Pre-construct prefix masks

IPV4 can hold at most 33 different masks, which are being held
in immutable arrays. We can save significant amount of allocation
and parsing if we just pre-compute these quads.

JIRA: OPNFLWPLUG-1067
Change-Id: I8eb5507b9615373f0526e7bb2e8a1d7132634295
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>

diff --git a/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/core/sal/convertor/common/IpConversionUtil.java b/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/core/sal/convertor/common/IpConversionUtil.java
index 4fe4d390816984330a4027234e934a090da29922..44ee4cc59019603ca7a6ff0ca9026964b221ec91 100644 (file)
--- a/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/core/sal/convertor/common/IpConversionUtil.java
+++ b/openflowplugin/src/main/java/org/opendaylight/openflowplugin/openflow/md/core/sal/convertor/common/IpConversionUtil.java
@@ -47,7 +47,6 @@ public final class IpConversionUtil {
     private static final int INT16SZ = 2;
     private static final int IPV4_ADDRESS_LENGTH = 32;
     private static final int IPV6_ADDRESS_LENGTH = 128;
-    private static final DottedQuad DEFAULT_ARBITRARY_BITMASK = new DottedQuad("255.255.255.255");
     private static final Ipv6ArbitraryMask DEFAULT_IPV6_ARBITRARY_BITMASK =
             new Ipv6ArbitraryMask("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff");
 
@@ -73,6 +72,24 @@ public final class IpConversionUtil {
         PREFIX_BYTEARRAYS = a;
     }
 
+    private static final DottedQuad[] IPV4_BITMASKS;
+
+    static {
+        final DottedQuad[] quads = new DottedQuad[IPV4_ADDRESS_LENGTH + 1];
+
+        for (int i = 0; i <= IPV4_ADDRESS_LENGTH; ++i) {
+            final long maskBits = 0xffffffff << IPV4_ADDRESS_LENGTH - i;
+            quads[i] = new DottedQuad(new StringBuilder(15)
+                .append((maskBits & 0x0000000000ff000000L) >> 24).append('.')
+                .append((maskBits & 0x0000000000ff0000) >> 16).append('.')
+                .append((maskBits & 0x0000000000ff00) >> 8).append('.')
+                .append(maskBits & 0xff).toString());
+        }
+
+        IPV4_BITMASKS = quads;
+    }
+
+
     private IpConversionUtil() {
         throw new UnsupportedOperationException("This class should not be instantiated.");
     }
@@ -158,7 +175,7 @@ public final class IpConversionUtil {
 
     public static DottedQuad createArbitraryBitMask(final byte[] bitmask)  {
         if (bitmask == null) {
-            return DEFAULT_ARBITRARY_BITMASK;
+            return IPV4_BITMASKS[IPV4_ADDRESS_LENGTH];
         }
 
         final String hostAddress;
@@ -631,17 +648,7 @@ public final class IpConversionUtil {
 
     public static DottedQuad extractIpv4AddressMask(final Ipv4Prefix ipv4Prefix) {
         final String value = ipv4Prefix.getValue();
-        final int cidrMask = Integer.parseInt(value.substring(value.indexOf('/') + 1));
-        if (cidrMask == IPV4_ADDRESS_LENGTH) {
-            return DEFAULT_ARBITRARY_BITMASK;
-        }
-
-        final long maskBits = 0xffffffff << IPV4_ADDRESS_LENGTH - cidrMask;
-        return new DottedQuad(new StringBuilder(15)
-            .append((maskBits & 0x0000000000ff000000L) >> 24).append('.')
-            .append((maskBits & 0x0000000000ff0000) >> 16).append('.')
-            .append((maskBits & 0x0000000000ff00) >> 8).append('.')
-            .append(maskBits & 0xff).toString());
+        return IPV4_BITMASKS[Integer.parseInt(value.substring(value.indexOf('/') + 1))];
     }
 
     @Nullable
@@ -686,7 +693,7 @@ public final class IpConversionUtil {
         if (mask != null && mask.getValue() != null) {
             maskValue = mask.getValue();
         } else {
-            maskValue = DEFAULT_ARBITRARY_BITMASK.getValue();
+            maskValue = IPV4_BITMASKS[IPV4_ADDRESS_LENGTH].getValue();
         }
 
         final InetAddress maskInIpFormat;