From 0cc07a6a9135908224e3e99eea11e77a5772a667 Mon Sep 17 00:00:00 2001
From: leventov <leventov@ya.ru>
Date: Wed, 17 Dec 2014 20:16:35 +0700
Subject: [PATCH] HCOLL-143 print a warning on attempt of creation too large
 ChronicleMap or ChronicleSet on Windows

---
 .../chronicle/map/ChronicleMapBuilder.java    |  4 ++-
 .../chronicle/map/VanillaChronicleMap.java    | 31 +++++++++++++++++++
 .../chronicle/map/WarnOnWindowsTest.java      | 30 ++++++++++++++++++
 3 files changed, 64 insertions(+), 1 deletion(-)
 create mode 100644 src/test/java/net/openhft/chronicle/map/WarnOnWindowsTest.java

diff --git a/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java b/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java
index 04b9b53e7..9c62c7314 100755
--- a/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java
+++ b/src/main/java/net/openhft/chronicle/map/ChronicleMapBuilder.java
@@ -1172,6 +1172,7 @@ public final class ChronicleMapBuilder<K, V> implements Cloneable,
         try {
             pushingToMapEventListener();
             VanillaChronicleMap<K, ?, ?, V, ?, ?> map = newMap(singleHashReplication, channel);
+            map.warnOnWindows();
             BytesStore bytesStore = new DirectStore(JDKObjectSerializer.INSTANCE,
                     map.sizeInBytes(), true);
             map.createMappedStoreAndSegments(bytesStore);
@@ -1209,7 +1210,8 @@ public final class ChronicleMapBuilder<K, V> implements Cloneable,
     }
 
     private VanillaChronicleMap<K, ?, ?, V, ?, ?> newMap(
-            SingleChronicleHashReplication singleHashReplication, ReplicationChannel channel) throws IOException {
+            SingleChronicleHashReplication singleHashReplication, ReplicationChannel channel)
+            throws IOException {
         boolean replicated = singleHashReplication != null || channel != null;
         preMapConstruction(replicated);
         if (replicated) {
diff --git a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
index c8c54a67b..deae98e0c 100755
--- a/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
+++ b/src/main/java/net/openhft/chronicle/map/VanillaChronicleMap.java
@@ -32,6 +32,7 @@ import net.openhft.chronicle.hash.serialization.BytesInterop;
 import net.openhft.chronicle.hash.serialization.BytesReader;
 import net.openhft.chronicle.hash.serialization.SizeMarshaller;
 import net.openhft.chronicle.hash.serialization.internal.*;
+import net.openhft.lang.Jvm;
 import net.openhft.lang.collection.DirectBitSet;
 import net.openhft.lang.collection.SingleThreadedDirectBitSet;
 import net.openhft.lang.io.*;
@@ -237,7 +238,37 @@ class VanillaChronicleMap<K, KI, MKI extends MetaBytesInterop<K, ? super KI>,
         return offset;
     }
 
+    void warnOnWindows() {
+        if (!Jvm.isWindows())
+            return;
+        long offHeapMapSize = sizeInBytes();
+        long oneGb = GIGABYTES.toBytes(1L);
+        double offHeapMapSizeInGb = offHeapMapSize * 1.0 / oneGb;
+        if (offHeapMapSize > GIGABYTES.toBytes(4L)) {
+            System.out.printf(
+                    "WARNING: On Windows, you probably cannot create a ChronicleMap\n" +
+                    "of more than 4 GB. The configured map requires %.2f GB of off-heap memory.\n",
+                    offHeapMapSizeInGb);
+        }
+        try {
+            long freePhysicalMemory = Jvm.freePhysicalMemoryOnWindowsInBytes();
+            if (offHeapMapSize > freePhysicalMemory * 0.9) {
+                double freePhysicalMemoryInGb = freePhysicalMemory * 1.0 / oneGb;
+                System.out.printf(
+                        "WARNING: On Windows, you probably cannot create a ChronicleMap\n" +
+                        "of more than 90%% of available free memory in the system.\n" +
+                        "The configured map requires %.2f GB of off-heap memory.\n" +
+                        "There is only %.2f GB of free physical memory in the system.\n",
+                        offHeapMapSizeInGb, freePhysicalMemoryInGb);
+
+            }
+        } catch (IOException e) {
+            // ignore -- anyway we just warn the user
+        }
+    }
+
     final long createMappedStoreAndSegments(File file) throws IOException {
+        warnOnWindows();
         return createMappedStoreAndSegments(new MappedStore(file, FileChannel.MapMode.READ_WRITE,
                 sizeInBytes(), JDKObjectSerializer.INSTANCE));
     }
diff --git a/src/test/java/net/openhft/chronicle/map/WarnOnWindowsTest.java b/src/test/java/net/openhft/chronicle/map/WarnOnWindowsTest.java
new file mode 100644
index 000000000..c3c0e36bc
--- /dev/null
+++ b/src/test/java/net/openhft/chronicle/map/WarnOnWindowsTest.java
@@ -0,0 +1,30 @@
+/*
+ * Copyright 2014 Higher Frequency Trading http://www.higherfrequencytrading.com
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.openhft.chronicle.map;
+
+import org.junit.Ignore;
+import org.junit.Test;
+
+public class WarnOnWindowsTest {
+
+    @Test
+    @Ignore("This test results to OOM/jvm crash, run manually to verify warning output")
+    public void warnOnWindowsTest() {
+        ChronicleMapBuilder.of(Long.class, Long.class)
+                .entries(1_000_000_000).create();
+    }
+}