104 lines
3.0 KiB
Go
104 lines
3.0 KiB
Go
package singleton_test
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import (
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"sync"
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"sync/atomic"
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"testing"
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"github.com/google/uuid"
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"github.com/navidrome/navidrome/utils/singleton"
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. "github.com/onsi/ginkgo/v2"
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. "github.com/onsi/gomega"
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)
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func TestSingleton(t *testing.T) {
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RegisterFailHandler(Fail)
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RunSpecs(t, "Singleton Suite")
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}
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var _ = Describe("GetInstance", func() {
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type T struct{ id string }
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var numInstancesCreated int
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constructor := func() *T {
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numInstancesCreated++
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return &T{id: uuid.NewString()}
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}
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It("calls the constructor to create a new instance", func() {
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instance := singleton.GetInstance(constructor)
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Expect(numInstancesCreated).To(Equal(1))
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Expect(instance).To(BeAssignableToTypeOf(&T{}))
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})
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It("does not call the constructor the next time", func() {
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instance := singleton.GetInstance(constructor)
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newInstance := singleton.GetInstance(constructor)
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Expect(newInstance.id).To(Equal(instance.id))
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Expect(numInstancesCreated).To(Equal(1))
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})
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It("makes a distinction between a type and its pointer", func() {
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instance := singleton.GetInstance(constructor)
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newInstance := singleton.GetInstance(func() T {
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numInstancesCreated++
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return T{id: uuid.NewString()}
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})
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Expect(instance).To(BeAssignableToTypeOf(&T{}))
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Expect(newInstance).To(BeAssignableToTypeOf(T{}))
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Expect(newInstance.id).ToNot(Equal(instance.id))
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Expect(numInstancesCreated).To(Equal(2))
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})
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It("only calls the constructor once when called concurrently", func() {
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// This test creates 80000 goroutines that call GetInstance concurrently. If the constructor is called more than once, the test will fail.
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const numCallsToDo = 80000
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var numCallsDone atomic.Uint32
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// This WaitGroup is used to make sure all goroutines are ready before the test starts
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prepare := sync.WaitGroup{}
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prepare.Add(numCallsToDo)
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// This WaitGroup is used to synchronize the start of all goroutines as simultaneous as possible
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start := sync.WaitGroup{}
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start.Add(1)
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// This WaitGroup is used to wait for all goroutines to be done
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done := sync.WaitGroup{}
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done.Add(numCallsToDo)
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numInstancesCreated = 0
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for i := 0; i < numCallsToDo; i++ {
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go func() {
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// This is needed to make sure the test does not hang if it fails
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defer GinkgoRecover()
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// Wait for all goroutines to be ready
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start.Wait()
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instance := singleton.GetInstance(func() struct{ I int } {
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numInstancesCreated++
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return struct{ I int }{I: numInstancesCreated}
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})
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// Increment the number of calls done
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numCallsDone.Add(1)
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// Flag the main WaitGroup that this goroutine is done
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done.Done()
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// Make sure the instance we get is always the same one
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Expect(instance.I).To(Equal(1))
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}()
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// Flag that this goroutine is ready to start
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prepare.Done()
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}
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prepare.Wait() // Wait for all goroutines to be ready
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start.Done() // Start all goroutines
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done.Wait() // Wait for all goroutines to be done
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Expect(numCallsDone.Load()).To(Equal(uint32(numCallsToDo)))
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Expect(numInstancesCreated).To(Equal(1))
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})
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})
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