Cache estimated duration for execution

In case of having 1000s of ongoing builds opening main pages can take
some time if list of executors are opened. It happens because for every
queury that comes from jelly we re-calculate the value from scratch. And
calculation needs to load some builds from disk. The worst thing is that it
happens for every user separately.

core/src/main/java/hudson/model/Executor.java

@@ -87,6 +87,7 @@ public class Executor extends Thread implements ModelObject {
     protected final @Nonnull Computer owner;
     private final Queue queue;
     private final ReadWriteLock lock = new ReentrantReadWriteLock();
+    private static final int DEFAULT_ESTIMATED_DURATION = -1;
 
     @GuardedBy("lock")
     private long startTime;
@@ -105,6 +106,11 @@ public class Executor extends Thread implements ModelObject {
     @GuardedBy("lock")
     private Queue.Executable executable;
 
+    /**
+     * Calculation of estimated duration needs some time, so, it's better to cache it once executable is known
+     */
+    private long executableEstimatedDuration = DEFAULT_ESTIMATED_DURATION;
+
     /**
      * Used to mark that the execution is continuing asynchronously even though {@link Executor} as {@link Thread}
      * has finished.
@@ -396,6 +402,8 @@ public class Executor extends Thread implements ModelObject {
                     return;
                 }
 
+                executableEstimatedDuration = executable.getEstimatedDuration();
+
                 if (executable instanceof Actionable) {
                     if (LOGGER.isLoggable(Level.FINER)) {
                         LOGGER.log(FINER, "when running {0} from {1} we are copying {2} actions whereas the item currently has {3}", new Object[] {executable, workUnit.context.item, workUnit.context.actions, workUnit.context.item.getAllActions()});
@@ -451,6 +459,7 @@ public class Executor extends Thread implements ModelObject {
             if (asynchronousExecution == null) {
                 finish2();
             }
+            executableEstimatedDuration = DEFAULT_ESTIMATED_DURATION;
         }
     }
 
@@ -686,18 +695,9 @@ public class Executor extends Thread implements ModelObject {
      */
     @Exported
     public int getProgress() {
-        long d;
-        lock.readLock().lock();
-        try {
-            if (executable == null) {
-                return -1;
-            }
-            d = executable.getEstimatedDuration();
-        } finally {
-            lock.readLock().unlock();
-        }
+        long d = executableEstimatedDuration;
         if (d <= 0) {
-            return -1;
+            return DEFAULT_ESTIMATED_DURATION;
         }
 
         int num = (int) (getElapsedTime() * 100 / d);
@@ -716,19 +716,17 @@ public class Executor extends Thread implements ModelObject {
      */
     @Exported
     public boolean isLikelyStuck() {
-        long d;
-        long elapsed;
         lock.readLock().lock();
         try {
             if (executable == null) {
                 return false;
             }
-
-            elapsed = getElapsedTime();
-            d = executable.getEstimatedDuration();
         } finally {
             lock.readLock().unlock();
         }
+
+        long elapsed = getElapsedTime();
+        long d = executableEstimatedDuration;
         if (d >= 0) {
             // if it's taking 10 times longer than ETA, consider it stuck
             return d * 10 < elapsed;
@@ -776,17 +774,7 @@ public class Executor extends Thread implements ModelObject {
      * until the build completes.
      */
     public String getEstimatedRemainingTime() {
-        long d;
-        lock.readLock().lock();
-        try {
-            if (executable == null) {
-                return Messages.Executor_NotAvailable();
-            }
-
-            d = executable.getEstimatedDuration();
-        } finally {
-            lock.readLock().unlock();
-        }
+        long d = executableEstimatedDuration;
         if (d < 0) {
             return Messages.Executor_NotAvailable();
         }
@@ -804,24 +792,14 @@ public class Executor extends Thread implements ModelObject {
      * it as a number of milli-seconds.
      */
     public long getEstimatedRemainingTimeMillis() {
-        long d;
-        lock.readLock().lock();
-        try {
-            if (executable == null) {
-                return -1;
-            }
-
-            d = executable.getEstimatedDuration();
-        } finally {
-            lock.readLock().unlock();
-        }
+        long d = executableEstimatedDuration;
         if (d < 0) {
-            return -1;
+            return DEFAULT_ESTIMATED_DURATION;
         }
 
         long eta = d - getElapsedTime();
         if (eta <= 0) {
-            return -1;
+            return DEFAULT_ESTIMATED_DURATION;
         }
 
         return eta;
@@ -906,16 +884,10 @@ public class Executor extends Thread implements ModelObject {
      * Returns when this executor started or should start being idle.
      */
     public long getIdleStartMilliseconds() {
-        lock.readLock().lock();
-        try {
-            if (isIdle())
-                return Math.max(creationTime, owner.getConnectTime());
-            else {
-                return Math.max(startTime + Math.max(0, executable == null ? -1 : executable.getEstimatedDuration()),
-                        System.currentTimeMillis() + 15000);
-            }
-        } finally {
-            lock.readLock().unlock();
+        if (isIdle())
+            return Math.max(creationTime, owner.getConnectTime());
+        else {
+            return Math.max(startTime + Math.max(0, executableEstimatedDuration), System.currentTimeMillis() + 15000);
         }
     }
 
@@ -981,7 +953,7 @@ public class Executor extends Thread implements ModelObject {
      */
     @Deprecated
     public static long getEstimatedDurationFor(Executable e) {
-        return e == null ? -1 : e.getEstimatedDuration();
+        return e == null ? DEFAULT_ESTIMATED_DURATION : e.getEstimatedDuration();
     }
 
     /**