SPY-190: Remove the no-operation isInterrupted() call. Document interruption policy.

Motivation
----------
Avoid confusion. Make the interruption policy more clear.

Modifications
-------------
Remove the no-operation isInterrupted() call.
Document interruption policy.

Result
------
Better understandable concurrency code.

Change-Id: Iaf63f8a246c45e9ed9ebfe9c4239043cbe9e2039
Reviewed-on: http://review.couchbase.org/58266
Reviewed-by: Michael Nitschinger <[email protected]>
Tested-by: Michael Nitschinger <[email protected]>

Author: Christian Esken

src/main/java/net/spy/memcached/internal/OperationFuture.java

@@ -207,6 +207,9 @@ public void setCas(long inCas) {
  /**
    * Get the CAS for this operation.
    *
+   * The interrupted status of the current thread is cleared by this method.
+   * Inspect the returned OperationStatus to check whether an interruption has taken place.
+   *
    * @throws UnsupportedOperationException If this is for an ASCII protocol
    * configured client.
    * @return the CAS for this operation or null if unsuccessful.
@@ -218,7 +221,6 @@ public Long getCas() {
         get();
       } catch (InterruptedException e) {
         status = new OperationStatus(false, "Interrupted", StatusCode.INTERRUPTED);
-        Thread.currentThread().isInterrupted();
       } catch (ExecutionException e) {
         getLogger().warn("Error getting cas of operation", e);
       }
@@ -235,6 +237,9 @@ public Long getCas() {
    * Note that the operation status may change as the operation is tried and
    * potentially retried against the servers specified by the NodeLocator.
    *
+   * The interrupted status of the current thread is cleared by this method.
+   * Inspect the returned OperationStatus to check whether an interruption has taken place.
+   *
    * @return OperationStatus
    */
   public OperationStatus getStatus() {
@@ -243,7 +248,6 @@ public OperationStatus getStatus() {
         get();
       } catch (InterruptedException e) {
         status = new OperationStatus(false, "Interrupted", StatusCode.INTERRUPTED);
-        Thread.currentThread().isInterrupted();
       } catch (ExecutionException e) {
         getLogger().warn("Error getting status of operation", e);
       }