Implement relay url provider

api/clients/v2/relay/key_lock.go

@@ -0,0 +1,44 @@
+package relay
+
+import (
+	"sync"
+)
+
+// KeyLock is a utility that provides a way to lock access to a given key of type T
+//
+// This utility is useful in situations where you want to synchronize operations for something that doesn't exist
+// in a concrete form. For example, perhaps you only want to create connections with a given peer on a single
+// thread of execution, but the new peer could appear simultaneously in concurrent operations. This utility allows
+// the first thread which encounters the new peer to perform necessary initialization tasks, and store generated
+// artifacts in a central location for subsequent callers to access.
+type KeyLock[T comparable] struct {
+	// Map from key T to a mutex that corresponds to that key
+	keyMutexMap map[T]*sync.Mutex
+	// Used to lock access to the keyMutexMap, so that only a single mutex is created for each key
+	globalMutex sync.Mutex
+}
+
+// NewKeyLock constructs a KeyLock utility
+func NewKeyLock[T comparable]() *KeyLock[T] {
+	return &KeyLock[T]{
+		keyMutexMap: make(map[T]*sync.Mutex),
+	}
+}
+
+// AcquireKeyLock acquires an exclusive lock on a conceptual key, and returns a function to release the lock
+//
+// The caller MUST eventually invoke the returned unlock function, or all future calls with the same key will block
+// indefinitely
+func (kl *KeyLock[T]) AcquireKeyLock(key T) func() {
+	// we must globally synchronize access to the mutex map, so that only a single mutex will be created for a given key
+	kl.globalMutex.Lock()
+	keyMutex, valueAlreadyExists := kl.keyMutexMap[key]
+	if !valueAlreadyExists {
+		keyMutex = &sync.Mutex{}
+		kl.keyMutexMap[key] = keyMutex
+	}
+	kl.globalMutex.Unlock()
+
+	keyMutex.Lock()
+	return keyMutex.Unlock
+}

api/clients/v2/relay/key_lock_test.go

@@ -0,0 +1,63 @@
+package relay
+
+import (
+	"sync"
+	"sync/atomic"
+	"testing"
+
+	"github.com/Layr-Labs/eigenda/common/testutils/random"
+	"github.com/stretchr/testify/require"
+)
+
+func TestKeyLock(t *testing.T) {
+	// test in a field of 100 unique keys
+	keyCount := 100
+
+	// keep an atomic count, and a non-atomic count for each key
+	// the atomic count can be used at the end of the test, to make sure that the non-atomic count was handled correctly
+	atomicKeyAccessCounts := make([]atomic.Uint32, keyCount)
+	nonAtomicKeyAccessCounts := make([]uint32, keyCount)
+	for i := 0; i < keyCount; i++ {
+		atomicKeyAccessCounts = append(atomicKeyAccessCounts, atomic.Uint32{})
+		nonAtomicKeyAccessCounts = append(nonAtomicKeyAccessCounts, uint32(0))
+	}
+
+	keyLock := NewKeyLock[uint32]()
+
+	var waitGroup sync.WaitGroup
+
+	targetValue := uint32(1000)
+	worker := func() {
+		workerRandom := random.NewTestRandom()
+
+		for {
+			// randomly select a key to access
+			keyToAccess := uint32(workerRandom.Intn(keyCount))
+			newValue := atomicKeyAccessCounts[keyToAccess].Add(1)
+
+			unlock := keyLock.AcquireKeyLock(keyToAccess)
+			// increment the non-atomic count after acquiring access
+			// if the access controls are working correctly, this is a safe operation
+			nonAtomicKeyAccessCounts[keyToAccess] = nonAtomicKeyAccessCounts[keyToAccess] + 1
+			unlock()
+
+			// each worker stops looping after it sees a counter that has increased to targetValue
+			if newValue >= targetValue {
+				break
+			}
+		}
+
+		waitGroup.Done()
+	}
+
+	// start up 100 concurrent workers
+	for i := 0; i < 100; i++ {
+		waitGroup.Add(1)
+		go worker()
+	}
+	waitGroup.Wait()
+
+	for i := 0; i < keyCount; i++ {
+		require.Equal(t, atomicKeyAccessCounts[i].Load(), nonAtomicKeyAccessCounts[i])
+	}
+}

api/clients/v2/relay/relay_url_provider.go

@@ -0,0 +1,66 @@
+package relay
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/Layr-Labs/eigenda/common"
+	relayRegistryBindings "github.com/Layr-Labs/eigenda/contracts/bindings/EigenDARelayRegistry"
+	v2 "github.com/Layr-Labs/eigenda/core/v2"
+
+	"github.com/ethereum/go-ethereum/accounts/abi/bind"
+	gethcommon "github.com/ethereum/go-ethereum/common"
+)
+
+// RelayUrlProvider provides relay URL strings, based on relay key
+type RelayUrlProvider interface {
+	// GetRelayUrl gets the URL string for a given relayKey
+	GetRelayUrl(ctx context.Context, relayKey v2.RelayKey) (string, error)
+	// GetRelayCount returns the number of relays in the registry
+	GetRelayCount(ctx context.Context) (uint32, error)
+}
+
+// relayUrlProvider provides relay URL strings, based on relay key.
+type relayUrlProvider struct {
+	relayRegistryCaller *relayRegistryBindings.ContractEigenDARelayRegistryCaller
+}
+
+var _ RelayUrlProvider = &relayUrlProvider{}
+
+// NewRelayUrlProvider constructs a relayUrlProvider
+func NewRelayUrlProvider(
+	ethClient common.EthClient,
+	relayRegistryAddress gethcommon.Address,
+) (RelayUrlProvider, error) {
+	relayRegistryContractCaller, err := relayRegistryBindings.NewContractEigenDARelayRegistryCaller(
+		relayRegistryAddress, ethClient)
+	if err != nil {
+		return nil, fmt.Errorf("NewContractEigenDARelayRegistryCaller: %w", err)
+	}
+
+	return &relayUrlProvider{
+		relayRegistryCaller: relayRegistryContractCaller,
+	}, nil
+}
+
+// GetRelayUrl gets the URL string for a given relayKey
+func (rup *relayUrlProvider) GetRelayUrl(ctx context.Context, relayKey v2.RelayKey) (string, error) {
+	relayUrl, err := rup.relayRegistryCaller.RelayKeyToUrl(&bind.CallOpts{Context: ctx}, relayKey)
+	if err != nil {
+		return "", fmt.Errorf("fetch relay key (%d) URL from EigenDARelayRegistry contract: %w", relayKey, err)
+	}
+
+	return relayUrl, nil
+}
+
+// GetRelayCount gets the number of relays that exist in the registry
+func (rup *relayUrlProvider) GetRelayCount(ctx context.Context) (uint32, error) {
+	// NextRelayKey initializes to 0, and is incremented each time a relay is added
+	// current logic doesn't support removing relays, so NextRelayKey therefore corresponds directly to relay count
+	relayCount, err := rup.relayRegistryCaller.NextRelayKey(&bind.CallOpts{Context: ctx})
+	if err != nil {
+		return 0, fmt.Errorf("get next relay key from EigenDARelayRegistry contract: %w", err)
+	}
+
+	return relayCount, nil
+}