com.documents4j.job.AggregatingConverter Maven / Gradle / Ivy
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package com.documents4j.job;
import com.documents4j.api.*;
import com.documents4j.throwables.ConverterAccessException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.File;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.*;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* A converter that aggregates several other converters and serves as a load balancer between these converters.
* At the same time, the converter automatically deregisters
*/
public class AggregatingConverter implements IAggregatingConverter, IConverterFailureCallback, Runnable {
private static final Logger LOGGER = LoggerFactory.getLogger(AggregatingConverter.class);
private final CopyOnWriteArrayList converters;
private final ISelectionStrategy selectionStrategy;
private final IConverterFailureCallback converterFailureCallback;
private final boolean propagateShutDown;
private volatile Future selfCheck;
protected AggregatingConverter(CopyOnWriteArrayList converters,
ISelectionStrategy selectionStrategy, IConverterFailureCallback converterFailureCallback,
boolean propagateShutDown) {
this.converters = converters;
this.selectionStrategy = selectionStrategy;
this.converterFailureCallback = converterFailureCallback;
this.propagateShutDown = propagateShutDown;
}
/**
* Creates a new builder instance.
*
* @return A new builder instance.
*/
public static Builder builder() {
return new Builder();
}
/**
* Creates a new aggregation converter of the given converters.
*
* @param converters The converters to aggregate.
* @return A new aggregation converter
*/
public static IAggregatingConverter make(IConverter... converters) {
checkNotNull(converters);
return make(Arrays.asList(converters));
}
/**
* Creates a new aggregation converter of the given converters.
*
* @param converters The available converters.
* @return A new aggregation converter
*/
public static IAggregatingConverter make(Collection converters) {
checkNotNull(converters);
return builder().aggregates(converters).build();
}
@Override
public Map> getSupportedConversions() {
Map> supportedConversions = new HashMap>();
for (IConverter converter : converters) {
for (Map.Entry> entry : converter.getSupportedConversions().entrySet()) {
Set targetTypes = supportedConversions.computeIfAbsent(entry.getKey(), k -> new HashSet());
targetTypes.addAll(entry.getValue());
}
}
return supportedConversions;
}
@Override
public boolean isOperational() {
for (IConverter converter : converters) {
if (converter.isOperational()) {
return true;
}
}
return false;
}
protected IConverter nextConverter(DocumentType sourceFormat, DocumentType targetFormat) {
List supportingConverters = new ArrayList(converters.size());
for (IConverter converter : converters) {
Set documentTypes = converter.getSupportedConversions().get(sourceFormat);
if (documentTypes != null && documentTypes.contains(targetFormat)) {
supportingConverters.add(converter);
}
}
if (supportingConverters.isEmpty()) {
LOGGER.trace("No converter available for conversion of {} to {}", sourceFormat, targetFormat);
return new ImpossibleConverter();
}
IConverter converter = selectionStrategy.select(supportingConverters);
LOGGER.trace("Selected {} for conversion of {} to {}", converter, sourceFormat, targetFormat);
return new FailureAwareConverter(converter, this);
}
@Override
public IConversionJobWithSourceUnspecified convert(File source) {
return convert(new FileSourceFromFile(source));
}
@Override
public IConversionJobWithSourceUnspecified convert(InputStream source) {
return convert(source, ConverterAdapter.DEFAULT_CLOSE_STREAM);
}
@Override
public IConversionJobWithSourceUnspecified convert(InputStream source, boolean close) {
return convert(new InputStreamSourceFromInputStream(source, close));
}
@Override
public IConversionJobWithSourceUnspecified convert(IFileSource source) {
return new AggregatedFileSourceConversionWithSourceUnspecified(source);
}
@Override
public IConversionJobWithSourceUnspecified convert(IInputStreamSource source) {
return new AggregatedInputStreamConversionWithSourceUnspecified(source);
}
@Override
public boolean register(IConverter converter) {
if (converters.addIfAbsent(converter)) {
LOGGER.info("Registered converter {} with {}", converter, this);
return true;
} else {
return false;
}
}
@Override
public boolean remove(IConverter converter) {
if (converters.remove(converter)) {
LOGGER.info("Removed converter {} from {}", converter, this);
return true;
} else {
return false;
}
}
@Override
public Set getConverters() {
return new HashSet(converters);
}
@Override
public void shutDown() {
if (selfCheck != null) {
selfCheck.cancel(true);
}
try {
if (propagateShutDown) {
List exceptions = new ArrayList();
for (IConverter converter : converters) {
try {
converter.shutDown();
} catch (RuntimeException e) {
exceptions.add(e);
}
}
if (!exceptions.isEmpty()) {
throw new ConverterAccessException("Shutting down aggregated converters caused at least one exception", exceptions.get(0));
}
}
} finally {
converters.clear();
}
}
@Override
public void kill() {
if (selfCheck != null) {
selfCheck.cancel(true);
}
try {
if (propagateShutDown) {
List exceptions = new ArrayList();
for (IConverter converter : converters) {
try {
converter.kill();
} catch (RuntimeException e) {
exceptions.add(e);
}
}
if (!exceptions.isEmpty()) {
throw new ConverterAccessException("Shutting down aggregated converters caused at least one exception", exceptions.get(0));
}
}
} finally {
converters.clear();
}
}
@Override
public void onFailure(IConverter converter) {
if (converters.remove(converter)) {
try {
converter.shutDown();
} catch (RuntimeException exception) {
LOGGER.error("Could not shut down {}", converter, exception);
} finally {
converterFailureCallback.onFailure(converter);
}
}
}
@Override
public void run() {
for (IConverter converter : converters) {
if (!converter.isOperational()) {
if (converters.remove(converter)) {
try {
converter.shutDown();
} catch (RuntimeException e) {
LOGGER.warn("Could not shut down {} during deregistration", converter, e);
} finally {
converterFailureCallback.onFailure(converter);
}
}
}
}
}
/**
* A builder for creating an {@link AggregatingConverter}.
*
* Note: This builder is not thread safe.
*/
public static class Builder {
private final LinkedHashSet converters = new LinkedHashSet();
private ISelectionStrategy selectionStrategy = new RoundRobinSelectionStrategy();
private IConverterFailureCallback converterFailureCallback = new NoOpConverterFailureCallback();
private boolean propagateShutDown = true;
private Builder() {
// empty
}
/**
* Registers the given converters for delegation for the built converter.
*
* @param converters The additional converters to delegate to.
* @return This builder instance.
*/
public Builder aggregates(IConverter... converters) {
checkNotNull(converters);
return aggregates(Arrays.asList(converters));
}
/**
* Registers the given converters for delegation for the built converter.
*
* @param converters The additional converters to delegate to.
* @return This builder instance.
*/
public Builder aggregates(Collection converters) {
checkNotNull(converters);
this.converters.addAll(converters);
return this;
}
/**
* Registers a callback that is invoked when a converter is failing. Any previously registered callback is removed.
*
* @param converterFailureCallback The callback to notify over failed conversions.
* @return This builder instance.
*/
public Builder callback(IConverterFailureCallback converterFailureCallback) {
checkNotNull(converterFailureCallback);
this.converterFailureCallback = converterFailureCallback;
return this;
}
/**
* Registers a strategy for selecting one of several converters that this instance aggregates.
* By default, the build converter applies a round-robin aggregation strategy.
*
* @param selectionStrategy The selection strategy to apply.
* @return This builder instance.
*/
public Builder selectionStrategy(ISelectionStrategy selectionStrategy) {
checkNotNull(selectionStrategy);
this.selectionStrategy = selectionStrategy;
return this;
}
/**
* @param propagateShutDown {@code true} if shutting down this converter should also shut down any aggregated converters.
* @return This builder instance.
*/
public Builder propagateShutDown(boolean propagateShutDown) {
this.propagateShutDown = propagateShutDown;
return this;
}
/**
* Creates the specified converter.
*
* @return The specified converter.
*/
public IAggregatingConverter build() {
return new AggregatingConverter(new CopyOnWriteArrayList(converters),
selectionStrategy, converterFailureCallback,
propagateShutDown);
}
/**
* Creates the specified converter and additionally registers a job to regularly investigate any aggregated converter for
* its functionality. If a converter proves to no longer be operational, it is removed as if a conversion had failed.
*
* @param executorService The executor service to run the regular check.
* @param delay The delay between checks.
* @param timeUnit The time unit of the delay.
* @return The specified converter.
*/
public IAggregatingConverter build(ScheduledExecutorService executorService, long delay, TimeUnit timeUnit) {
AggregatingConverter converter = new AggregatingConverter(new CopyOnWriteArrayList(converters),
selectionStrategy, converterFailureCallback,
propagateShutDown);
converter.selfCheck = executorService.schedule(converter, delay, timeUnit);
return converter;
}
}
private class AggregatedFileSourceConversionWithSourceUnspecified implements IConversionJobWithSourceUnspecified {
private final IFileSource source;
private AggregatedFileSourceConversionWithSourceUnspecified(IFileSource source) {
this.source = source;
}
@Override
public IConversionJobWithSourceSpecified as(DocumentType sourceFormat) {
return new AggregatedFileSourceConversionWithSourceSpecified(source, sourceFormat);
}
}
private class AggregatedFileSourceConversionWithSourceSpecified implements IConversionJobWithSourceSpecified {
private final IFileSource source;
private final DocumentType sourceFormat;
private AggregatedFileSourceConversionWithSourceSpecified(IFileSource source, DocumentType sourceFormat) {
this.source = source;
this.sourceFormat = sourceFormat;
}
@Override
public IConversionJobWithTargetUnspecified to(File target) {
return to(target, new NoopFileConsumer());
}
@Override
public IConversionJobWithTargetUnspecified to(File target, IFileConsumer callback) {
return new AggregatedFileSourceToFileConsumerConversionWithSourceSpecified(source, sourceFormat, target, callback);
}
@Override
public IConversionJobWithTargetUnspecified to(OutputStream target) {
return to(target, ConversionJobWithSourceSpecifiedAdapter.DEFAULT_CLOSE_STREAM);
}
@Override
public IConversionJobWithTargetUnspecified to(OutputStream target, boolean closeStream) {
return to(new OutputStreamToInputStreamConsumer(target, closeStream));
}
@Override
public IConversionJobWithTargetUnspecified to(IInputStreamConsumer callback) {
return new AggregatedFileSourceToInputStreamConsumerConversionWithSourceSpecified(source, sourceFormat, callback);
}
}
private class AggregatedFileSourceToFileConsumerConversionWithSourceSpecified implements IConversionJobWithTargetUnspecified {
private final IFileSource source;
private final DocumentType sourceFormat;
private final File target;
private final IFileConsumer callback;
private AggregatedFileSourceToFileConsumerConversionWithSourceSpecified(IFileSource source, DocumentType sourceFormat,
File target, IFileConsumer callback) {
this.source = source;
this.sourceFormat = sourceFormat;
this.target = target;
this.callback = callback;
}
@Override
public IConversionJobWithPriorityUnspecified as(DocumentType targetFormat) {
return nextConverter(sourceFormat, targetFormat).convert(source).as(sourceFormat).to(target, callback).as(targetFormat);
}
}
private class AggregatedFileSourceToInputStreamConsumerConversionWithSourceSpecified implements IConversionJobWithTargetUnspecified {
private final IFileSource source;
private final DocumentType sourceFormat;
private final IInputStreamConsumer callback;
private AggregatedFileSourceToInputStreamConsumerConversionWithSourceSpecified(IFileSource source, DocumentType sourceFormat,
IInputStreamConsumer callback) {
this.source = source;
this.sourceFormat = sourceFormat;
this.callback = callback;
}
@Override
public IConversionJobWithPriorityUnspecified as(DocumentType targetFormat) {
return nextConverter(sourceFormat, targetFormat).convert(source).as(sourceFormat).to(callback).as(targetFormat);
}
}
private class AggregatedInputStreamConversionWithSourceUnspecified implements IConversionJobWithSourceUnspecified {
private final IInputStreamSource source;
public AggregatedInputStreamConversionWithSourceUnspecified(IInputStreamSource source) {
this.source = source;
}
@Override
public IConversionJobWithSourceSpecified as(DocumentType sourceFormat) {
return new AggregatedInputStreamSourceConversionWithSourceSpecified(source, sourceFormat);
}
}
private class AggregatedInputStreamSourceConversionWithSourceSpecified implements IConversionJobWithSourceSpecified {
private final IInputStreamSource source;
private final DocumentType sourceFormat;
private AggregatedInputStreamSourceConversionWithSourceSpecified(IInputStreamSource source, DocumentType sourceFormat) {
this.source = source;
this.sourceFormat = sourceFormat;
}
@Override
public IConversionJobWithTargetUnspecified to(File target) {
return to(target, new NoopFileConsumer());
}
@Override
public IConversionJobWithTargetUnspecified to(File target, IFileConsumer callback) {
return new AggregatedInputStreamSourceToFileConsumerConversionWithSourceSpecified(source, sourceFormat, target, callback);
}
@Override
public IConversionJobWithTargetUnspecified to(OutputStream target) {
return to(target, ConversionJobWithSourceSpecifiedAdapter.DEFAULT_CLOSE_STREAM);
}
@Override
public IConversionJobWithTargetUnspecified to(OutputStream target, boolean closeStream) {
return to(new OutputStreamToInputStreamConsumer(target, closeStream));
}
@Override
public IConversionJobWithTargetUnspecified to(IInputStreamConsumer callback) {
return new AggregatedInputStreamSourceToInputStreamConsumerConversionWithSourceSpecified(source, sourceFormat, callback);
}
}
private class AggregatedInputStreamSourceToFileConsumerConversionWithSourceSpecified implements IConversionJobWithTargetUnspecified {
private final IInputStreamSource source;
private final DocumentType sourceFormat;
private final File target;
private final IFileConsumer callback;
private AggregatedInputStreamSourceToFileConsumerConversionWithSourceSpecified(IInputStreamSource source, DocumentType sourceFormat,
File target, IFileConsumer callback) {
this.source = source;
this.sourceFormat = sourceFormat;
this.target = target;
this.callback = callback;
}
@Override
public IConversionJobWithPriorityUnspecified as(DocumentType targetFormat) {
return nextConverter(sourceFormat, targetFormat).convert(source).as(sourceFormat).to(target, callback).as(targetFormat);
}
}
private class AggregatedInputStreamSourceToInputStreamConsumerConversionWithSourceSpecified implements IConversionJobWithTargetUnspecified {
private final IInputStreamSource source;
private final DocumentType sourceFormat;
private final IInputStreamConsumer callback;
private AggregatedInputStreamSourceToInputStreamConsumerConversionWithSourceSpecified(IInputStreamSource source, DocumentType sourceFormat,
IInputStreamConsumer callback) {
this.source = source;
this.sourceFormat = sourceFormat;
this.callback = callback;
}
@Override
public IConversionJobWithPriorityUnspecified as(DocumentType targetFormat) {
return nextConverter(sourceFormat, targetFormat).convert(source).as(sourceFormat).to(callback).as(targetFormat);
}
}
}