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// 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 core
import (
"fmt"
"sync"
"github.com/dexon-foundation/dexon-consensus/common"
"github.com/dexon-foundation/dexon-consensus/core/types"
)
type blockConfirmedEvent struct {
block *types.Block
}
type blockDeliveredEvent struct {
blockHash common.Hash
blockPosition types.Position
result *types.FinalizationResult
}
// nonBlocking implements these interfaces and is a decorator for
// them that makes the methods to be non-blocking.
// - Application
// - Debug
// - It also provides nonblockig for db update.
type nonBlocking struct {
app Application
debug Debug
eventChan chan interface{}
events []interface{}
eventsChange *sync.Cond
running sync.WaitGroup
}
func newNonBlocking(app Application, debug Debug) *nonBlocking {
nonBlockingModule := &nonBlocking{
app: app,
debug: debug,
eventChan: make(chan interface{}, 6),
events: make([]interface{}, 0, 100),
eventsChange: sync.NewCond(&sync.Mutex{}),
}
go nonBlockingModule.run()
return nonBlockingModule
}
func (nb *nonBlocking) addEvent(event interface{}) {
nb.eventsChange.L.Lock()
defer nb.eventsChange.L.Unlock()
nb.events = append(nb.events, event)
nb.eventsChange.Broadcast()
}
func (nb *nonBlocking) run() {
// This go routine consume the first event from events and call the
// corresponding methods of Application/Debug/db.
for {
var event interface{}
func() {
nb.eventsChange.L.Lock()
defer nb.eventsChange.L.Unlock()
for len(nb.events) == 0 {
nb.eventsChange.Wait()
}
event = nb.events[0]
nb.events = nb.events[1:]
nb.running.Add(1)
}()
switch e := event.(type) {
case blockConfirmedEvent:
nb.app.BlockConfirmed(*e.block)
case blockDeliveredEvent:
nb.app.BlockDelivered(e.blockHash, e.blockPosition, *e.result)
default:
fmt.Printf("Unknown event %v.", e)
}
nb.running.Done()
nb.eventsChange.Broadcast()
}
}
// wait will wait for all event in events finishes.
func (nb *nonBlocking) wait() {
nb.eventsChange.L.Lock()
defer nb.eventsChange.L.Unlock()
for len(nb.events) > 0 {
nb.eventsChange.Wait()
}
nb.running.Wait()
}
// PreparePayload cannot be non-blocking.
func (nb *nonBlocking) PreparePayload(position types.Position) ([]byte, error) {
return nb.app.PreparePayload(position)
}
// PrepareWitness cannot be non-blocking.
func (nb *nonBlocking) PrepareWitness(height uint64) (types.Witness, error) {
return nb.app.PrepareWitness(height)
}
// VerifyBlock cannot be non-blocking.
func (nb *nonBlocking) VerifyBlock(block *types.Block) types.BlockVerifyStatus {
return nb.app.VerifyBlock(block)
}
// BlockConfirmed is called when a block is confirmed and added to lattice.
func (nb *nonBlocking) BlockConfirmed(block types.Block) {
nb.addEvent(blockConfirmedEvent{&block})
}
// BlockDelivered is called when a block is add to the compaction chain.
func (nb *nonBlocking) BlockDelivered(blockHash common.Hash,
blockPosition types.Position, result types.FinalizationResult) {
nb.addEvent(blockDeliveredEvent{
blockHash: blockHash,
blockPosition: blockPosition,
result: &result,
})
}
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