func (t *Table) GetDocumentConsistent(key *Key, consistentRead bool, v interface{}) error {
q := NewDynamoQuery(t)
q.AddKey(key)
if consistentRead {
q.SetConsistentRead(consistentRead)
}
jsonResponse, err := t.Server.queryServer(target("GetItem"), q)
if err != nil {
return err
}
// Deserialize from []byte to JSON.
var response DynamoResponse
err = json.Unmarshal(jsonResponse, &response)
if err != nil {
return err
}
// If Item is nil the item doesn't exist.
if response.Item == nil {
return ErrNotFound
}
// Delete the keys from the response.
t.deleteKeyFromItem(response.Item)
// Convert back to standard struct/JSON object.
err = dynamizer.FromDynamo(response.Item, v)
if err != nil {
return err
}
return nil
}
func (t *Table) BatchGetDocument(keys []*Key, consistentRead bool, v interface{}) ([]error, error) {
numKeys := len(keys)
rv := reflect.ValueOf(v)
if rv.Kind() != reflect.Slice {
return nil, fmt.Errorf("v must be a slice with the same length as keys")
} else if rv.Len() != numKeys {
return nil, fmt.Errorf("v must be a slice with the same length as keys")
}
// Create a map to track which keys have been processed, since DynamoDB
// doesn't return items in any particular order.
//
// N.B. This map is of type Key - not *Key - so that equality is based on
// the hash and range key values, not the pointer address.
processed := make(map[Key]bool)
errs := make([]error, numKeys)
numRetries := 0
target := target("BatchGetItem")
for {
q := NewDynamoBatchGetQuery(t)
// Add requested keys to the query, skipping over those for which we
// already have responses.
for _, key := range keys {
if _, ok := processed[*key]; ok {
continue
}
if err := q.AddKey(key); err != nil {
return nil, err
}
}
if consistentRead {
q.SetConsistentRead(consistentRead)
}
jsonResponse, err := t.Server.queryServer(target, q)
if err != nil {
return nil, err
}
var response DynamoBatchGetResponse
err = json.Unmarshal(jsonResponse, &response)
if err != nil {
return nil, err
}
// DynamoDB doesn't return the items in any particular order, but we promise
// callers that we will. So we build a map of key to response to match up
// inputs to return values.
responses := make(map[Key]dynamizer.DynamoItem)
for _, item := range response.Responses[t.Name] {
key, err := t.getKeyFromItem(item)
if err != nil {
return nil, err
}
t.deleteKeyFromItem(item)
responses[key] = item
}
// Handle unprocessed keys. We return a special error code so that the
// caller can decide how to handle the partial result. This allows callers
// to utilize the responses we do have available right away.
unprocessed := make(map[Key]bool)
numUnprocessed := 0
if r, ok := response.UnprocessedKeys[t.Name]; ok {
for _, item := range r.Keys {
key, err := t.getKeyFromItem(item)
if err != nil {
return nil, err
}
unprocessed[key] = true
numUnprocessed++
}
}
// Package the responses maintaining the original ordering as specified
// by the caller. Set ErrNotProcessed for all unprocessed in keys in
// case we don't retry.
for i, key := range keys {
if _, ok := processed[*key]; ok {
continue
}
if item, ok := responses[*key]; ok {
errs[i] = dynamizer.FromDynamo(item, rv.Index(i))
processed[*key] = true
} else if _, ok := unprocessed[*key]; !ok {
errs[i] = ErrNotFound
processed[*key] = true
} else {
errs[i] = ErrNotProcessed
}
}
// If we are done, or we're not going to retry, return now.
if numUnprocessed == 0 || !t.Server.RetryPolicy.ShouldRetry(target, nil, errProvisionedThroughputExceeded, numRetries) {
return errs, nil
}
// Sleep according to the retry strategy and then attempt again with the
// remaining keys.
time.Sleep(t.Server.RetryPolicy.Delay(target, nil, errProvisionedThroughputExceeded, numRetries))
numRetries++
}
}
