper around a FileTransfer object that is used to know when the FileTransfer was last used, so that * we have the ability to close connections that are "idle," or unused for some period of time. */ private static class FileTransferIdleWrapper { private final FileTransfer fileTransfer; private final long lastUsed; public FileTransferIdleWrapper(final FileTransfer fileTransfer, final long lastUsed) { this.fileTransfer = fileTransfer; this.lastUsed = lastUsed; } public FileTransfer getFileTransfer() { return fileTransfer; } public long getLastUsed() { return this.lastUsed; } } }