MVStore: power failure could corrupt the store, if writes were re-ordered.

h2/src/docsrc/html/changelog.html

@@ -21,6 +21,8 @@ Change Log
 
 <h2>Next Version (unreleased)</h2>
 <ul>
+<li>MVStore: power failure could corrupt the store, if writes were re-ordered.
+</li>
 <li>For compatibility with other databases, support for (double and float)
     -0.0 has been removed. 0.0 is used instead.
 </li>

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

@@ -22,9 +22,9 @@ import java.util.concurrent.ConcurrentHashMap;
 import org.h2.compress.CompressDeflate;
 import org.h2.compress.CompressLZF;
 import org.h2.compress.Compressor;
+import org.h2.mvstore.Page.PageChildren;
 import org.h2.mvstore.cache.CacheLongKeyLIRS;
 import org.h2.mvstore.type.StringDataType;
-import org.h2.mvstore.Page.PageChildren;
 import org.h2.util.MathUtils;
 import org.h2.util.New;
 
@@ -240,6 +240,13 @@ public class MVStore {
      * The time the store was created, in milliseconds since 1970.
      */
     private long creationTime;
+
+    /**
+     * How long to retain old, persisted chunks, in milliseconds. For larger or
+     * equal to zero, a chunk is never directly overwritten if unused, but
+     * instead, the unused field is set. If smaller zero, chunks are directly
+     * overwritten if unused.
+     */
     private int retentionTime;
 
     private long lastCommitTime;
@@ -270,6 +277,8 @@ public class MVStore {
 
     private IllegalStateException panicException;
 
+    private long lastTimeAbsolute;
+
     /**
      * Create and open the store.
      *
@@ -337,7 +346,7 @@ public class MVStore {
                 fileStore.open(fileName, readOnly, encryptionKey);
             }
             if (fileStore.size() == 0) {
-                creationTime = getTime();
+                creationTime = getTimeAbsolute();
                 lastCommitTime = creationTime;
                 storeHeader.put("H", 2);
                 storeHeader.put("blockSize", BLOCK_SIZE);
@@ -354,7 +363,7 @@ public class MVStore {
                 Arrays.fill(encryptionKey, (char) 0);
             }
         }
-        lastCommitTime = getTime();
+        lastCommitTime = getTimeSinceCreation();
 
         // setAutoCommitDelay starts the thread, but only if
         // the parameter is different from the old value
@@ -520,13 +529,15 @@ public class MVStore {
     }
 
     private Chunk getChunkForVersion(long version) {
-        Chunk c = lastChunk;
-        while (true) {
-            if (c == null || c.version <= version) {
-                return c;
+        Chunk newest = null;
+        for (Chunk c : chunks.values()) {
+            if (c.version <= version) {
+                if (newest == null || c.id > newest.id) {
+                    newest = c;
+                }
             }
-            c = chunks.get(c.id - 1);
         }
+        return newest;
     }
 
     /**
@@ -546,10 +557,9 @@ public class MVStore {
     }
 
     private synchronized void readStoreHeader() {
-        boolean validHeader = false;
-        // we don't know yet which chunk and version are the newest
-        long newestVersion = -1;
-        long chunkBlock = -1;
+        Chunk newest = null;
+        boolean validStoreHeader = false;
+        // find out which chunk and version are the newest
         // read the first two blocks
         ByteBuffer fileHeaderBlocks = fileStore.readFully(0, 2 * BLOCK_SIZE);
         byte[] buff = new byte[BLOCK_SIZE];
@@ -578,18 +588,22 @@ public class MVStore {
                     continue;
                 }
                 long version = DataUtils.readHexLong(m, "version", 0);
-                if (version > newestVersion) {
-                    newestVersion = version;
+                if (newest == null || version > newest.version) {
+                    validStoreHeader = true;
                     storeHeader.putAll(m);
-                    chunkBlock = DataUtils.readHexLong(m, "block", 0);
                     creationTime = DataUtils.readHexLong(m, "created", 0);
-                    validHeader = true;
+                    int chunkId = DataUtils.readHexInt(m, "chunk", 0);
+                    long block = DataUtils.readHexLong(m, "block", 0);
+                    Chunk test = readChunkHeaderAndFooter(block);
+                    if (test != null && test.id == chunkId) {
+                        newest = test;
+                    }
                 }
             } catch (Exception e) {
                 continue;
             }
         }
-        if (!validHeader) {
+        if (!validStoreHeader) {
             throw DataUtils.newIllegalStateException(
                     DataUtils.ERROR_FILE_CORRUPT,
                     "Store header is corrupt: {0}", fileStore);
@@ -629,58 +643,51 @@ public class MVStore {
             creationTime = now;
             storeHeader.put("created", creationTime);
         }
-
-        Chunk footer = readChunkFooter(fileStore.size());
-        if (footer != null) {
-            if (footer.version > newestVersion) {
-                newestVersion = footer.version;
-                chunkBlock = footer.block;
+        Chunk test = readChunkFooter(fileStore.size());
+        if (test != null) {
+            test = readChunkHeaderAndFooter(test.block);
+            if (test != null) {
+                if (newest == null || test.version > newest.version) {
+                    newest = test;
                 }
             }
-        if (chunkBlock <= 0) {
+        }
+        if (newest == null) {
             // no chunk
             return;
         }
-
         // read the chunk header and footer,
         // and follow the chain of next chunks
-        lastChunk = null;
         while (true) {
-            Chunk header;
-            try {
-                header = readChunkHeader(chunkBlock);
-            } catch (Exception e) {
-                // invalid chunk header: ignore, but stop
+            if (newest.next == 0 ||
+                    newest.next >= fileStore.size() / BLOCK_SIZE) {
+                // no (valid) next
                 break;
             }
-            if (header.version < newestVersion) {
-                // we have reached the end
+            test = readChunkHeaderAndFooter(newest.next);
+            if (test == null || test.id <= newest.id) {
                 break;
             }
-            footer = readChunkFooter((chunkBlock + header.len) * BLOCK_SIZE);
-            if (footer == null || footer.id != header.id) {
-                // invalid chunk footer, or the wrong one
-                break;
+            newest = test;
         }
-            lastChunk = header;
-            newestVersion = header.version;
-            if (header.next == 0 ||
-                    header.next >= fileStore.size() / BLOCK_SIZE) {
-                // no (valid) next
-                break;
+        setLastChunk(newest);
+        loadChunkMeta();
+        // read all chunk headers and footers within the retention time,
+        // to detect unwritten data after a power failure
+        verifyLastChunks();
+        // build the free space list
+        for (Chunk c : chunks.values()) {
+            if (c.pageCountLive == 0) {
+                // remove this chunk in the next save operation
+                registerFreePage(currentVersion, c.id, 0, 0);
             }
-            chunkBlock = header.next;
+            long start = c.block * BLOCK_SIZE;
+            int length = c.len * BLOCK_SIZE;
+            fileStore.markUsed(start, length);
         }
-        if (lastChunk == null) {
-            // no valid chunk
-            return;
     }
-        lastMapId = lastChunk.mapId;
-        currentVersion = lastChunk.version;
-        setWriteVersion(currentVersion);
-        chunks.put(lastChunk.id, lastChunk);
-        meta.setRootPos(lastChunk.metaRootPos, -1);
 
+    private void loadChunkMeta() {
         // load the chunk metadata: we can load in any order,
         // because loading chunk metadata might recursively load another chunk
         for (Iterator<String> it = meta.keyIterator("chunk."); it.hasNext();) {
@@ -699,18 +706,83 @@ public class MVStore {
                 chunks.put(c.id, c);
             }
         }
-        // build the free space list
-        for (Chunk c : chunks.values()) {
-            if (c.pageCountLive == 0) {
-                // remove this chunk in the next save operation
-                registerFreePage(currentVersion, c.id, 0, 0);
     }
-            long start = c.block * BLOCK_SIZE;
-            int length = c.len * BLOCK_SIZE;
-            fileStore.markUsed(start, length);
+
+    private void setLastChunk(Chunk last) {
+        lastChunk = last;
+        if (last == null) {
+            // no valid chunk
+            lastMapId = 0;
+            currentVersion = 0;
+            meta.setRootPos(0, -1);
+        } else {
+            lastMapId = last.mapId;
+            currentVersion = last.version;
+            chunks.put(last.id, last);
+            meta.setRootPos(last.metaRootPos, -1);
+        }
+        setWriteVersion(currentVersion);
+    }
+
+    private void verifyLastChunks() {
+        long time = getTimeSinceCreation();
+        ArrayList<Integer> ids = new ArrayList<Integer>(chunks.keySet());
+        Collections.sort(ids);
+        int newestValidChunk = -1;
+        Chunk old = null;
+        for (Integer chunkId : ids) {
+            Chunk c = chunks.get(chunkId);
+            if (old != null && c.time < old.time) {
+                // old chunk (maybe leftover from a previous crash)
+                break;
+            }
+            old = c;
+            if (c.time + retentionTime < time) {
+                // old chunk, no need to verify
+                newestValidChunk = c.id;
+                continue;
+            }
+            Chunk test = readChunkHeaderAndFooter(c.block);
+            if (test == null || test.id != c.id) {
+                break;
+            }
+            newestValidChunk = chunkId;
+        }
+        Chunk newest = chunks.get(newestValidChunk);
+        if (newest != lastChunk) {
+            // to avoid re-using newer chunks later on, we could clear
+            // the headers and footers of those, but we might not know about all
+            // of them, so that could be incomplete - but we check that newer
+            // chunks are written after older chunks, so we are safe
+            rollbackTo(newest == null ? 0 : newest.version);
         }
     }
 
+    /**
+     * Read a chunk header and footer, and verify the stored data is consistent.
+     *
+     * @param block the block
+     * @return the chunk, or null if the header or footer don't match or are not
+     *         consistent
+     */
+    private Chunk readChunkHeaderAndFooter(long block) {
+        Chunk header;
+        try {
+            header = readChunkHeader(block);
+        } catch (Exception e) {
+            // invalid chunk header: ignore, but stop
+            return null;
+        }
+        if (header == null) {
+            return null;
+        }
+        Chunk footer = readChunkFooter((block + header.len) * BLOCK_SIZE);
+        if (footer == null || footer.id != header.id) {
+            return null;
+        }
+        return header;
+    }
+
     /**
      * Try to read a chunk footer.
      *
@@ -782,7 +854,8 @@ public class MVStore {
         if (closed) {
             return;
         }
-        if (fileStore != null && !fileStore.isReadOnly()) {
+        FileStore f = fileStore;
+        if (f != null && !f.isReadOnly()) {
             stopBackgroundThread();
             if (hasUnsavedChanges()) {
                 commitAndSave();
@@ -979,11 +1052,12 @@ public class MVStore {
 
     private long storeNowTry() {
         freeUnusedChunks();
+
         int currentUnsavedPageCount = unsavedMemory;
         long storeVersion = currentStoreVersion;
         long version = ++currentVersion;
         setWriteVersion(version);
-        long time = getTime();
+        long time = getTimeSinceCreation();
         lastCommitTime = time;
         retainChunk = null;
 
@@ -1166,7 +1240,6 @@ public class MVStore {
             // may only shrink after the store header was written
             shrinkFileIfPossible(1);
         }
-
         for (MVMap<?, ?> m : changed) {
             Page p = m.getRoot();
             if (p.getTotalCount() > 0) {
@@ -1192,7 +1265,7 @@ public class MVStore {
         }
         Set<Integer> referenced = collectReferencedChunks();
         ArrayList<Chunk> free = New.arrayList();
-        long time = getTime();
+        long time = getTimeSinceCreation();
         for (Chunk c : chunks.values()) {
             if (!referenced.contains(c.id)) {
                 free.add(c);
@@ -1347,12 +1420,14 @@ public class MVStore {
     }
 
     private boolean canOverwriteChunk(Chunk c, long time) {
+        if (retentionTime >= 0) {
             if (c.time + retentionTime > time) {
                 return false;
             }
             if (c.unused == 0 || c.unused + retentionTime / 2 > time) {
                 return false;
             }
+        }
         Chunk r = retainChunk;
         if (r != null && c.version > r.version) {
             return false;
@@ -1360,8 +1435,21 @@ public class MVStore {
         return true;
     }
 
-    private long getTime() {
-        return System.currentTimeMillis() - creationTime;
+    private long getTimeSinceCreation() {
+        return Math.max(0, getTimeAbsolute() - creationTime);
+    }
+
+    private long getTimeAbsolute() {
+        long now = System.currentTimeMillis();
+        if (lastTimeAbsolute != 0 && now < lastTimeAbsolute) {
+            // time seems to have run backwards - this can happen
+            // when the system time is adjusted, for example
+            // on a leap second
+            now = lastTimeAbsolute;
+        } else {
+            lastTimeAbsolute = now;
+        }
+        return now;
     }
 
     /**
@@ -1394,20 +1482,12 @@ public class MVStore {
                     c.maxLenLive += f.maxLenLive;
                     c.pageCountLive += f.pageCountLive;
                     if (c.pageCountLive < 0 && c.pageCountLive > -MARKED_FREE) {
-                        throw DataUtils.newIllegalStateException(
-                                DataUtils.ERROR_INTERNAL,
-                                "Corrupt page count {0}", c.pageCountLive);
+                        // can happen after a rollback
+                        c.pageCountLive = 0;
                     }
                     if (c.maxLenLive < 0 && c.maxLenLive > -MARKED_FREE) {
-                        throw DataUtils.newIllegalStateException(
-                                DataUtils.ERROR_INTERNAL,
-                                "Corrupt max length {0}", c.maxLenLive);
-                    }
-                    if (c.pageCountLive <= 0 && c.maxLenLive > 0 ||
-                            c.maxLenLive <= 0 && c.pageCountLive > 0) {
-                        throw DataUtils.newIllegalStateException(
-                                DataUtils.ERROR_INTERNAL,
-                                "Corrupt max length {0}", c.maxLenLive);
+                        // can happen after a rollback
+                        c.maxLenLive = 0;
                     }
                     modified.add(c);
                 }
@@ -1441,6 +1521,9 @@ public class MVStore {
         if (savedPercent < minPercent) {
             return;
         }
+        if (!closed) {
+            sync();
+        }
         fileStore.truncate(end);
     }
 
@@ -1548,7 +1631,7 @@ public class MVStore {
         int oldRetentionTime = retentionTime;
         boolean oldReuse = reuseSpace;
         try {
-            retentionTime = 0;
+            retentionTime = -1;
             freeUnusedChunks();
             if (fileStore.getFillRate() > targetFillRate) {
                 return false;
@@ -1618,7 +1701,7 @@ public class MVStore {
             buff.position(0);
             c.writeChunkHeader(buff, chunkHeaderLen);
             buff.position(length - Chunk.FOOTER_LENGTH);
-            buff.put(lastChunk.getFooterBytes());
+            buff.put(c.getFooterBytes());
             buff.position(0);
             write(end, buff.getBuffer());
             releaseWriteBuffer(buff);
@@ -1629,7 +1712,6 @@ public class MVStore {
         // update the metadata (store at the end of the file)
         reuseSpace = false;
         commitAndSave();
-
         sync();
 
         // now re-use the empty space
@@ -1655,7 +1737,7 @@ public class MVStore {
             c.block = pos / BLOCK_SIZE;
             c.writeChunkHeader(buff, chunkHeaderLen);
             buff.position(length - Chunk.FOOTER_LENGTH);
-            buff.put(lastChunk.getFooterBytes());
+            buff.put(c.getFooterBytes());
             buff.position(0);
             write(pos, buff.getBuffer());
             releaseWriteBuffer(buff);
@@ -1674,7 +1756,11 @@ public class MVStore {
      * implementation calls FileChannel.force(true).
      */
     public void sync() {
-        fileStore.sync();
+        checkOpen();
+        FileStore f = fileStore;
+        if (f != null) {
+            f.sync();
+        }
     }
 
     /**
@@ -1723,7 +1809,7 @@ public class MVStore {
         long maxLengthSum = 0;
         long maxLengthLiveSum = 0;
 
-        long time = getTime();
+        long time = getTimeSinceCreation();
 
         for (Chunk c : chunks.values()) {
             // ignore young chunks, because we don't optimize those
@@ -2061,6 +2147,7 @@ public class MVStore {
         if (oldMeta == null) {
             return false;
         }
+        try {
             for (Iterator<String> it = oldMeta.keyIterator("chunk.");
                     it.hasNext();) {
                 String chunkKey = it.next();
@@ -2068,8 +2155,19 @@ public class MVStore {
                     break;
                 }
                 if (!meta.containsKey(chunkKey)) {
+                    String s = oldMeta.get(chunkKey);
+                    Chunk c2 = Chunk.fromString(s);
+                    Chunk test = readChunkHeaderAndFooter(c2.block);
+                    if (test == null || test.id != c2.id) {
                         return false;
                     }
+                    // we store this chunk
+                    chunks.put(c2.id, c2);
+                }
+            }
+        } catch (IllegalStateException e) {
+            // the chunk missing where the metadata is stored
+            return false;
         }
         return true;
     }
@@ -2183,43 +2281,43 @@ public class MVStore {
         meta.rollbackTo(version);
         metaChanged = false;
         boolean loadFromFile = false;
-        // get the largest chunk with a version
-        // higher or equal the requested version
-        Chunk removeChunksNewerThan = null;
-        Chunk c = lastChunk;
-        while (true) {
-            if (c == null || c.version < version) {
-                break;
+        // find out which chunks to remove,
+        // and which is the newest chunk to keep
+        // (the chunk list can have gaps)
+        ArrayList<Integer> remove = new ArrayList<Integer>();
+        Chunk keep = null;
+        for (Chunk c : chunks.values()) {
+            if (c.version > version) {
+                remove.add(c.id);
+            } else if (keep == null || keep.id < c.id) {
+                keep = c;
             }
-            removeChunksNewerThan = c;
-            c = chunks.get(c.id - 1);
         }
-        Chunk last = lastChunk;
-        if (removeChunksNewerThan != null &&
-                last.version > removeChunksNewerThan.version) {
+        if (remove.size() > 0) {
+            // remove the youngest first, so we don't create gaps
+            // (in case we remove many chunks)
+            Collections.sort(remove, Collections.reverseOrder());
             revertTemp(version);
             loadFromFile = true;
-            while (true) {
-                last = lastChunk;
-                if (last == null) {
-                    break;
-                } else if (last.version <= removeChunksNewerThan.version) {
-                    break;
-                }
-                chunks.remove(lastChunk.id);
-                long start = last.block * BLOCK_SIZE;
-                int length = last.len * BLOCK_SIZE;
+            for (int id : remove) {
+                Chunk c = chunks.remove(id);
+                long start = c.block * BLOCK_SIZE;
+                int length = c.len * BLOCK_SIZE;
                 fileStore.free(start, length);
-                // need to overwrite the chunk,
-                // so it can not be used
+                // overwrite the chunk,
+                // so it is not be used later on
                 WriteBuffer buff = getWriteBuffer();
                 buff.limit(length);
                 // buff.clear() does not set the data
                 Arrays.fill(buff.getBuffer().array(), (byte) 0);
                 write(start, buff.getBuffer());
                 releaseWriteBuffer(buff);
-                lastChunk = chunks.get(lastChunk.id - 1);
+                // only really needed if we remove many chunks, when writes are
+                // re-ordered - but we do it always, because rollback is not
+                // performance criticial
+                sync();
             }
+            lastChunk = keep;
             writeStoreHeader();
             readStoreHeader();
         }
@@ -2233,12 +2331,10 @@ public class MVStore {
                     m.setRootPos(getRootPos(meta, id), -1);
                 }
             }
-
         }
         // rollback might have rolled back the stored chunk metadata as well
         if (lastChunk != null) {
-            c = chunks.get(lastChunk.id - 1);
-            if (c != null) {
+            for (Chunk c : chunks.values()) {
                 meta.put(Chunk.getMetaKey(c.id), c.asString());
             }
         }
@@ -2371,7 +2467,7 @@ public class MVStore {
         // could also commit when there are many unsaved pages,
         // but according to a test it doesn't really help
 
-        long time = getTime();
+        long time = getTimeSinceCreation();
         if (time <= lastCommitTime + autoCommitDelay) {
             return;
         }

h2/src/test/org/h2/test/TestAll.java

@@ -795,6 +795,7 @@ kill -9 `jps -l | grep "org.h2.test." | cut -d " " -f 1`
         addTest(new TestMVTableEngine());
         addTest(new TestObjectDataType());
         addTest(new TestRandomMapOps());
+        addTest(new TestReorderWrites());
         addTest(new TestSpinLock());
         addTest(new TestStreamStore());
         addTest(new TestTransactionStore());

h2/src/test/org/h2/test/poweroff/TestReorderWrites.java

@@ -13,6 +13,7 @@ import java.util.Map;
 import java.util.Random;
 
 import org.h2.mvstore.MVStore;
+import org.h2.mvstore.MVStoreTool;
 import org.h2.store.fs.FilePath;
 import org.h2.store.fs.FileUtils;
 import org.h2.test.TestBase;
@@ -24,6 +25,8 @@ import org.h2.test.utils.FilePathReorderWrites;
  */
 public class TestReorderWrites  extends TestBase {
 
+    private static final boolean LOG = false;
+
     /**
      * Run just this test.
      *
@@ -35,16 +38,16 @@ public class TestReorderWrites  extends TestBase {
 
     @Override
     public void test() throws Exception {
+        testMVStore();
         testFileSystem();
-        // testMVStore();
     }
 
     private void testMVStore() {
         FilePathReorderWrites fs = FilePathReorderWrites.register();
         String fileName = "reorder:memFS:test.mv";
-        Random r = new Random(1);
-        for (int i = 0; i < 100; i++) {
-            System.out.println(i + " tst --------------------------------");
+        for (int i = 0; i < 1000; i++) {
+            log(i + " --------------------------------");
+            Random r = new Random(i);
             fs.setPowerOffCountdown(100, i);
             FileUtils.delete(fileName);
             MVStore store = new MVStore.Builder().
@@ -52,12 +55,12 @@ public class TestReorderWrites  extends TestBase {
                     autoCommitDisabled().open();
             // store.setRetentionTime(10);
             Map<Integer, byte[]> map = store.openMap("data");
-            map.put(0, new byte[1]);
+            map.put(-1, new byte[1]);
             store.commit();
-         //   if (r.nextBoolean()) {
             store.getFileStore().sync();
-            //}
-            fs.setPowerOffCountdown(4 + r.nextInt(20), i);
+            int stop = 4 + r.nextInt(20);
+            log("synched start");
+            fs.setPowerOffCountdown(stop, i);
             try {
                 for (int j = 1; j < 100; j++) {
                     Map<Integer, Integer> newMap = store.openMap("d" + j);
@@ -69,31 +72,61 @@ public class TestReorderWrites  extends TestBase {
                     } else {
                         map.put(key, new byte[len]);
                     }
+                    log("op " + j + ": ");
                     store.commit();
+                    switch (r.nextInt(10)) {
+                    case 0:
+                        log("op compact");
+                        store.compact(100, 10 * 1024);
+                        break;
+                    case 1:
+                        log("op compactMoveChunks");
+                        store.compactMoveChunks();
+                        log("op compactMoveChunks done");
+                        break;
+                    }
                 }
                 // write has to fail at some point
                 fail();
             } catch (IllegalStateException e) {
+                log("stop " + e);
                 // expected
             }
+            try {
                 store.close();
-            System.out.println("-------------------------------- test");
+            } catch (IllegalStateException e) {
+                // expected
+                store.closeImmediately();
+            }
+            log("verify");
             fs.setPowerOffCountdown(100, 0);
-            System.out.println("file size: " + FileUtils.size(fileName));
+            if (LOG) {
+                MVStoreTool.dump(fileName, true);
+            }
             store = new MVStore.Builder().
                     fileName(fileName).
                     autoCommitDisabled().open();
             map = store.openMap("data");
-            assertEquals(1, map.get(0).length);
+            if (!map.containsKey(-1)) {
+                fail("key not found, size=" + map.size() + " i=" + i);
+            } else {
+                assertEquals("i=" + i, 1, map.get(-1).length);
+            }
             for (int j = 0; j < 100; j++) {
                 Map<Integer, Integer> newMap = store.openMap("d" + j);
                 newMap.get(j);
             }
-            // map.keySet();
+            map.keySet();
             store.close();
         }
     }
 
+    private static void log(String message) {
+        if (LOG) {
+            System.out.println(message);
+        }
+    }
+
     private void testFileSystem() throws IOException {
         FilePathReorderWrites fs = FilePathReorderWrites.register();
         String fileName = "reorder:memFS:test";

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

@@ -948,6 +948,10 @@ public class TestMVStore extends TestBase {
                 break;
             }
         }
+        // the last chunk is at the end
+        s.setReuseSpace(false);
+        map = s.openMap("test2");
+        map.put(1, new byte[1000]);
         s.close();
         FilePath f = FilePath.get(fileName);
         int blockSize = 4 * 1024;
@@ -976,6 +980,8 @@ public class TestMVStore extends TestBase {
                 s = openStore(fileName);
                 map = s.openMap("test");
                 assertEquals(100, map.get(0).length);
+                map = s.openMap("test2");
+                assertFalse(map.containsKey(1));
                 s.close();
             } else {
                 // both headers are corrupt
@@ -1414,7 +1420,7 @@ public class TestMVStore extends TestBase {
         assertEquals(0, m.size());
         s.commit();
         // ensure only nodes are read, but not leaves
-        assertEquals(41, s.getFileStore().getReadCount());
+        assertEquals(45, s.getFileStore().getReadCount());
         assertTrue(s.getFileStore().getWriteCount() < 5);
         s.close();
     }
@@ -1579,7 +1585,6 @@ public class TestMVStore extends TestBase {
         data.put("2", "World");
         s.commit();
         assertEquals(1, s.getCurrentVersion());
-        assertFalse(m.containsKey("chunk.2"));
 
         assertEquals("[data]", s.getMapNames().toString());
         assertEquals("data", s.getMapName(data.getId()));
@@ -1599,8 +1604,6 @@ public class TestMVStore extends TestBase {
         s.rollbackTo(1);
         assertEquals("Hello", data.get("1"));
         assertEquals("World", data.get("2"));
-        assertFalse(m.containsKey("chunk.1"));
-        assertFalse(m.containsKey("chunk.2"));
 
         s.close();
     }

h2/src/test/org/h2/test/utils/FilePathReorderWrites.java

@@ -105,10 +105,11 @@ public class FilePathReorderWrites extends FilePathWrapper {
         if (powerFailureCountdown == 0) {
             return;
         }
-        if (--powerFailureCountdown > 0) {
-            return;
+        if (powerFailureCountdown < 0) {
+            throw POWER_FAILURE;
         }
-        if (powerFailureCountdown >= -1) {
+        powerFailureCountdown--;
+        if (powerFailureCountdown == 0) {
             powerFailureCountdown--;
             throw POWER_FAILURE;
         }
@@ -122,7 +123,7 @@ public class FilePathReorderWrites extends FilePathWrapper {
         IOUtils.copy(in, out);
         FileChannel base = getBase().open(mode);
         FileChannel readBase = copy.open(mode);
-        return new FilePowerFailure(this, base, readBase);
+        return new FileReorderWrites(this, base, readBase);
     }
 
     @Override
@@ -140,7 +141,7 @@ public class FilePathReorderWrites extends FilePathWrapper {
 /**
  * An file that checks for errors before each write operation.
  */
-class FilePowerFailure extends FileBase {
+class FileReorderWrites extends FileBase {
 
     private final FilePathReorderWrites file;
     /**
@@ -162,7 +163,7 @@ class FilePowerFailure extends FileBase {
 
     private int id;
 
-    FilePowerFailure(FilePathReorderWrites file, FileChannel base, FileChannel readBase) {
+    FileReorderWrites(FilePathReorderWrites file, FileChannel base, FileChannel readBase) {
         this.file = file;
         this.base = base;
         this.readBase = readBase;