GLS Feature Usage

Server side enable request context backup

• Option on
  • Use the server option WithContextBackup;
  • The first parameter enable indicates that the GLS is enabled;
  • The second option, async, means to enable asynchronous implicitly pass-through (indicating that the context in the asynchronous call to go func () is also transparent fallback)

svr := xxx.NewServer(new(XXXImpl), server.WithContextBackup(true, true))

• Adjust localsession management options by environment variables
  • First, enable WithContextBackup on the Server side.
  • Configure CLOUDWEGO_SESSION_CONFIG_KEY ``= [{Whether to enable asynchronous pass-through}] [, {Global sharding number}] [, {GC interval}] in environment variables , all three options are optional, null means use default value
    • Ex: true,10,1h means, turn on asynchronous + sharding 10 buckets + 1 hour GC interval

Client start request context fallback

• Option on
  • Use the client option WithContextBackup;
  • The parameter handler represents the backup logic BackupHandler customized by the business.

func(prev, cur context.Context) (ctx context.Context, backup bool)

• Prev parameter represents the context of the backup
• Cur parameter represents the context obtained by the current client
• Ctx return value represents the final context where the user completes processing
• Backup return value indicates whether to continue localsession built-in fallback backup , mainly metainfo Persistent KVS pass-through at present

var expectedKey interface{}
cli := xxx.NewClient(serverName, client.WithContextBackup(func(prev, cur context.Context) (ctx context.Context, backup bool) {
    if v := cur.Value(expectedKey); v != nil {
    // expectedKey exists, no need for recover context
        return cur, false
    }
    // expectedKey doesn't exists, need recover context from prev
    ctx = context.WithValue(cur, expectedKey, prev.Value(expectedKey))
    return ctx, true
})