setddblock

README

setddblock

setddblock is setlock like command line tool with AWS DynamoDB

Usage

$ setddblock -xN ddb://ddb_lock_table/lock_item_id your_command

Usage: setddblock [ -nNxX ] [--endpoint <endpoint>] [--debug --version] ddb://<table_name>/<item_id> your_command
Flags:
  -n
        No delay. If fn is locked by another process, setlock gives up.
  -N
        (Default.) Delay. If fn is locked by another process, setlock waits until it can obtain a new lock.
  -x
        If fn cannot be update-item (or put-item) or locked, setlock exits zero.
  -X
        (Default.) If fn cannot be update-item (or put-item) or locked, setlock prints an error message and exits nonzero.
  --debug
        show debug log
  --endpoint string
        If you switch remote, set AWS DynamoDB endpoint url.
  --region string
        aws region
  --timeout string
        set command timeout
  --version
        show version

the required IAM Policy is as follows:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": [
                "dynamodb:CreateTable",
                "dynamodb:UpdateTimeToLive",
                "dynamodb:PutItem",
                "dynamodb:DescribeTable",
                "dynamodb:GetItem",
                "dynamodb:UpdateItem"
            ],
            "Resource": "*"
        }
    ]
}

If the lock table has already been created, dynamodb:CreateTable and dynamodb:UpdateTimeToLive are not required.

Install

binary packages

Releases.

Homebrew tap

$ brew install mashiike/tap/setddblock

Usage as a library

setddblock.New(url string, optFns ...func(*setddblock.Options)) returns a DynamoDBLocker that satisfies the sync.Locker interface.

l, err := setddblock.New("ddb://ddb_lock_table/lock_item_id")
if err != nil {
	// ...
}
func () {
    l.Lock()
    defer l.Unlock()
    // ...
}()

Note: If Lock or Unlock fails, for example because you can't connect to DynamoDB, it will panic.
If you don't want it to panic, use LockWithError() and UnlockWithErr(). Alternatively, use the WithNoPanic option.

more infomation see go doc.

License

see LICENSE file.

Documentation

Index

• Variables
• func Recover(e interface{}) error
• func WithContext(ctx context.Context) func(opts *Options)
• func WithDelay(delay bool) func(opts *Options)
• func WithEndpoint(endpoint string) func(opts *Options)
• func WithLeaseDuration(d time.Duration) func(opts *Options)
• func WithLogger(logger Logger) func(opts *Options)
• func WithNoPanic() func(opts *Options)
• func WithRegion(region string) func(opts *Options)
• type DynamoDBLocker
  • func New(urlStr string, optFns ...func(*Options)) (*DynamoDBLocker, error)
  • func (l *DynamoDBLocker) ClearLastErr()
  • func (l *DynamoDBLocker) LastErr() error
  • func (l *DynamoDBLocker) Lock()
  • func (l *DynamoDBLocker) LockWithErr(ctx context.Context) (bool, error)
  • func (l *DynamoDBLocker) Unlock()
  • func (l *DynamoDBLocker) UnlockWithErr(ctx context.Context) error
• type Logger
• type Options

Variables

var (
	DefaultLeaseDuration = 10 * time.Second
)

Default values

Functions

func Recover

func Recover(e interface{}) error

Recover for Lock() and Unlock() panic

func WithContext

func WithContext(ctx context.Context) func(opts *Options)

WithContext specifies the Context used by Lock() and Unlock().

func WithDelay

func WithDelay(delay bool) func(opts *Options)

WithDelay will delay the acquisition of the lock if it fails to acquire the lock. This is similar to the N option of setlock. The default is delay enalbed(true). Specify false if you want to exit immediately if Lock acquisition fails.

func WithEndpoint

func WithEndpoint(endpoint string) func(opts *Options)

WithEndpoint is an endpoint specification option for Local development. Please enter the URL of DynamoDB Local etc.

func WithLeaseDuration

func WithLeaseDuration(d time.Duration) func(opts *Options)

WithLeaseDuration affects the heartbeat interval and TTL after Lock acquisition. The default is 10 seconds

func WithLogger

func WithLogger(logger Logger) func(opts *Options)

WithLogger is a setting to enable the log output of DynamoDB Locker. By default, Logger that does not output anywhere is specified.

func WithNoPanic

func WithNoPanic() func(opts *Options)

WithNoPanic changes the behavior so that it does not panic if an error occurs in the Lock () and Unlock () functions. Check the LastErr () function to see if an error has occurred when WithNoPanic is specified.

func WithRegion

func WithRegion(region string) func(opts *Options)

WithRegion specifies the AWS Region. Default AWS_DEFAULT_REGION env

Types

type DynamoDBLocker

type DynamoDBLocker struct {
	// contains filtered or unexported fields
}

DynamoDB Locker implements the sync.Locker interface and provides a Lock mechanism using DynamoDB.

func New

func New(urlStr string, optFns ...func(*Options)) (*DynamoDBLocker, error)

New returns *DynamoDBLocker

func (*DynamoDBLocker) ClearLastErr

func (l *DynamoDBLocker) ClearLastErr()

func (*DynamoDBLocker) LastErr

func (l *DynamoDBLocker) LastErr() error

func (*DynamoDBLocker) Lock

func (l *DynamoDBLocker) Lock()

Lock for implements sync.Locker

func (*DynamoDBLocker) LockWithErr

func (l *DynamoDBLocker) LockWithErr(ctx context.Context) (bool, error)

LockWithErr try get lock. The return value of bool indicates whether Lock has been released. If true, it is Lock Granted.

func (*DynamoDBLocker) Unlock

func (l *DynamoDBLocker) Unlock()

Unlock for implements sync.Locker

func (*DynamoDBLocker) UnlockWithErr

func (l *DynamoDBLocker) UnlockWithErr(ctx context.Context) error

UnlockWithErr unlocks. Delete DynamoDB items

type Logger

type Logger interface {
	Print(v ...interface{})
	Printf(format string, v ...interface{})
	Println(v ...interface{})
}

Logger is a Logging interface used inside DynamoDB Locker

type Options

type Options struct {
	NoPanic       bool
	Logger        Logger
	Delay         bool
	Endpoint      string
	Region        string
	LeaseDuration time.Duration
	// contains filtered or unexported fields
}

Options are for changing the behavior of DynamoDB Locker and are changed by the function passed to the New () function. See the WithXXX options for more information.