From a6b97cd5accc0c748bbafe554c722509f1da868f Mon Sep 17 00:00:00 2001
From: John May <john@nextmovesoftware.com>
Date: Sun, 9 Oct 2016 17:00:08 +0100
Subject: [PATCH] Cache dictionary databases - faster initialisation.

---
 .../org/openscience/cdk/dict/Dictionary.java  |  2 +-
 .../cdk/dict/DictionaryDatabase.java          | 39 ++++++++++++-------
 2 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/base/dict/src/main/java/org/openscience/cdk/dict/Dictionary.java b/base/dict/src/main/java/org/openscience/cdk/dict/Dictionary.java
index 905bfd0ea16..2d4da426c7f 100644
--- a/base/dict/src/main/java/org/openscience/cdk/dict/Dictionary.java
+++ b/base/dict/src/main/java/org/openscience/cdk/dict/Dictionary.java
@@ -95,7 +95,7 @@ public static Dictionary unmarshal(Reader reader) {
         return dict;
     }
 
-    public void addEntry(Entry entry) {
+    void addEntry(Entry entry) {
         entries.put(entry.getID().toLowerCase(), entry);
     }
 
diff --git a/base/dict/src/main/java/org/openscience/cdk/dict/DictionaryDatabase.java b/base/dict/src/main/java/org/openscience/cdk/dict/DictionaryDatabase.java
index e23f3188309..a62eecb7c29 100644
--- a/base/dict/src/main/java/org/openscience/cdk/dict/DictionaryDatabase.java
+++ b/base/dict/src/main/java/org/openscience/cdk/dict/DictionaryDatabase.java
@@ -25,6 +25,7 @@
 
 import java.io.InputStreamReader;
 import java.io.Reader;
+import java.util.HashMap;
 import java.util.Hashtable;
 import java.util.Iterator;
 import java.util.Map;
@@ -44,6 +45,8 @@
  */
 public class DictionaryDatabase {
 
+    private static final Map<String,Dictionary> cache = new HashMap<>();
+
     public final static String      DICTREFPROPERTYNAME = "org.openscience.cdk.dict";
 
     private ILoggingTool            logger              = LoggingToolFactory
@@ -76,23 +79,29 @@ private Dictionary readDictionary(String databaseLocator, String type) {
             databaseLocator += "." + type.substring(0, type.length() - 6);
         else
             databaseLocator += "." + type;
-        logger.info("Reading dictionary from ", databaseLocator);
-        try {
-            InputStreamReader reader = new InputStreamReader(this.getClass().getClassLoader()
-                    .getResourceAsStream(databaseLocator));
-            if (type.equals("owl")) {
-                dictionary = OWLFile.unmarshal(reader);
-            } else if (type.equals("owl_React")) {
-                dictionary = OWLReact.unmarshal(reader);
-            } else { // assume XML using Castor
-                dictionary = Dictionary.unmarshal(reader);
+        if (cache.containsKey(databaseLocator)) {
+            return cache.get(databaseLocator);
+        }
+        else {
+            logger.info("Reading dictionary from ", databaseLocator);
+            try {
+                InputStreamReader reader = new InputStreamReader(this.getClass().getClassLoader()
+                                                                     .getResourceAsStream(databaseLocator));
+                if (type.equals("owl")) {
+                    dictionary = OWLFile.unmarshal(reader);
+                } else if (type.equals("owl_React")) {
+                    dictionary = OWLReact.unmarshal(reader);
+                } else { // assume XML using Castor
+                    dictionary = Dictionary.unmarshal(reader);
+                }
+            } catch (Exception exception) {
+                dictionary = null;
+                logger.error("Could not read dictionary ", databaseLocator);
+                logger.debug(exception);
             }
-        } catch (Exception exception) {
-            dictionary = null;
-            logger.error("Could not read dictionary ", databaseLocator);
-            logger.debug(exception);
+            cache.put(databaseLocator, dictionary);
+            return dictionary;
         }
-        return dictionary;
     }
 
     /**