Snappy compression failures (#257)

Replace the JNI based snappy library with an all Java version.  
This will help work on #251 because the error messages are more reasonable

ethereum/p2p/build.gradle

@@ -29,7 +29,7 @@ dependencies {
   implementation 'com.google.guava:guava'
   implementation 'io.vertx:vertx-core'
   implementation 'org.apache.logging.log4j:log4j-api'
-  implementation 'org.xerial.snappy:snappy-java'
+  implementation 'org.iq80.snappy:snappy'
 
   runtime 'org.apache.logging.log4j:log4j-core'
 

ethereum/p2p/src/main/java/tech/pegasys/pantheon/ethereum/p2p/rlpx/framing/SnappyCompressor.java

@@ -14,9 +14,7 @@ package tech.pegasys.pantheon.ethereum.p2p.rlpx.framing;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
-import java.io.IOException;
-
-import org.xerial.snappy.Snappy;
+import org.iq80.snappy.Snappy;
 
 /**
  * A strategy for compressing and decompressing data with the Snappy algorithm.
@@ -28,30 +26,18 @@ public class SnappyCompressor implements Compressor {
   @Override
   public byte[] compress(final byte[] uncompressed) {
     checkNotNull(uncompressed, "input data must not be null");
-    try {
-      return Snappy.compress(uncompressed);
-    } catch (final IOException e) {
-      throw new CompressionException("Snappy compression failed", e);
-    }
+    return Snappy.compress(uncompressed);
   }
 
   @Override
   public byte[] decompress(final byte[] compressed) {
     checkNotNull(compressed, "input data must not be null");
-    try {
-      return Snappy.uncompress(compressed);
-    } catch (final IOException e) {
-      throw new CompressionException("Snappy decompression failed", e);
-    }
+    return Snappy.uncompress(compressed, 0, compressed.length);
   }
 
   @Override
   public int uncompressedLength(final byte[] compressed) {
     checkNotNull(compressed, "input data must not be null");
-    try {
-      return Snappy.uncompressedLength(compressed);
-    } catch (final IOException e) {
-      throw new CompressionException("Snappy uncompressedLength failed", e);
-    }
+    return Snappy.getUncompressedLength(compressed, 0);
   }
 }

ethereum/p2p/src/test/java/tech/pegasys/pantheon/ethereum/p2p/rlpx/framing/FramerTest.java

@@ -33,8 +33,8 @@ import com.fasterxml.jackson.databind.JsonNode;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.Unpooled;
+import org.iq80.snappy.Snappy;
 import org.junit.Test;
-import org.xerial.snappy.Snappy;
 
 public class FramerTest {
   private static final ObjectMapper MAPPER = new ObjectMapper();

gradle/versions.gradle

@@ -41,7 +41,7 @@ dependencyManagement {
 
     dependency('io.pkts:pkts-core:3.0.2')
 
-    dependency('org.xerial.snappy:snappy-java:1.1.7.1')
+    dependency("org.iq80.snappy:snappy:0.4")
 
     dependency('com.github.docker-java:docker-java:3.0.14')