ENT-1439 Use thread-local MessageDigest. (#541)

core/build.gradle

@@ -133,6 +133,9 @@ dependencies {
 
     // required to use @Type annotation
     compile "org.hibernate:hibernate-core:$hibernate_version"
+
+    // FastThreadLocal
+    compile "io.netty:netty-common:$netty_version"
 }
 
 // TODO Consider moving it to quasar-utils in the future (introduced with PR-1388)

core/src/main/kotlin/net/corda/core/crypto/SecureHash.kt

@@ -10,6 +10,7 @@
 
 package net.corda.core.crypto
 
+import io.netty.util.concurrent.FastThreadLocal
 import net.corda.core.serialization.CordaSerializable
 import net.corda.core.utilities.OpaqueBytes
 import net.corda.core.utilities.parseAsHex
@@ -63,12 +64,16 @@ sealed class SecureHash(bytes: ByteArray) : OpaqueBytes(bytes) {
             }
         }
 
+        private val threadLocalSha256MessageDigest = object : FastThreadLocal<MessageDigest>() {
+            override fun initialValue() = MessageDigest.getInstance("SHA-256")
+        }
+
         /**
          * Computes the SHA-256 hash value of the [ByteArray].
          * @param bytes The [ByteArray] to hash.
          */
         @JvmStatic
-        fun sha256(bytes: ByteArray) = SHA256(MessageDigest.getInstance("SHA-256").digest(bytes))
+        fun sha256(bytes: ByteArray) = SHA256(threadLocalSha256MessageDigest.get().digest(bytes))
 
         /**
          * Computes the SHA-256 hash of the [ByteArray], and then computes the SHA-256 hash of the hash.

core/src/test/kotlin/net/corda/core/crypto/SecureHashTest.kt

@@ -0,0 +1,11 @@
+package net.corda.core.crypto
+
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class SecureHashTest {
+    @Test
+    fun `sha256 does not retain state between same-thread invocations`() {
+        assertEquals(SecureHash.sha256("abc"), SecureHash.sha256("abc"))
+    }
+}

node/build.gradle

@@ -33,6 +33,7 @@ configurations {
         // We don't need these because we already include netty-all.
         exclude group: 'io.netty', module: 'netty-transport'
         exclude group: 'io.netty', module: 'netty-handler'
+        exclude group: 'io.netty', module: 'netty-common'
     }
 
     integrationTestCompile.extendsFrom testCompile