gotosocial/vendor/codeberg.org/gruf/go-cache/v3/result/cache.go

342 lines
7.5 KiB
Go
Raw Normal View History

package result
import (
"reflect"
"time"
"codeberg.org/gruf/go-cache/v3/ttl"
)
// Cache ...
type Cache[Value any] struct {
cache ttl.Cache[int64, result[Value]] // underlying result cache
lookups structKeys // pre-determined struct lookups
copy func(Value) Value // copies a Value type
next int64 // update key counter
}
// New returns a new initialized Cache, with given lookups and underlying value copy function.
func New[Value any](lookups []string, copy func(Value) Value) *Cache[Value] {
return NewSized(lookups, copy, 64)
}
// NewSized returns a new initialized Cache, with given lookups, underlying value copy function and provided capacity.
func NewSized[Value any](lookups []string, copy func(Value) Value, cap int) *Cache[Value] {
var z Value
// Determine generic type
t := reflect.TypeOf(z)
// Iteratively deref pointer type
for t.Kind() == reflect.Pointer {
t = t.Elem()
}
// Ensure that this is a struct type
if t.Kind() != reflect.Struct {
panic("generic parameter type must be struct (or ptr to)")
}
// Allocate new cache object
c := &Cache[Value]{copy: copy}
c.lookups = make([]keyFields, len(lookups))
for i, lookup := range lookups {
// Generate keyed field info for lookup
c.lookups[i].pkeys = make(map[string]int64, cap)
c.lookups[i].lookup = lookup
c.lookups[i].populate(t)
}
// Create and initialize underlying cache
c.cache.Init(0, cap, 0)
c.SetEvictionCallback(nil)
c.SetInvalidateCallback(nil)
return c
}
// Start will start the cache background eviction routine with given sweep frequency. If already
// running or a freq <= 0 provided, this is a no-op. This will block until eviction routine started.
func (c *Cache[Value]) Start(freq time.Duration) bool {
return c.cache.Start(freq)
}
// Stop will stop cache background eviction routine. If not running this
// is a no-op. This will block until the eviction routine has stopped.
func (c *Cache[Value]) Stop() bool {
return c.cache.Stop()
}
// SetTTL sets the cache item TTL. Update can be specified to force updates of existing items
// in the cache, this will simply add the change in TTL to their current expiry time.
func (c *Cache[Value]) SetTTL(ttl time.Duration, update bool) {
c.cache.SetTTL(ttl, update)
}
// SetEvictionCallback sets the eviction callback to the provided hook.
func (c *Cache[Value]) SetEvictionCallback(hook func(Value)) {
if hook == nil {
// Ensure non-nil hook.
hook = func(Value) {}
}
c.cache.SetEvictionCallback(func(item *ttl.Entry[int64, result[Value]]) {
for _, key := range item.Value.Keys {
// Delete key->pkey lookup
pkeys := key.fields.pkeys
delete(pkeys, key.value)
}
if item.Value.Error != nil {
// Skip error hooks
return
}
// Call user hook.
hook(item.Value.Value)
})
}
// SetInvalidateCallback sets the invalidate callback to the provided hook.
func (c *Cache[Value]) SetInvalidateCallback(hook func(Value)) {
if hook == nil {
// Ensure non-nil hook.
hook = func(Value) {}
}
c.cache.SetInvalidateCallback(func(item *ttl.Entry[int64, result[Value]]) {
for _, key := range item.Value.Keys {
if key.fields != nil {
// Delete key->pkey lookup
pkeys := key.fields.pkeys
delete(pkeys, key.value)
}
}
if item.Value.Error != nil {
// Skip error hooks
return
}
// Call user hook.
hook(item.Value.Value)
})
}
// Load ...
func (c *Cache[Value]) Load(lookup string, load func() (Value, error), keyParts ...any) (Value, error) {
var (
zero Value
res result[Value]
)
// Get lookup map by name.
kfields := c.getFields(lookup)
lmap := kfields.pkeys
// Generate cache key string.
ckey := genkey(keyParts...)
// Acquire cache lock
c.cache.Lock()
// Look for primary key
pkey, ok := lmap[ckey]
if ok {
// Fetch the result for primary key
entry, _ := c.cache.Cache.Get(pkey)
res = entry.Value
}
// Done with lock
c.cache.Unlock()
if !ok {
// Generate new result from fresh load.
res.Value, res.Error = load()
if res.Error != nil {
// This load returned an error, only
// store this item under provided key.
res.Keys = []cacheKey{{
value: ckey,
fields: kfields,
}}
} else {
// This was a successful load, generate keys.
res.Keys = c.lookups.generate(res.Value)
}
// Acquire cache lock.
c.cache.Lock()
defer c.cache.Unlock()
// Attempt to cache this result.
if key, ok := c.storeResult(res); !ok {
return zero, ConflictError{key}
}
}
// Catch and return error
if res.Error != nil {
return zero, res.Error
}
// Return a copy of value from cache
return c.copy(res.Value), nil
}
// Store ...
func (c *Cache[Value]) Store(value Value, store func() error) error {
// Attempt to store this value.
if err := store(); err != nil {
return err
}
// Prepare cached result.
result := result[Value]{
Keys: c.lookups.generate(value),
Value: c.copy(value),
Error: nil,
}
// Acquire cache lock.
c.cache.Lock()
defer c.cache.Unlock()
// Attempt to cache result, only return conflict
// error if the appropriate flag has been set.
if key, ok := c.storeResult(result); !ok {
return ConflictError{key}
}
return nil
}
// Has ...
func (c *Cache[Value]) Has(lookup string, keyParts ...any) bool {
var res result[Value]
// Get lookup map by name.
kfields := c.getFields(lookup)
lmap := kfields.pkeys
// Generate cache key string.
ckey := genkey(keyParts...)
// Acquire cache lock
c.cache.Lock()
// Look for primary key
pkey, ok := lmap[ckey]
if ok {
// Fetch the result for primary key
entry, _ := c.cache.Cache.Get(pkey)
res = entry.Value
}
// Done with lock
c.cache.Unlock()
// Check for non-error result.
return ok && (res.Error == nil)
}
// Invalidate ...
func (c *Cache[Value]) Invalidate(lookup string, keyParts ...any) {
// Get lookup map by name.
kfields := c.getFields(lookup)
lmap := kfields.pkeys
// Generate cache key string.
ckey := genkey(keyParts...)
// Look for primary key
c.cache.Lock()
pkey, ok := lmap[ckey]
c.cache.Unlock()
if !ok {
return
}
// Invalid by primary key
c.cache.Invalidate(pkey)
}
// Clear empties the cache, calling the invalidate callback.
func (c *Cache[Value]) Clear() {
c.cache.Clear()
}
// Len ...
func (c *Cache[Value]) Len() int {
return c.cache.Cache.Len()
}
// Cap ...
func (c *Cache[Value]) Cap() int {
return c.cache.Cache.Cap()
}
func (c *Cache[Value]) getFields(name string) *keyFields {
for _, k := range c.lookups {
// Find key fields with name
if k.lookup == name {
return &k
}
}
panic("invalid lookup: " + name)
}
func (c *Cache[Value]) storeResult(res result[Value]) (string, bool) {
for _, key := range res.Keys {
pkeys := key.fields.pkeys
// Look for cache primary key
pkey, ok := pkeys[key.value]
if ok {
// Look for overlap with non error keys,
// as an overlap for some but not all keys
// could produce inconsistent results.
entry, _ := c.cache.Cache.Get(pkey)
if entry.Value.Error == nil {
return key.value, false
}
}
}
// Get primary key
pkey := c.next
c.next++
// Store all primary key lookups
for _, key := range res.Keys {
pkeys := key.fields.pkeys
pkeys[key.value] = pkey
}
// Store main entry under primary key, using evict hook if needed
c.cache.Cache.SetWithHook(pkey, &ttl.Entry[int64, result[Value]]{
Expiry: time.Now().Add(c.cache.TTL),
Key: pkey,
Value: res,
}, func(_ int64, item *ttl.Entry[int64, result[Value]]) {
c.cache.Evict(item)
})
return "", true
}
type result[Value any] struct {
// keys accessible under
Keys []cacheKey
// cached value
Value Value
// cached error
Error error
}