Following changes:

 # Upgraded Jackson
 # When deserializing a 'Result', use first (latest) entry instead of last entry.
 # Moved codec initialization from clinit to init
 # Avoid multiple class validations
 # Minor improvements to test cases

README.md

@@ -412,7 +412,7 @@ Add below entry within the `dependencies` section of your `pom.xml`:
 <dependency>
   <groupId>com.flipkart</groupId>
   <artifactId>hbase-object-mapper</artifactId>
-  <version>1.14.1</version>
+  <version>1.15</version>
 </dependency>
 ```
 
@@ -423,7 +423,7 @@ See artifact details: [com.flipkart:hbase-object-mapper on **Maven Central**](ht
 To build this project, follow below simple steps:
 
  1. Do a `git clone` of this repository
- 2. Checkout latest stable version `git checkout v1.14.1`
+ 2. Checkout latest stable version `git checkout v1.15`
  3. Execute `mvn clean install` from shell
 
 ### Please note:

pom.xml

@@ -11,7 +11,7 @@
     <modelVersion>4.0.0</modelVersion>
     <groupId>com.flipkart</groupId>
     <artifactId>hbase-object-mapper</artifactId>
-    <version>1.14.1</version>
+    <version>1.15</version>
     <url>https://github.com/flipkart-incubator/hbase-orm</url>
     <scm>
         <url>https://github.com/flipkart-incubator/hbase-orm</url>
@@ -64,7 +64,7 @@
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
-            <version>2.9.10.3</version>
+            <version>2.9.10.4</version>
         </dependency>
         <dependency>
             <groupId>com.google.guava</groupId>
@@ -75,7 +75,7 @@
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
-            <version>1.18.10</version>
+            <version>1.18.12</version>
             <scope>test</scope>
         </dependency>
         <dependency>

src/main/java/com/flipkart/hbaseobjectmapper/AbstractHBDAO.java

@@ -139,7 +139,7 @@ protected AbstractHBDAO(Configuration configuration) throws IOException {
     public T get(R rowKey, int numVersionsToFetch) throws IOException {
         try (Table table = getHBaseTable()) {
             Result result = table.get(new Get(toBytes(rowKey)).readVersions(numVersionsToFetch));
-            return hbObjectMapper.readValue(rowKey, result, hbRecordClass);
+            return hbObjectMapper.readValueFromResult(result, hbRecordClass);
         }
     }
 
@@ -177,7 +177,7 @@ public Get getGet(R rowKey) {
     public T getOnGet(Get get) throws IOException {
         try (Table table = getHBaseTable()) {
             Result result = table.get(get);
-            return hbObjectMapper.readValue(result, hbRecordClass);
+            return hbObjectMapper.readValueFromResult(result, hbRecordClass);
         }
     }
 
@@ -192,7 +192,7 @@ public List<T> getOnGets(List<Get> gets) throws IOException {
         try (Table table = getHBaseTable()) {
             Result[] results = table.get(gets);
             for (Result result : results) {
-                records.add(hbObjectMapper.readValue(result, hbRecordClass));
+                records.add(hbObjectMapper.readValueFromResult(result, hbRecordClass));
             }
         }
         return records;
@@ -216,7 +216,7 @@ public T[] get(R[] rowKeys, int numVersionsToFetch) throws IOException {
         try (Table table = getHBaseTable()) {
             Result[] results = table.get(gets);
             for (int i = 0; i < records.length; i++) {
-                records[i] = hbObjectMapper.readValue(rowKeys[i], results[i], hbRecordClass);
+                records[i] = hbObjectMapper.readValueFromResult(results[i], hbRecordClass);
             }
         }
         return records;
@@ -250,7 +250,7 @@ public List<T> get(List<R> rowKeys, int numVersionsToFetch) throws IOException {
         try (Table table = getHBaseTable()) {
             Result[] results = table.get(gets);
             for (Result result : results) {
-                records.add(hbObjectMapper.readValue(result, hbRecordClass));
+                records.add(hbObjectMapper.readValueFromResult(result, hbRecordClass));
             }
         }
         return records;
@@ -323,7 +323,7 @@ public List<T> get(Scan scan) throws IOException {
         try (Table table = getHBaseTable();
              ResultScanner scanner = table.getScanner(scan)) {
             for (Result result : scanner) {
-                records.add(hbObjectMapper.readValue(result, hbRecordClass));
+                records.add(hbObjectMapper.readValueFromResult(result, hbRecordClass));
             }
         }
         return records;
@@ -518,7 +518,7 @@ public Increment getIncrement(R rowKey) {
     public T increment(Increment increment) throws IOException {
         try (Table table = getHBaseTable()) {
             Result result = table.increment(increment);
-            return hbObjectMapper.readValue(result, hbRecordClass);
+            return hbObjectMapper.readValueFromResult(result, hbRecordClass);
         }
     }
 
@@ -569,7 +569,7 @@ public T append(R rowKey, Map<String, Object> valuesToAppend) throws IOException
         }
         try (Table table = getHBaseTable()) {
             Result result = table.append(append);
-            return hbObjectMapper.readValue(result, hbRecordClass);
+            return hbObjectMapper.readValueFromResult(result, hbRecordClass);
         }
     }
 
@@ -599,7 +599,7 @@ public Append getAppend(R rowKey) {
     public T append(Append append) throws IOException {
         try (Table table = getHBaseTable()) {
             Result result = table.append(append);
-            return hbObjectMapper.readValue(result, hbRecordClass);
+            return hbObjectMapper.readValueFromResult(result, hbRecordClass);
         }
     }
 
@@ -623,7 +623,7 @@ public List<T> get(R startRowKey, R endRowKey) throws IOException {
      * @throws IOException When HBase call fails
      */
     public R persist(HBRecord<R> record) throws IOException {
-        Put put = hbObjectMapper.writeValueAsPut(record);
+        Put put = hbObjectMapper.writeValueAsPut0(record);
         try (Table table = getHBaseTable()) {
             table.put(put);
             return record.composeRowKey();
@@ -640,9 +640,9 @@ public R persist(HBRecord<R> record) throws IOException {
     public List<R> persist(List<T> records) throws IOException {
         List<Put> puts = new ArrayList<>(records.size());
         List<R> rowKeys = new ArrayList<>(records.size());
-        for (HBRecord<R> object : records) {
-            puts.add(hbObjectMapper.writeValueAsPut(object));
-            rowKeys.add(object.composeRowKey());
+        for (HBRecord<R> record : records) {
+            puts.add(hbObjectMapper.writeValueAsPut0(record));
+            rowKeys.add(record.composeRowKey());
         }
         try (Table table = getHBaseTable()) {
             table.put(puts);

src/main/java/com/flipkart/hbaseobjectmapper/HBObjectMapper.java

@@ -37,8 +37,6 @@
  */
 public class HBObjectMapper {
 
-    private static final Codec DEFAULT_CODEC = new BestSuitCodec();
-
     private final Codec codec;
 
     /**
@@ -60,7 +58,7 @@ public HBObjectMapper(Codec codec) {
      * @see #HBObjectMapper(Codec)
      */
     public HBObjectMapper() {
-        this(DEFAULT_CODEC);
+        this(new BestSuitCodec());
     }
 
     /**
@@ -88,7 +86,10 @@ <R extends Serializable & Comparable<R>, T extends HBRecord<R>> R bytesToRowKey(
      *
      * @see #convertRecordToMap(HBRecord)
      */
-    private <R extends Serializable & Comparable<R>, T extends HBRecord<R>> T convertMapToRecord(byte[] rowKeyBytes, NavigableMap<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>> map, Class<T> clazz) {
+    private <R extends Serializable & Comparable<R>, T extends HBRecord<R>> T convertMapToRecord(
+            byte[] rowKeyBytes,
+            NavigableMap<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>> map,
+            Class<T> clazz) {
         Collection<Field> fields = getHBColumnFields0(clazz).values();
         WrappedHBTable<R, T> hbTable = new WrappedHBTable<>(clazz);
         R rowKey = bytesToRowKey(rowKeyBytes, hbTable.getCodecFlags(), clazz);
@@ -115,8 +116,8 @@ record = clazz.getDeclaredConstructor()
                 if (columnVersionsMap == null || columnVersionsMap.isEmpty()) {
                     continue;
                 }
-                Map.Entry<Long, byte[]> lastEntry = columnVersionsMap.lastEntry();
-                objectSetFieldValue(record, field, lastEntry.getValue(), hbColumn.codecFlags());
+                Map.Entry<Long, byte[]> firstEntry = columnVersionsMap.firstEntry();
+                objectSetFieldValue(record, field, firstEntry.getValue(), hbColumn.codecFlags());
             } else {
                 objectSetFieldValue(record, field, columnVersionsMap, hbColumn.codecFlags());
             }
@@ -253,7 +254,8 @@ private void validateHBColumnField(Field field) {
      * @see #convertMapToRecord(byte[], NavigableMap, Class)
      */
     @SuppressWarnings("unchecked")
-    private <R extends Serializable & Comparable<R>, T extends HBRecord<R>> NavigableMap<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>> convertRecordToMap(HBRecord<R> record) {
+    private <R extends Serializable & Comparable<R>, T extends HBRecord<R>>
+    NavigableMap<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>> convertRecordToMap(HBRecord<R> record) {
         Class<T> clazz = (Class<T>) record.getClass();
         Collection<Field> fields = getHBColumnFields0(clazz).values();
         NavigableMap<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>> map = new TreeMap<>(Bytes.BYTES_COMPARATOR);
@@ -341,6 +343,10 @@ private <R extends Serializable & Comparable<R>> NavigableMap<Long, byte[]> getF
     @SuppressWarnings("unchecked")
     public <R extends Serializable & Comparable<R>, T extends HBRecord<R>> Put writeValueAsPut(HBRecord<R> record) {
         validateHBClass((Class<T>) record.getClass());
+        return writeValueAsPut0(record);
+    }
+
+    <R extends Serializable & Comparable<R>> Put writeValueAsPut0(HBRecord<R> record) {
         Put put = new Put(composeRowKey(record));
         for (Map.Entry<byte[], NavigableMap<byte[], NavigableMap<Long, byte[]>>> fe : convertRecordToMap(record).entrySet()) {
             byte[] family = fe.getKey();
@@ -456,18 +462,13 @@ public <R extends Serializable & Comparable<R>, T extends HBRecord<R>> T readVal
         return readValueFromResult(result, clazz);
     }
 
-    <R extends Serializable & Comparable<R>, T extends HBRecord<R>> T readValue(R rowKey, Result result, Class<T> clazz) {
-        if (rowKey == null)
-            return readValueFromResult(result, clazz);
-        else
-            return readValueFromRowAndResult(rowKeyToBytes(rowKey, WrappedHBTable.getCodecFlags(clazz)), result, clazz);
-    }
-
     private boolean isResultEmpty(Result result) {
-        return result == null || result.isEmpty() || result.getRow() == null || result.getRow().length == 0;
+        if (result == null || result.isEmpty()) return true;
+        byte[] rowBytes = result.getRow();
+        return rowBytes == null || rowBytes.length == 0;
     }
 
-    private <R extends Serializable & Comparable<R>, T extends HBRecord<R>> T readValueFromResult(Result result, Class<T> clazz) {
+    <R extends Serializable & Comparable<R>, T extends HBRecord<R>> T readValueFromResult(Result result, Class<T> clazz) {
         if (isResultEmpty(result)) return null;
         return convertMapToRecord(result.getRow(), result.getMap(), clazz);
     }

src/main/java/com/flipkart/hbaseobjectmapper/HBObjectMapperFactory.java

@@ -13,10 +13,16 @@ private HBObjectMapperFactory() {
     /**
      * Default instance of {@link HBObjectMapper}
      */
-    private static final HBObjectMapper hbObjectMapper = new HBObjectMapper();
+    private static HBObjectMapper hbObjectMapper;
+    private static final Object[] lock = new Object[0];
 
     static HBObjectMapper construct(Codec codec) {
-        return codec == null ? hbObjectMapper : new HBObjectMapper(codec);
+        if (hbObjectMapper == null) {
+            synchronized (lock) {
+                hbObjectMapper = codec == null ? new HBObjectMapper() : new HBObjectMapper(codec);
+            }
+        }
+        return hbObjectMapper;
     }
 }
 

src/main/java/com/flipkart/hbaseobjectmapper/codec/BestSuitCodec.java

@@ -1,8 +1,6 @@
 package com.flipkart.hbaseobjectmapper.codec;
 
-import com.fasterxml.jackson.databind.DeserializationFeature;
-import com.fasterxml.jackson.databind.JavaType;
-import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.*;
 import com.flipkart.hbaseobjectmapper.Flag;
 import com.flipkart.hbaseobjectmapper.codec.exceptions.DeserializationException;
 import com.flipkart.hbaseobjectmapper.codec.exceptions.SerializationException;

src/test/java/com/flipkart/hbaseobjectmapper/testcases/TestHBObjectMapper.java

@@ -213,13 +213,13 @@ public void testInvalidObjects() {
             String errorMessage = "An object with " + p.getSecond() + " should've thrown an " + p.getThird().getName();
             try {
                 hbMapper.writeValueAsResult(record);
-                fail(errorMessage + " while converting bean to Result\nFailing object = " + record);
+                fail(String.format("%s while converting bean to Result%nFailing object = %s", errorMessage, record));
             } catch (IllegalArgumentException ex) {
                 assertEquals(p.getThird(), ex.getClass(), "Mismatch in type of exception thrown");
             }
             try {
                 hbMapper.writeValueAsPut(record);
-                fail(errorMessage + " while converting bean to Put\nFailing object = " + record);
+                fail(String.format("%s while converting bean to Put%nFailing object = %s", errorMessage, record));
             } catch (IllegalArgumentException ex) {
                 assertEquals(p.getThird(), ex.getClass(), "Mismatch in type of exception thrown");
             }
@@ -324,22 +324,24 @@ public void testUninstantiatableClass() {
 
     @Test
     public void testHBColumnMultiVersion() {
-        Double[] testNumbers = new Double[]{3.14159, 2.71828, 0.0};
-        for (Double n : testNumbers) {
+        Double[] numbers = new Double[]{0.0, 3.14159, 2.71828};
+        for (Double number : numbers) {
             // Written as unversioned, read as versioned
-            Result result = hbMapper.writeValueAsResult(new CrawlNoVersion("key").setF1(n));
+            Result result = hbMapper.writeValueAsResult(new CrawlNoVersion("key").setF1(number));
             Crawl versioned = hbMapper.readValue(result, Crawl.class);
             NavigableMap<Long, Double> columnHistory = versioned.getF1();
             assertEquals(1, columnHistory.size(), "Column history size mismatch");
-            assertEquals(n, columnHistory.lastEntry().getValue(), String.format("Inconsistency between %s and %s", HBColumn.class.getSimpleName(), HBColumnMultiVersion.class.getSimpleName()));
+            assertEquals(number, columnHistory.lastEntry().getValue(), String.format("Inconsistency between %s and %s",
+                    HBColumn.class.getSimpleName(), HBColumnMultiVersion.class.getSimpleName()));
             // Written as versioned, read as unversioned
-            Crawl key = new Crawl("key").addF1(Double.MAX_VALUE).addF1(Double.MAX_VALUE).addF1(Double.MAX_VALUE);
-            Crawl versionedCrawl = key.addF1(n);
-            Result result1 = hbMapper.writeValueAsResult(versionedCrawl);
-            CrawlNoVersion unversionedCrawl = hbMapper.readValue(result1, CrawlNoVersion.class);
-            Double f1 = unversionedCrawl.getF1();
-            System.out.println(unversionedCrawl);
-            assertEquals(n, f1, String.format("Inconsistency between %s and %s\nVersioned (persisted) object = %s\nUnversioned (retrieved) object = %s ", HBColumnMultiVersion.class.getSimpleName(), HBColumn.class.getSimpleName(), versionedCrawl, unversionedCrawl));
+            Crawl crawl = new Crawl("key").addF1(Double.MAX_VALUE).addF1(Double.MAX_VALUE).addF1(Double.MAX_VALUE);
+            Crawl versionedCrawl = crawl.addF1(number);
+            Result crawlAsResult = hbMapper.writeValueAsResult(versionedCrawl);
+            CrawlNoVersion unversionedCrawl = hbMapper.readValue(crawlAsResult, CrawlNoVersion.class);
+            assertEquals(number, unversionedCrawl.getF1(), String.format("Inconsistency between %s and %s%n" +
+                            "Versioned (persisted) object = %s%nUnversioned (retrieved) object = %s",
+                    HBColumnMultiVersion.class.getSimpleName(), HBColumn.class.getSimpleName(),
+                    versionedCrawl, unversionedCrawl));
         }
     }
 }

src/test/java/com/flipkart/hbaseobjectmapper/testcases/TestsAbstractHBDAO.java

@@ -47,7 +47,8 @@ public static void setup() {
             fail("The environmental variable " + InMemoryHBaseCluster.INMEMORY_CLUSTER_START_TIMEOUT + " is specified incorrectly (Must be numeric)");
         } catch (Exception e) {
             e.printStackTrace(System.err);
-            fail("Failed to connect to HBase. Aborted execution of DAO-related test cases. Reason:\n" + e.getMessage());
+            fail(String.format("Failed to connect to HBase. Aborted execution of DAO-related test cases." +
+                    "Reason:%n%s", e.getMessage()));
         }
     }
 
@@ -107,9 +108,9 @@ public void testCRUD() throws IOException {
             final List<Citizen> records = TestObjects.validCitizenObjects;
             assertEquals("citizens", citizenDao.getTableName());
             final Set<String> columnFamiliesCitizen = citizenDao.getColumnFamiliesAndVersions().keySet(), columnFamiliesCitizenSummary = citizenSummaryDAO.getColumnFamiliesAndVersions().keySet();
-            assertEquals(s("main", "optional"), columnFamiliesCitizen, "Issue with column families of 'citizens' table\n" + columnFamiliesCitizen);
+            assertEquals(s("main", "optional"), columnFamiliesCitizen, "Issue with column families of 'citizens' table%n" + columnFamiliesCitizen);
             assertEquals("citizens_summary", citizenSummaryDAO.getTableName());
-            assertEquals(s("a"), columnFamiliesCitizenSummary, "Issue with column families of 'citizens_summary' table\n" + columnFamiliesCitizenSummary);
+            assertEquals(s("a"), columnFamiliesCitizenSummary, "Issue with column families of 'citizens_summary' table%n" + columnFamiliesCitizenSummary);
             String[] allRowKeys = new String[records.size()];
             Map<String, Map<String, Object>> expectedFieldValues = new HashMap<>();
             for (int i = 0; i < records.size(); i++) { // for each test object,
@@ -358,7 +359,7 @@ public void testVersioning() throws IOException {
                     rowKeysList.add(key);
                 }
             }
-            String[] rowKeys = rowKeysList.toArray(new String[rowKeysList.size()]);
+            String[] rowKeys = rowKeysList.toArray(new String[0]);
 
             Set<Double> oldestValuesRangeScan = new HashSet<>(), oldestValuesBulkScan = new HashSet<>();
             for (int k = 1; k <= NUM_VERSIONS; k++) {

src/test/java/com/flipkart/hbaseobjectmapper/testcases/entities/Crawl.java

@@ -5,6 +5,7 @@
 
 import java.util.NavigableMap;
 import java.util.TreeMap;
+import java.util.concurrent.TimeUnit;
 
 @HBTable(name = "crawls", families = {@Family(name = "a", versions = 10)})
 @ToString
@@ -34,6 +35,10 @@ public void parseRowKey(String rowKey) {
     }
 
     public Crawl addF1(Double f1) {
+        try {
+            TimeUnit.MILLISECONDS.sleep(10);
+        } catch (InterruptedException ignored) {
+        }
         this.f1.put(System.currentTimeMillis(), f1);
         return this;
     }

src/test/java/com/flipkart/hbaseobjectmapper/testcases/util/cluster/InMemoryHBaseCluster.java

@@ -1,7 +1,6 @@
 package com.flipkart.hbaseobjectmapper.testcases.util.cluster;
 
 import org.apache.hadoop.hbase.HBaseTestingUtility;
-import org.apache.hadoop.hbase.MiniHBaseCluster;
 import org.apache.hadoop.hbase.client.Connection;
 
 import java.io.IOException;
@@ -44,6 +43,9 @@ public Connection start() throws IOException {
             throw new IOException("Error starting an in-memory HBase cluster", e);
         }
         connection = utility.getConnection();
+        if (connection == null) {
+            throw new IllegalStateException("Connection could not be established with in-memory HBase cluster");
+        }
         return connection;
     }