MVStore: concurrent compaction and store operations could result in an IllegalStateException.

h2/src/docsrc/html/changelog.html

@@ -17,7 +17,8 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>Issue 594: Profiler.copyInThread does not work properly.
+<ul><li>MVStore: concurrent compaction and store operations could result in an IllegalStateException.
+</li><li>Issue 594: Profiler.copyInThread does not work properly.
 </li></ul>
 
 <h2>Version 1.4.184 Beta (2014-12-19)</h2>

h2/src/main/org/h2/mvstore/MVStore.java

@@ -1184,7 +1184,7 @@ public class MVStore {
         return version;
     }
 
-    private void freeUnusedChunks() {
+    private synchronized void freeUnusedChunks() {
         if (lastChunk == null) {
             return;
         }
@@ -1256,26 +1256,36 @@ public class MVStore {
         if (DataUtils.getPageType(pos) == DataUtils.PAGE_TYPE_LEAF) {
             return null;
         }
-        PageChildren r = cacheChunkRef.get(pos);
+        PageChildren r;
+        if (cacheChunkRef != null) {
+            r = cacheChunkRef.get(pos);
+        } else {
+            r = null;
+        }
         if (r == null) {
+            if (cache != null) {
                 Page p = cache.get(pos);
-            if (p == null) {
+                if (p != null) {
+                    r = new PageChildren(p);
+                }
+            }
+            if (r == null) {
                 Chunk c = getChunk(pos);
                 long filePos = c.block * BLOCK_SIZE;
                 filePos += DataUtils.getPageOffset(pos);
                 if (filePos < 0) {
                     throw DataUtils.newIllegalStateException(
                             DataUtils.ERROR_FILE_CORRUPT,
-                            "Negative position {0}", filePos);
+                            "Negative position {0}; p={1}, c={2}", filePos, pos, c.toString());
                 }
                 long maxPos = (c.block + c.len) * BLOCK_SIZE;
                 r = PageChildren.read(fileStore, pos, mapId, filePos, maxPos);
-            } else {
-                r = new PageChildren(p);
             }
             r.removeDuplicateChunkReferences();
+            if (cacheChunkRef != null) {
                 cacheChunkRef.put(pos, r);
             }
+        }
         if (r.children.length == 0) {
             int chunk = DataUtils.getPageChunkId(pos);
             if (chunk == parentChunk) {

h2/src/test/org/h2/test/store/TestConcurrent.java

@@ -50,6 +50,7 @@ public class TestConcurrent extends TestMVStore {
         FileUtils.createDirectories(getBaseDir());
         FileUtils.deleteRecursive("memFS:", false);
         
+        testConcurrentSaveCompact();
         testConcurrentDataType();
         testConcurrentAutoCommitAndChange();
         testConcurrentReplaceAndRead();
@@ -65,6 +66,40 @@ public class TestConcurrent extends TestMVStore {
         testConcurrentRead();
     }
     
+    private void testConcurrentSaveCompact() throws Exception {
+        String fileName = "memFS:testConcurrentSaveCompact";
+        FileUtils.delete(fileName);
+        final MVStore s = new MVStore.Builder().
+                fileName(fileName).
+                cacheSize(0).
+                open();
+        try {
+            s.setRetentionTime(0);
+            final MVMap<Integer, Integer> dataMap = s.openMap("data");
+            Task task = new Task() {
+                @Override
+                public void call() throws Exception {
+                    int i = 0;
+                    while (!stop) {
+                        s.compact(100, 1024 * 1024);
+                        dataMap.put(i % 1000, i * 10);
+                        s.commit();
+                        i++;
+                    }
+                }
+            };
+            task.execute();
+            for (int i = 0; i < 1000 && !task.isFinished(); i++) {
+                s.compact(100, 1024 * 1024);
+                dataMap.put(i % 1000, i * 10);
+                s.commit();
+            }
+            task.get();
+        } finally {
+            s.close();
+        }
+    }
+
     private void testConcurrentDataType() throws InterruptedException {
         final ObjectDataType type = new ObjectDataType();
         final Object[] data = new Object[]{