From 666a951c5f77d919c9cbd08b8bf9c68412825824 Mon Sep 17 00:00:00 2001
From: Dmitry Barashev <dbarashev@ganttproject.biz>
Date: Sat, 28 Sep 2024 16:27:52 +0400
Subject: [PATCH] Corrected two-phase barrier behavior

---
 .../java/biz/ganttproject/app/Barriers.kt     | 22 +++++---
 .../ganttproject/GanttProjectImpl.kt          |  1 +
 .../java/biz/ganttproject/app/BarriersTest.kt | 53 +++++++++++++++++++
 3 files changed, 69 insertions(+), 7 deletions(-)
 create mode 100644 ganttproject/src/test/java/biz/ganttproject/app/BarriersTest.kt

diff --git a/ganttproject/src/main/java/biz/ganttproject/app/Barriers.kt b/ganttproject/src/main/java/biz/ganttproject/app/Barriers.kt
index 8107d6ec54..ff8b4f5212 100644
--- a/ganttproject/src/main/java/biz/ganttproject/app/Barriers.kt
+++ b/ganttproject/src/main/java/biz/ganttproject/app/Barriers.kt
@@ -75,8 +75,17 @@ class TwoPhaseBarrierImpl<T>(private val value: T) : Barrier<T>, BarrierEntrance
   private val counter = AtomicInteger(0)
   private val exits = mutableListOf<BarrierExit<T>>()
   private val activities = mutableMapOf<String, OnBarrierReached>()
+
+  var isActive: Boolean = false
+    set(value) {
+      field = value
+      if (value && counter.get() == 0) {
+        exits.forEach { it(this.value) }
+      }
+    }
+
   override fun await(code: BarrierExit<T>) {
-    if (counter.get() == 0) {
+    if (isActive && counter.get() == 0) {
       code(value)
     } else {
       exits.add(code)
@@ -84,12 +93,16 @@ class TwoPhaseBarrierImpl<T>(private val value: T) : Barrier<T>, BarrierEntrance
   }
 
   override fun register(activity: String): OnBarrierReached {
+    assert(!isActive) {
+      "You need to register barrier activities before it gets active"
+    }
     return {
       if (counter.get() > 0) {
         BARRIER_LOGGER.debug("Barrier reached: $activity")
         //println("Barrier reached: $activity")
         activities.remove(activity)
-        tick()
+        counter.decrementAndGet()
+        isActive = true
       }
     }.also {
       BARRIER_LOGGER.debug("Barrier waiting: $activity")
@@ -98,11 +111,6 @@ class TwoPhaseBarrierImpl<T>(private val value: T) : Barrier<T>, BarrierEntrance
       counter.incrementAndGet()
     }
   }
-  private fun tick() {
-    if (counter.decrementAndGet() == 0) {
-      exits.forEach { it(value) }
-    }
-  }
 }
 
 /**
diff --git a/ganttproject/src/main/java/net/sourceforge/ganttproject/GanttProjectImpl.kt b/ganttproject/src/main/java/net/sourceforge/ganttproject/GanttProjectImpl.kt
index d6112b5e80..4be5773191 100644
--- a/ganttproject/src/main/java/net/sourceforge/ganttproject/GanttProjectImpl.kt
+++ b/ganttproject/src/main/java/net/sourceforge/ganttproject/GanttProjectImpl.kt
@@ -149,6 +149,7 @@ open class GanttProjectImpl(
     for (l in listeners) {
       l.projectOpened(barrier, barrier)
     }
+    barrier.isActive = true
   }
 
   @Throws(Document.DocumentException::class, IOException::class)
diff --git a/ganttproject/src/test/java/biz/ganttproject/app/BarriersTest.kt b/ganttproject/src/test/java/biz/ganttproject/app/BarriersTest.kt
new file mode 100644
index 0000000000..5cf8834501
--- /dev/null
+++ b/ganttproject/src/test/java/biz/ganttproject/app/BarriersTest.kt
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2024 BarD Software s.r.o., Dmitry Barashev.
+ *
+ * This file is part of GanttProject, an opensource project management tool.
+ *
+ * GanttProject is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ * GanttProject is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GanttProject.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package biz.ganttproject.app
+
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+
+class BarriersTest {
+
+  @Test
+  fun `two phase barrier exit registered before entrance`() {
+    var exitCalled = false
+    val barrier = TwoPhaseBarrierImpl<Boolean>(true)
+    barrier.await {
+      assertTrue(it)
+      exitCalled = true
+    }
+    assertFalse(exitCalled)
+
+    barrier.register("Entrance activity").let { entrance -> entrance() }
+    assertTrue(exitCalled)
+  }
+
+  @Test
+  fun `two phase barrier exit registered after entrance`() {
+    var exitCalled = false
+    val barrier = TwoPhaseBarrierImpl<Boolean>(true)
+    barrier.register("Entrance activity").let { entrance -> entrance() }
+    barrier.await {
+      assertTrue(it)
+      exitCalled = true
+    }
+    assertTrue(exitCalled)
+  }
+
+}
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