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https://git.mills.io/prologic/msgbus.git
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6bfb669347
Closes #31 Adds support for a write-ahead-log (WAL) for messages per queue/topic. This is now the new default behaviour and adds a new CLI flag `-l/--log-path` and Env var `LOG_PATH` to configure where the logs are stored. On startup, the message bus will refill the queues with the contents of messages from persisted log files with the most recent `-Q/--max-queue-size` number of items. That is, on startup/crash the queues/topics will always contain the same messages as if the message bus had never restarted or crashed in the first place. This has a benefit of actually making the per-topic sequence number _actually_ monotic increasing integers and something that can be relied upon when indexing into a queue/topic for subscribers with the `-i/--index` / `Index` option. Co-authored-by: James Mills <prologic@shortcircuit.net.au> Reviewed-on: https://git.mills.io/prologic/msgbus/pulls/33
105 lines
2.2 KiB
Go
105 lines
2.2 KiB
Go
package msgbus
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import (
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"fmt"
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"os"
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"github.com/tidwall/wal"
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)
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const (
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// DefaultBind is the default bind address
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DefaultBind = ":8000"
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// DefaultLogPath is the default path to write logs to (wal)
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DefaultLogPath = "./logs"
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// DefaultMaxQueueSize is the default maximum size of queues
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DefaultMaxQueueSize = 1024 // ~8MB per queue (1000 * 4KB)
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// DefaultMaxPayloadSize is the default maximum payload size
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DefaultMaxPayloadSize = 8192 // 8KB
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// DefaultBufferLength is the default buffer length for subscriber chans
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DefaultBufferLength = 256
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// DefaultMetrics is the default for whether to enable metrics
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DefaultMetrics = false
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// DefaultNoSync is the default for whether to disable faync after writing
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// messages to the write-ahead-log (wal) files. The default is `false` which
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// is safer and will prevent corruption in event of crahses or power failure,
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// but is slower.
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DefaultNoSync = false
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)
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var DefaultOptions = &Options{
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LogPath: DefaultLogPath,
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BufferLength: DefaultBufferLength,
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MaxQueueSize: DefaultMaxQueueSize,
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MaxPayloadSize: DefaultMaxPayloadSize,
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Metrics: DefaultMetrics,
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NoSync: DefaultNoSync,
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}
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// Options ...
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type Options struct {
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LogPath string
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BufferLength int
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MaxQueueSize int
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MaxPayloadSize int
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Metrics bool
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NoSync bool
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}
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type Option func(opts *Options) error
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func WithLogPath(logPath string) Option {
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return func(opts *Options) error {
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if err := os.MkdirAll(logPath, 0755); err != nil {
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return fmt.Errorf("error creating log path %s: %w", logPath, err)
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}
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opts.LogPath = logPath
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return nil
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}
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}
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func WithBufferLength(bufferLength int) Option {
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return func(opts *Options) error {
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opts.BufferLength = bufferLength
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return nil
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}
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}
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func WithMaxQueueSize(maxQueueSize int) Option {
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return func(opts *Options) error {
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opts.MaxQueueSize = maxQueueSize
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return nil
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}
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}
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func WithMaxPayloadSize(maxPayloadSize int) Option {
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return func(opts *Options) error {
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opts.MaxPayloadSize = maxPayloadSize
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return nil
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}
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}
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func WithMetrics(metrics bool) Option {
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return func(opts *Options) error {
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opts.Metrics = metrics
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return nil
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}
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}
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func WithNoSync(noSync bool) Option {
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return func(opts *Options) error {
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wal.DefaultOptions.NoSync = noSync
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return nil
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}
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}
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