slotprovider

Experimental package. Manages a number of free slots which can be acquired and released concurrently.
No blocking: If there is no free slot, the Acquire method returns immediately with false.
There are 5 implementations .

• Using int64 with padding and atomic package
• Using int64 and atomic package
• Using sync.Mutex
• Using 1 buffered channel
• Using 2 channels and go routine to manage free slots

Benchmark results:

(MacBook Pro Early 2015, 2.7 GHz Intel Core i5)

godep go test -bench=.
goos: darwin
goarch: amd64
pkg: github.com/chrisport/slotprovider
Benchmark_AtomicUInt64-4                                30000000                50.4 ns/op
Benchmark_AtomicUInt64Padded-4                          20000000                52.6 ns/op
Benchmark_Mutex-4                                       20000000                74.2 ns/op
Benchmark_SingleChan-4                                  10000000               100 ns/op

Benchmark_AtomicUInt64_parallel-4                       30000000                54.2 ns/op
Benchmark_AtomicUInt64Padded_parallel-4                 30000000                57.2 ns/op
Benchmark_Mutex_parallel-4                              10000000               188 ns/op
Benchmark_SingleChan_parallel-4                         10000000               210 ns/op

Example usage

nrOfSlots := 2
var sp slotprovider.SlotProvider

sp = slotprovider.NewWithAtomicUInt64(nrOfSlots)
// sp = slotprovider.NewWithAtomicUInt64Padded(nrOfSlots)
// sp = slotprovider.NewWithMutex(nrOfSlots)
// sp = slotprovider.NewWithSingleChannel(nrOfSlots)
// sp = slotprovider.NewWithMultiChannel(nrOfSlots, context.Background())


hasSlot,_ := sp.AcquireSlot() // hasSlot2 = true
hasSlot2,_ := sp.AcquireSlot() // hasSlot2 = true
hasSlot3, release := sp.AcquireSlot() // hasSlot3 = false

release()

hasSlot4 := sp.AcquireSlot() // hasSlot4 = true

Note:

• hasSlot: indicate whether or not the requester has acquired a slot. If false, there was no free slot left.
• release: function to release the acquired slot
  • a release function can be called safely, even if no slot has been acquired
  • a release function must not be called multiple times, this might create new slots.

Contribution

Any ideas, feedback and contributions will be appreciated. Please implement at least the same set of tests as the other implementations.