Appendix: Crash Course in Go

Go

Always google it as “golang”
Approaching four years old
Thompson, Pike, Cox, Griesemer
Statically typed
Not classically object-oriented
CSP primitives as syntax

CSP

Tony Hoare’s Communicating Sequential Processes in CACM volume 21 issue 8
“Do not communicate by sharing memory; instead, share memory by communicating.”
Useful for connection handling, critical sections, and pooled operations

Channels

ch := make(chan int, 1) // buffer length of 1
ch <- 47 // send
<-ch // receive

Buffered or unbuffered
Concurrent send and receive operations
Faster than mutexes
Buffered channels can easily be misused and introduce data-loss risks

Goroutines

in := make(chan int)
out := make(chan int)

go func() {
    prev := 0
    for {
        next := <-in
        out <- prev + next
        prev = next
    }
}()

Inexpensive green threads
Semi-cooperatively scheduled

Structs

type Table struct {
    ID             string
    GameID         string
    RoundID        string
    Players        []Player
    NextTransition time.Time
    // ...
}

Structs are types
Zero or more named and typed members
Structs can embed other structs

Methods

func (ct *CreateTable) Apply(ac ApplyContext) (*Table, error) {
    t := &Table{
        ID: ct.TableID,
        // ...
    }
    if err := ac.Store(t.ID, t); nil != err {
        return nil, err
    }
    return t, nil
}

Method receiver may be any Go type
Zero or more typed return values
Embedded structs embed methods, too

Interfaces

type ObjectStore interface {
    Load(string, interface{}) error
    LoadExcl(string, interface{}) (sync.Locker, error)
    Store(string, interface{}) error
    StoreExcl(string, interface{}, sync.Locker) error
}

Interfaces are also types
Zero or more method signatures
Types that implement all methods implement the interface implicitly
if foo, ok := i.(Foo); ok {}

Tags and reflection

type Table struct {
    ID     string `bson:"i" index:"-" ring:"-"`
    GameID string `bson:"g" index:"GameID_TableID"`
    // ...
}

Distribution keys, secondary indexes, and serialized names are declared via tags
reflect can introspect everything

Meanwhile, back at the ranch...

rcrowley.org/talks/surge-2013.html

Thank you