CM File Manager - Make AsyncResultExecutable's cancel() and end() innocuous

Ensure that cancel() and end() calls don't block the current thread
unnecessarily waiting for a notify().

Change-Id: I05843c8e1bdf880243e1fe9a226809aeaf33986b

3 files changed, 43 insertions, 14 deletions

diff --git a/src/com/cyanogenmod/filemanager/activities/SearchActivity.java b/src/com/cyanogenmod/filemanager/activities/SearchActivity.java
index 7c6bb2f2..b632c78e 100644
--- a/src/com/cyanogenmod/filemanager/activities/SearchActivity.java
+++ b/src/com/cyanogenmod/filemanager/activities/SearchActivity.java
@@ -241,6 +241,7 @@ public class SearchActivity extends Activity
                 @Override
                 public void run() {
                     try {
+                        mExecutable = null;
                         mAdapter.stopStreaming();
                         int resultsSize = mAdapter.resultsSize();
                         mStreamingSearchProgress.setVisibility(View.INVISIBLE);
@@ -481,7 +482,7 @@ public class SearchActivity extends Activity
         super.onPause();
         // stop search if the activity moves out of the foreground
         if (mExecutable != null) {
-            mExecutable.cancel();
+            mExecutable.end();
         }
     }
 
@@ -973,7 +974,7 @@ public class SearchActivity extends Activity
             case KeyEvent.KEYCODE_BACK:
                 // release Console lock held by the async search task
                 if (mExecutable != null) {
-                    mExecutable.cancel();
+                    mExecutable.end();
                 }
                 back(true, null, false);
                 return true;
@@ -991,7 +992,7 @@ public class SearchActivity extends Activity
           case android.R.id.home:
               // release Console lock held by the async search task
               if (mExecutable != null) {
-                  mExecutable.cancel();
+                  mExecutable.end();
               }
               back(true, null, false);
               return true;
@@ -1008,7 +1009,7 @@ public class SearchActivity extends Activity
         // cancel search query if in progress
         // *need* to do this as the async query holds a lock on the Console and we need the Console
         // to gather additional file info in order to process the click event
-        if (mSearchInProgress) mExecutable.cancel();
+        if (mSearchInProgress) mExecutable.end();
 
         try {
             SearchResult result = ((SearchResultAdapter)parent.getAdapter()).getItem(position);
diff --git a/src/com/cyanogenmod/filemanager/commands/java/FindCommand.java b/src/com/cyanogenmod/filemanager/commands/java/FindCommand.java
index 2a7ccf54..e4f1b08c 100644
--- a/src/com/cyanogenmod/filemanager/commands/java/FindCommand.java
+++ b/src/com/cyanogenmod/filemanager/commands/java/FindCommand.java
@@ -43,8 +43,8 @@ public class FindCommand extends Program implements FindExecutable {
     private final String[] mQueryRegExp;
     private final ConcurrentAsyncResultListener mAsyncResultListener;
 
-    private boolean mCancelled;
-    private boolean mEnded;
+    private volatile boolean mCancelled;
+    private volatile boolean mEnded;
     private final Object mSync = new Object();
 
     /**
@@ -110,6 +110,15 @@ public class FindCommand extends Program implements FindExecutable {
             findRecursive(f);
         }
 
+        // record program's execution termination
+        synchronized (mSync) {
+            mEnded = true;
+            // account for the delay between the end of findRecursive and setting program
+            // termination flag (mEnded)
+            // notify again in case a thread entered wait state since
+            mSync.notify();
+        }
+
         if (this.mAsyncResultListener != null) {
             this.mAsyncResultListener.onAsyncEnd(this.mCancelled);
         }
@@ -187,8 +196,12 @@ public class FindCommand extends Program implements FindExecutable {
     public boolean cancel() {
         try {
             synchronized (this.mSync) {
-                this.mCancelled = true;
-                this.mSync.wait(5000L);
+                // ensure the program is running before attempting to cancel
+                // there won't be a corresponding lock.notify() otherwise
+                if (!mEnded) {
+                    this.mCancelled = true;
+                    this.mSync.wait(5000L);
+                }
             }
         } catch (Exception e) {/**NON BLOCK**/}
         return true;
@@ -201,8 +214,11 @@ public class FindCommand extends Program implements FindExecutable {
     public boolean end() {
         try {
             synchronized (this.mSync) {
-                this.mEnded = true;
-                this.mSync.wait(5000L);
+                // ensure the program is running before attempting to terminate
+                if (!mEnded) {
+                    this.mEnded = true;
+                    this.mSync.wait(5000L);
+                }
             }
         } catch (Exception e) {/**NON BLOCK**/}
         return true;
diff --git a/src/com/cyanogenmod/filemanager/commands/secure/FindCommand.java b/src/com/cyanogenmod/filemanager/commands/secure/FindCommand.java
index 33d0ace0..35289e5a 100644
--- a/src/com/cyanogenmod/filemanager/commands/secure/FindCommand.java
+++ b/src/com/cyanogenmod/filemanager/commands/secure/FindCommand.java
@@ -44,8 +44,8 @@ public class FindCommand extends Program implements FindExecutable {
     private final String[] mQueryRegExp;
     private final ConcurrentAsyncResultListener mAsyncResultListener;
 
-    private boolean mCancelled;
-    private boolean mEnded;
+    private volatile boolean mCancelled;
+    private volatile boolean mEnded;
     private final Object mSync = new Object();
 
     /**
@@ -118,6 +118,15 @@ public class FindCommand extends Program implements FindExecutable {
         // Find the data
         findRecursive(f);
 
+        // record program's execution termination
+        synchronized (mSync) {
+            mEnded = true;
+            // account for the delay between the end of findRecursive and setting program
+            // termination flag (mEnded)
+            // notify again in case a thread entered wait state since
+            mSync.notify();
+        }
+
         if (this.mAsyncResultListener != null) {
             this.mAsyncResultListener.onAsyncEnd(this.mCancelled);
         }
@@ -198,7 +207,9 @@ public class FindCommand extends Program implements FindExecutable {
     @Override
     public boolean cancel() {
         try {
-            synchronized (this.mSync) {
+            // ensure the program is running before attempting to cancel
+            // there won't be a corresponding lock.notify() otherwise
+            if (!mEnded) {
                 this.mCancelled = true;
                 this.mSync.wait(5000L);
             }
@@ -212,7 +223,8 @@ public class FindCommand extends Program implements FindExecutable {
     @Override
     public boolean end() {
         try {
-            synchronized (this.mSync) {
+            // ensure the program is running before attempting to terminate
+            if (!mEnded) {
                 this.mEnded = true;
                 this.mSync.wait(5000L);
             }