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aof.go

aof.go - Overview​

This file implements the Append-Only File (AOF) functionality for a database, providing persistence by writing all operations to a file.

Detailed Documentation​

AOF​

type AOF struct {
	file   *os.File
	writer *bufio.Writer
	mutex  sync.Mutex
	path   string
}
  • Purpose: Represents an Append-Only File. It holds the file, writer, mutex for concurrent access, and the file path.
  • Fields:
    • file: A pointer to the underlying os.File.
    • writer: A pointer to a bufio.Writer for buffered writing to the file.
    • mutex: A sync.Mutex to protect concurrent access to the file.
    • path: The path to the AOF file.

FileMode​

const (
	FileMode int = 0644
)
  • Purpose: Defines the file mode for creating the AOF file (0644).

NewAOF​

func NewAOF(path string) (*AOF, error) {
  • Purpose: Creates a new AOF instance. Opens the file in append mode, creating it if it doesn't exist.
  • Parameters:
    • path: The path to the AOF file.
  • Returns:
    • A pointer to the new AOF instance.
    • An error if opening the file fails.

(a *AOF) Write​

func (a *AOF) Write(operation string) error {
  • Purpose: Writes an operation string to the AOF file. It locks the mutex, writes the operation with a newline, flushes the buffer, and syncs the file to disk.
  • Parameters:
    • operation: The string representing the operation to be written.
  • Returns: An error if writing or syncing fails.

(a *AOF) Close​

func (a *AOF) Close() error {
  • Purpose: Closes the AOF file. Flushes the buffer before closing.
  • Returns: An error if flushing or closing fails.

(a *AOF) Load​

func (a *AOF) Load() ([]string, error) {
  • Purpose: Loads the operations from the AOF file. Reads each line as a separate operation.
  • Returns:
    • A slice of strings, where each string is an operation.
    • An error if opening, scanning, or closing the file fails.

Getting Started Relevance​