Log jemalloc presence and version at startup (#4738)

Signed-off-by: Fabio Di Fabio <fabio.difabio@consensys.net>

util/build.gradle

@@ -32,6 +32,7 @@ dependencies {
   api 'org.slf4j:slf4j-api'
 
   implementation 'com.google.guava:guava'
+  implementation 'net.java.dev.jna:jna'
   implementation 'org.apache.commons:commons-lang3'
   implementation 'org.apache.logging.log4j:log4j-core'
   implementation 'org.apache.logging.log4j:log4j-slf4j2-impl'

util/src/main/java/org/hyperledger/besu/util/platform/PlatformDetector.java

@@ -23,6 +23,11 @@ import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+import com.sun.jna.ptr.IntByReference;
+import com.sun.jna.ptr.PointerByReference;
+
 /**
  * Detects OS and VMs.
  *
@@ -36,6 +41,7 @@ public class PlatformDetector {
   private static String _vm;
   private static String _arch;
   private static String _glibc;
+  private static String _jemalloc;
 
   /**
    * Gets OS type.
@@ -98,6 +104,14 @@ public class PlatformDetector {
     return _glibc;
   }
 
+  public static String getJemalloc() {
+    if (_jemalloc == null) {
+      detectJemalloc();
+    }
+
+    return _jemalloc;
+  }
+
   private static final String UNKNOWN = "unknown";
 
   private static void detect() {
@@ -306,4 +320,23 @@ public class PlatformDetector {
 
     return matcher.find() ? matcher.group() : null;
   }
+
+  private static void detectJemalloc() {
+    interface JemallocLib extends Library {
+      int mallctl(
+          String property,
+          PointerByReference value,
+          IntByReference len,
+          String newValue,
+          int newLen);
+    }
+
+    final JemallocLib jemallocLib = Native.load("jemalloc", JemallocLib.class);
+
+    PointerByReference pVersion = new PointerByReference();
+    IntByReference pSize = new IntByReference(Native.POINTER_SIZE);
+    jemallocLib.mallctl("version", pVersion, pSize, null, 0);
+
+    _jemalloc = pVersion.getValue().getString(0);
+  }
 }