GEODE-6871: Disk free space info exposed via JMX (apache#4067)

* GEODE-6871: Disk free space info exposed via JMX

- fix test cases naming
- defaults for getDiskUsagePercentage & getDiskFreePercentage
- Change test case name

geode-core/src/integrationTest/java/org/apache/geode/internal/cache/DiskStoreImplIntegrationTest.java

@@ -105,9 +105,10 @@ public void queueSizeStatIncrementedAfterAsyncFlush() throws Exception {
   }
 
   @Test
-  public void givenDiskStoreIsCreatedWithMaxSize_thenGetDiskUsagePercentageShouldBeZero()
+  public void givenDiskStoreIsCreatedWithMaxSizeThenDiskUsagePercentagesShouldBeZeroAndDiskFreePercentagesShouldBe100()
       throws Exception {
 
+    final int ALLOWED_MARGIN = 1;
     File[] diskDirs = new File[2];
     diskDirs[0] = temporaryDirectory.newFolder("dir1");
     diskDirs[1] = temporaryDirectory.newFolder("dir2");
@@ -121,13 +122,16 @@ public void givenDiskStoreIsCreatedWithMaxSize_thenGetDiskUsagePercentageShouldB
     DiskStore diskStore = cache.findDiskStore(DISK_STORE_NAME);
 
     assertEquals(0, ((DiskStoreImpl) diskStore).getDiskUsagePercentage(), 0);
+    assertEquals(100, ((DiskStoreImpl) diskStore).getDiskFreePercentage(),
+        ALLOWED_MARGIN);
   }
 
   @Test
-  public void givenDiskStoreIsCreatedWithMaxSize_whenDataIsStored_thenGetDiskUsagePercentageShouldBeIncreased()
+  public void givenDiskStoreIsCreatedWithMaxSizeWhenDataIsStoredThenDiskPercentagesShouldBeModified()
       throws Exception {
 
     final int ESTIMATED_USAGE_PERCENTAGE = 7; // Estimated disk percentage for NUM_ENTRIES
+    final int ESTIMATED_FREE_PERCENTAGE = 100 - ESTIMATED_USAGE_PERCENTAGE;
     final int ALLOWED_MARGIN = 2;
 
     File[] diskDirs = new File[2];
@@ -150,10 +154,12 @@ public void givenDiskStoreIsCreatedWithMaxSize_whenDataIsStored_thenGetDiskUsage
 
     assertEquals(ESTIMATED_USAGE_PERCENTAGE, ((DiskStoreImpl) diskStore).getDiskUsagePercentage(),
         ALLOWED_MARGIN);
+    assertEquals(ESTIMATED_FREE_PERCENTAGE, ((DiskStoreImpl) diskStore).getDiskFreePercentage(),
+        ALLOWED_MARGIN);
   }
 
   @Test
-  public void givenDiskStoreIsCreatedWithDefaultSize_thenGetDiskUsagePercentageShouldNotBeAvailable()
+  public void givenDiskStoreIsCreatedWithDefaultSizeThenDiskPercentagesShouldNotBeAvailable()
       throws Exception {
 
     File[] diskDirs = new File[2];
@@ -166,10 +172,12 @@ public void givenDiskStoreIsCreatedWithDefaultSize_thenGetDiskUsagePercentageSho
 
     assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
         ((DiskStoreImpl) diskStore).getDiskUsagePercentage(), 0);
+    assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
+        ((DiskStoreImpl) diskStore).getDiskFreePercentage(), 0);
   }
 
   @Test
-  public void givenDiskStoreIsCreatedWithDefaultSize_whenDataIsStored_thenGetDiskUsagePercentageShouldNotBeAvailable()
+  public void givenDiskStoreIsCreatedWithDefaultSizeWhenDataIsStoredThenDiskPercentagesShouldNotBeAvailable()
       throws Exception {
 
     File[] diskDirs = new File[2];
@@ -186,10 +194,12 @@ public void givenDiskStoreIsCreatedWithDefaultSize_whenDataIsStored_thenGetDiskU
 
     assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
         ((DiskStoreImpl) diskStore).getDiskUsagePercentage(), 0);
+    assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
+        ((DiskStoreImpl) diskStore).getDiskFreePercentage(), 0);
   }
 
   @Test
-  public void givenDiskStoreIsCreatedWithAtLeastOneDefaultSize_thenGetDiskUsagePercentageShouldNotBeAvailable()
+  public void givenDiskStoreIsCreatedWithAtLeastOneDefaultSizeThenDiskPercentagesShouldNotBeAvailable()
       throws Exception {
 
     File[] diskDirs = new File[3];
@@ -210,12 +220,14 @@ public void givenDiskStoreIsCreatedWithAtLeastOneDefaultSize_thenGetDiskUsagePer
 
       assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
           ((DiskStoreImpl) diskStore).getDiskUsagePercentage(), 0);
+      assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
+          ((DiskStoreImpl) diskStore).getDiskFreePercentage(), 0);
       cache.close();
     }
   }
 
   @Test
-  public void givenDiskStoreIsCreatedWithAtLeastOneDefaultSize_whenDataIsStored_thenGetDiskUsagePercentageShouldNotBeAvailable()
+  public void givenDiskStoreIsCreatedWithAtLeastOneDefaultSizeWhenDataIsStoredThenDiskPercentagesShouldNotBeAvailable()
       throws Exception {
 
     File[] diskDirs = new File[2];
@@ -236,10 +248,12 @@ public void givenDiskStoreIsCreatedWithAtLeastOneDefaultSize_whenDataIsStored_th
 
     assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
         ((DiskStoreImpl) diskStore).getDiskUsagePercentage(), 0);
+    assertEquals(ManagementConstants.NOT_AVAILABLE_FLOAT,
+        ((DiskStoreImpl) diskStore).getDiskFreePercentage(), 0);
   }
 
   @Test
-  public void whenMaxOplogFileDoesNotFitInDir_thenNextDirIsSelected() throws Exception {
+  public void whenMaxOplogFileDoesNotFitInDirThenNextDirIsSelected() throws Exception {
 
     File[] diskDirs = new File[3];
     diskDirs[0] = temporaryDirectory.newFolder("dir1");

geode-core/src/main/java/org/apache/geode/internal/cache/DiskStoreImpl.java

@@ -4666,4 +4666,14 @@ public float getDiskUsagePercentage() {
     return usage;
   }
 
+  /**
+   * Returns the free space percentage of the disk store, or -1 in case
+   * one or more directories have unlimited storage.
+   */
+  public float getDiskFreePercentage() {
+    if (this.totalDiskStoreSpace == ManagementConstants.NOT_AVAILABLE_LONG) {
+      return ManagementConstants.NOT_AVAILABLE_FLOAT;
+    }
+    return (100 - getDiskUsagePercentage());
+  }
 }

geode-core/src/main/java/org/apache/geode/management/DiskStoreMXBean.java

@@ -15,6 +15,7 @@
 package org.apache.geode.management;
 
 import org.apache.geode.cache.DiskStore;
+import org.apache.geode.management.internal.ManagementConstants;
 import org.apache.geode.management.internal.security.ResourceOperation;
 import org.apache.geode.security.ResourcePermission.Operation;
 import org.apache.geode.security.ResourcePermission.Resource;
@@ -192,9 +193,22 @@ public interface DiskStoreMXBean {
   float getDiskUsageCriticalPercentage();
 
   /**
-   * Returns the usage percentage of the disk storage
+   * Returns the usage percentage of this disk storage if directories where created with max size.
+   *
+   * @since Geode 1.10
+   */
+  default float getDiskUsagePercentage() {
+    return ManagementConstants.NOT_AVAILABLE_FLOAT;
+  }
+
+  /**
+   * Returns the free percentage of this disk storage if directories where created with max size.
+   *
+   * * @since Geode 1.11
    */
-  float getDiskUsagePercentage();
+  default float getDiskFreePercentage() {
+    return ManagementConstants.NOT_AVAILABLE_FLOAT;
+  }
 
   /**
    * Sets the value of the disk usage warning percentage.

geode-core/src/main/java/org/apache/geode/management/internal/beans/DiskStoreMBean.java

@@ -171,6 +171,11 @@ public float getDiskUsagePercentage() {
     return bridge.getDiskUsagePercentage();
   }
 
+  @Override
+  public float getDiskFreePercentage() {
+    return bridge.getDiskFreePercentage();
+  }
+
   public DiskStoreMBeanBridge getBridge() {
     return bridge;
   }

geode-core/src/main/java/org/apache/geode/management/internal/beans/DiskStoreMBeanBridge.java

@@ -273,4 +273,8 @@ public void setDiskUsageCriticalPercentage(float criticalPercent) {
   public float getDiskUsagePercentage() {
     return diskStore.getDiskUsagePercentage();
   }
+
+  public float getDiskFreePercentage() {
+    return diskStore.getDiskFreePercentage();
+  }
 }