concurrent solver

main.go

@@ -1,33 +1,39 @@
 package main
 
 import (
+	"context"
 	"crypto"
 	_ "crypto/sha1"
-	"encoding/base64"
+	"encoding/hex"
 	"fmt"
 	"math/rand"
 	"os"
+	"runtime"
 	"time"
 )
 
 func main() {
 	g := Generator{
 		Difficulty: 25,
+		Timeout:    10 * time.Second,
 	}
 	c := g.RandomChallenge()
 	c.Solve()
+	if c.Validate() {
 		fmt.Println(c.String())
+	}
 }
 
 type Challenge struct {
 	Input    [48]byte
 	Date     [20]byte
-	Difficulty byte
 	Solution int64
 	bytes    []byte
+	Generator
 }
 type Generator struct {
 	Difficulty byte
+	Timeout    time.Duration
 }
 
 func (g *Generator) RandomChallenge() Challenge {
@@ -41,7 +47,7 @@ func (g *Generator) RandomChallenge() Challenge {
 	return Challenge{
 		Input:     [48]byte(bytes),
 		Date:      [20]byte(hash),
-		Difficulty: g.Difficulty,
+		Generator: *g,
 	}
 }
 
@@ -70,25 +76,59 @@ func (c *Challenge) Solve() {
 	c.bytes = append(c.bytes, c.Input[:]...)
 	c.bytes = append(c.bytes, c.Date[:]...)
 	timer := time.Now()
+	solution := make(chan int64)
+	ctx, cancel := context.WithCancel(context.Background())
+	count := runtime.NumCPU()
+	for i := range count {
+		go func(id int, ctx context.Context) {
+			i := int64(id)
+			defer cancel()
 			for {
-		s := c.Validate()
+				select {
+				case <-ctx.Done():
+					return
+				default:
+					s := c.CheckValue(i)
 					if s {
-			fmt.Fprintf(os.Stderr, "%s: found solution %d in %dms\n", c.String(), c.Solution, time.Since(timer).Milliseconds())
+						solution <- i
+						fmt.Fprintf(os.Stderr, "[thread %d] ", id)
+						cancel()
 						break
 					}
 					if c.Solution > 0xffffffffffffff {
-			fmt.Fprintf(os.Stderr, "%s: could not find solution!", c.String())
+						fmt.Fprintf(os.Stderr, "%s (thread %d): could not find solution!\n", c.String(), id)
+						cancel()
+						break
 					}
-		c.Solution++
+					if time.Since(timer) > c.Timeout {
+						fmt.Fprintf(os.Stderr, "%s (thread %d): timed out!\n", c.String(), id)
+						cancel()
+						break
+					}
+					i += int64(count)
+				}
+			}
+		}(i, ctx)
+	}
+	select {
+	case c.Solution = <-solution:
+		cancel()
+		fmt.Fprintf(os.Stderr, "%s: found solution %d in %dms\n", c.String(), c.Solution, time.Since(timer).Milliseconds())
+		break
+	case <-ctx.Done():
+		cancel()
+		break
 	}
 }
 func (c *Challenge) CheckValue(v int64) bool {
+	bytes := make([]byte, len(c.bytes))
+	copy(bytes, c.bytes)
 	for i := range 8 {
-		c.bytes[75-i] = byte(v >> (i * 8))
+		bytes[75-i] = byte(v >> (i * 8))
 	}
 	sum := make([]byte, 20)
 	hash := crypto.SHA1.New()
-	hash.Write(c.bytes)
+	hash.Write(bytes)
 	sum = hash.Sum(nil)
 	count := 0
 	for _, c := range sum {
@@ -112,5 +152,5 @@ func (c *Challenge) String() string {
 	for i := range 7 {
 		bytes[75-i] = byte(c.Solution >> (i * 8))
 	}
-	return base64.URLEncoding.EncodeToString(bytes)
+	return hex.EncodeToString(bytes)
 }