database/sql: remove extra RemoveDep call

This should have been removed in 45c12efb4635. Not a correctness
issue, but unnecessary work.

This CL also adds paranoia checks in removeDep so this doesn't
happen again.

Fixes #5502

R=adg
CC=gobot, golang-dev, google
https://golang.org/cl/9543043

diff --git a/src/pkg/database/sql/sql.go b/src/pkg/database/sql/sql.go
index 968cb7475295718af37adb4b4f55d5acc338d71e..ebb7f440e0f123756ad1872d30b10b2ecdad8e5c 100644 (file)
--- a/src/pkg/database/sql/sql.go
+++ b/src/pkg/database/sql/sql.go
@@ -357,21 +357,27 @@ func (db *DB) removeDep(x finalCloser, dep interface{}) error {
 
 func (db *DB) removeDepLocked(x finalCloser, dep interface{}) func() error {
        //println(fmt.Sprintf("removeDep(%T %p, %T %p)", x, x, dep, dep))
-       done := false
 
-       xdep := db.dep[x]
-       if xdep != nil {
-               delete(xdep, dep)
-               if len(xdep) == 0 {
-                       delete(db.dep, x)
-                       done = true
-               }
+       xdep, ok := db.dep[x]
+       if !ok {
+               panic(fmt.Sprintf("unpaired removeDep: no deps for %T", x))
        }
 
-       if !done {
+       l0 := len(xdep)
+       delete(xdep, dep)
+
+       switch len(xdep) {
+       case l0:
+               // Nothing removed. Shouldn't happen.
+               panic(fmt.Sprintf("unpaired removeDep: no %T dep on %T", dep, x))
+       case 0:
+               // No more dependencies.
+               delete(db.dep, x)
+               return x.finalClose
+       default:
+               // Dependencies remain.
                return func() error { return nil }
        }
-       return x.finalClose
 }
 
 // Open opens a database specified by its database driver name and a
@@ -1261,7 +1267,6 @@ func (s *Stmt) finalClose() error {
        for _, v := range s.css {
                s.db.noteUnusedDriverStatement(v.dc, v.si)
                v.dc.removeOpenStmt(v.si)
-               s.db.removeDep(v.dc, s)
        }
        s.css = nil
        return nil