/
client.go
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/
client.go
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// Copyright 2018 Burak Sezer
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package transport
import (
"fmt"
"net"
"os"
"sync"
"time"
"github.com/buraksezer/olric/internal/protocol"
"github.com/buraksezer/pool"
)
// Client is the client implementation for the internal TCP server.
// It maintains a connection pool and manages request-response cycle.
type Client struct {
mu sync.RWMutex
dialer *net.Dialer
config *ClientConfig
roundrobin *RoundRobin
pools map[string]pool.Pool
}
// ClientConfig configuration parameters of the client.
type ClientConfig struct {
Addrs []string
DialTimeout time.Duration
KeepAlive time.Duration
MinConn int
MaxConn int
}
// NewClient returns a new Client.
func NewClient(cc *ClientConfig) *Client {
if cc == nil {
panic("ClientConfig cannot be nil")
}
if cc.MaxConn == 0 {
cc.MaxConn = 1
}
dialer := &net.Dialer{
Timeout: cc.DialTimeout,
KeepAlive: cc.KeepAlive,
}
c := &Client{
roundrobin: NewRoundRobin(cc.Addrs),
dialer: dialer,
config: cc,
pools: make(map[string]pool.Pool),
}
return c
}
// Close all the connections in the connection pool.
func (c *Client) Close() {
c.mu.Lock()
defer c.mu.Unlock()
for _, p := range c.pools {
p.Close()
}
}
// CloseWithAddr closes the connection for given addr, if any exists.
func (c *Client) CloseWithAddr(addr string) {
c.mu.Lock()
defer c.mu.Unlock()
p, ok := c.pools[addr]
if !ok {
p.Close()
delete(c.pools, addr)
}
}
// getPool creates a new pool for a given addr or returns an exiting one.
func (c *Client) getPool(addr string) (pool.Pool, error) {
factory := func() (net.Conn, error) {
return c.dialer.Dial("tcp", addr)
}
c.mu.Lock()
defer c.mu.Unlock()
cpool, ok := c.pools[addr]
if ok {
return cpool, nil
}
cpool, err := pool.NewChannelPool(c.config.MinConn, c.config.MaxConn, factory)
if err != nil {
return nil, err
}
c.pools[addr] = cpool
return cpool, nil
}
// ClosePool closes the underlying connections in a pool,
// deletes from Olric's pools map and frees resources.
func (c *Client) ClosePool(addr string) {
c.mu.Lock()
defer c.mu.Unlock()
p, ok := c.pools[addr]
if ok {
// Close the pool. This closes the underlying connections.
p.Close()
// Delete from Olric.
delete(c.pools, addr)
}
}
// RequestTo initiates a request-response cycle to given host.
func (c *Client) RequestTo(addr string, op protocol.OpCode, req *protocol.Message) (*protocol.Message, error) {
cpool, err := c.getPool(addr)
if err != nil {
return nil, err
}
req.Magic = protocol.MagicReq
req.Op = op
conn, err := cpool.Get()
if err != nil {
return nil, err
}
var deadConn bool
defer func() {
var connErr error
if !(deadConn) {
// The conn returns to the pool
connErr = conn.Close()
} else {
// marks the connection not usable any more, to let the pool close it instead of returning it to pool.
pc, _ := conn.(*pool.PoolConn)
pc.MarkUnusable()
connErr = pc.Close()
}
if connErr != nil {
_, _ = fmt.Fprintf(os.Stderr, "[ERROR] Failed to close connection: %v", connErr)
}
}()
err = req.Write(conn)
if err != nil {
deadConn = true
return nil, err
}
var resp protocol.Message
err = resp.Read(conn)
if err != nil {
deadConn = true
return nil, err
}
return &resp, err
}
// Request initiates a request-response cycle to randomly selected host.
func (c *Client) Request(op protocol.OpCode, req *protocol.Message) (*protocol.Message, error) {
addr := c.roundrobin.Get()
return c.RequestTo(addr, op, req)
}