feat: Parameterize cache size in CachingParser

src/main/java/ua_parser/CachingParser.java

@@ -14,15 +14,19 @@
  * the need to parse the same useragent over and over again.
  *
  * This class introduces a very simple LRU cache to reduce the number of times
- * the parsing is actually done.
+ * the parsing is actually done. The default cache size is 1000 and can be
+ * configured as object creation.
+ *
+ * Note: The object handles one cache per parsing method - be carefull when using big sizes.
  *
  * @author Niels Basjes
  *
  */
 public class CachingParser extends Parser {
 
-  // TODO: Make configurable
-  private static final int       CACHE_SIZE     = 1000;
+  private static final String    INVALID_CACHE_SIZE_ERROR_MESSAGE = "Invalid cache size provided - Should be greater than 0";
+
+  private int                    cacheSize     = 1000;
 
   private Map<String, Client>    cacheClient    = null;
   private Map<String, UserAgent> cacheUserAgent = null;
@@ -39,6 +43,19 @@ public CachingParser(InputStream regexYaml) {
     super(regexYaml);
   }
 
+  public CachingParser(int cacheSize) throws IOException {
+    super();
+    assert cacheSize > 0: INVALID_CACHE_SIZE_ERROR_MESSAGE;
+    this.cacheSize = cacheSize;
+  }
+
+  public CachingParser(InputStream regexYaml, int cacheSize) {
+    super(regexYaml);
+    assert cacheSize > 0: INVALID_CACHE_SIZE_ERROR_MESSAGE;
+    this.cacheSize = cacheSize;
+  }
+
+
   // ------------------------------------------
 
   @Override
@@ -47,7 +64,7 @@ public Client parse(String agentString) {
       return null;
     }
     if (cacheClient == null) {
-      cacheClient = new LRUMap<>(CACHE_SIZE);
+      cacheClient = new LRUMap<>(cacheSize);
     }
     Client client = cacheClient.get(agentString);
     if (client != null) {
@@ -66,7 +83,7 @@ public UserAgent parseUserAgent(String agentString) {
       return null;
     }
     if (cacheUserAgent == null) {
-      cacheUserAgent = new LRUMap<>(CACHE_SIZE);
+      cacheUserAgent = new LRUMap<>(cacheSize);
     }
     UserAgent userAgent = cacheUserAgent.get(agentString);
     if (userAgent != null) {
@@ -85,7 +102,7 @@ public Device parseDevice(String agentString) {
       return null;
     }
     if (cacheDevice == null) {
-      cacheDevice = new LRUMap<>(CACHE_SIZE);
+      cacheDevice = new LRUMap<>(cacheSize);
     }
     Device device = cacheDevice.get(agentString);
     if (device != null) {
@@ -105,7 +122,7 @@ public OS parseOS(String agentString) {
     }
 
     if (cacheOS == null) {
-      cacheOS = new LRUMap<>(CACHE_SIZE);
+      cacheOS = new LRUMap<>(cacheSize);
     }
     OS os = cacheOS.get(agentString);
     if (os != null) {

src/test/java/ua_parser/CachingParserTest.java

@@ -28,6 +28,16 @@ Parser parserFromStringConfig(String configYamlAsString) throws Exception {
     return new CachingParser(yamlInput);
   }
 
+  @Test
+  public void testCachingParserCorrectSizeInit() throws Exception {
+      parser = new CachingParser(10);
+  }
+
+  @Test (expected = java.lang.AssertionError.class)
+  public void testCachingParserIncorrectSizeInit() throws Exception{
+      parser = new CachingParser(0);
+  }
+
   @Test
   public void testCachedParseUserAgent() {
     super.testParseUserAgent();