database/sql: count connections expired in foreground with MaxLifetimeClosed

Previously the connection pool would only count connections
expired in the background connectionCleaner goroutine towards the
MaxLifetimeClosed stat.

This change increments the stat correctly when checking for
expiry in when acquiring and releasing a connection.

Fixes #38058

Change-Id: Id707ddd40a42a4c38658d5f2931da131647d6c29
GitHub-Last-Rev: 0f205ede439efa355a628b6112450f2ca9ced005
GitHub-Pull-Request: golang/go#38263
Reviewed-on: https://go-review.googlesource.com/c/go/+/227278
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>

diff --git a/src/database/sql/sql.go b/src/database/sql/sql.go
index b63d5591f6d9d2c9decffd7cabe15efdd74e6828..6e317144451ac94566200b4d4b06eabf7ed78e8c 100644 (file)
--- a/src/database/sql/sql.go
+++ b/src/database/sql/sql.go
@@ -432,7 +432,7 @@ type DB struct {
        waitCount         int64 // Total number of connections waited for.
        maxIdleClosed     int64 // Total number of connections closed due to idle count.
        maxIdleTimeClosed int64 // Total number of connections closed due to idle time.
-       maxLifetimeClosed int64 // Total number of connections closed due to max free limit.
+       maxLifetimeClosed int64 // Total number of connections closed due to max connection lifetime limit.
 
        stop func() // stop cancels the connection opener and the session resetter.
 }
@@ -1208,11 +1208,13 @@ func (db *DB) conn(ctx context.Context, strategy connReuseStrategy) (*driverConn
                copy(db.freeConn, db.freeConn[1:])
                db.freeConn = db.freeConn[:numFree-1]
                conn.inUse = true
-               db.mu.Unlock()
                if conn.expired(lifetime) {
+                       db.maxLifetimeClosed++
+                       db.mu.Unlock()
                        conn.Close()
                        return nil, driver.ErrBadConn
                }
+               db.mu.Unlock()
 
                // Reset the session if required.
                if err := conn.resetSession(ctx); err == driver.ErrBadConn {
@@ -1268,6 +1270,9 @@ func (db *DB) conn(ctx context.Context, strategy connReuseStrategy) (*driverConn
                        // This prioritizes giving a valid connection to a client over the exact connection
                        // lifetime, which could expire exactly after this point anyway.
                        if strategy == cachedOrNewConn && ret.err == nil && ret.conn.expired(lifetime) {
+                               db.mu.Lock()
+                               db.maxLifetimeClosed++
+                               db.mu.Unlock()
                                ret.conn.Close()
                                return nil, driver.ErrBadConn
                        }
@@ -1352,6 +1357,7 @@ func (db *DB) putConn(dc *driverConn, err error, resetSession bool) {
        }
 
        if err != driver.ErrBadConn && dc.expired(db.maxLifetime) {
+               db.maxLifetimeClosed++
                err = driver.ErrBadConn
        }
        if debugGetPut {