feat: Make FaultInjector more generic

3 files changed, 51 insertions, 21 deletions

diff --git a/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FailureDomain.kt b/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FailureDomain.kt
index b1c7ccd3..91ca9b83 100644
--- a/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FailureDomain.kt
+++ b/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FailureDomain.kt
@@ -24,11 +24,18 @@
 
 package com.atlarge.opendc.core.failure
 
+import kotlinx.coroutines.CoroutineScope
+
 /**
  * A logical or physical component in a computing environment which may fail.
  */
 public interface FailureDomain {
     /**
+     * The lifecycle of the failure domain to which a [FaultInjector] will attach.
+     */
+    public val scope: CoroutineScope
+
+    /**
      * Fail the domain externally.
      */
     public suspend fun fail()
diff --git a/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FaultInjector.kt b/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FaultInjector.kt
new file mode 100644
index 00000000..ac7a08de
--- /dev/null
+++ b/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FaultInjector.kt
@@ -0,0 +1,35 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2020 atlarge-research
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package com.atlarge.opendc.core.failure
+
+/**
+ * An interface for stochastically injecting faults into a running system.
+ */
+public interface FaultInjector {
+    /**
+     * Enqueue the specified [FailureDomain] into the queue as candidate for failure injection in the future.
+     */
+    public fun enqueue(domain: FailureDomain)
+}
diff --git a/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FailureInjector.kt b/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/UncorrelatedFaultInjector.kt
index 456e18bb..95127deb 100644
--- a/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/FailureInjector.kt
+++ b/opendc/opendc-core/src/main/kotlin/com/atlarge/opendc/core/failure/UncorrelatedFaultInjector.kt
@@ -25,34 +25,22 @@
 package com.atlarge.opendc.core.failure
 
 import kotlinx.coroutines.delay
-import kotlinx.coroutines.isActive
-import java.util.Random
-import kotlin.coroutines.coroutineContext
+import kotlinx.coroutines.launch
 import kotlin.math.ln
-import kotlin.random.asKotlinRandom
+import kotlin.random.Random
 
 /**
- * An entity that injects failures into a system.
- *
- * @param failureDomains The failure domains to be included.
+ * A [FaultInjector] that injects uncorrelated faults into the system, meaning that failures of the subsystems are
+ * independent.
  */
-public class FailureInjector(private val failureDomains: List<FailureDomain>) {
-    /**
-     * The [Random] instance to generate the failures.
-     */
-    private val random = Random()
-
+public class UncorrelatedFaultInjector(private val mu: Double = 256.0, private val random: Random = Random.Default) : FaultInjector {
     /**
-     * Start the failure injector process.
+     * Enqueue the specified [FailureDomain] to fail some time in the future.
      */
-    public suspend operator fun invoke() {
-        val targets = HashSet(failureDomains)
-        val mu = 20.0
-        while (targets.isNotEmpty() && coroutineContext.isActive) {
+    override fun enqueue(domain: FailureDomain) {
+        domain.scope.launch {
             delay(random.expovariate(mu))
-            val target = targets.random(random.asKotlinRandom())
-            targets -= target
-            target.fail()
+            domain.fail()
         }
     }