Added SystemInfo producer

src/java/org/apache/cassandra/service/StartupChecks.java

@@ -422,7 +422,7 @@ public void execute(StartupChecksOptions options) throws StartupException
         @Override
         public void execute(StartupChecksOptions options)
         {
-            Optional<String> degradations = new SystemInfo().isDegraded();
+            Optional<String> degradations = SystemInfo.instance().isDegraded();
 
             if (degradations.isPresent())
                     logger.warn("Cassandra server running in degraded mode. " + degradations.get());

src/java/org/apache/cassandra/utils/FBUtilities.java

@@ -137,7 +137,7 @@ public class FBUtilities
 
     private static int availableProcessors = CASSANDRA_AVAILABLE_PROCESSORS.getInt(DatabaseDescriptor.getAvailableProcessors());
 
-    private static volatile Supplier<Semver> kernelVersionSupplier = Suppliers.memoize(() -> new SystemInfo().getKernelVersion());
+    private static volatile Supplier<Semver> kernelVersionSupplier = Suppliers.memoize(() -> SystemInfo.instance().getKernelVersion());
 
     public static void setAvailableProcessors(int value)
     {

src/java/org/apache/cassandra/utils/SystemInfo.java

@@ -59,6 +59,30 @@ public final class SystemInfo
 
     private static final Pattern SPACES_PATTERN = Pattern.compile("\\s+");
 
+    private static Supplier<SystemInfo> provider = () -> new SystemInfo();
+
+    /**
+     * Sets the Supplier of the SystemInfo.
+     * <p>
+     *     If {@code null} is passed as the provider the provider will be reset to the default provider.
+     * </p>
+     * @param provider the Supplier of SystemInfo that will be used for {@code instance} calls. May be null.
+     */
+    public static void setProvider(Supplier<SystemInfo> provider) {
+        SystemInfo.provider = provider == null ? () -> new SystemInfo() : provider;
+    }
+
+    /**
+     * Gets an instance of SystemInfo.  Whether the SystemInfo instance is new or memoized depends upon the
+     * implementation of the provider specified by {@code setProvider}.  By default a new version of SystemInfo
+     * is created on every call.
+     * @return
+     */
+    public static SystemInfo instance()
+    {
+        return provider.get();
+    }
+
     /**
      * The oshi.SystemInfo has the following note:
      * Platform-specific Hardware and Software objects are retrieved via memoized suppliers. To conserve memory at the
@@ -70,7 +94,8 @@ public final class SystemInfo
      */
     private final oshi.SystemInfo si;
 
-    public SystemInfo()
+    // package private for testing
+    SystemInfo()
     {
         si = new oshi.SystemInfo();
     }

test/distributed/org/apache/cassandra/distributed/test/ResourceLeakTest.java

@@ -91,7 +91,7 @@ static String outputFilename(String base, String description, String extension)
      */
     private static Long getProcessId()
     {
-        long pid = new SystemInfo().getPid();
+        long pid = SystemInfo.instance().getPid();
 
         if (pid >= 0)
             return Long.valueOf(pid);

test/unit/org/apache/cassandra/utils/SystemInfoTest.java

@@ -29,7 +29,7 @@ public class SystemInfoTest {
     public void testGetKernelVersion()
     {
         Assume.assumeTrue(FBUtilities.isLinux);
-        Semver kernelVersion = new SystemInfo().getKernelVersion();
+        Semver kernelVersion = SystemInfo.instance().getKernelVersion();
         assertThat(kernelVersion).isGreaterThan(new Semver("0.0.0", Semver.SemverType.LOOSE));
         assertThat(kernelVersion).isLessThan(new Semver("100.0.0", Semver.SemverType.LOOSE));
     }