Add the ability to remove toggle listeners that you have added (#69)

* Fix synchronizing on the right object when adding a new listener

* Add the ability to remove the toggle listeners

src/main/kotlin/io/getunleash/UnleashClient.kt

@@ -155,6 +155,15 @@ class UnleashClient(
         refreshPolicy.addTogglesUpdatedListener(listener)
     }
 
+    /**
+     * Removes a TogglesUpdatedListener from our [io.getunleash.polling.RefreshPolicy]
+     * @param listener the listener to remove
+     * @since 0.2
+     */
+    override fun removeTogglesUpdatedListener(listener: TogglesUpdatedListener) {
+        refreshPolicy.removeTogglesUpdatedListener(listener)
+    }
+
     /**
      * Adds a TogglesErroredListener to our [io.getunleash.polling.RefreshPolicy]
      * @param listener the listener to add
@@ -163,4 +172,13 @@ class UnleashClient(
     override fun addTogglesErroredListener(listener: TogglesErroredListener) {
         refreshPolicy.addTogglesErroredListener(listener)
     }
+
+    /**
+     * Removes a TogglesErroredListener from our [io.getunleash.polling.RefreshPolicy]
+     * @param listener The listener to remove
+     * @since 0.2
+     */
+    override fun removeTogglesErroredListener(listener: TogglesErroredListener) {
+        refreshPolicy.removeTogglesErroredListener(listener)
+    }
 }

src/main/kotlin/io/getunleash/UnleashClientSpec.kt

@@ -12,7 +12,9 @@ interface UnleashClientSpec : Closeable {
     fun updateContext(context: UnleashContext): CompletableFuture<Void>
     fun getContext(): UnleashContext
     fun addTogglesUpdatedListener(listener: TogglesUpdatedListener)
+    fun removeTogglesUpdatedListener(listener: TogglesUpdatedListener)
     fun addTogglesErroredListener(listener: TogglesErroredListener)
+    fun removeTogglesErroredListener(listener: TogglesErroredListener)
 
     fun startPolling()
     fun isPolling(): Boolean

src/main/kotlin/io/getunleash/polling/RefreshPolicy.kt

@@ -135,17 +135,29 @@ abstract class RefreshPolicy(
     }
 
     fun addTogglesUpdatedListener(listener: TogglesUpdatedListener): Unit {
-        synchronized(listener) {
+        synchronized(listeners) {
             listeners.add(listener)
         }
     }
 
+    fun removeTogglesUpdatedListener(listener: TogglesUpdatedListener) {
+        synchronized(listeners) {
+            listeners.remove(listener)
+        }
+    }
+
     fun addTogglesErroredListener(errorListener: TogglesErroredListener): Unit {
         synchronized(errorListeners) {
             errorListeners.add(errorListener)
         }
     }
 
+    fun removeTogglesErroredListener(listener: TogglesErroredListener): Unit {
+        synchronized(errorListeners) {
+            errorListeners.remove(listener)
+        }
+    }
+
     fun addTogglesCheckedListener(checkListener: TogglesCheckedListener) {
         synchronized(checkListeners) {
             checkListeners.add(checkListener)

src/test/kotlin/io/getunleash/polling/RefreshPolicyTest.kt

@@ -1,7 +1,14 @@
 package io.getunleash.polling
 
+import io.getunleash.UnleashConfig
+import io.getunleash.UnleashContext
+import io.getunleash.data.Toggle
+import java9.util.concurrent.CompletableFuture
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
+import org.mockito.kotlin.mock
+import java.util.concurrent.atomic.AtomicBoolean
+import java.util.concurrent.atomic.LongAdder
 
 
 class RefreshPolicyTest {
@@ -11,4 +18,31 @@ class RefreshPolicyTest {
         val s = RefreshPolicy.sha256("expected")
         assertThat(s).isEqualTo("cea23dd4b87e8b00d19fb9ccaaef93e97353c7353e2070f3baf05aeb3995dff4")
     }
+
+    @Test
+    fun `Can add and remove an update listener`() {
+        val refreshPolicy = object : RefreshPolicy(
+            unleashFetcher = mock(),
+            cache = mock(),
+            logger = mock(),
+            config = UnleashConfig("", ""),
+            context = UnleashContext(),
+        ) {
+            override val isReady: AtomicBoolean = AtomicBoolean(true)
+
+            override fun getConfigurationAsync(): CompletableFuture<Map<String, Toggle>> {
+                error("Not applicable")
+            }
+
+            override fun startPolling() {}
+            override fun isPolling(): Boolean = false
+        }
+        val checks = LongAdder()
+        val togglesUpdatedListener = TogglesUpdatedListener { checks.add(1) }
+        refreshPolicy.addTogglesUpdatedListener(togglesUpdatedListener)
+        refreshPolicy.broadcastTogglesUpdated()
+        refreshPolicy.removeTogglesUpdatedListener(togglesUpdatedListener)
+        refreshPolicy.broadcastTogglesUpdated()
+        assertThat(checks.sum()).isEqualTo(1)
+    }
 }