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package structr
import (
"strings"
)
// IndexConfig defines config variables
// for initializing a struct index.
type IndexConfig struct {
// Fields should contain a comma-separated
// list of struct fields used when generating
// keys for this index. Nested fields should
// be specified using periods. An example:
// "Username,Favorites.Color"
Fields string
// Multiple indicates whether to accept multiple
// possible values for any single index key. The
// default behaviour is to only accept one value
// and overwrite existing on any write operation.
Multiple bool
// AllowZero indicates whether to accept zero
// value fields in index keys. i.e. whether to
// index structs for this set of field values
// IF any one of those field values is the zero
// value for that type. The default behaviour
// is to skip indexing structs for this lookup
// when any of the indexing fields are zero.
AllowZero bool
}
// Index is an exposed Cache internal model, used to
// generate keys and store struct results by the init
// defined key generation configuration. This model is
// exposed to provide faster lookups in the case that
// you would like to manually provide the used index
// via the Cache.___By() series of functions, or access
// the underlying index key generator.
type Index[StructType any] struct {
// name is the actual name of this
// index, which is the unparsed
// string value of contained fields.
name string
// struct field key serializer.
keygen KeyGen[StructType]
// backing in-memory data store of
// generated index keys to result lists.
data map[string]*list[*result[StructType]]
// whether to allow
// multiple results
// per index key.
unique bool
}
// init initializes this index with the given configuration.
func (i *Index[T]) init(config IndexConfig) {
fields := strings.Split(config.Fields, ",")
i.name = config.Fields
i.keygen = NewKeyGen[T](fields, config.AllowZero)
i.unique = !config.Multiple
i.data = make(map[string]*list[*result[T]])
}
// KeyGen returns the key generator associated with this index.
func (i *Index[T]) KeyGen() *KeyGen[T] {
return &i.keygen
}
func index_append[T any](c *Cache[T], i *Index[T], key string, res *result[T]) {
// Acquire + setup indexkey.
ikey := indexkey_acquire(c)
ikey.entry.Value = res
ikey.key = key
ikey.index = i
// Append to result's indexkeys.
res.keys = append(res.keys, ikey)
// Get list at key.
l := i.data[key]
if l == nil {
// Allocate new list.
l = list_acquire(c)
i.data[key] = l
} else if i.unique {
// Remove currently
// indexed result.
old := l.head
l.remove(old)
// Get ptr to old
// result before we
// release to pool.
res := old.Value
// Drop this index's key from
// old res now not indexed here.
result_dropIndex(c, res, i)
if len(res.keys) == 0 {
// Old res now unused,
// release to mem pool.
result_release(c, res)
}
}
// Add result indexkey to
// front of results list.
l.pushFront(&ikey.entry)
}
func index_deleteOne[T any](c *Cache[T], i *Index[T], ikey *indexkey[T]) {
// Get list at key.
l := i.data[ikey.key]
if l == nil {
return
}
// Remove from list.
l.remove(&ikey.entry)
if l.len == 0 {
// Remove list from map.
delete(i.data, ikey.key)
// Release list to pool.
list_release(c, l)
}
}
func index_delete[T any](c *Cache[T], i *Index[T], key string, fn func(*result[T])) {
if fn == nil {
panic("nil fn")
}
// Get list at key.
l := i.data[key]
if l == nil {
return
}
// Delete data at key.
delete(i.data, key)
// Iterate results in list.
for x := 0; x < l.len; x++ {
// Pop current head.
res := l.head.Value
l.remove(l.head)
// Delete index's key
// from result tracking.
result_dropIndex(c, res, i)
// Call hook.
fn(res)
}
// Release list to pool.
list_release(c, l)
}
type indexkey[T any] struct {
// linked list entry the related
// result is stored under in the
// Index.data[key] linked list.
entry elem[*result[T]]
// key is the generated index key
// the related result is indexed
// under, in the below index.
key string
// index is the index that the
// related result is indexed in.
index *Index[T]
}
func indexkey_acquire[T any](c *Cache[T]) *indexkey[T] {
var ikey *indexkey[T]
if len(c.keyPool) == 0 {
// Allocate new key.
ikey = new(indexkey[T])
} else {
// Pop result from pool slice.
ikey = c.keyPool[len(c.keyPool)-1]
c.keyPool = c.keyPool[:len(c.keyPool)-1]
}
return ikey
}
func indexkey_release[T any](c *Cache[T], ikey *indexkey[T]) {
// Reset indexkey.
ikey.entry.Value = nil
ikey.key = ""
ikey.index = nil
// Release indexkey to memory pool.
c.keyPool = append(c.keyPool, ikey)
}
|
