add events package (#2341)

* add events package

* update go version

events/options.go

@@ -0,0 +1,144 @@
+package events
+
+import "time"
+
+type Options struct{}
+
+type Option func(o *Options)
+
+type StoreOptions struct {
+	TTL    time.Duration
+	Backup Backup
+}
+
+type StoreOption func(o *StoreOptions)
+
+// PublishOptions contains all the options which can be provided when publishing an event
+type PublishOptions struct {
+	// Metadata contains any keys which can be used to query the data, for example a customer id
+	Metadata map[string]string
+	// Timestamp to set for the event, if the timestamp is a zero value, the current time will be used
+	Timestamp time.Time
+}
+
+// PublishOption sets attributes on PublishOptions
+type PublishOption func(o *PublishOptions)
+
+// WithMetadata sets the Metadata field on PublishOptions
+func WithMetadata(md map[string]string) PublishOption {
+	return func(o *PublishOptions) {
+		o.Metadata = md
+	}
+}
+
+// WithTimestamp sets the timestamp field on PublishOptions
+func WithTimestamp(t time.Time) PublishOption {
+	return func(o *PublishOptions) {
+		o.Timestamp = t
+	}
+}
+
+// ConsumeOptions contains all the options which can be provided when subscribing to a topic
+type ConsumeOptions struct {
+	// Group is the name of the consumer group, if two consumers have the same group the events
+	// are distributed between them
+	Group string
+	// Offset is the time from which the messages should be consumed from. If not provided then
+	// the messages will be consumed starting from the moment the Subscription starts.
+	Offset time.Time
+	// AutoAck if true (default true), automatically acknowledges every message so it will not be redelivered.
+	// If false specifies that each message need ts to be manually acknowledged by the subscriber.
+	// If processing is successful the message should be ack'ed to remove the message from the stream.
+	// If processing is unsuccessful the message should be nack'ed (negative acknowledgement) which will mean it will
+	// remain on the stream to be processed again.
+	AutoAck bool
+	AckWait time.Duration
+	// RetryLimit indicates number of times a message is retried
+	RetryLimit int
+	// CustomRetries indicates whether to use RetryLimit
+	CustomRetries bool
+}
+
+// ConsumeOption sets attributes on ConsumeOptions
+type ConsumeOption func(o *ConsumeOptions)
+
+// WithGroup sets the consumer group to be part of when consuming events
+func WithGroup(q string) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.Group = q
+	}
+}
+
+// WithOffset sets the offset time at which to start consuming events
+func WithOffset(t time.Time) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.Offset = t
+	}
+}
+
+// WithAutoAck sets the AutoAck field on ConsumeOptions and an ackWait duration after which if no ack is received
+// the message is requeued in case auto ack is turned off
+func WithAutoAck(ack bool, ackWait time.Duration) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.AutoAck = ack
+		o.AckWait = ackWait
+	}
+}
+
+// WithRetryLimit sets the RetryLimit field on ConsumeOptions.
+// Set to -1 for infinite retries (default)
+func WithRetryLimit(retries int) ConsumeOption {
+	return func(o *ConsumeOptions) {
+		o.RetryLimit = retries
+		o.CustomRetries = true
+	}
+}
+
+func (s ConsumeOptions) GetRetryLimit() int {
+	if !s.CustomRetries {
+		return -1
+	}
+	return s.RetryLimit
+}
+
+// WriteOptions contains all the options which can be provided when writing an event to a store
+type WriteOptions struct {
+	// TTL is the duration the event should be recorded for, a zero value TTL indicates the event should
+	// be stored indefinately
+	TTL time.Duration
+}
+
+// WriteOption sets attributes on WriteOptions
+type WriteOption func(o *WriteOptions)
+
+// WithTTL sets the TTL attribute on WriteOptions
+func WithTTL(d time.Duration) WriteOption {
+	return func(o *WriteOptions) {
+		o.TTL = d
+	}
+}
+
+// ReadOptions contains all the options which can be provided when reading events from a store
+type ReadOptions struct {
+	// Limit the number of results to return
+	Limit uint
+	// Offset the results by this number, useful for paginated queries
+	Offset uint
+}
+
+// ReadOption sets attributes on ReadOptions
+type ReadOption func(o *ReadOptions)
+
+// ReadLimit sets the limit attribute on ReadOptions
+func ReadLimit(l uint) ReadOption {
+	return func(o *ReadOptions) {
+		o.Limit = 1
+	}
+}
+
+// ReadOffset sets the offset attribute on ReadOptions
+func ReadOffset(l uint) ReadOption {
+	return func(o *ReadOptions) {
+		o.Offset = 1
+	}
+}