email

README

email

Outbound email queue backed by SQLite. Other modules enqueue messages by inserting rows into outbound_mail; a background worker drains the queue via a pluggable Sender.

Sender

Sender is func(ctx, to, subj, msg) error. Two implementations are provided:

• NewGoogleSmtpSender(from, senderName) — sends via smtp.gmail.com:587 using Google application-default credentials with the https://mail.google.com/ scope and domain-wide delegation (Subject: from). Messages are sent as text/html; charset=UTF-8. Internally rate-limited to 1 send per 5 seconds. Panics at construction if credentials cannot be loaded.
• Noop fallback (used when New is called with a nil sender) — prints the message to stdout.

Worker behavior

AttachWorkers registers two pollers:

• Workqueue poller, ticked every 1s, rate-limited to maxRPS = 1 send/sec at the module level (in addition to any limits inside the Sender).
• Hourly cleanup that deletes any outbound_mail row older than 1 hour (by created), regardless of send state.

Queue semantics

• Selection: oldest send_at <= now where created is within the last hour. Messages older than 1 hour are never sent — they will be cleaned up.
• Success: row is deleted.
• Failure: send_at is pushed out using exponential backoff: send_at = now + 2 * (send_at - created). Combined with the 1-hour created cutoff, this caps total retry duration to ~1 hour.
• Schema is auto-migrated on New.

Documentation

Index

• type Module
  • func New(d *sql.DB, es Sender) *Module
  • func (m *Module) AttachWorkers(mgr *engine.ProcMgr)
  • func (m *Module) GetItem(ctx context.Context) (message, error)
  • func (m *Module) ProcessItem(ctx context.Context, item message) error
  • func (m *Module) UpdateItem(ctx context.Context, item message, success bool) (err error)
• type Sender
  • func NewGoogleSmtpSender(from, senderName string) Sender

Types

type Module

type Module struct {
	Sender Sender
	// contains filtered or unexported fields
}

func New

func New(d *sql.DB, es Sender) *Module

func (*Module) AttachWorkers

func (m *Module) AttachWorkers(mgr *engine.ProcMgr)

func (*Module) GetItem

func (m *Module) GetItem(ctx context.Context) (message, error)

func (*Module) ProcessItem

func (m *Module) ProcessItem(ctx context.Context, item message) error

func (*Module) UpdateItem

func (m *Module) UpdateItem(ctx context.Context, item message, success bool) (err error)

type Sender

type Sender func(ctx context.Context, to, subj string, msg []byte) error

func NewGoogleSmtpSender

func NewGoogleSmtpSender(from, senderName string) Sender