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authorJanoš Guljaš <janos@users.noreply.github.com>2018-11-27 01:49:01 +0800
committerAnton Evangelatov <anton.evangelatov@gmail.com>2018-11-27 01:49:01 +0800
commitc207edf2a3a6f48b4fc78cc55982d648eedab198 (patch)
treeaed389f1cdaf964d3125971dbc81465175962015 /swarm/shed/field_uint64.go
parent4f0d978eaaebdd118af3bfe623782c70601daaed (diff)
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swarm: add database abstractions (shed package) (#18183)
Diffstat (limited to 'swarm/shed/field_uint64.go')
-rw-r--r--swarm/shed/field_uint64.go108
1 files changed, 108 insertions, 0 deletions
diff --git a/swarm/shed/field_uint64.go b/swarm/shed/field_uint64.go
new file mode 100644
index 000000000..80e0069ae
--- /dev/null
+++ b/swarm/shed/field_uint64.go
@@ -0,0 +1,108 @@
+// Copyright 2018 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package shed
+
+import (
+ "encoding/binary"
+
+ "github.com/syndtr/goleveldb/leveldb"
+)
+
+// Uint64Field provides a way to have a simple counter in the database.
+// It transparently encodes uint64 type value to bytes.
+type Uint64Field struct {
+ db *DB
+ key []byte
+}
+
+// NewUint64Field returns a new Uint64Field.
+// It validates its name and type against the database schema.
+func (db *DB) NewUint64Field(name string) (f Uint64Field, err error) {
+ key, err := db.schemaFieldKey(name, "uint64")
+ if err != nil {
+ return f, err
+ }
+ return Uint64Field{
+ db: db,
+ key: key,
+ }, nil
+}
+
+// Get retrieves a uint64 value from the database.
+// If the value is not found in the database a 0 value
+// is returned and no error.
+func (f Uint64Field) Get() (val uint64, err error) {
+ b, err := f.db.Get(f.key)
+ if err != nil {
+ if err == leveldb.ErrNotFound {
+ return 0, nil
+ }
+ return 0, err
+ }
+ return binary.BigEndian.Uint64(b), nil
+}
+
+// Put encodes uin64 value and stores it in the database.
+func (f Uint64Field) Put(val uint64) (err error) {
+ return f.db.Put(f.key, encodeUint64(val))
+}
+
+// PutInBatch stores a uint64 value in a batch
+// that can be saved later in the database.
+func (f Uint64Field) PutInBatch(batch *leveldb.Batch, val uint64) {
+ batch.Put(f.key, encodeUint64(val))
+}
+
+// Inc increments a uint64 value in the database.
+// This operation is not goroutine save.
+func (f Uint64Field) Inc() (val uint64, err error) {
+ val, err = f.Get()
+ if err != nil {
+ if err == leveldb.ErrNotFound {
+ val = 0
+ } else {
+ return 0, err
+ }
+ }
+ val++
+ return val, f.Put(val)
+}
+
+// IncInBatch increments a uint64 value in the batch
+// by retreiving a value from the database, not the same batch.
+// This operation is not goroutine save.
+func (f Uint64Field) IncInBatch(batch *leveldb.Batch) (val uint64, err error) {
+ val, err = f.Get()
+ if err != nil {
+ if err == leveldb.ErrNotFound {
+ val = 0
+ } else {
+ return 0, err
+ }
+ }
+ val++
+ f.PutInBatch(batch, val)
+ return val, nil
+}
+
+// encode transforms uint64 to 8 byte long
+// slice in big endian encoding.
+func encodeUint64(val uint64) (b []byte) {
+ b = make([]byte, 8)
+ binary.BigEndian.PutUint64(b, val)
+ return b
+}