RFR: Remove map synchronization from SignatureAndHashAlgorithm

[Steven Davidovitz]

With the removal of the synchronization on priorityMap inside
'SignatureAndHashAlgorithm.getSupportedAlgorithms' in rev daaace32c979
[1], it seems unnecessary to use a synchronizedSortedMap.
Benchmarking, I see a 2x performance increase by using the bare
TreeMap.

measureModified   sample  11336330 11949.506 ± 1775.776  ns/op
measureOriginal    sample  10855026 23003.654 ± 2286.571  ns/op

Thanks,
Steven Davidovitz

1: http://hg.openjdk.java.net/jdk9/dev/jdk/rev/daaace32c979

diff --git a/src/java.base/share/classes/sun/security/ssl/SignatureAndHashAlgorithm.java
b/src/java.base/share/classes/sun/security/ssl/SignatureAndHashAlgorithm.java
--- a/src/java.base/share/classes/sun/security/ssl/SignatureAndHashAlgorithm.java
+++ b/src/java.base/share/classes/sun/security/ssl/SignatureAndHashAlgorithm.java
@@ -396,46 +396,42 @@
     }

     static {
-        supportedMap = Collections.synchronizedSortedMap(
-            new TreeMap<Integer, SignatureAndHashAlgorithm>());
-        priorityMap = Collections.synchronizedSortedMap(
-            new TreeMap<Integer, SignatureAndHashAlgorithm>());
-
-        synchronized (supportedMap) {
-            int p = SUPPORTED_ALG_PRIORITY_MAX_NUM;
-            supports(HashAlgorithm.MD5,         SignatureAlgorithm.RSA,
-                    "MD5withRSA",           --p);
-            supports(HashAlgorithm.SHA1,        SignatureAlgorithm.DSA,
-                    "SHA1withDSA",          --p);
-            supports(HashAlgorithm.SHA1,        SignatureAlgorithm.RSA,
-                    "SHA1withRSA",          --p);
-            supports(HashAlgorithm.SHA1,        SignatureAlgorithm.ECDSA,
-                    "SHA1withECDSA",        --p);
+        supportedMap = new TreeMap<Integer, SignatureAndHashAlgorithm>();
+        priorityMap = new TreeMap<Integer, SignatureAndHashAlgorithm>();

-            if (Security.getProvider("SunMSCAPI") == null) {
-                supports(HashAlgorithm.SHA224,      SignatureAlgorithm.DSA,
-                        "SHA224withDSA",        --p);
-                supports(HashAlgorithm.SHA224,      SignatureAlgorithm.RSA,
-                        "SHA224withRSA",        --p);
-                supports(HashAlgorithm.SHA224,      SignatureAlgorithm.ECDSA,
-                        "SHA224withECDSA",      --p);
-            }
+        int p = SUPPORTED_ALG_PRIORITY_MAX_NUM;
+        supports(HashAlgorithm.MD5,         SignatureAlgorithm.RSA,
+                "MD5withRSA",           --p);
+        supports(HashAlgorithm.SHA1,        SignatureAlgorithm.DSA,
+                "SHA1withDSA",          --p);
+        supports(HashAlgorithm.SHA1,        SignatureAlgorithm.RSA,
+                "SHA1withRSA",          --p);
+        supports(HashAlgorithm.SHA1,        SignatureAlgorithm.ECDSA,
+                "SHA1withECDSA",        --p);

-            supports(HashAlgorithm.SHA256,      SignatureAlgorithm.DSA,
-                    "SHA256withDSA",        --p);
-            supports(HashAlgorithm.SHA256,      SignatureAlgorithm.RSA,
-                    "SHA256withRSA",        --p);
-            supports(HashAlgorithm.SHA256,      SignatureAlgorithm.ECDSA,
-                    "SHA256withECDSA",      --p);
-            supports(HashAlgorithm.SHA384,      SignatureAlgorithm.RSA,
-                    "SHA384withRSA",        --p);
-            supports(HashAlgorithm.SHA384,      SignatureAlgorithm.ECDSA,
-                    "SHA384withECDSA",      --p);
-            supports(HashAlgorithm.SHA512,      SignatureAlgorithm.RSA,
-                    "SHA512withRSA",        --p);
-            supports(HashAlgorithm.SHA512,      SignatureAlgorithm.ECDSA,
-                    "SHA512withECDSA",      --p);
+        if (Security.getProvider("SunMSCAPI") == null) {
+            supports(HashAlgorithm.SHA224,      SignatureAlgorithm.DSA,
+                    "SHA224withDSA",        --p);
+            supports(HashAlgorithm.SHA224,      SignatureAlgorithm.RSA,
+                    "SHA224withRSA",        --p);
+            supports(HashAlgorithm.SHA224,      SignatureAlgorithm.ECDSA,
+                    "SHA224withECDSA",      --p);
         }
+
+        supports(HashAlgorithm.SHA256,      SignatureAlgorithm.DSA,
+                "SHA256withDSA",        --p);
+        supports(HashAlgorithm.SHA256,      SignatureAlgorithm.RSA,
+                "SHA256withRSA",        --p);
+        supports(HashAlgorithm.SHA256,      SignatureAlgorithm.ECDSA,
+                "SHA256withECDSA",      --p);
+        supports(HashAlgorithm.SHA384,      SignatureAlgorithm.RSA,
+                "SHA384withRSA",        --p);
+        supports(HashAlgorithm.SHA384,      SignatureAlgorithm.ECDSA,
+                "SHA384withECDSA",      --p);
+        supports(HashAlgorithm.SHA512,      SignatureAlgorithm.RSA,
+                "SHA512withRSA",        --p);
+        supports(HashAlgorithm.SHA512,      SignatureAlgorithm.ECDSA,
+                "SHA512withECDSA",      --p);
     }
 }