SOLR-4960: fix race in CoreContainer.getCore

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1496620 13f79535-47bb-0310-9956-ffa450edef68

solr/CHANGES.txt

@@ -192,7 +192,10 @@ Bug Fixes
 
 * SOLR-4949: UI Analysis page dropping characters from input box (steffkes)
 
-* SOLR-4960: race condition in shutdown of CoreContainer. (yonik)
+* SOLR-4960: Fix race conditions in shutdown of CoreContainer
+  and getCore that could cause a request to attempt to use a core that
+  has shut down. (yonik)
+
 
 Optimizations
 ----------------------

solr/core/src/java/org/apache/solr/core/CoreContainer.java

@@ -844,7 +844,7 @@ public class CoreContainer
     try {
       name = checkDefault(name);
 
-      SolrCore core = solrCores.getCoreFromAnyList(name);
+      SolrCore core = solrCores.getCoreFromAnyList(name, false);
       if (core == null)
         throw new SolrException( SolrException.ErrorCode.BAD_REQUEST, "No such core: " + name );
 
@@ -952,10 +952,9 @@ public class CoreContainer
     name = checkDefault(name);
 
     // Do this in two phases since we don't want to lock access to the cores over a load.
-    SolrCore core = solrCores.getCoreFromAnyList(name);
+    SolrCore core = solrCores.getCoreFromAnyList(name, true);
 
     if (core != null) {
-      core.open();
       return core;
     }
 

solr/core/src/java/org/apache/solr/core/SolrCores.java

@@ -303,20 +303,20 @@ class SolrCores {
     }
   }
 
-  protected SolrCore getCoreFromAnyList(String name) {
-    SolrCore core;
-
+  /* If you don't increment the reference count, someone could close the core before you use it. */
+  protected SolrCore getCoreFromAnyList(String name, boolean incRefCount) {
     synchronized (modifyLock) {
-      core = cores.get(name);
-      if (core != null) {
-        return core;
+      SolrCore core = cores.get(name);
+
+      if (core == null) {
+        core = transientCores.get(name);
       }
 
-      if (dynamicDescriptors.size() == 0) {
-        return null; // Nobody even tried to define any transient cores, so we're done.
+      if (core != null && incRefCount) {
+        core.open();
       }
-      // Now look for already loaded transient cores.
-      return transientCores.get(name);
+
+      return core;
     }
   }
 
@@ -429,7 +429,7 @@ class SolrCores {
         if (! pendingCoreOps.add(name)) {
           CoreContainer.log.warn("Replaced an entry in pendingCoreOps {}, we should not be doing this", name);
         }
-        return getCoreFromAnyList(name); // we might have been _unloading_ the core, so return the core if it was loaded.
+        return getCoreFromAnyList(name, false); // we might have been _unloading_ the core, so return the core if it was loaded.
       }
     }
     return null;