Revert "Compress/Encrypt Blocks in the background (#1227)"

[jarifibrahim]

This reverts commit b13b927.
This commit is being reverted because we have seen some crashes which could be caused by it. We haven't been able to reproduce the crashes yet.

Related to #1389, #1388, #1387
Also, see https://discuss.dgraph.io/t/current-state-of-badger-crashes/7602

Conflicts:

• options.go
• table/builder.go

diff --cc options.go
index 4a0d1e0,4fbe091..0000000
--- a/options.go
+++ b/options.go
@@@ -176,16 -155,12 +176,25 @@@ func DefaultOptions(path string) Option
  
  func buildTableOptions(opt Options) table.Options {
  	return table.Options{
++<<<<<<< HEAD
 +		TableSize:               uint64(opt.MaxTableSize),
 +		BlockSize:               opt.BlockSize,
 +		BloomFalsePositive:      opt.BloomFalsePositive,
 +		LoadBloomsOnOpen:        opt.LoadBloomsOnOpen,
 +		LoadingMode:             opt.TableLoadingMode,
 +		ChkMode:                 opt.ChecksumVerificationMode,
 +		Compression:             opt.Compression,
 +		ZSTDCompressionLevel:    opt.ZSTDCompressionLevel,
 +		KeepBlockIndicesInCache: opt.KeepBlockIndicesInCache,
 +		KeepBlocksInCache:       opt.KeepBlocksInCache,
++=======
+ 		BlockSize:            opt.BlockSize,
+ 		BloomFalsePositive:   opt.BloomFalsePositive,
+ 		LoadingMode:          opt.TableLoadingMode,
+ 		ChkMode:              opt.ChecksumVerificationMode,
+ 		Compression:          opt.Compression,
+ 		ZSTDCompressionLevel: opt.ZSTDCompressionLevel,
++>>>>>>> parent of b13b927... Compress/Encrypt Blocks in the background (#1227)
  	}
  }
  
diff --cc table/builder.go
index 312f8f7,2651949..0000000
--- a/table/builder.go
+++ b/table/builder.go
@@@ -101,75 -82,6 +82,78 @@@ func NewTableBuilder(opts Options) *Bui
  		keyHashes:  make([]uint64, 0, 1024), // Avoid some malloc calls.
  		opt:        &opts,
  	}
++<<<<<<< HEAD
 +
 +	// If encryption or compression is not enabled, do not start compression/encryption goroutines
 +	// and write directly to the buffer.
 +	if b.opt.Compression == options.None && b.opt.DataKey == nil {
 +		return b
 +	}
 +
 +	count := 2 * runtime.NumCPU()
 +	b.blockChan = make(chan *bblock, count*2)
 +
 +	b.wg.Add(count)
 +	for i := 0; i < count; i++ {
 +		go b.handleBlock()
 +	}
 +	return b
 +}
 +
 +var slicePool = sync.Pool{
 +	New: func() interface{} {
 +		// Make 4 KB blocks for reuse.
 +		b := make([]byte, 0, 4<<10)
 +		return &b
 +	},
 +}
 +
 +func (b *Builder) handleBlock() {
 +	defer b.wg.Done()
 +	for item := range b.blockChan {
 +		// Extract the block.
 +		blockBuf := item.data[item.start:item.end]
 +		var dst *[]byte
 +		// Compress the block.
 +		if b.opt.Compression != options.None {
 +			var err error
 +
 +			dst = slicePool.Get().(*[]byte)
 +			*dst = (*dst)[:0]
 +
 +			blockBuf, err = b.compressData(*dst, blockBuf)
 +			y.Check(err)
 +		}
 +		if b.shouldEncrypt() {
 +			eBlock, err := b.encrypt(blockBuf)
 +			y.Check(y.Wrapf(err, "Error while encrypting block in table builder."))
 +			blockBuf = eBlock
 +		}
 +
 +		// BlockBuf should always less than or equal to allocated space. If the blockBuf is greater
 +		// than allocated space that means the data from this block cannot be stored in its
 +		// existing location and trying to copy it over would mean we would over-write some data
 +		// of the next block.
 +		allocatedSpace := (item.end - item.start) + padding + 1
 +		y.AssertTruef(uint32(len(blockBuf)) <= allocatedSpace, "newend: %d oldend: %d padding: %d",
 +			item.start+uint32(len(blockBuf)), item.end, padding)
 +
 +		// Acquire the buflock here. The builder.grow function might change
 +		// the b.buf while this goroutine was running.
 +		b.bufLock.Lock()
 +		// Copy over compressed/encrypted data back to the main buffer.
 +		copy(b.buf[item.start:], blockBuf)
 +		b.bufLock.Unlock()
 +
 +		// Fix the boundary of the block.
 +		item.end = item.start + uint32(len(blockBuf))
 +
 +		if dst != nil {
 +			slicePool.Put(dst)
 +		}
 +	}
++=======
++>>>>>>> parent of b13b927... Compress/Encrypt Blocks in the background (#1227)
  }
  
  // Close closes the TableBuilder.

---

This change is