linstrom/storage/cache.go

package storage

import (
	"errors"
	"strings"

	"github.com/redis/go-redis/v9"
	"github.com/rs/zerolog/log"
	"gitlab.com/mstarongitlab/linstrom/util"
)

// various prefixes for accessing items in the cache (since it's a simple key-value store)
const (
	cacheUserHandleToIdPrefix    = "acc-name-to-id:"
	cacheLocalUsernameToIdPrefix = "acc-local-name-to-id:"
	cachePasskeyIdToAccIdPrefix  = "acc-pkey-id-to-id:"
	cacheUserIdToAccPrefix       = "acc-id-to-data:"
	cacheNoteIdToNotePrefix      = "note-id-to-data:"
)

// An error describing the case where some value was just not found in the cache
var errCacheNotFound = errors.New("not found in cache")

// Find an account id in cache using a given user handle ("@bob@example.com" or "bob@example.com")
// accId contains the Id of the account if found
// err contains an error describing why an account's id couldn't be found
// The most common one should be errCacheNotFound
func (s *Storage) cacheHandleToAccUid(handle string) (accId *string, err error) {
	defer util.Untrace(util.Trace(&log.Logger))
	// Where to put the data (in case it's found)
	var target string
	found, err := s.cache.Get(cacheUserHandleToIdPrefix+strings.TrimLeft(handle, "@"), &target)
	// If nothing was found, check error
	if !found {
		// Case error is set and NOT redis' error for nothing found: Return that error
		if err != nil && !errors.Is(err, redis.Nil) {
			return nil, err
		} else {
			// Else return errCacheNotFound
			return nil, errCacheNotFound
		}
	}
	return &target, nil
}

// Find a local account's id in cache using a given username ("bob")
// accId containst the Id of the account if found
// err contains an error describing why an account's id couldn't be found
// The most common one should be errCacheNotFound
func (s *Storage) cacheLocalUsernameToAccUid(username string) (accId *string, err error) {
	defer util.Untrace(util.Trace(&log.Logger))
	// Where to put the data (in case it's found)
	var target string
	found, err := s.cache.Get(cacheLocalUsernameToIdPrefix+username, &target)
	// If nothing was found, check error
	if !found {
		// Case error is set and NOT redis' error for nothing found: Return that error
		if err != nil && !errors.Is(err, redis.Nil) {
			return nil, err
		} else {
			// Else return errCacheNotFound
			return nil, errCacheNotFound
		}
	}
	return &target, nil
}

func (s *Storage) cachePkeyIdToAccId(pkeyId []byte) (accId *string, err error) {
	defer util.Untrace(util.Trace(&log.Logger))
	// Where to put the data (in case it's found)
	var target string
	found, err := s.cache.Get(cachePasskeyIdToAccIdPrefix+string(pkeyId), &target)
	// If nothing was found, check error
	if !found {
		// Case error is set and NOT redis' error for nothing found: Return that error
		if err != nil && !errors.Is(err, redis.Nil) {
			return nil, err
		} else {
			// Else return errCacheNotFound
			return nil, errCacheNotFound
		}
	}
	return &target, nil
}

// Find an account's data in cache using a given account id
// acc contains the full account as stored last time if found
// err contains an error describing why an account couldn't be found
// The most common one should be errCacheNotFound
func (s *Storage) cacheAccIdToData(id string) (acc *Account, err error) {
	defer util.Untrace(util.Trace(&log.Logger))
	var target Account
	found, err := s.cache.Get(cacheUserIdToAccPrefix+id, &target)
	if !found {
		if err != nil && !errors.Is(err, redis.Nil) {
			return nil, err
		} else {
			return nil, errCacheNotFound
		}
	}
	return &target, nil
}

// Find a cached note given its ID
// note contains the full note as stored last time if found
// err contains an error describing why a note couldn't be found
// The most common one should be errCacheNotFound
func (s *Storage) cacheNoteIdToData(id string) (note *Note, err error) {
	defer util.Untrace(util.Trace(&log.Logger))
	target := Note{}
	found, err := s.cache.Get(cacheNoteIdToNotePrefix+id, &target)
	if !found {
		if err != nil && !errors.Is(err, redis.Nil) {
			return nil, err
		} else {
			return nil, errCacheNotFound
		}
	}
	return &target, nil
}