- Add Package Pooler For SMTP :

* implement SMTP lib interface
* check number of sent mail in a time lapse before sending new mail
* if time since last reset is over, reset counter
* add feature to call a user function on each counter reset
- Pkg SMTP : Fix race detection & segFault
- Pkg Mailer : add new function to parse all template value with the given map[string]string

errors/modules.go

@@ -39,16 +39,17 @@ const (
 	MinPkgLDAP        = 1000
 	MinPkgMail        = 1100
 	MinPkgMailer      = 1200
-	MinPkgNetwork     = 1300
-	MinPkgNats        = 1400
-	MinPkgNutsDB      = 1500
-	MinPkgOAuth       = 1600
-	MinPkgAws         = 1700
-	MinPkgRouter      = 1800
-	MinPkgSemaphore   = 1900
-	MinPkgSMTP        = 2000
-	MinPkgStatic      = 2100
-	MinPkgVersion     = 2200
+	MinPkgMailPooler  = 1300
+	MinPkgNetwork     = 1400
+	MinPkgNats        = 1500
+	MinPkgNutsDB      = 1600
+	MinPkgOAuth       = 1700
+	MinPkgAws         = 1800
+	MinPkgRouter      = 1900
+	MinPkgSemaphore   = 2000
+	MinPkgSMTP        = 2100
+	MinPkgStatic      = 2200
+	MinPkgVersion     = 2300
 
 	MinAvailable = 4000
 

mailPooler/config.go

@@ -0,0 +1,44 @@
+/*
+ *  MIT License
+ *
+ *  Copyright (c) 2021 Nicolas JUHEL
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ *
+ */
+
+package mailPooler
+
+import (
+	"time"
+
+	liberr "github.com/nabbar/golib/errors"
+)
+
+type FuncCaller func() liberr.Error
+
+type Config struct {
+	Max  int           `json:"max" yaml:"max" toml:"max" mapstructure:"max"`
+	Wait time.Duration `json:"wait" yaml:"wait" toml:"wait" mapstructure:"wait"`
+	_fct FuncCaller
+}
+
+func (c *Config) SetFuncCaller(fct FuncCaller) {
+	c._fct = fct
+}

mailPooler/counter.go

@@ -0,0 +1,129 @@
+/*
+ *  MIT License
+ *
+ *  Copyright (c) 2021 Nicolas JUHEL
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ *
+ */
+
+package mailPooler
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	liberr "github.com/nabbar/golib/errors"
+)
+
+type Counter interface {
+	Pool(ctx context.Context) liberr.Error
+	Reset() liberr.Error
+	Clone() Counter
+}
+
+type counter struct {
+	m   sync.Mutex
+	num int
+
+	max int
+	dur time.Duration
+	tim time.Time
+
+	fct FuncCaller
+}
+
+func newCounter(max int, dur time.Duration, fct FuncCaller) Counter {
+	return &counter{
+		m:   sync.Mutex{},
+		num: max,
+		max: max,
+		dur: dur,
+		tim: time.Time{},
+		fct: fct,
+	}
+}
+
+func (c *counter) Pool(ctx context.Context) liberr.Error {
+	c.m.Lock()
+	defer c.m.Unlock()
+
+	if c.max <= 0 || c.dur <= 0 {
+		return nil
+	}
+
+	if e := ctx.Err(); e != nil {
+		return ErrorMailPoolerContext.ErrorParent(e)
+	}
+
+	if c.tim.IsZero() {
+		c.num = c.max
+	} else if time.Since(c.tim) > c.dur {
+		c.num = c.max
+		c.tim = time.Time{}
+	}
+
+	if c.num > 0 {
+		c.num--
+		c.tim = time.Now()
+	} else {
+		time.Sleep(c.dur - time.Since(c.tim))
+
+		c.num = c.max - 1
+		c.tim = time.Now()
+
+		if e := ctx.Err(); e != nil {
+			return ErrorMailPoolerContext.ErrorParent(e)
+		} else if err := c.fct(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (c *counter) Reset() liberr.Error {
+	c.m.Lock()
+	defer c.m.Unlock()
+
+	if c.max <= 0 || c.dur <= 0 {
+		return nil
+	}
+
+	c.num = c.max
+	c.tim = time.Time{}
+
+	if err := c.fct(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (c *counter) Clone() Counter {
+	return &counter{
+		m:   sync.Mutex{},
+		num: c.num,
+		max: c.max,
+		dur: c.dur,
+		tim: time.Time{},
+		fct: c.fct,
+	}
+}

mailPooler/error.go

@@ -0,0 +1,60 @@
+/*
+ *  MIT License
+ *
+ *  Copyright (c) 2021 Nicolas JUHEL
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ *
+ */
+
+package mailPooler
+
+import "github.com/nabbar/golib/errors"
+
+const (
+	ErrorParamsEmpty errors.CodeError = iota + errors.MinPkgMailPooler
+	ErrorMailPooler
+	ErrorMailPoolerContext
+)
+
+var isCodeError = false
+
+func IsCodeError() bool {
+	return isCodeError
+}
+
+func init() {
+	isCodeError = errors.ExistInMapMessage(ErrorParamsEmpty)
+	errors.RegisterIdFctMessage(ErrorParamsEmpty, getMessage)
+}
+
+func getMessage(code errors.CodeError) (message string) {
+	switch code {
+	case errors.UNK_ERROR:
+		return ""
+	case ErrorParamsEmpty:
+		return "given parameters is empty"
+	case ErrorMailPooler:
+		return "generic mail pooler error"
+	case ErrorMailPoolerContext:
+		return "context has trigger error"
+	}
+
+	return ""
+}

mailPooler/pooler.go

@@ -0,0 +1,125 @@
+/*
+ *  MIT License
+ *
+ *  Copyright (c) 2021 Nicolas JUHEL
+ *
+ *  Permission is hereby granted, free of charge, to any person obtaining a copy
+ *  of this software and associated documentation files (the "Software"), to deal
+ *  in the Software without restriction, including without limitation the rights
+ *  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *  copies of the Software, and to permit persons to whom the Software is
+ *  furnished to do so, subject to the following conditions:
+ *
+ *  The above copyright notice and this permission notice shall be included in all
+ *  copies or substantial portions of the Software.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ *  SOFTWARE.
+ *
+ */
+
+package mailPooler
+
+import (
+	"context"
+	"errors"
+	liberr "github.com/nabbar/golib/errors"
+	libsmtp "github.com/nabbar/golib/smtp"
+	"io"
+	"net/smtp"
+)
+
+type Pooler interface {
+	Reset() liberr.Error
+	NewPooler() Pooler
+
+	libsmtp.SMTP
+}
+
+type pooler struct {
+	s libsmtp.SMTP
+	c Counter
+}
+
+func New(cfg *Config, cli libsmtp.SMTP) Pooler {
+	if cli == nil {
+		return &pooler{
+			s: nil,
+			c: newCounter(cfg.Max, cfg.Wait, cfg._fct),
+		}
+	} else {
+		return &pooler{
+			s: cli.Clone(),
+			c: newCounter(cfg.Max, cfg.Wait, cfg._fct),
+		}
+	}
+}
+
+func (p *pooler) Reset() liberr.Error {
+	if p.s == nil {
+		return ErrorParamsEmpty.ErrorParent(errors.New("smtp client is not define"))
+	}
+
+	if err := p.c.Reset(); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (p *pooler) NewPooler() Pooler {
+	if p.s == nil {
+		return &pooler{
+			s: nil,
+			c: p.c.Clone(),
+		}
+	} else {
+		return &pooler{
+			s: p.s.Clone(),
+			c: p.c.Clone(),
+		}
+	}
+}
+
+func (p *pooler) Send(ctx context.Context, from string, to []string, data io.WriterTo) liberr.Error {
+	if p.s == nil {
+		return ErrorParamsEmpty.ErrorParent(errors.New("smtp client is not define"))
+	}
+
+	if err := p.c.Pool(ctx); err != nil {
+		return err
+	}
+
+	return p.s.Send(ctx, from, to, data)
+}
+
+func (p *pooler) Client(ctx context.Context) (*smtp.Client, liberr.Error) {
+	if p.s == nil {
+		return nil, ErrorParamsEmpty.ErrorParent(errors.New("smtp client is not define"))
+	}
+
+	return p.s.Client(ctx)
+}
+
+func (p *pooler) Close() {
+	if p.s != nil {
+		p.s.Close()
+	}
+}
+
+func (p *pooler) Check(ctx context.Context) liberr.Error {
+	if p.s == nil {
+		return ErrorParamsEmpty.ErrorParent(errors.New("smtp client is not define"))
+	}
+
+	return p.s.Check(ctx)
+}
+
+func (p *pooler) Clone() libsmtp.SMTP {
+	return p.NewPooler()
+}

mailer/interface.go

@@ -61,6 +61,8 @@ type Mailer interface {
 	SetTroubleText(text string)
 	GetTroubleText() string
 
+	ParseData(data map[string]string)
+
 	GenerateHTML() (*bytes.Buffer, liberr.Error)
 	GeneratePlainText() (*bytes.Buffer, liberr.Error)
 }

mailer/render.go

@@ -27,11 +27,58 @@ package mailer
 
 import (
 	"bytes"
+	"strings"
 
 	"github.com/matcornic/hermes/v2"
 	liberr "github.com/nabbar/golib/errors"
 )
 
+func (e *email) ParseData(data map[string]string) {
+	for k, v := range data {
+		e.p.Copyright = strings.ReplaceAll(e.p.Copyright, k, v)
+		e.p.Link = strings.ReplaceAll(e.p.Link, k, v)
+		e.p.Logo = strings.ReplaceAll(e.p.Logo, k, v)
+		e.p.Name = strings.ReplaceAll(e.p.Name, k, v)
+		e.p.TroubleText = strings.ReplaceAll(e.p.TroubleText, k, v)
+
+		e.b.Greeting = strings.ReplaceAll(e.b.Greeting, k, v)
+		e.b.Name = strings.ReplaceAll(e.b.Name, k, v)
+		e.b.Signature = strings.ReplaceAll(e.b.Signature, k, v)
+		e.b.Title = strings.ReplaceAll(e.b.Title, k, v)
+
+		e.b.FreeMarkdown = hermes.Markdown(strings.ReplaceAll(string(e.b.FreeMarkdown), k, v))
+
+		for i := range e.b.Intros {
+			e.b.Intros[i] = strings.ReplaceAll(e.b.Intros[i], k, v)
+		}
+
+		for i := range e.b.Outros {
+			e.b.Outros[i] = strings.ReplaceAll(e.b.Outros[i], k, v)
+		}
+
+		for i := range e.b.Dictionary {
+			e.b.Dictionary[i].Key = strings.ReplaceAll(e.b.Dictionary[i].Key, k, v)
+			e.b.Dictionary[i].Value = strings.ReplaceAll(e.b.Dictionary[i].Value, k, v)
+		}
+
+		for i := range e.b.Table.Data {
+			for j := range e.b.Table.Data[i] {
+				e.b.Table.Data[i][j].Key = strings.ReplaceAll(e.b.Table.Data[i][j].Key, k, v)
+				e.b.Table.Data[i][j].Value = strings.ReplaceAll(e.b.Table.Data[i][j].Value, k, v)
+			}
+		}
+
+		for i := range e.b.Actions {
+			e.b.Actions[i].Instructions = strings.ReplaceAll(e.b.Actions[i].Instructions, k, v)
+			e.b.Actions[i].InviteCode = strings.ReplaceAll(e.b.Actions[i].InviteCode, k, v)
+			e.b.Actions[i].Button.Link = strings.ReplaceAll(e.b.Actions[i].Button.Link, k, v)
+			e.b.Actions[i].Button.Text = strings.ReplaceAll(e.b.Actions[i].Button.Text, k, v)
+			e.b.Actions[i].Button.Color = strings.ReplaceAll(e.b.Actions[i].Button.Color, k, v)
+			e.b.Actions[i].Button.TextColor = strings.ReplaceAll(e.b.Actions[i].Button.TextColor, k, v)
+		}
+	}
+}
+
 func (e *email) GenerateHTML() (*bytes.Buffer, liberr.Error) {
 	return e.generated(e.genHtml)
 }

smtp/interface.go

@@ -34,6 +34,7 @@ import (
 	"net/url"
 	"strconv"
 	"strings"
+	"sync"
 
 	"github.com/nabbar/golib/errors"
 )
@@ -90,6 +91,7 @@ func NewSMTP(cfg Config, tlsConfig *tls.Config) (SMTP, errors.Error) {
 		return nil, ErrorParamsEmpty.Error(nil)
 	} else {
 		return &smtpClient{
+			mut: sync.Mutex{},
 			cfg: cfg,
 			tls: tlsConfig,
 		}, nil

smtp/model.go

@@ -33,11 +33,13 @@ import (
 	"net"
 	"net/smtp"
 	"strings"
+	"sync"
 
 	"github.com/nabbar/golib/errors"
 )
 
 type smtpClient struct {
+	mut sync.Mutex
 	con net.Conn
 	cli *smtp.Client
 	tls *tls.Config
@@ -47,6 +49,7 @@ type smtpClient struct {
 // Check Try to initiate SMTP dial and negotiation and try to close connection.
 func (s smtpClient) Clone() SMTP {
 	return &smtpClient{
+		mut: sync.Mutex{},
 		con: nil,
 		cli: nil,
 		tls: s.tls,
@@ -56,30 +59,22 @@ func (s smtpClient) Clone() SMTP {
 
 // Close Terminate SMTP negotiation client and close connection.
 func (s *smtpClient) Close() {
-	if s.cli != nil {
-		if e := s.cli.Quit(); e != nil {
-			_ = s.cli.Close()
-		}
-		s.cli = nil
-	}
-
-	if s.con != nil {
-		_ = s.con.Close()
-		s.con = nil
-	}
+	s.mut.Lock()
+	defer s.mut.Unlock()
+	s._close()
 }
 
 // Check Try to initiate SMTP dial and negotiation and try to close connection.
 func (s *smtpClient) Check(ctx context.Context) errors.Error {
-	defer s.Close()
+	s.mut.Lock()
+	defer func() {
+		s._close()
+		s.mut.Unlock()
+	}()
 
-	if s.cli == nil {
-		if _, e := s.Client(ctx); e != nil {
-			return e
-		}
-	}
-
-	if e := s.cli.Noop(); e != nil {
+	if c, err := s._client(ctx); err != nil {
+		return err
+	} else if e := c.Noop(); e != nil {
 		return ErrorSMTPClientNoop.ErrorParent(e)
 	}
 
@@ -88,36 +83,10 @@ func (s *smtpClient) Check(ctx context.Context) errors.Error {
 
 // Client Get SMTP Client interface.
 func (s *smtpClient) Client(ctx context.Context) (*smtp.Client, errors.Error) {
-	if s.cli == nil {
-		var (
-			addr = s.cfg.GetHost()
-			tlsc = s.tls.Clone()
-		)
+	s.mut.Lock()
+	defer s.mut.Unlock()
 
-		if s.cfg.GetTlSServerName() != "" && s.cfg.GetNet() != NET_UNIX {
-			tlsc.ServerName = s.cfg.GetTlSServerName()
-		}
-
-		if s.cfg.IsTLSSkipVerify() && s.cfg.GetNet() != NET_UNIX {
-			tlsc.InsecureSkipVerify = true
-		}
-
-		if s.cfg.GetPort() > 0 {
-			addr = fmt.Sprintf("%s:%v", s.cfg.GetHost(), s.cfg.GetPort())
-		}
-
-		if cli, con, err := s.tryClient(ctx, addr, tlsc); err != nil {
-			return nil, err
-		} else if err := s.auth(cli, addr); err != nil {
-			return nil, err
-		} else {
-			s.Close()
-			s.con = con
-			s.cli = cli
-		}
-	}
-
-	return s.cli, nil
+	return s._client(ctx)
 }
 
 // validateLine checks to see if a line has CR or LF as per RFC 5321.
@@ -134,46 +103,54 @@ func (s *smtpClient) Send(ctx context.Context, from string, to []string, data io
 
 	var (
 		e error
+		c *smtp.Client
 		w io.WriteCloser
+
+		err errors.Error
 	)
 
+	s.mut.Lock()
+
 	defer func() {
 		if w != nil {
 			_ = w.Close()
 		}
 
-		s.Close()
+		//mandatory for SMTP protocol
+		s._close()
+
+		s.mut.Unlock()
 	}()
 
-	if err := s.validateLine(from); err != nil {
+	if err = s.validateLine(from); err != nil {
 		return err
 	}
 
 	for _, recp := range to {
-		if err := s.validateLine(recp); err != nil {
+		if err = s.validateLine(recp); err != nil {
 			return err
 		}
 	}
 
-	if err := s.Check(ctx); err != nil {
-		return err
+	if c, err = s._client(ctx); err != nil {
+		return ErrorSMTPClientInit.Error(err)
 	}
 
-	if _, e = s.Client(ctx); e != nil {
-		return ErrorSMTPClientInit.ErrorParent(e)
+	if e = c.Noop(); e != nil {
+		return ErrorSMTPClientNoop.ErrorParent(e)
 	}
 
-	if e = s.cli.Mail(from); e != nil {
+	if e = c.Mail(from); e != nil {
 		return ErrorSMTPClientMail.ErrorParent(e)
 	}
 
 	for _, addr := range to {
-		if e = s.cli.Rcpt(addr); e != nil {
+		if e = c.Rcpt(addr); e != nil {
 			return ErrorSMTPClientRcpt.ErrorParent(e)
 		}
 	}
 
-	if w, e = s.cli.Data(); e != nil {
+	if w, e = c.Data(); e != nil {
 		return ErrorSMTPClientData.ErrorParent(e)
 	}
 
@@ -183,3 +160,62 @@ func (s *smtpClient) Send(ctx context.Context, from string, to []string, data io
 
 	return nil
 }
+
+func (s *smtpClient) _client(ctx context.Context) (*smtp.Client, errors.Error) {
+	if s.cli != nil && s.con != nil {
+		return s.cli, nil
+	}
+
+	if s.con == nil && s.cli != nil {
+		if e := s.cli.Quit(); e != nil {
+			_ = s.cli.Close()
+		}
+	} else if s.con != nil && s.cli == nil {
+		_ = s.con.Close()
+	}
+
+	s.cli = nil
+	s.con = nil
+
+	var (
+		addr = s.cfg.GetHost()
+		tlsc = s.tls.Clone()
+	)
+
+	if s.cfg.GetTlSServerName() != "" && s.cfg.GetNet() != NET_UNIX {
+		tlsc.ServerName = s.cfg.GetTlSServerName()
+	}
+
+	if s.cfg.IsTLSSkipVerify() && s.cfg.GetNet() != NET_UNIX {
+		tlsc.InsecureSkipVerify = true
+	}
+
+	if s.cfg.GetPort() > 0 {
+		addr = fmt.Sprintf("%s:%v", s.cfg.GetHost(), s.cfg.GetPort())
+	}
+
+	if cli, con, err := s.tryClient(ctx, addr, tlsc); err != nil {
+		return nil, err
+	} else if err = s.auth(cli, addr); err != nil {
+		return nil, err
+	} else {
+		s.con = con
+		s.cli = cli
+	}
+
+	return s.cli, nil
+}
+
+func (s *smtpClient) _close() {
+	if s.cli != nil {
+		if e := s.cli.Quit(); e != nil {
+			_ = s.cli.Close()
+		}
+		s.cli = nil
+	}
+
+	if s.con != nil {
+		_ = s.con.Close()
+		s.con = nil
+	}
+}

test/test-mail/main.go

@@ -35,15 +35,17 @@ import (
 	libiot "github.com/nabbar/golib/ioutils"
 	liblog "github.com/nabbar/golib/logger"
 	libsnd "github.com/nabbar/golib/mail"
+	libpool "github.com/nabbar/golib/mailPooler"
 	libtpl "github.com/nabbar/golib/mailer"
+	libsem "github.com/nabbar/golib/semaphore"
 	libsmtp "github.com/nabbar/golib/smtp"
 )
 
 const (
-	CONFIG_SMTP_DSN   = "login@email-example.com:password@tcp4(smtp.mail.example.com:25)/starttls?ServerName=mail.domain.com"
-	CONFIG_EMAIL_FROM = "email@example.com"
-	CONFIG_EMAIL_TO   = "email@example.com"
-	CONFIG_SUBJECT    = "Testing Send Mail"
+	_ConfigSmtpDSN   = "login@email-example.com:password@tcp4(smtp.mail.example.com:25)/starttls?ServerName=mail.domain.com"
+	_ConfigEmailFrom = "email@example.com"
+	_ConfigEmailTo   = "email@example.com"
+	_ConfigSubject   = "Testing Send Mail"
 )
 
 var (
@@ -71,22 +73,36 @@ func init() {
 
 func main() {
 	var (
-		cli libsmtp.SMTP
+		cli libpool.Pooler
 		err liberr.Error
+		sem = libsem.NewSemaphoreWithContext(ctx, 0)
 	)
 
 	defer func() {
+		sem.DeferMain()
 		cnl()
 		if cli != nil {
 			cli.Close()
 		}
 	}()
 
-	cli = getSmtp()
+	//cli = getSmtp()
+	cli = getPool()
 
-	err = getSendMail(getTemplate()).SendClose(ctx, cli)
+	snd := getSendMail(getTemplate())
 
-	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "sending email", err)
+	//	err = getSendMail(getTemplate()).SendClose(ctx, cli)
+	for i := 0; i < 5; i++ {
+		_ = sem.NewWorker()
+		go func() {
+			defer sem.DeferWorker()
+			err = snd.Send(ctx, cli)
+			liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "[sender] sending email", err)
+			time.Sleep(2 * time.Second)
+		}()
+	}
+
+	_ = sem.WaitAll()
 }
 
 func getTemplate() libtpl.Mailer {
@@ -127,27 +143,43 @@ func getTemplate() libtpl.Mailer {
 }
 
 func getSmtp() libsmtp.SMTP {
-	cfg, err := libsmtp.NewConfig(CONFIG_SMTP_DSN)
-	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "smtp config parsing", err)
+	cfg, err := libsmtp.NewConfig(_ConfigSmtpDSN)
+	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "[smtp] config parsing", err)
 
 	/* #nosec */
 	//nolint #nosec
 	s, err := libsmtp.NewSMTP(cfg, &tls.Config{})
-	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "smtp create client", err)
-	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "smtp checking working", s.Check(ctx))
+	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "[smtp] init", err)
+	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "[smtp] checking working", s.Check(ctx))
 
 	return s
 }
 
+func getPool() libpool.Pooler {
+	cfg := &libpool.Config{
+		Max:  2,
+		Wait: 10 * time.Second,
+	}
+	cfg.SetFuncCaller(func() liberr.Error {
+		liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "[mail pooler] reset counter", nil)
+		return nil
+	})
+
+	p := libpool.New(cfg, getSmtp())
+	liblog.FatalLevel.LogErrorCtxf(liblog.InfoLevel, "[mail pooler] init", nil)
+
+	return p
+}
+
 func getSendMail(tpl libtpl.Mailer) libsnd.Sender {
 	m := libsnd.New()
 
-	m.Email().SetFrom(CONFIG_EMAIL_FROM)
-	m.Email().SetRecipients(libsnd.RecipientTo, CONFIG_EMAIL_TO)
+	m.Email().SetFrom(_ConfigEmailFrom)
+	m.Email().SetRecipients(libsnd.RecipientTo, _ConfigEmailTo)
 
 	m.SetCharset("UTF-8")
 	m.SetPriority(libsnd.PriorityNormal)
-	m.SetSubject(CONFIG_SUBJECT)
+	m.SetSubject(_ConfigSubject)
 	m.SetEncoding(libsnd.EncodingBinary)
 	m.SetDateTime(time.Now())