// Write apply the given batch to the DB. The batch records will be applied
// sequentially. Write might be used concurrently, when used concurrently and
// batch is small enough, write will try to merge the batches. Set NoWriteMerge
// option to true to disable write merge.
//
// It is safe to modify the contents of the arguments after Write returns but
// not before. Write will not modify content of the batch.
func (db *DB) Write(batch *Batch, wo *opt.WriteOptions) error {
if err := db.ok(); err != nil || batch == nil || batch.Len() == 0 {
return err
}
// If the batch size is larger than write buffer, it may justified to write
// using transaction instead. Using transaction the batch will be written
// into tables directly, skipping the journaling.
if batch.internalLen > db.s.o.GetWriteBuffer() && !db.s.o.GetDisableLargeBatchTransaction() {
tr, err := db.OpenTransaction()
if err != nil {
return err
}
if err := tr.Write(batch, wo); err != nil {
tr.Discard()
return err
}
return tr.Commit()
}
merge := !wo.GetNoWriteMerge() && !db.s.o.GetNoWriteMerge()
sync := wo.GetSync() && !db.s.o.GetNoSync()
// Acquire write lock.
if merge {
select {
case db.writeMergeC <- writeMerge{sync: sync, batch: batch}:
if <-db.writeMergedC {
// Write is merged.
return <-db.writeAckC
}
// Write is not merged, the write lock is handed to us. Continue.
case db.writeLockC <- struct{}{}:
// Write lock acquired.
case err := <-db.compPerErrC:
// Compaction error.
return err
case <-db.closeC:
// Closed
return ErrClosed
}
} else {
select {
case db.writeLockC <- struct{}{}:
// Write lock acquired.
case err := <-db.compPerErrC:
// Compaction error.
return err
case <-db.closeC:
// Closed
return ErrClosed
}
}
return db.writeLocked(batch, nil, merge, sync)
}
func (db *DB) putRec(kt keyType, key, value []byte, wo *opt.WriteOptions) error {
if err := db.ok(); err != nil {
return err
}
merge := !wo.GetNoWriteMerge() && !db.s.o.GetNoWriteMerge()
sync := wo.GetSync() && !db.s.o.GetNoSync()
// Acquire write lock.
if merge {
select {
case db.writeMergeC <- writeMerge{sync: sync, keyType: kt, key: key, value: value}:
if <-db.writeMergedC {
// Write is merged.
return <-db.writeAckC
}
// Write is not merged, the write lock is handed to us. Continue.
case db.writeLockC <- struct{}{}:
// Write lock acquired.
case err := <-db.compPerErrC:
// Compaction error.
return err
case <-db.closeC:
// Closed
return ErrClosed
}
} else {
select {
case db.writeLockC <- struct{}{}:
// Write lock acquired.
case err := <-db.compPerErrC:
// Compaction error.
return err
case <-db.closeC:
// Closed
return ErrClosed
}
}
batch := db.batchPool.Get().(*Batch)
batch.Reset()
batch.appendRec(kt, key, value)
return db.writeLocked(batch, batch, merge, sync)
}