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Make StartupStatus thread-safe, so we can add items at any time.

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This commit is contained in:
j2blake 2011-11-23 20:10:53 +00:00
parent 7439e02964
commit 350faa50fa
1 changed files with 84 additions and 22 deletions
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106
webapp/src/edu/cornell/mannlib/vitro/webapp/startup/StartupStatus.java
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@ -5,7 +5,6 @@ package edu.cornell.mannlib.vitro.webapp.startup;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.servlet.ServletContext;
@ -17,6 +16,9 @@ import org.apache.commons.logging.LogFactory;
/**
* Accumulates a list of messages from the StartupManager, and from the context
* listeners that the run during startup.
*
* This is thread-safe, with immutable items in the list and synchronized access
* to the list.
*/
public class StartupStatus {
private static final Log log = LogFactory.getLog(StartupStatus.class);
@ -45,7 +47,7 @@ public class StartupStatus {
// methods to set status - note that these write to the log also.
// ----------------------------------------------------------------------
private List<StatusItem> itemList = new ArrayList<StatusItem>();
private SynchronizedStatusItemList itemList = new SynchronizedStatusItemList();
public void info(ServletContextListener listener, String message) {
addItem(StatusItem.Level.INFO, listener, message, null);
@ -84,12 +86,10 @@ public class StartupStatus {
/** Create a simple item for this listener if no other exists. */
public void listenerExecuted(ServletContextListener listener) {
for (StatusItem item : itemList) {
if (item.getSourceName().equals(listener.getClass().getName())) {
return;
}
List<StatusItem> itemsForThisListener = getItemsForListener(listener);
if (itemsForThisListener.isEmpty()) {
addItem(StatusItem.Level.INFO, listener, "Ran successfully.", null);
}
addItem(StatusItem.Level.INFO, listener, "Ran successfully.", null);
}
private void addItem(StatusItem.Level level, ServletContextListener source,
@ -133,33 +133,29 @@ public class StartupStatus {
}
public List<StatusItem> getStatusItems() {
return Collections.unmodifiableList(itemList);
return itemList.filterItems(StatusItemFilter.ALL_ITEMS_FILTER);
}
public List<StatusItem> getErrorItems() {
List<StatusItem> list = new ArrayList<StartupStatus.StatusItem>();
for (StatusItem item : itemList) {
if (item.level == StatusItem.Level.FATAL) {
list.add(item);
}
}
return list;
return itemList.filterItems(StatusItemFilter.ERROR_ITEMS_FILTER);
}
public List<StatusItem> getWarningItems() {
List<StatusItem> list = new ArrayList<StartupStatus.StatusItem>();
for (StatusItem item : itemList) {
if (item.level == StatusItem.Level.WARNING) {
list.add(item);
}
}
return list;
return itemList.filterItems(StatusItemFilter.WARNING_ITEMS_FILTER);
}
public List<StatusItem> getItemsForListener(ServletContextListener listener) {
return itemList.filterItems(StatusItemFilter.listenerFilter(listener));
}
// ----------------------------------------------------------------------
// helper classes
// ----------------------------------------------------------------------
/**
* An immutable item that can't throw an exception during construction and
* will always contain suitable, non-null values.
*/
public static class StatusItem {
public enum Level {
INFO, WARNING, FATAL, NOT_EXECUTED
@ -257,4 +253,70 @@ public class StartupStatus {
}
/**
* A filter class and some basic instances.
*/
private static abstract class StatusItemFilter {
public abstract boolean accept(StatusItem item);
public static final StatusItemFilter ALL_ITEMS_FILTER = new StatusItemFilter() {
@Override
public boolean accept(StatusItem item) {
return true;
}
};
public static final StatusItemFilter ERROR_ITEMS_FILTER = new StatusItemFilter() {
@Override
public boolean accept(StatusItem item) {
return item.level == StatusItem.Level.FATAL;
}
};
public static final StatusItemFilter WARNING_ITEMS_FILTER = new StatusItemFilter() {
@Override
public boolean accept(StatusItem item) {
return item.level == StatusItem.Level.WARNING;
}
};
public static StatusItemFilter listenerFilter(
ServletContextListener listener) {
final String listenerName = listener.getClass().getName();
return new StatusItemFilter() {
@Override
public boolean accept(StatusItem item) {
return item.getSourceName().equals(listenerName);
}
};
}
}
/**
* A list, with synchronized methods for adding to it, and for getting a
* filtered subset of it.
*/
private class SynchronizedStatusItemList {
private final List<StatusItem> list = new ArrayList<StatusItem>();
public void add(StatusItem item) {
synchronized (list) {
list.add(item);
}
}
public List<StatusItem> filterItems(StatusItemFilter filter) {
List<StatusItem> filteredList = new ArrayList<StatusItem>();
synchronized (list) {
for (StatusItem item : list) {
if (filter.accept(item)) {
filteredList.add(item);
}
}
}
return filteredList;
}
}
}