fix tests and restore performance

index.js

@@ -268,7 +268,6 @@ module.exports = function AsyncAppendOnlyLog(filename, opts) {
       if (err) return cb(err)
       const actualBlockBuf = blocksWithDeletables.get(blockIndex) || blockBuf
       Record.overwriteWithZeroes(actualBlockBuf, getOffsetInBlock(offset))
-      mergeDeletedRecords(actualBlockBuf)
       blocksWithDeletables.set(blockIndex, actualBlockBuf)
       scheduleFlushDelete()
       cb()
@@ -331,6 +330,7 @@ module.exports = function AsyncAppendOnlyLog(filename, opts) {
     blocksWithDeletables.delete(blockIndex)
     blocksWithDeletables.set(-1, null) // indicate that flush is active
 
+    mergeDeletedRecords(blockBuf)
     writeWithFSync(blockStart, blockBuf, null, function flushedDelete(err) {
       blocksWithDeletables.delete(-1) // indicate that flush is not active
       if (err) {

test/compaction.js

@@ -162,13 +162,13 @@ tape('shift many blocks', async (t) => {
             // block 0
             [0x11, 0x22, 0x33],
             // block 1
-            [0x44, null, null],
+            [0x44, null, 0x77],
             // block 2
-            [0x77, 0x88, 0x99],
+            [0x88, 0x99, 0xaa],
             // block 3
-            [0xaa, null, 0xcc],
+            [null, 0xcc, 0xdd],
             // block 4
-            [0xdd, 0xee, 0xff],
+            [0xee, 0xff],
           ].flat(),
           'log has 5 blocks and some holes'
         )
@@ -282,7 +282,7 @@ tape('cannot read truncated regions of the log', async (t) => {
             // block 0
             [0x11, 0x22, 0x33],
             // block 1
-            [0x44, null, null],
+            [0x44, null],
             // block 2
             [null, 0x88, 0x99],
           ].flat(),

test/delete.js

@@ -230,7 +230,7 @@ tape('merge consecutive deletes', async function (t) {
   t.error(err2)
   const [err3] = await run(log.del)(offset3)
   t.error(err3)
-  await run(log.onDrain)()
+  await run(log.onDeletesFlushed)()
 
   const [errB2, blockAfter] = await run(log.getBlock)(0)
   t.error(errB2)