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minio/vendor/gopkg.in/mgo.v2/server.go

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// mgo - MongoDB driver for Go
//
// Copyright (c) 2010-2012 - Gustavo Niemeyer <gustavo@niemeyer.net>
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package mgo
import (
"errors"
"net"
"sort"
"sync"
"time"
"gopkg.in/mgo.v2/bson"
)
// ---------------------------------------------------------------------------
// Mongo server encapsulation.
type mongoServer struct {
sync.RWMutex
Addr string
ResolvedAddr string
tcpaddr *net.TCPAddr
unusedSockets []*mongoSocket
liveSockets []*mongoSocket
closed bool
abended bool
sync chan bool
dial dialer
pingValue time.Duration
pingIndex int
pingCount uint32
pingWindow [6]time.Duration
info *mongoServerInfo
}
type dialer struct {
old func(addr net.Addr) (net.Conn, error)
new func(addr *ServerAddr) (net.Conn, error)
}
func (dial dialer) isSet() bool {
return dial.old != nil || dial.new != nil
}
type mongoServerInfo struct {
Master bool
Mongos bool
Tags bson.D
MaxWireVersion int
SetName string
}
var defaultServerInfo mongoServerInfo
func newServer(addr string, tcpaddr *net.TCPAddr, sync chan bool, dial dialer) *mongoServer {
server := &mongoServer{
Addr: addr,
ResolvedAddr: tcpaddr.String(),
tcpaddr: tcpaddr,
sync: sync,
dial: dial,
info: &defaultServerInfo,
}
// Once so the server gets a ping value, then loop in background.
server.pinger(false)
go server.pinger(true)
return server
}
var errPoolLimit = errors.New("per-server connection limit reached")
var errServerClosed = errors.New("server was closed")
// AcquireSocket returns a socket for communicating with the server.
// This will attempt to reuse an old connection, if one is available. Otherwise,
// it will establish a new one. The returned socket is owned by the call site,
// and will return to the cache when the socket has its Release method called
// the same number of times as AcquireSocket + Acquire were called for it.
// If the poolLimit argument is greater than zero and the number of sockets in
// use in this server is greater than the provided limit, errPoolLimit is
// returned.
func (server *mongoServer) AcquireSocket(poolLimit int, timeout time.Duration) (socket *mongoSocket, abended bool, err error) {
for {
server.Lock()
abended = server.abended
if server.closed {
server.Unlock()
return nil, abended, errServerClosed
}
n := len(server.unusedSockets)
if poolLimit > 0 && len(server.liveSockets)-n >= poolLimit {
server.Unlock()
return nil, false, errPoolLimit
}
if n > 0 {
socket = server.unusedSockets[n-1]
server.unusedSockets[n-1] = nil // Help GC.
server.unusedSockets = server.unusedSockets[:n-1]
info := server.info
server.Unlock()
err = socket.InitialAcquire(info, timeout)
if err != nil {
continue
}
} else {
server.Unlock()
socket, err = server.Connect(timeout)
if err == nil {
server.Lock()
// We've waited for the Connect, see if we got
// closed in the meantime
if server.closed {
server.Unlock()
socket.Release()
socket.Close()
return nil, abended, errServerClosed
}
server.liveSockets = append(server.liveSockets, socket)
server.Unlock()
}
}
return
}
panic("unreachable")
}
// Connect establishes a new connection to the server. This should
// generally be done through server.AcquireSocket().
func (server *mongoServer) Connect(timeout time.Duration) (*mongoSocket, error) {
server.RLock()
master := server.info.Master
dial := server.dial
server.RUnlock()
logf("Establishing new connection to %s (timeout=%s)...", server.Addr, timeout)
var conn net.Conn
var err error
switch {
case !dial.isSet():
// Cannot do this because it lacks timeout support. :-(
//conn, err = net.DialTCP("tcp", nil, server.tcpaddr)
conn, err = net.DialTimeout("tcp", server.ResolvedAddr, timeout)
case dial.old != nil:
conn, err = dial.old(server.tcpaddr)
case dial.new != nil:
conn, err = dial.new(&ServerAddr{server.Addr, server.tcpaddr})
default:
panic("dialer is set, but both dial.old and dial.new are nil")
}
if err != nil {
logf("Connection to %s failed: %v", server.Addr, err.Error())
return nil, err
}
logf("Connection to %s established.", server.Addr)
stats.conn(+1, master)
return newSocket(server, conn, timeout), nil
}
// Close forces closing all sockets that are alive, whether
// they're currently in use or not.
func (server *mongoServer) Close() {
server.Lock()
server.closed = true
liveSockets := server.liveSockets
unusedSockets := server.unusedSockets
server.liveSockets = nil
server.unusedSockets = nil
server.Unlock()
logf("Connections to %s closing (%d live sockets).", server.Addr, len(liveSockets))
for i, s := range liveSockets {
s.Close()
liveSockets[i] = nil
}
for i := range unusedSockets {
unusedSockets[i] = nil
}
}
// RecycleSocket puts socket back into the unused cache.
func (server *mongoServer) RecycleSocket(socket *mongoSocket) {
server.Lock()
if !server.closed {
server.unusedSockets = append(server.unusedSockets, socket)
}
server.Unlock()
}
func removeSocket(sockets []*mongoSocket, socket *mongoSocket) []*mongoSocket {
for i, s := range sockets {
if s == socket {
copy(sockets[i:], sockets[i+1:])
n := len(sockets) - 1
sockets[n] = nil
sockets = sockets[:n]
break
}
}
return sockets
}
// AbendSocket notifies the server that the given socket has terminated
// abnormally, and thus should be discarded rather than cached.
func (server *mongoServer) AbendSocket(socket *mongoSocket) {
server.Lock()
server.abended = true
if server.closed {
server.Unlock()
return
}
server.liveSockets = removeSocket(server.liveSockets, socket)
server.unusedSockets = removeSocket(server.unusedSockets, socket)
server.Unlock()
// Maybe just a timeout, but suggest a cluster sync up just in case.
select {
case server.sync <- true:
default:
}
}
func (server *mongoServer) SetInfo(info *mongoServerInfo) {
server.Lock()
server.info = info
server.Unlock()
}
func (server *mongoServer) Info() *mongoServerInfo {
server.Lock()
info := server.info
server.Unlock()
return info
}
func (server *mongoServer) hasTags(serverTags []bson.D) bool {
NextTagSet:
for _, tags := range serverTags {
NextReqTag:
for _, req := range tags {
for _, has := range server.info.Tags {
if req.Name == has.Name {
if req.Value == has.Value {
continue NextReqTag
}
continue NextTagSet
}
}
continue NextTagSet
}
return true
}
return false
}
var pingDelay = 5 * time.Second
func (server *mongoServer) pinger(loop bool) {
var delay time.Duration
if raceDetector {
// This variable is only ever touched by tests.
globalMutex.Lock()
delay = pingDelay
globalMutex.Unlock()
} else {
delay = pingDelay
}
op := queryOp{
collection: "admin.$cmd",
query: bson.D{{"ping", 1}},
flags: flagSlaveOk,
limit: -1,
}
for {
if loop {
time.Sleep(delay)
}
op := op
socket, _, err := server.AcquireSocket(0, 3*delay)
if err == nil {
start := time.Now()
_, _ = socket.SimpleQuery(&op)
delay := time.Now().Sub(start)
server.pingWindow[server.pingIndex] = delay
server.pingIndex = (server.pingIndex + 1) % len(server.pingWindow)
server.pingCount++
var max time.Duration
for i := 0; i < len(server.pingWindow) && uint32(i) < server.pingCount; i++ {
if server.pingWindow[i] > max {
max = server.pingWindow[i]
}
}
socket.Release()
server.Lock()
if server.closed {
loop = false
}
server.pingValue = max
server.Unlock()
logf("Ping for %s is %d ms", server.Addr, max/time.Millisecond)
} else if err == errServerClosed {
return
}
if !loop {
return
}
}
}
type mongoServerSlice []*mongoServer
func (s mongoServerSlice) Len() int {
return len(s)
}
func (s mongoServerSlice) Less(i, j int) bool {
return s[i].ResolvedAddr < s[j].ResolvedAddr
}
func (s mongoServerSlice) Swap(i, j int) {
s[i], s[j] = s[j], s[i]
}
func (s mongoServerSlice) Sort() {
sort.Sort(s)
}
func (s mongoServerSlice) Search(resolvedAddr string) (i int, ok bool) {
n := len(s)
i = sort.Search(n, func(i int) bool {
return s[i].ResolvedAddr >= resolvedAddr
})
return i, i != n && s[i].ResolvedAddr == resolvedAddr
}
type mongoServers struct {
slice mongoServerSlice
}
func (servers *mongoServers) Search(resolvedAddr string) (server *mongoServer) {
if i, ok := servers.slice.Search(resolvedAddr); ok {
return servers.slice[i]
}
return nil
}
func (servers *mongoServers) Add(server *mongoServer) {
servers.slice = append(servers.slice, server)
servers.slice.Sort()
}
func (servers *mongoServers) Remove(other *mongoServer) (server *mongoServer) {
if i, found := servers.slice.Search(other.ResolvedAddr); found {
server = servers.slice[i]
copy(servers.slice[i:], servers.slice[i+1:])
n := len(servers.slice) - 1
servers.slice[n] = nil // Help GC.
servers.slice = servers.slice[:n]
}
return
}
func (servers *mongoServers) Slice() []*mongoServer {
return ([]*mongoServer)(servers.slice)
}
func (servers *mongoServers) Get(i int) *mongoServer {
return servers.slice[i]
}
func (servers *mongoServers) Len() int {
return len(servers.slice)
}
func (servers *mongoServers) Empty() bool {
return len(servers.slice) == 0
}
// BestFit returns the best guess of what would be the most interesting
// server to perform operations on at this point in time.
func (servers *mongoServers) BestFit(serverTags []bson.D) *mongoServer {
var best *mongoServer
for _, next := range servers.slice {
if best == nil {
best = next
best.RLock()
if serverTags != nil && !next.info.Mongos && !best.hasTags(serverTags) {
best.RUnlock()
best = nil
}
continue
}
next.RLock()
swap := false
switch {
case serverTags != nil && !next.info.Mongos && !next.hasTags(serverTags):
// Must have requested tags.
case next.info.Master != best.info.Master:
// Prefer slaves.
swap = best.info.Master
case absDuration(next.pingValue-best.pingValue) > 15*time.Millisecond:
// Prefer nearest server.
swap = next.pingValue < best.pingValue
case len(next.liveSockets)-len(next.unusedSockets) < len(best.liveSockets)-len(best.unusedSockets):
// Prefer servers with less connections.
swap = true
}
if swap {
best.RUnlock()
best = next
} else {
next.RUnlock()
}
}
if best != nil {
best.RUnlock()
}
return best
}
func absDuration(d time.Duration) time.Duration {
if d < 0 {
return -d
}
return d
}