Added proxies for the disk Command

src/main/java/com/acme/commands/Disk/BasicDiskStatusCmd.java → src/main/java/com/acme/commands/Disk/DiskStatusCmd.java

@@ -4,33 +4,38 @@
 import com.acme.commands.StatusCommand;
 import com.acme.executors.ICommandExecutor;
 import com.acme.executors.SimpleCommandExecutor;
-import org.springframework.beans.factory.annotation.Autowired;
 
 /**
  * Command for determining the basic disk status
  */
-public class BasicDiskStatusCmd implements StatusCommand {
+public class DiskStatusCmd implements StatusCommand {
 
     private ICommandExecutor executor;
 
     private final long Id;
     private final String template;
     private final String name;
+    private final GenerateDiskStatusCmd cmd;
 
     private DiskStatus status;
 
-    public BasicDiskStatusCmd(long Id, String template, String name) {
+    public DiskStatusCmd(long Id, String template, String name, GenerateDiskStatusCmd cmd) {
         this.Id = Id;
         this.template = template;
         this.name = name;
+        this.cmd = cmd;
+
         executor = new SimpleCommandExecutor();
     }
 
+    public DiskStatusCmd(long Id, String template, String name) {
+        this(Id, template, name, new GenerateDiskStatusCmd());
+    }
+
     @Override
     public void execute() {
-        status = new DiskStatus(Id, String.format(template, name));
-        GenerateDiskStatusCmd cmd = new GenerateDiskStatusCmd();
         executor.executeCommand(cmd);
+        status = new DiskStatus(Id, String.format(template, name));
         status.setStatusDesc(cmd.getResult());
     }
 

src/main/java/com/acme/commands/Disk/FastResponseDiskStatusCmd.java

@@ -0,0 +1,46 @@
+package com.acme.commands.Disk;
+
+import com.acme.beans.DiskStatus;
+
+public class FastResponseDiskStatusCmd extends DiskStatusCmd {
+
+    private final long Id;
+    private final String template;
+    private final String name;
+
+    private DiskStatusCmd cmd;
+
+    public FastResponseDiskStatusCmd(long Id, String template, String name, DiskStatusCmd cmd) {
+        super(Id, template, name);
+
+        this.Id = Id;
+        this.template = template;
+        this.name = name;
+        this.cmd = cmd;
+    }
+
+    public FastResponseDiskStatusCmd(long Id, String template, String name) {
+        this(Id, template, name, new DiskStatusCmd(Id, template, name));
+    }
+
+    @Override
+    public void execute() {
+        Thread executionThread = new Thread( () -> cmd.execute() );
+        executionThread.start();
+        try {
+            Thread.sleep(2500);
+        } catch (InterruptedException e) {
+            e.printStackTrace();
+        }
+    }
+
+    @Override
+    public DiskStatus getResult() {
+        DiskStatus result = cmd.getResult();
+        if (result == null || result.getStatusDesc() == null){
+            result = new DiskStatus(Id, String.format(template, name));
+            result.setStatusDesc("Unknown");
+        }
+        return result;
+    }
+}

src/main/java/com/acme/commands/Disk/ResourceEfficientDiskStatusGenerationCmd.java

@@ -0,0 +1,53 @@
+package com.acme.commands.Disk;
+
+/**
+ * Singleton proxy for generating the disk status, so that only one instance of the command will be executed at once
+ */
+public class ResourceEfficientDiskStatusGenerationCmd extends GenerateDiskStatusCmd {
+
+    private String statusDesc = "unknown";
+
+    private boolean isRunning;
+    private static ResourceEfficientDiskStatusGenerationCmd cmd = new ResourceEfficientDiskStatusGenerationCmd();
+
+    private ResourceEfficientDiskStatusGenerationCmd() {
+    }
+
+    public static ResourceEfficientDiskStatusGenerationCmd getInstance(){
+        return cmd;
+    }
+
+    @Override
+    public void execute() {
+
+        boolean willExecute;
+        synchronized (this){
+            if (isRunning){
+                willExecute = false;
+                try {
+                    this.wait();
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            } else {
+                isRunning = true;
+                willExecute = true;
+            }
+        }
+
+        if (willExecute){
+            statusDesc = super.createStatusDesc();
+            synchronized (this){
+                isRunning = false;
+                this.notifyAll();
+            }
+        }
+
+    }
+
+    @Override
+    public String getResult() {
+        return statusDesc;
+    }
+
+}

src/main/java/com/acme/commands/Disk/SecureDiskStatusCmd.java

@@ -0,0 +1,49 @@
+package com.acme.commands.Disk;
+
+import com.acme.beans.DiskStatus;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.lang.invoke.MethodHandles;
+
+/**
+ * Proxy decorator for ensuring that only registered users can execute the disk status command
+ */
+public class SecureDiskStatusCmd extends DiskStatusCmd {
+    private final long Id;
+    private final String template;
+    private final String name;
+
+    private DiskStatusCmd cmd;
+
+    protected static final Logger LOGGER = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
+
+    public SecureDiskStatusCmd(long Id, String template, String name, DiskStatusCmd cmd) {
+        super(Id, template, name);
+
+        this.Id = Id;
+        this.template = template;
+        this.name = name;
+        this.cmd = cmd;
+    }
+
+    public SecureDiskStatusCmd(long Id, String template, String name) {
+        this(Id, template, name, new DiskStatusCmd(Id, template, name));
+    }
+
+    @Override
+    public void execute() {
+        if (name == null || name.equals("Anonymous")) {
+            return;
+        }
+
+        LOGGER.info("User '{}' was allowed to access disk status information", name);
+
+        cmd.execute();
+    }
+
+    @Override
+    public DiskStatus getResult() {
+        return cmd.getResult();
+    }
+}

src/main/java/com/acme/statusmgr/StatusController.java

@@ -1,7 +1,10 @@
 package com.acme.statusmgr;
 
 import com.acme.DecoratorFactory;
-import com.acme.commands.Disk.BasicDiskStatusCmd;
+import com.acme.commands.Disk.DiskStatusCmd;
+import com.acme.commands.Disk.FastResponseDiskStatusCmd;
+import com.acme.commands.Disk.ResourceEfficientDiskStatusGenerationCmd;
+import com.acme.commands.Disk.SecureDiskStatusCmd;
 import com.acme.commands.Server.BasicServerStatusCmd;
 import com.acme.commands.Server.DetailedServerStatusCmd;
 import com.acme.executors.ICommandExecutor;
@@ -74,7 +77,9 @@ public ServerStatus getCurrentDetailedServerStatus(@RequestParam(value = "name",
 
     @RequestMapping("/disk/status")
     public DiskStatus getCurrentDiskStatus(@RequestParam(value = "name", defaultValue = "Anonymous") String name) {
-        BasicDiskStatusCmd cmd = new BasicDiskStatusCmd(counter.incrementAndGet(), template, name);
+        long Id = counter.incrementAndGet();
+        DiskStatusCmd cmd = new DiskStatusCmd(Id, template, name, ResourceEfficientDiskStatusGenerationCmd.getInstance());
+        cmd = new SecureDiskStatusCmd(Id, template, name, new FastResponseDiskStatusCmd(Id, template, name, cmd));
         executor.executeCommand(cmd);
         return cmd.getResult();
     }

src/test/java/com/acme/statusmgr/StatusCommandTests.java

@@ -3,7 +3,7 @@
 import com.acme.beans.DiskStatus;
 import com.acme.beans.ServerStatus;
 import com.acme.beans.complex.ComplexDecoratorFactory;
-import com.acme.commands.Disk.BasicDiskStatusCmd;
+import com.acme.commands.Disk.DiskStatusCmd;
 import com.acme.commands.Server.BasicServerStatusCmd;
 import com.acme.commands.Server.DetailedServerStatusCmd;
 import com.acme.executors.ICommandExecutor;
@@ -83,7 +83,7 @@ public void simplifiedDetailedServerStatusCommandShouldCreateSimplifiedStatus()
     @Test
     public void basicDiskStatusCommandShouldCreateBasicStatus() {
 
-        BasicDiskStatusCmd cmd = new BasicDiskStatusCmd(5, "Server Status requested by %s", "Anonymous");
+        DiskStatusCmd cmd = new DiskStatusCmd(5, "Server Status requested by %s", "Anonymous");
 
         executor.executeCommand(cmd);
         DiskStatus result = cmd.getResult();