Make sure an external snapshot is opened just once for the same snapshot file.

Author: jisedlac

visualvm/application/src/com/sun/tools/visualvm/application/snapshot/ApplicationSnapshotProvider.java

@@ -191,7 +191,13 @@ public void run() {
 
                     File storageDirectory = persistent ? ApplicationSnapshotsSupport.getStorageDirectory() :
                                                          Storage.getTemporaryStorageDirectory();
-                    File snapshotDirectory = Utils.extractArchive(archive, storageDirectory);
+                    
+                    File snapshotDirectory = new File(storageDirectory, archive.getName());
+                    
+                    // Only extract the archive if not already extracted (subsequent opening of the same snapshot)
+                    if (!snapshotDirectory.isDirectory() || !snapshotDirectory.canRead())
+                        snapshotDirectory = Utils.extractArchive(archive, storageDirectory);
+                    
                     if (snapshotDirectory != null) {
                         Storage storage = new Storage(snapshotDirectory, PROPERTIES_FILENAME);
                         ApplicationSnapshot snapshot = new ApplicationSnapshot(snapshotDirectory, storage);

visualvm/core/src/com/sun/tools/visualvm/core/snapshot/Snapshot.java

@@ -30,6 +30,7 @@
 import com.sun.tools.visualvm.core.datasupport.Utils;
 import com.sun.tools.visualvm.core.ui.DataSourceWindowManager;
 import java.io.File;
+import java.util.Objects;
 
 /**
  * Abstract implementation of Snapshot.
@@ -46,6 +47,8 @@ public abstract class Snapshot extends DataSource {
     private File file;
     private final SnapshotCategory category;
 
+    private String snapshotID;
+    
 
     /**
      * Creates new instance of AbstractSnapshot with the data stored in a file.
@@ -98,6 +101,7 @@ protected final void setFile(File newFile) {
         if (file == null && newFile == null) return;
         File oldFile = file;
         file = newFile;
+        if (oldFile == null) snapshotID = null;
         getChangeSupport().firePropertyChange(PROPERTY_FILE, oldFile, newFile);
     }
 
@@ -193,5 +197,34 @@ protected Storage createStorage() {
     protected final boolean isInSnapshot() {
         return getOwner() instanceof Snapshot;
     }
+    
+    
+    /**
+     * Returns ID of the Snapshot. The ID should be based on the snapshot file
+     * if available and will only be computed for the first non-null file.
+     *
+     * @return ID of the Snapshot
+     *
+     * @since VisualVM 1.4
+     */
+    protected String computeSnapshotID() {
+        File f = getFile();
+        return f == null ? super.hashCode() + "-no_file" : f.getPath(); // NOI18N
+    }
+    
+    private String getSnapshotID() {
+        if (snapshotID == null) snapshotID = computeSnapshotID();
+        return snapshotID;
+    }
+    
+    
+    public boolean equals(Object o) {
+        if (!(o instanceof Snapshot)) return false;
+        return Objects.equals(getSnapshotID(), ((Snapshot)o).getSnapshotID());
+    }
+    
+    public int hashCode() {
+        return Objects.hashCode(getSnapshotID());
+    }
 
 }