com.paypal.butterfly.extensions.api.upgrade.UpgradePath Maven / Gradle / Ivy
package com.paypal.butterfly.extensions.api.upgrade;
import com.paypal.butterfly.extensions.api.Extension;
import com.paypal.butterfly.extensions.api.exception.ButterflyRuntimeException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Upgrade paths enable upgrading an application from one version to a target version,
* which means executing a collection of sequential upgrade steps. This collection
* might be made of only one upgrade step as well.
*
* @author facarvalho
*/
public final class UpgradePath {
private static final Logger logger = LoggerFactory.getLogger(UpgradeStep.class);
private static final String DESCRIPTION_FORMAT = "Upgrade path from version %s to version %s";
// The first upgrade step to be executed in this upgrade path
// It must never be null, and it might be the only one,
// if the version it upgrades to is the same as upgradeVersion
private UpgradeStep firstStep;
// The target, or final, version this upgrade path will upgrade the application to
private String upgradeVersion;
// The next upgrade step to be executed. At first, this is same as firstStep.
// As the transformation happens, step by step, this reference is updated to
// the next upgrade step to be executed.
// It might be null, if there is no more upgrade step to be executed next
private UpgradeStep nextStep;
// The description of the upgrade path, pretty much a message stating the versions
// "from" and "to"
private String description;
public UpgradePath(Class firstStepClass) {
this(firstStepClass, null);
}
@SuppressWarnings("PMD.AvoidReassigningParameters")
public UpgradePath(Class firstStepClass, String upgradeVersion) {
if (firstStepClass == null) {
throw new IllegalArgumentException("First step class cannot be null");
}
try {
this.firstStep = firstStepClass.newInstance();
} catch (InstantiationException e) {
String exceptionMessage = "Upgrade step class " + firstStepClass + " could not be instantiated. Run Butterfly in debug mode, double check if its extension has been properly registered, and also double check if it complies with Butterfly extensions API";
logger.error(exceptionMessage, e);
throw new ButterflyRuntimeException(exceptionMessage, e);
} catch (IllegalAccessException e) {
String exceptionMessage = "Upgrade step class " + firstStepClass + " could not be accessed";
logger.error(exceptionMessage, e);
throw new ButterflyRuntimeException(exceptionMessage, e);
}
if (upgradeVersion == null || upgradeVersion.isEmpty()) {
upgradeVersion = getLastVersion();
} else if(!upgradeVersionValidation(upgradeVersion)) {
throw new IllegalArgumentException("Upgrade version " + upgradeVersion + " is invalid");
}
this.nextStep = firstStep;
this.upgradeVersion = upgradeVersion;
description = String.format(DESCRIPTION_FORMAT, firstStep.getCurrentVersion(), upgradeVersion);
}
/*
* Returns the latest version possible based on the chain
* of {@link UpgradeStep} objects, and the one on its end
*/
private String getLastVersion() {
UpgradeStep us = firstStep;
while (us.getNextStep() != null) {
us = us.getNextStep();
}
return us.getNextVersion();
}
/*
* Returns true only {@code targetVersion} is valid, in other words,
* if it is the "upgrade to" version of one of the {@link UpgradeStep}
* objects in the chain
*/
private boolean upgradeVersionValidation(String targetVersion) {
UpgradeStep us = firstStep;
do {
if (us.getNextVersion().equals(targetVersion)) {
return true;
}
us = us.getNextStep();
} while (us != null);
return false;
}
/**
* Returns the original version to upgrade the application from
* in this upgrade path
*
* @return the original version to upgrade the application from
* in this upgrade path
*/
public String getOriginalVersion() {
return firstStep.getCurrentVersion();
}
/**
* Returns the target version to upgrade the application to
* in this upgrade path
*
* @return the target version to upgrade the application to
* in this upgrade path
*/
public String getUpgradeVersion() {
return upgradeVersion;
}
/**
* Returns the {@link Extension} class associated
* with this upgrade path via its first upgrade step
*
* @return the {@link Extension} class associated
* with this upgrade path
*/
public Class getExtension() {
return firstStep.getExtensionClass();
}
public String getDescription() {
return description;
}
/**
* Returns true only if the upgrade path would not return
* null if {@link #next()} was called
*
* @return if there is a next upgrade step to be executed
*/
public boolean hasNext() {
return nextStep != null;
}
/**
* Returns the next {@link UpgradeStep} to be executed and
* move its internal cursor to the following {@link UpgradeStep}
* object to be executed, if existent
*
* @return the next {@link UpgradeStep} to be executed
*/
public UpgradeStep next() {
if (!hasNext()) {
return null;
}
UpgradeStep stepToReturn = nextStep;
if (stepToReturn.getNextVersion().equals(upgradeVersion)) {
nextStep = null;
} else {
nextStep = nextStep.getNextStep();
}
return stepToReturn;
}
/**
* Return the name of the upgrade template to be performed
* as the first step in this upgrade path
*
* @return the name of the upgrade template to be performed
* as the first step in this upgrade path
*/
public String getFirstStepTemplateName() {
return firstStep.getClass().getName();
}
}