mysql client pool work for indexer; temporary glue in blobserver

lib/go/mysqlindexer/enumerate.go

@@ -28,6 +28,6 @@ func (mi *Indexer) EnumerateBlobs(dest chan *blobref.SizedBlobRef,
 	limit uint,
 	waitSeconds int) os.Error {
 	// TODO: finish
-	return os.NewError("Fetch isn't supported by the MySQL indexer")
+	return os.NewError("EnumerateBlobs isn't supported by the MySQL indexer")
 }
 

lib/go/mysqlindexer/mysqlindexer.go

@@ -37,6 +37,49 @@ type Indexer struct {
 	cachedClients []*mysql.Client
 }
 
+func (mi *Indexer) IsAlive() (ok bool, err os.Error) {
+	var client *mysql.Client
+	client, err = mi.getConnection()
+	defer mi.releaseConnection(client)
+
+	if err != nil {
+		return
+	}
+	err = client.Query("SELECT 1 + 1")
+	if err != nil {
+		return
+	}
+	_, err = client.UseResult()
+	if err != nil {
+		return
+	}
+	client.FreeResult()
+	return true, nil
+}
+
+// Get a free cached connection or allocate a new one.
+func (mi *Indexer) getConnection() (client *mysql.Client, err os.Error) {
+	mi.clientLock.Lock()
+	if len(mi.cachedClients) > 0 {
+		defer mi.clientLock.Unlock()
+		client = mi.cachedClients[len(mi.cachedClients)-1]
+		mi.cachedClients = mi.cachedClients[:len(mi.cachedClients)-1]
+		// TODO: Outside the mutex, double check that the client is still good.
+		return
+	}
+	mi.clientLock.Unlock()
+
+	client, err = mysql.DialTCP(mi.Host, mi.User, mi.Password, mi.Database)
+	return
+}
+
+// Release a client to the cached client pool.
+func (mi *Indexer) releaseConnection(client *mysql.Client) {
+	mi.clientLock.Lock()
+	defer mi.clientLock.Unlock()
+	mi.cachedClients = append(mi.cachedClients, client)
+}
+
 func (mi *Indexer) GetBlobHub(partition blobserver.Partition) blobserver.BlobHub {
 	mi.hubLock.Lock()
 	defer mi.hubLock.Unlock()

server/go/blobserver/camlistored.go

@@ -20,8 +20,11 @@ import (
 	"os"
 )
 
-var flagStorageRoot *string = flag.String("root", "/tmp/camliroot", "Root directory to store files")
-var flagRequestLog *bool = flag.Bool("reqlog", false, "Log incoming requests")
+var flagStorageRoot = flag.String("root", "/tmp/camliroot", "Root directory to store files")
+var flagRequestLog = flag.Bool("reqlog", false, "Log incoming requests")
+
+// TODO: Temporary
+var flagDevMySql = flag.Bool("devmysqlindexer", false, "Temporary option to enable MySQL indexer on /indexer")
 
 var storage blobserver.Storage
 var indexerStorage blobserver.Storage
@@ -178,13 +181,20 @@ func main() {
 	ws.HandleFunc("/camli/", handleCamli)
 
 	// TODO: temporary
-	if true {
-		indexerStorage = &mysqlindexer.Indexer{}
+	if *flagDevMySql {
+		myIndexer := &mysqlindexer.Indexer{
+		Host: "localhost",
+		User: "root",
+		Password: "root",
+		Database: "camlistore",
+		}
+		if ok, err := myIndexer.IsAlive(); !ok {
+			log.Fatalf("Could not connect indexer to MySQL server: %s", err)
+		}
+		indexerStorage = myIndexer
 		ws.HandleFunc("/indexer/", handleIndexRequest)
 	}
 
-
-
 	ws.Handle("/js/", http.FileServer("../../clients/js", "/js/"))
 	ws.Serve()
 }