1 files changed, 112 insertions, 0 deletions
diff --git a/core/utils/round-based-config.go b/core/utils/round-based-config.go
new file mode 100644
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--- /dev/null
+++ b/core/utils/round-based-config.go
@@ -0,0 +1,112 @@
+// Copyright 2018 The dexon-consensus Authors
+// This file is part of the dexon-consensus library.
+//
+// The dexon-consensus 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 dexon-consensus 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 dexon-consensus library. If not, see
+// <http://www.gnu.org/licenses/>.
+
+package utils
+
+import (
+	"fmt"
+
+	"github.com/dexon-foundation/dexon-consensus/core/types"
+)
+
+// RoundBasedConfig is based config for rounds and provide boundary checking
+// for rounds.
+type RoundBasedConfig struct {
+	roundID          uint64
+	roundBeginHeight uint64
+	roundEndHeight   uint64
+	roundLength      uint64
+}
+
+// SetupRoundBasedFields setup round based fields, including round ID, the
+// length of rounds.
+func (c *RoundBasedConfig) SetupRoundBasedFields(
+	roundID uint64, cfg *types.Config) {
+	if c.roundLength > 0 {
+		panic(fmt.Errorf("duplicated set round based fields: %d",
+			c.roundLength))
+	}
+	c.roundID = roundID
+	c.roundLength = cfg.RoundLength
+}
+
+// SetRoundBeginHeight gives the beginning height for the initial round provided
+// when constructed.
+func (c *RoundBasedConfig) SetRoundBeginHeight(begin uint64) {
+	if c.roundBeginHeight != 0 {
+		panic(fmt.Errorf("duplicated set round begin height: %d",
+			c.roundBeginHeight))
+	}
+	c.roundBeginHeight = begin
+	c.roundEndHeight = begin + c.roundLength
+}
+
+// IsLastBlock checks if a block is the last block of this round.
+func (c *RoundBasedConfig) IsLastBlock(b *types.Block) bool {
+	if b.Position.Round != c.roundID {
+		panic(fmt.Errorf("attempt to compare by different round: %s, %d",
+			b, c.roundID))
+	}
+	return b.Position.Height+1 == c.roundEndHeight
+}
+
+// ExtendLength extends round ending height by the length of current round.
+func (c *RoundBasedConfig) ExtendLength() {
+	c.roundEndHeight += c.roundLength
+}
+
+// Contains checks if a block height is in this round.
+func (c *RoundBasedConfig) Contains(h uint64) bool {
+	return c.roundBeginHeight <= h && c.roundEndHeight > h
+}
+
+// RoundID returns the round ID of this config.
+func (c *RoundBasedConfig) RoundID() uint64 {
+	if c.roundLength == 0 {
+		panic(fmt.Errorf("config is not initialized: %d", c.roundID))
+	}
+	return c.roundID
+}
+
+// RoundEndHeight returns next checkpoint to varify if this round is ended.
+func (c *RoundBasedConfig) RoundEndHeight() uint64 {
+	if c.roundLength == 0 {
+		panic(fmt.Errorf("config is not initialized: %d", c.roundID))
+	}
+	return c.roundEndHeight
+}
+
+// AppendTo a config in previous round.
+func (c *RoundBasedConfig) AppendTo(other RoundBasedConfig) {
+	if c.roundID != other.roundID+1 {
+		panic(fmt.Errorf("round IDs of configs not continuous: %d %d",
+			c.roundID, other.roundID))
+	}
+	c.SetRoundBeginHeight(other.roundEndHeight)
+}
+
+// LastPeriodBeginHeight returns the begin height of last period. For example,
+// if a round is extended twice, then the return from this method is:
+//
+//    begin + 2 * roundLength - roundLength
+//
+func (c *RoundBasedConfig) LastPeriodBeginHeight() uint64 {
+	if c.roundLength == 0 {
+		panic(fmt.Errorf("config is not initialized: %d", c.roundID))
+	}
+	return c.roundEndHeight - c.roundLength
+}