amfora/subscriptions/structs.go

package subscriptions

import (
	"sync"
	"time"

	"github.com/mmcdole/gofeed"
)

/*
Example stored JSON.

{
	"feeds": {
		"url1": <gofeed.Feed>,
		"url2": <gofeed.Feed>,
	},
	"pages": {
		"url1": {
			"hash": <hash>,
			"changed": <time>
		},
		"url2": {
			"hash": <hash>,
			"changed": <time>
		}
	}
}

"pages" are the pages tracked for changes that aren't feeds.
The hash used is SHA-256.
The time is in RFC 3339 format, preferably in the UTC timezone.
*/

// Decoded JSON
type jsonData struct {
	feedMu *sync.RWMutex
	pageMu *sync.RWMutex
	Feeds  map[string]*gofeed.Feed `json:"feeds,omitempty"`
	Pages  map[string]*pageJSON    `json:"pages,omitempty"`
}

// Lock locks both feed and page mutexes.
func (j *jsonData) Lock() {
	j.feedMu.Lock()
	j.pageMu.Lock()
}

// Unlock unlocks both feed and page mutexes.
func (j *jsonData) Unlock() {
	j.feedMu.Unlock()
	j.pageMu.Unlock()
}

// RLock read-locks both feed and page mutexes.
func (j *jsonData) RLock() {
	j.feedMu.RLock()
	j.pageMu.RLock()
}

// RUnlock read-unlocks both feed and page mutexes.
func (j *jsonData) RUnlock() {
	j.feedMu.RUnlock()
	j.pageMu.RUnlock()
}

type pageJSON struct {
	Hash    string    `json:"hash"`
	Changed time.Time `json:"changed"` // When the latest change happened
}

// Global instance of jsonData - loaded from JSON and used
var data = jsonData{
	feedMu: &sync.RWMutex{},
	pageMu: &sync.RWMutex{},
	// Maps are created in Init()
}

// PageEntry is a single item on a subscriptions page.
// It is used for both feeds and pages.
type PageEntry struct {
	Prefix    string // Feed/log title, author, etc - something before the post title
	Title     string
	URL       string
	Published time.Time
}

// PageEntries is new-to-old list of Entry structs, used to create a
// subscriptions page.
// It should always be assumed to be sorted when used in other packages,
// by post time, from newest to oldest.
type PageEntries struct {
	Entries []*PageEntry
}

// Implement sort.Interface

func (e *PageEntries) Len() int {
	return len(e.Entries)
}

func (e *PageEntries) Less(i, j int) bool {
	return e.Entries[i].Published.After(e.Entries[j].Published)
}

func (e *PageEntries) Swap(i, j int) {
	e.Entries[i], e.Entries[j] = e.Entries[j], e.Entries[i]
}