put assertion in place first

filestore.clear() added, verifyLastChunk() moved to make assertions happy

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

@@ -99,6 +99,8 @@ public class FreeSpaceBitSet {
             int start = set.nextClearBit(i);
             int end = set.nextSetBit(start + 1);
             if (end < 0 || end - start >= blocks) {
+                assert set.nextSetBit(start) == -1 || set.nextSetBit(start) >= start + blocks :
+                        "Double alloc: " + Integer.toHexString(start) + "/" + Integer.toHexString(blocks) + " " + this;
                 set.set(start, start + blocks);
                 return getPos(start);
             }
@@ -115,6 +117,8 @@ public class FreeSpaceBitSet {
     public void markUsed(long pos, int length) {
         int start = getBlock(pos);
         int blocks = getBlockCount(length);
+        assert set.nextSetBit(start) == -1 || set.nextSetBit(start) >= start + blocks :
+                "Double mark: " + Integer.toHexString(start) + "/" + Integer.toHexString(blocks) + " " + this;
         set.set(start, start + blocks);
     }
 
@@ -127,6 +131,8 @@ public class FreeSpaceBitSet {
     public void free(long pos, int length) {
         int start = getBlock(pos);
         int blocks = getBlockCount(length);
+        assert set.nextClearBit(start) >= start + blocks :
+                "Double free: " + Integer.toHexString(start) + "/" + Integer.toHexString(blocks) + " " + this;
         set.clear(start, start + blocks);
     }
 

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

@@ -664,8 +664,8 @@ public final class MVStore {
         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
+        fileStore.clear();
         for (Chunk c : chunks.values()) {
             if (c.pageCountLive == 0) {
                 // remove this chunk in the next save operation
@@ -675,6 +675,9 @@ public final class MVStore {
             int length = c.len * BLOCK_SIZE;
             fileStore.markUsed(start, length);
         }
+        assert fileStore.getFileLengthInUse() == measureFileLengthInUse() :
+                fileStore.getFileLengthInUse() + " != " + measureFileLengthInUse();
+        verifyLastChunks();
     }
 
     private void loadChunkMeta() {
@@ -1143,6 +1146,8 @@ public final class MVStore {
 
         c.block = filePos / BLOCK_SIZE;
         c.len = length / BLOCK_SIZE;
+        assert fileStore.getFileLengthInUse() == measureFileLengthInUse() :
+                fileStore.getFileLengthInUse() + " != " + measureFileLengthInUse() + " " + c;
         c.metaRootPos = metaRoot.getPos();
         // calculate and set the likely next position
         if (reuseSpace) {
@@ -1257,6 +1262,8 @@ public final class MVStore {
                     long start = c.block * BLOCK_SIZE;
                     int length = c.len * BLOCK_SIZE;
                     fileStore.free(start, length);
+                    assert fileStore.getFileLengthInUse() == measureFileLengthInUse() :
+                            fileStore.getFileLengthInUse() + " != " + measureFileLengthInUse();
                 } else {
                     if (c.unused == 0) {
                         c.unused = time;
@@ -2304,6 +2311,8 @@ public final class MVStore {
                 long start = c.block * BLOCK_SIZE;
                 int length = c.len * BLOCK_SIZE;
                 fileStore.free(start, length);
+                assert fileStore.getFileLengthInUse() == measureFileLengthInUse() :
+                        fileStore.getFileLengthInUse() + " != " + measureFileLengthInUse();
                 // overwrite the chunk,
                 // so it is not be used later on
                 WriteBuffer buff = getWriteBuffer();