Add package cluster :

- based on dragonboat lib (https://github.com/lni/dragonboat)
- add extended config with validate
- add backend managment to allow simple implementation for backend simple, cocurrent & disk
- has no backend implemented and must be a lib for a cluster mode of one backend

cluster/configEngine.go

@@ -0,0 +1,107 @@
+/***********************************************************************************************************************
+ *
+ *   MIT License
+ *
+ *   Copyright (c) 2021 Nicolas JUHEL
+ *
+ *   Permission is hereby granted, free of charge, to any person obtaining a copy
+ *   of this software and associated documentation files (the "Software"), to deal
+ *   in the Software without restriction, including without limitation the rights
+ *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *   copies of the Software, and to permit persons to whom the Software is
+ *   furnished to do so, subject to the following conditions:
+ *
+ *   The above copyright notice and this permission notice shall be included in all
+ *   copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *   SOFTWARE.
+ *
+ *
+ **********************************************************************************************************************/
+
+package cluster
+
+import (
+	"fmt"
+
+	"github.com/go-playground/validator/v10"
+	dgbcfg "github.com/lni/dragonboat/v3/config"
+	liberr "github.com/nabbar/golib/errors"
+)
+
+type ConfigEngine struct {
+	// ExecShards is the number of execution shards in the first stage of the
+	// execution engine. Default value is 16. Once deployed, this value can not
+	// be changed later.
+	ExecShards uint64 `mapstructure:"exec_shards" json:"exec_shards" yaml:"exec_shards" toml:"exec_shards"`
+
+	// CommitShards is the number of commit shards in the second stage of the
+	// execution engine. Default value is 16.
+	CommitShards uint64 `mapstructure:"commit_shards" json:"commit_shards" yaml:"commit_shards" toml:"commit_shards"`
+
+	// ApplyShards is the number of apply shards in the third stage of the
+	// execution engine. Default value is 16.
+	ApplyShards uint64 `mapstructure:"apply_shards" json:"apply_shards" yaml:"apply_shards" toml:"apply_shards"`
+
+	// SnapshotShards is the number of snapshot shards in the forth stage of the
+	// execution engine. Default value is 48.
+	SnapshotShards uint64 `mapstructure:"snapshot_shards" json:"snapshot_shards" yaml:"snapshot_shards" toml:"snapshot_shards"`
+
+	// CloseShards is the number of close shards used for closing stopped
+	// state machines. Default value is 32.
+	CloseShards uint64 `mapstructure:"close_shards" json:"close_shards" yaml:"close_shards" toml:"close_shards"`
+}
+
+func (c ConfigEngine) GetDGBConfigEngine() dgbcfg.EngineConfig {
+	d := dgbcfg.EngineConfig{}
+
+	if c.ExecShards > 0 {
+		d.ExecShards = c.ExecShards
+	}
+
+	if c.CommitShards > 0 {
+		d.CommitShards = c.CommitShards
+	}
+
+	if c.ApplyShards > 0 {
+		d.ApplyShards = c.ApplyShards
+	}
+
+	if c.SnapshotShards > 0 {
+		d.SnapshotShards = c.SnapshotShards
+	}
+
+	if c.CloseShards > 0 {
+		d.CloseShards = c.CloseShards
+	}
+
+	return d
+}
+
+func (c ConfigEngine) Validate() liberr.Error {
+	val := validator.New()
+	err := val.Struct(c)
+
+	if e, ok := err.(*validator.InvalidValidationError); ok {
+		return ErrorValidateEngine.ErrorParent(e)
+	}
+
+	out := ErrorValidateEngine.Error(nil)
+
+	for _, e := range err.(validator.ValidationErrors) {
+		//nolint goerr113
+		out.AddParent(fmt.Errorf("config field '%s' is not validated by constraint '%s'", e.Field(), e.ActualTag()))
+	}
+
+	if out.HasParent() {
+		return out
+	}
+
+	return nil
+}