Hudson can now monitor the swap space of slaves.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@10668 71c3de6d-444a-0410-be80-ed276b4c234a

core/pom.xml

@@ -485,6 +485,11 @@
       <artifactId>winp</artifactId>
       <version>1.5</version>
     </dependency>
+    <dependency>
+      <groupId>org.jvnet.hudson</groupId>
+      <artifactId>memory-monitor</artifactId>
+      <version>1.1</version>
+    </dependency>
     <dependency>
       <groupId>com.octo.captcha</groupId>
       <artifactId>jcaptcha-all</artifactId>

core/src/main/java/hudson/node_monitors/NodeMonitor.java

@@ -80,6 +80,7 @@ public abstract class NodeMonitor implements ExtensionPoint, Describable<NodeMon
             LIST.load(ClockMonitor.class);
             if(Functions.isMustangOrAbove())
                 LIST.load(DiskSpaceMonitor.class);
+            LIST.load(SwapSpaceMonitor.class);
             LIST.load(ArchitectureMonitor.class);
         } catch (Throwable e) {
             Logger.getLogger(NodeMonitor.class.getName()).log(Level.SEVERE, "Failed to load built-in monitors",e);

core/src/main/java/hudson/node_monitors/SwapSpaceMonitor.java

+package hudson.node_monitors;
+
+import hudson.Util;
+import hudson.model.Computer;
+import hudson.remoting.Callable;
+import net.sf.json.JSONObject;
+import org.jvnet.hudson.MemoryMonitor;
+import org.jvnet.hudson.MemoryUsage;
+import org.kohsuke.stapler.StaplerRequest;
+
+import java.io.IOException;
+
+/**
+ * Checks the swap space availability.
+ *
+ * @author Kohsuke Kawaguchi
+ * @sine 1.233
+ */
+public class SwapSpaceMonitor extends NodeMonitor {
+    public AbstractNodeMonitorDescriptor getDescriptor() {
+        return DESCRIPTOR;
+    }
+
+    /**
+     * Returns the HTML representation of the space.
+     */
+    public String toHtml(MemoryUsage usage) {
+        if(usage.availableSwapSpace==-1)
+            return "N/A";
+
+        long free = usage.availableSwapSpace;
+        free/=1024L;   // convert to KB
+        free/=1024L;   // convert to MB
+        if(free>256 || usage.totalSwapSpace/usage.availableSwapSpace<5)
+            return usage+"MB"; // if we have more than 256MB free or less than 80% filled up, it's OK
+
+        // Otherwise considered dangerously low.
+        return Util.wrapToErrorSpan(usage+"MB");
+    }
+
+    public static final AbstractNodeMonitorDescriptor<MemoryUsage> DESCRIPTOR = new AbstractNodeMonitorDescriptor<MemoryUsage>(DiskSpaceMonitor.class) {
+        protected MemoryUsage monitor(Computer c) throws IOException, InterruptedException {
+            return c.getChannel().call(new MonitorTask());
+        }
+
+        public String getDisplayName() {
+            return "Free Swap Space";
+        }
+
+        @Override
+        public NodeMonitor newInstance(StaplerRequest req, JSONObject formData) throws FormException {
+            return new SwapSpaceMonitor();
+        }
+    };
+
+    /**
+     * Obtains the string that represents the architecture.
+     */
+    private static class MonitorTask implements Callable<MemoryUsage,IOException> {
+        public MemoryUsage call() throws IOException {
+            return MemoryMonitor.get().monitor();
+        }
+
+        private static final long serialVersionUID = 1L;
+    }
+
+    static {
+        LIST.add(DESCRIPTOR);
+    }
+}