From d25b31e4c8ba0c3116749a03e1f28cad1df5ff45 Mon Sep 17 00:00:00 2001
From: Daniel Hess <dan9186@gmail.com>
Date: Sun, 11 Apr 2021 16:13:03 -0700
Subject: [PATCH 1/2] add callback blocker for general use

---
 cbblocker/cbblocker.go      | 38 ++++++++++++++++++++++++++++++++++
 cbblocker/dbblocker_test.go | 41 +++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 cbblocker/cbblocker.go
 create mode 100644 cbblocker/dbblocker_test.go

diff --git a/cbblocker/cbblocker.go b/cbblocker/cbblocker.go
new file mode 100644
index 0000000..d7025e3
--- /dev/null
+++ b/cbblocker/cbblocker.go
@@ -0,0 +1,38 @@
+package cbblocker
+
+import (
+	"time"
+)
+
+type Blocker struct {
+	callback func() error
+	duration time.Duration
+}
+
+func New(callback func() error, poll time.Duration) *Blocker {
+	return &Blocker{
+		callback: callback,
+		duration: poll,
+	}
+}
+
+func (g *Blocker) Blockit() <-chan bool {
+	pass := make(chan bool)
+
+	go func() {
+		for {
+			err := g.callback()
+			if err != nil {
+				<-time.After(g.duration)
+				continue
+			}
+
+			pass <- true
+			close(pass)
+
+			break
+		}
+	}()
+
+	return pass
+}
diff --git a/cbblocker/dbblocker_test.go b/cbblocker/dbblocker_test.go
new file mode 100644
index 0000000..658a203
--- /dev/null
+++ b/cbblocker/dbblocker_test.go
@@ -0,0 +1,41 @@
+package cbblocker_test
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/gomicro/blockit/cbblocker"
+
+	"github.com/franela/goblin"
+	. "github.com/onsi/gomega"
+)
+
+func TestCallbackBlockers(t *testing.T) {
+	g := goblin.Goblin(t)
+	RegisterFailHandler(func(m string, _ ...int) { g.Fail(m) })
+
+	g.Describe("Callback Blocking", func() {
+		g.It("should block until callback returns no error", func() {
+			ep := eventualPass{}
+
+			b := cbblocker.New(ep.do, 10*time.Millisecond)
+			Eventually(<-b.Blockit()).Should(BeTrue())
+			Expect(ep.Fails).To(Equal(4))
+		})
+	})
+}
+
+type eventualPass struct {
+	Fails int
+}
+
+func (ep *eventualPass) do() error {
+	if ep.Fails > 3 {
+		return nil
+	}
+
+	ep.Fails++
+
+	return fmt.Errorf("didn't pass")
+}

From f44b1a92d194f96750a2a2f48d68a026f1f13595 Mon Sep 17 00:00:00 2001
From: Daniel Hess <dan9186@gmail.com>
Date: Sun, 11 Apr 2021 16:13:16 -0700
Subject: [PATCH 2/2] reduce the dbblocker to use the callback blocker

---
 dbblocker/dbblocker.go | 35 ++++-------------------------------
 1 file changed, 4 insertions(+), 31 deletions(-)

diff --git a/dbblocker/dbblocker.go b/dbblocker/dbblocker.go
index 20607d4..0e7731d 100644
--- a/dbblocker/dbblocker.go
+++ b/dbblocker/dbblocker.go
@@ -3,38 +3,11 @@ package dbblocker
 import (
 	"database/sql"
 	"time"
-)
 
-// Blocker represents a SQL database connection to monitor for connectivity
-// and block until a connection is established.
-type Blocker struct {
-	db *sql.DB
-}
+	"github.com/gomicro/blockit/cbblocker"
+)
 
 // New takes a SQL database object and returns a newly instantiated Blocker
-func New(db *sql.DB) *Blocker {
-	return &Blocker{db: db}
-}
-
-// Blockit meets the blocker interface. It returns a read only channel that will
-// receive true when the database is connected.
-func (d *Blocker) Blockit() <-chan bool {
-	connected := make(chan bool)
-
-	go func() {
-		for {
-			err := d.db.Ping()
-			if err != nil {
-				<-time.After(1 * time.Second)
-				continue
-			}
-
-			connected <- true
-			close(connected)
-
-			break
-		}
-	}()
-
-	return connected
+func New(db *sql.DB) *cbblocker.Blocker {
+	return cbblocker.New(db.Ping, 1*time.Second)
 }