From 17710a23c450bba77c8eaddc19e88bb428fff391 Mon Sep 17 00:00:00 2001
From: Russ Cox <rsc@golang.org>
Date: Thu, 27 Feb 2014 22:43:10 -0500
Subject: [release-branch.go1.2] database/sql: Use all connections in pool

??? CL 40410043 / 8a7ac002f840
database/sql: Use all connections in pool

The last connection in the pool was not being handed out correctly.

R=golang-codereviews, gobot, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/40410043

Committer: Brad Fitzpatrick <bradfitz@golang.org>
???

LGTM=r
R=golang-codereviews, r
CC=golang-dev
https://codereview.appspot.com/68820044
---
 src/pkg/database/sql/sql.go      |  4 ++--
 src/pkg/database/sql/sql_test.go | 23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/src/pkg/database/sql/sql.go b/src/pkg/database/sql/sql.go
index dddf5a3f2..84a096513 100644
--- a/src/pkg/database/sql/sql.go
+++ b/src/pkg/database/sql/sql.go
@@ -620,8 +620,8 @@ func (db *DB) conn() (*driverConn, error) {
 	}
 
 	// If db.maxOpen > 0 and the number of open connections is over the limit
-	// or there are no free connection, then make a request and wait.
-	if db.maxOpen > 0 && (db.numOpen >= db.maxOpen || db.freeConn.Len() == 0) {
+	// and there are no free connection, make a request and wait.
+	if db.maxOpen > 0 && db.numOpen >= db.maxOpen && db.freeConn.Len() == 0 {
 		// Make the connRequest channel. It's buffered so that the
 		// connectionOpener doesn't block while waiting for the req to be read.
 		ch := make(chan interface{}, 1)
diff --git a/src/pkg/database/sql/sql_test.go b/src/pkg/database/sql/sql_test.go
index 093c0d64c..787a5c9f7 100644
--- a/src/pkg/database/sql/sql_test.go
+++ b/src/pkg/database/sql/sql_test.go
@@ -1005,6 +1005,29 @@ func TestMaxOpenConns(t *testing.T) {
 	}
 }
 
+func TestSingleOpenConn(t *testing.T) {
+	db := newTestDB(t, "people")
+	defer closeDB(t, db)
+
+	db.SetMaxOpenConns(1)
+
+	rows, err := db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+	// shouldn't deadlock
+	rows, err = db.Query("SELECT|people|name|")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = rows.Close(); err != nil {
+		t.Fatal(err)
+	}
+}
+
 // golang.org/issue/5323
 func TestStmtCloseDeps(t *testing.T) {
 	if testing.Short() {
-- 
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