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Track and check number of in-progress acquires

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This commit is contained in:
Jack Christensen 2016-07-15 14:46:50 -05:00
parent 7477020000
commit ecf158b086
1 changed files with 9 additions and 22 deletions
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31
conn_pool.go
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@ -18,6 +18,7 @@ type ConnPool struct {
availableConnections []*Conn availableConnections []*Conn
cond *sync.Cond cond *sync.Cond
config ConnConfig // config used when establishing connection config ConnConfig // config used when establishing connection
inProgressConnects int
maxConnections int maxConnections int
resetCount int resetCount int
afterConnect func(*Conn) error afterConnect func(*Conn) error
@ -133,33 +134,17 @@ func (p *ConnPool) acquire(deadline *time.Time) (*Conn, error) {
} }
// No connections are available, but we can create more // No connections are available, but we can create more
if len(p.allConnections) < p.maxConnections { if len(p.allConnections)+p.inProgressConnects < p.maxConnections {
// Create a placeholder connection.
placeholderConn := &Conn{}
p.allConnections = append(p.allConnections, placeholderConn)
// Create a new connection. // Create a new connection.
// Carefull here: createConnectionUnlocked() removes the current lock, // Careful here: createConnectionUnlocked() removes the current lock,
// creates a connection and then locks it back. // creates a connection and then locks it back.
c, err := p.createConnectionUnlocked() if c, err := p.createConnectionUnlocked(); err == nil {
// Take the placeholder out of the list of connections.
p.removeFromAllConnections(placeholderConn)
// Make sure create connection did not fail
if err != nil {
return nil, err
}
// If resetCount was updated since we started our connection, or
// there is no room in the list of allConnections
// (invalidateAcquired may remove our placeholder), try to re-acquire
// the connection.
if len(p.allConnections) < p.maxConnections {
// Put the new connection to the list.
c.poolResetCount = p.resetCount c.poolResetCount = p.resetCount
p.allConnections = append(p.allConnections, c) p.allConnections = append(p.allConnections, c)
return c, nil return c, nil
} else {
return nil, err
} }
// There is no room for the just created connection.
// Close it and try to re-acquire.
c.Close()
} else { } else {
// All connections are in use and we cannot create more // All connections are in use and we cannot create more
if p.logLevel >= LogLevelWarn { if p.logLevel >= LogLevelWarn {
@ -167,7 +152,7 @@ func (p *ConnPool) acquire(deadline *time.Time) (*Conn, error) {
} }
// Wait until there is an available connection OR room to create a new connection // Wait until there is an available connection OR room to create a new connection
for len(p.availableConnections) == 0 && len(p.allConnections) == p.maxConnections { for len(p.availableConnections) == 0 && len(p.allConnections)+p.inProgressConnects == p.maxConnections {
if p.deadlinePassed(deadline) { if p.deadlinePassed(deadline) {
return nil, errors.New("Timeout: All connections in pool are busy") return nil, errors.New("Timeout: All connections in pool are busy")
} }
@ -307,9 +292,11 @@ func (p *ConnPool) createConnection() (*Conn, error) {
// To avoid this we put Connect(p.config) outside of the lock (it is thread safe) // To avoid this we put Connect(p.config) outside of the lock (it is thread safe)
// what would allow us to make all the 20 connection in parallel (more or less). // what would allow us to make all the 20 connection in parallel (more or less).
func (p *ConnPool) createConnectionUnlocked() (*Conn, error) { func (p *ConnPool) createConnectionUnlocked() (*Conn, error) {
p.inProgressConnects++
p.cond.L.Unlock() p.cond.L.Unlock()
c, err := Connect(p.config) c, err := Connect(p.config)
p.cond.L.Lock() p.cond.L.Lock()
p.inProgressConnects--
if err != nil { if err != nil {
return nil, err return nil, err