Breaking Change: Fix WriteBatch APIs(#845)

* Remove SetWithTTL from WriteBatch as part of New EntryAPIs.
As we have removed SetWith functions from Txn struct. We can
do same for WriteBatch. Anyone can create Entry using new Entry
APIs and call SetEntry on WriteBatch.
* Change WriteBatch Set method to have same syntax as Txn.Set
* Fix DOCs for Entry APIs

Author: ashish-goswami

README.md

@@ -209,6 +209,18 @@ err := db.Update(func(txn *badger.Txn) error {
 })
 ```
 
+Key/Value pair can also be saved by first creating `Entry`, then setting this
+`Entry` using `Txn.SetEntry()`. `Entry` also exposes methods to set properties
+on it.
+
+```go
+err := db.Update(func(txn *badger.Txn) error {
+  e := NewEntry([]byte("answer"), []byte("42"))
+  err := txn.SetEntry(e)
+  return err
+})
+```
+
 This will set the value of the `"answer"` key to `"42"`. To retrieve this
 value, we can use the `Txn.Get()` method:
 
@@ -347,16 +359,40 @@ res, _ := m.Get() // res should have value 6 encoded
 ### Setting Time To Live(TTL) and User Metadata on Keys
 Badger allows setting an optional Time to Live (TTL) value on keys. Once the TTL has
 elapsed, the key will no longer be retrievable and will be eligible for garbage
-collection. A TTL can be set as a `time.Duration` value using the `Txn.SetWithTTL()`
-API method.
+collection. A TTL can be set as a `time.Duration` value using the `Entry.WithTTL()`
+and `Txn.SetEntry()` API methods.
+
+```go
+err := db.Update(func(txn *badger.Txn) error {
+  e := NewEntry([]byte("answer"), []byte("42")).WithTTL(time.Hour)
+  err := txn.SetEntry(e)
+  return err
+})
+```
 
 An optional user metadata value can be set on each key. A user metadata value
 is represented by a single byte. It can be used to set certain bits along
 with the key to aid in interpreting or decoding the key-value pair. User
-metadata can be set using the `Txn.SetWithMeta()` API method.
+metadata can be set using `Entry.WithMeta()` and `Txn.SetEntry()` API methods.
 
-`Txn.SetEntry()` can be used to set the key, value, user metatadata and TTL,
-all at once.
+```go
+err := db.Update(func(txn *badger.Txn) error {
+  e := NewEntry([]byte("answer"), []byte("42")).WithMeta(byte(1))
+  err := txn.SetEntry(e)
+  return err
+})
+```
+
+`Entry` APIs can be used to add the user metadata and TTL for same key. This `Entry`
+then can be set using `Txn.SetEntry()`.
+
+```go
+err := db.Update(func(txn *badger.Txn) error {
+  e := NewEntry([]byte("answer"), []byte("42")).WithMeta(byte(1)).WithTTL(time.Hour)
+  err := txn.SetEntry(e)
+  return err
+})
+```
 
 ### Iterating over keys
 To iterate over keys, we can use an `Iterator`, which can be obtained using the

badger/cmd/bank.go

@@ -388,7 +388,7 @@ func runTest(cmd *cobra.Command, args []string) error {
 
 	wb := db.NewWriteBatch()
 	for i := 0; i < numAccounts; i++ {
-		y.Check(wb.Set(key(i), toSlice(initialBal), 0))
+		y.Check(wb.Set(key(i), toSlice(initialBal)))
 	}
 	log.Println("Waiting for writes to be done...")
 	y.Check(wb.Flush())
@@ -485,7 +485,7 @@ func runTest(cmd *cobra.Command, args []string) error {
 				stream := db.NewStream()
 				stream.Send = func(list *pb.KVList) error {
 					for _, kv := range list.Kv {
-						if err := batch.Set(kv.Key, kv.Value, 0); err != nil {
+						if err := batch.Set(kv.Key, kv.Value); err != nil {
 							return err
 						}
 					}

badger/cmd/fill.go

@@ -62,7 +62,7 @@ func fillRandom(db *badger.DB, num uint64) error {
 	for i := uint64(1); i <= num; i++ {
 		key := make([]byte, keySz)
 		y.Check2(rand.Read(key))
-		if err := batch.Set(key, value, 0); err != nil {
+		if err := batch.Set(key, value); err != nil {
 			return err
 		}
 		if i%1e5 == 0 {

batch.go

@@ -18,7 +18,6 @@ package badger
 
 import (
 	"sync"
-	"time"
 
 	"github.com/dgraph-io/badger/y"
 )
@@ -102,16 +101,9 @@ func (wb *WriteBatch) SetEntry(e *Entry) error {
 	return nil
 }
 
-// Set is equivalent of Txn.SetWithMeta.
-func (wb *WriteBatch) Set(k, v []byte, meta byte) error {
-	e := &Entry{Key: k, Value: v, UserMeta: meta}
-	return wb.SetEntry(e)
-}
-
-// SetWithTTL is equivalent of Txn.SetWithTTL.
-func (wb *WriteBatch) SetWithTTL(key, val []byte, dur time.Duration) error {
-	expire := time.Now().Add(dur).Unix()
-	e := &Entry{Key: key, Value: val, ExpiresAt: uint64(expire)}
+// Set is equivalent of Txn.Set().
+func (wb *WriteBatch) Set(k, v []byte) error {
+	e := &Entry{Key: k, Value: v}
 	return wb.SetEntry(e)
 }
 

batch_test.go

@@ -40,7 +40,7 @@ func TestWriteBatch(t *testing.T) {
 		start := time.Now()
 
 		for i := 0; i < N; i++ {
-			require.NoError(t, wb.Set(key(i), val(i), 0))
+			require.NoError(t, wb.Set(key(i), val(i)))
 		}
 		for i := 0; i < M; i++ {
 			require.NoError(t, wb.Delete(key(i)))

iterator_test.go

@@ -79,7 +79,7 @@ func TestIteratePrefix(t *testing.T) {
 			if (i % 1000) == 0 {
 				t.Logf("Put i=%d\n", i)
 			}
-			require.NoError(t, batch.Set(bkey(i), val, 0))
+			require.NoError(t, batch.Set(bkey(i), val))
 		}
 		require.NoError(t, batch.Flush())
 
@@ -193,7 +193,7 @@ func BenchmarkIteratePrefixSingleKey(b *testing.B) {
 
 	batch := db.NewWriteBatch()
 	for i := 0; i < N; i++ {
-		y.Check(batch.Set(bkey(i), val, 0))
+		y.Check(batch.Set(bkey(i), val))
 	}
 	y.Check(batch.Flush())
 	var lsmFiles int

managed_db_test.go

@@ -114,7 +114,7 @@ func TestDropAll(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -150,7 +150,7 @@ func TestDropAllTwice(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -178,7 +178,7 @@ func TestDropAllWithPendingTxn(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -243,7 +243,7 @@ func TestDropReadOnly(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -275,7 +275,7 @@ func TestWriteAfterClose(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -366,7 +366,7 @@ func TestDropPrefix(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -417,7 +417,7 @@ func TestDropPrefixWithPendingTxn(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}
@@ -485,7 +485,7 @@ func TestDropPrefixReadOnly(t *testing.T) {
 	populate := func(db *DB) {
 		writer := db.NewWriteBatch()
 		for i := uint64(0); i < N; i++ {
-			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true), 0))
+			require.NoError(t, writer.Set([]byte(key("key", int(i))), val(true)))
 		}
 		require.NoError(t, writer.Flush())
 	}

value_test.go

@@ -455,8 +455,8 @@ func TestPersistLFDiscardStats(t *testing.T) {
 	require.NoError(t, txn.Commit(), "error while committing txn")
 
 	for i := 0; i < 500; i++ {
-		// use SetWithDiscard to delete entries, because this causes data to be flushed on disk,
-		// creating SSTs. Simple Delete was having data in Memtables only.
+		// use Entry.WithDiscard() to delete entries, because this causes data to be flushed on
+		// disk, creating SSTs. Simple Delete was having data in Memtables only.
 		err = db.Update(func(txn *Txn) error {
 			return txn.SetEntry(NewEntry([]byte(fmt.Sprintf("key%d", i)), v).WithDiscard())
 		})