Created
August 7, 2021 13:06
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full transaction IO code
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| package transactions | |
| import ( | |
| "encoding/binary" | |
| "google.golang.org/protobuf/proto" | |
| "io" | |
| "os" | |
| ) | |
| func WriteProtoToFile(filepath string, allTransactions []*TransactionJsonType) error { | |
| outFile, err := os.OpenFile(filepath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0666) | |
| if err != nil { | |
| return err | |
| } | |
| for _, item := range allTransactions { | |
| convertedItem := toProtoTransaction(item) | |
| encodedData, err := proto.Marshal(convertedItem) | |
| if err != nil { | |
| return err | |
| } | |
| // writing the length of the encoded item before writing the data | |
| buf := make([]byte, 4) | |
| binary.LittleEndian.PutUint32(buf, uint32(len(encodedData))) | |
| if _, err := outFile.Write(buf); err != nil { | |
| return err | |
| } | |
| // writing the actual transaction item to the file | |
| if _, err := outFile.Write(encodedData); err != nil { | |
| return err | |
| } | |
| } | |
| return nil | |
| } | |
| func ReadProtoFromFile(filepath string) ([][]byte, error) { | |
| file, err := os.Open(filepath) | |
| if err != nil { | |
| return nil, err | |
| } | |
| var offset int64 | |
| content := make([][]byte, 0) | |
| for { | |
| // reading the length of the encoded item before reading each item | |
| buf := make([]byte, 4) | |
| if _, err := file.ReadAt(buf, offset); err != nil { | |
| if err == io.EOF { | |
| break | |
| } | |
| return nil, err | |
| } | |
| itemSize := binary.LittleEndian.Uint32(buf) | |
| offset += 4 | |
| // reading the actual encoded item | |
| item := make([]byte, itemSize) | |
| if _, err := file.ReadAt(item, offset); err != nil { | |
| if err == io.EOF { | |
| break | |
| } | |
| return nil, err | |
| } | |
| content = append(content, item) | |
| offset += int64(itemSize) | |
| } | |
| return content, nil | |
| } |
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