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pool.go
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pool.go
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package gorethink
import (
"errors"
"fmt"
"net"
"sync"
"gopkg.in/fatih/pool.v2"
)
const maxBadConnRetries = 3
var (
errPoolClosed = errors.New("gorethink: pool is closed")
errConnClosed = errors.New("gorethink: conn is closed")
errConnBusy = errors.New("gorethink: conn is busy")
)
// A Pool is used to store a pool of connections to a single RethinkDB server
type Pool struct {
host Host
opts *ConnectOpts
pool pool.Pool
mu sync.RWMutex // protects following fields
closed bool
maxIdle int
maxOpen int
}
// NewPool creates a new connection pool for the given host
func NewPool(host Host, opts *ConnectOpts) (*Pool, error) {
maxOpen := opts.MaxOpen
if maxOpen == 0 {
maxOpen = 2
}
p, err := pool.NewChannelPool(opts.MaxIdle, maxOpen, func() (net.Conn, error) {
conn, err := NewConnection(host.String(), opts)
if err != nil {
return nil, err
}
return conn, err
})
if err != nil {
return nil, err
}
return &Pool{
pool: p,
host: host,
opts: opts,
}, nil
}
// Ping verifies a connection to the database is still alive,
// establishing a connection if necessary.
func (p *Pool) Ping() error {
_, pc, err := p.conn()
if err != nil {
return err
}
return pc.Close()
}
// Close closes the database, releasing any open resources.
//
// It is rare to Close a Pool, as the Pool handle is meant to be
// long-lived and shared between many goroutines.
func (p *Pool) Close() error {
p.mu.RLock()
defer p.mu.RUnlock()
if p.closed {
return nil
}
p.pool.Close()
return nil
}
func (p *Pool) conn() (*Connection, *pool.PoolConn, error) {
p.mu.RLock()
defer p.mu.RUnlock()
if p.closed {
return nil, nil, errPoolClosed
}
nc, err := p.pool.Get()
if err != nil {
return nil, nil, err
}
pc, ok := nc.(*pool.PoolConn)
if !ok {
// This should never happen!
return nil, nil, fmt.Errorf("Invalid connection in pool")
}
conn, ok := pc.Conn.(*Connection)
if !ok {
// This should never happen!
return nil, nil, fmt.Errorf("Invalid connection in pool")
}
return conn, pc, nil
}
// SetMaxIdleConns sets the maximum number of connections in the idle
// connection pool.
//
// If MaxOpenConns is greater than 0 but less than the new MaxIdleConns
// then the new MaxIdleConns will be reduced to match the MaxOpenConns limit
//
// If n <= 0, no idle connections are retained.
//
// Deprecated: This value should only be set when connecting
func (p *Pool) SetMaxIdleConns(n int) {
return
}
// SetMaxOpenConns sets the maximum number of open connections to the database.
//
// If MaxIdleConns is greater than 0 and the new MaxOpenConns is less than
// MaxIdleConns, then MaxIdleConns will be reduced to match the new
// MaxOpenConns limit
//
// If n <= 0, then there is no limit on the number of open connections.
// The default is 0 (unlimited).
//
// Deprecated: This value should only be set when connecting
func (p *Pool) SetMaxOpenConns(n int) {
return
}
// Query execution functions
// Exec executes a query without waiting for any response.
func (p *Pool) Exec(q Query) error {
var err error
for i := 0; i < maxBadConnRetries; i++ {
var c *Connection
var pc *pool.PoolConn
c, pc, err = p.conn()
if err != nil {
continue
}
defer pc.Close()
_, _, err = c.Query(q)
if c.isBad() {
pc.MarkUnusable()
} else {
break
}
}
return err
}
// Query executes a query and waits for the response
func (p *Pool) Query(q Query) (*Cursor, error) {
var cursor *Cursor
var err error
for i := 0; i < maxBadConnRetries; i++ {
var c *Connection
var pc *pool.PoolConn
c, pc, err = p.conn()
if err != nil {
continue
}
_, cursor, err = c.Query(q)
if err == nil {
cursor.releaseConn = releaseConn(c, pc)
}
break
}
return cursor, err
}
// Server returns the server name and server UUID being used by a connection.
func (p *Pool) Server() (ServerResponse, error) {
var response ServerResponse
var err error
for i := 0; i < maxBadConnRetries; i++ {
var c *Connection
var pc *pool.PoolConn
c, pc, err = p.conn()
if err != nil {
continue
}
defer pc.Close()
response, err = c.Server()
if c.isBad() {
pc.MarkUnusable()
} else {
break
}
}
return response, err
}
func releaseConn(c *Connection, pc *pool.PoolConn) func() error {
return func() error {
if c.isBad() {
pc.MarkUnusable()
}
return pc.Close()
}
}