From cac412527d7855af3f5e2f1406c8e9e56e3376d5 Mon Sep 17 00:00:00 2001
From: Martin Boehm <martin.boehm@1mbsoftware.net>
Date: Tue, 6 Mar 2018 13:13:30 +0100
Subject: [PATCH] Improve handling of os interrupt signal in
 connectBlocksParallel

---
 db/sync.go | 32 +++++++++++++-------------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/db/sync.go b/db/sync.go
index 6b96962b..16bc0a64 100644
--- a/db/sync.go
+++ b/db/sync.go
@@ -4,6 +4,7 @@ import (
 	"blockbook/bchain"
 	"os"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/golang/glog"
@@ -171,32 +172,36 @@ func (w *SyncWorker) connectBlocksParallel(lower, higher uint32) error {
 	var err error
 	var wg sync.WaitGroup
 	hch := make(chan hashHeight, w.syncWorkers)
-	running := make([]bool, w.syncWorkers)
+	hchClosed := atomic.Value{}
+	hchClosed.Store(false)
 	work := func(i int) {
 		defer wg.Done()
 		var err error
 		var block *bchain.Block
 		for hh := range hch {
-			running[i] = true
 			for {
 				block, err = w.chain.GetBlockWithoutHeader(hh.hash, hh.height)
 				if err != nil {
-					glog.Error("Connect block error ", err, ". Retrying...")
+					// signal came while looping in the error loop
+					if hchClosed.Load() == true {
+						glog.Error("Worker ", i, " connect block error ", err, ". Exiting...")
+						return
+					}
+					glog.Error("Worker ", i, " connect block error ", err, ". Retrying...")
 					time.Sleep(time.Millisecond * 500)
 				} else {
 					break
 				}
 			}
 			if w.dryRun {
-				running[i] = false
 				continue
 			}
 			err = w.db.ConnectBlock(block)
 			if err != nil {
-				glog.Error("Connect block ", hh.height, " ", hh.hash, " error ", err)
+				glog.Error("Worker ", i, " connect block ", hh.height, " ", hh.hash, " error ", err)
 			}
-			running[i] = false
 		}
+		glog.Info("Worker ", i, " exiting...")
 	}
 	for i := 0; i < w.syncWorkers; i++ {
 		wg.Add(1)
@@ -208,19 +213,6 @@ ConnectLoop:
 	for h := lower; h <= higher; {
 		select {
 		case <-w.chanOsSignal:
-			// wait for the workers to finish block
-			i := 0
-		WaitAgain:
-			for ; i < 60; i++ {
-				for _, r := range running {
-					if r {
-						glog.Info("Waiting ", i, "s for workers to finish ", running)
-						time.Sleep(time.Millisecond * 1000)
-						continue WaitAgain
-					}
-				}
-				break
-			}
 			err = errors.Errorf("connectBlocksParallel interrupted at height %d", h)
 			break ConnectLoop
 		default:
@@ -238,6 +230,8 @@ ConnectLoop:
 		}
 	}
 	close(hch)
+	// signal stop to workers that are in w.chain.GetBlockWithoutHeader error loop
+	hchClosed.Store(true)
 	wg.Wait()
 	return err
 }