mirror of
https://gitlab.com/pulsechaincom/prysm-pulse.git
synced 2024-12-25 04:47:18 +00:00
112 lines
3.0 KiB
Go
112 lines
3.0 KiB
Go
package ssz
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import (
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"fmt"
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"io"
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"reflect"
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"strings"
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"sync"
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)
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type encoder func(reflect.Value, *encbuf) error
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// Notice: we are not exactly following the spec which requires a decoder to return new index in the input buffer.
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// Our io.Reader is already capable of tracking its latest read location, so we decide to return the decoded byte size
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// instead. This makes our implementation look cleaner.
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type decoder func(io.Reader, reflect.Value) (uint32, error)
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type encodeSizer func(reflect.Value) (uint32, error)
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type hasher func(reflect.Value) ([]byte, error)
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type sszUtils struct {
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encoder
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encodeSizer
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decoder
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hasher
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}
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var (
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sszUtilsCacheMutex sync.RWMutex
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sszUtilsCache = make(map[reflect.Type]*sszUtils)
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)
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// Get cached encoder, encodeSizer and decoder implementation for a specified type.
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// With a cache we can achieve O(1) amortized time overhead for creating encoder, encodeSizer and decoder.
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func cachedSSZUtils(typ reflect.Type) (*sszUtils, error) {
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sszUtilsCacheMutex.RLock()
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utils := sszUtilsCache[typ]
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sszUtilsCacheMutex.RUnlock()
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if utils != nil {
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return utils, nil
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}
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// If not found in cache, will get a new one and put it into the cache
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sszUtilsCacheMutex.Lock()
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defer sszUtilsCacheMutex.Unlock()
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return cachedSSZUtilsNoAcquireLock(typ)
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}
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// This version is used when the caller is already holding the rw lock for sszUtilsCache.
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// It doesn't acquire new rw lock so it's free to recursively call itself without getting into
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// a deadlock situation.
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//
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// Make sure you are
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func cachedSSZUtilsNoAcquireLock(typ reflect.Type) (*sszUtils, error) {
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// Check again in case other goroutine has just acquired the lock
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// and already updated the cache
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utils := sszUtilsCache[typ]
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if utils != nil {
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return utils, nil
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}
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// Put a dummy value into the cache before generating.
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// If the generator tries to lookup the type of itself,
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// it will get the dummy value and won't call recursively forever.
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sszUtilsCache[typ] = new(sszUtils)
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utils, err := generateSSZUtilsForType(typ)
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if err != nil {
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// Don't forget to remove the dummy key when fail
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delete(sszUtilsCache, typ)
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return nil, err
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}
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// Overwrite the dummy value with real value
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*sszUtilsCache[typ] = *utils
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return sszUtilsCache[typ], nil
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}
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func generateSSZUtilsForType(typ reflect.Type) (utils *sszUtils, err error) {
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utils = new(sszUtils)
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if utils.encoder, utils.encodeSizer, err = makeEncoder(typ); err != nil {
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return nil, err
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}
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if utils.decoder, err = makeDecoder(typ); err != nil {
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return nil, err
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}
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if utils.hasher, err = makeHasher(typ); err != nil {
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return nil, err
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}
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return utils, nil
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}
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type field struct {
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index int
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name string
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sszUtils *sszUtils
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}
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func structFields(typ reflect.Type) (fields []field, err error) {
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for i := 0; i < typ.NumField(); i++ {
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f := typ.Field(i)
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if strings.Contains(f.Name, "XXX") {
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continue
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}
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utils, err := cachedSSZUtilsNoAcquireLock(f.Type)
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if err != nil {
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return nil, fmt.Errorf("failed to get ssz utils: %v", err)
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}
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name := f.Name
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fields = append(fields, field{i, name, utils})
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}
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return fields, nil
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}
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