cmd_ping.go

cmd_ping.go - Overview

This file defines the PING command, which returns "PONG" if no argument is provided, or "PONG" followed by the provided argument.

Detailed Documentation

cPING

var cPING = &CommandMeta{
	Name:      "PING",
	Syntax:    "PING",
	HelpShort: "PING returns PONG if no argument is provided, otherwise it returns PONG with the message.",
	HelpLong: `
PING returns PONG if no argument is provided, otherwise it returns PONG with the message argument.
	`,
	Examples: `
localhost:7379> PING
PONG
localhost:7379> PING Hello
PONG Hello
	`,
	Eval:    evalPING,
	Execute: executePING,
}

• Purpose: Defines the metadata for the PING command, including its name, syntax, help text, examples, and the functions to evaluate and execute it.
• Properties:
  • Name: The name of the command ("PING").
  • Syntax: The syntax of the command ("PING").
  • HelpShort: A short description of the command.
  • HelpLong: A longer description of the command.
  • Examples: Example usages of the command.
  • Eval: The function to evaluate the command (evalPING).
  • Execute: The function to execute the command (executePING).

init

func init() {
	CommandRegistry.AddCommand(cPING)
}

• Purpose: Registers the PING command with the CommandRegistry.
• Parameters: None
• Returns: None

evalPING

func evalPING(c *Cmd, s *dstore.Store) (*CmdRes, error) {
	if len(c.C.Args) >= 2 {
		return cmdResNil, errors.ErrWrongArgumentCount("PING")
	}
	if len(c.C.Args) == 0 {
		return &CmdRes{R: &wire.Response{
			Value: &wire.Response_VStr{VStr: "PONG"},
		}}, nil
	}
	return &CmdRes{R: &wire.Response{
		Value: &wire.Response_VStr{VStr: "PONG " + c.C.Args[0]},
	}}, nil
}

• Purpose: Evaluates the PING command. It checks the number of arguments and returns "PONG" or "PONG" with the provided message.
• Parameters:
  • c: A pointer to the Cmd struct, representing the command.
  • s: A pointer to a dstore.Store struct.
• Returns:
  • A pointer to a CmdRes struct, representing the command result.
  • An error, if any.

executePING

func executePING(c *Cmd, sm *shardmanager.ShardManager) (*CmdRes, error) {
	shard := sm.GetShardForKey("-")
	return evalPING(c, shard.Thread.Store())
}

• Purpose: Executes the PING command. It retrieves a shard and calls evalPING.
• Parameters:
  • c: A pointer to the Cmd struct, representing the command.
  • sm: A pointer to a shardmanager.ShardManager struct.
• Returns:
  • A pointer to a CmdRes struct, representing the command result.
  • An error, if any.

Getting Started Relevance