[jira] [Created] (HBASE-17300) Concurrently calling checkAndPut with expected value as null returns true unexpectedly

["Samarth Jain (JIRA)" <ji...@apache.org>]

Samarth Jain created HBASE-17300:
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             Summary: Concurrently calling checkAndPut with expected value as null returns true unexpectedly
                 Key: HBASE-17300
                 URL: https://issues.apache.org/jira/browse/HBASE-17300
             Project: HBase
          Issue Type: Bug
            Reporter: Samarth Jain


Attached is the test case. I have added some comments so hopefully the test makes sense. It actually is causing test failures on the Phoenix branches.
PS - I am using a bit of Phoenix API to get hold of HBaseAdmin. But it should be fairly straightforward to adopt it for HBase IT tests. 

The test fails consistently using HBase-0.98.23. It exhibits flappy behavior with the 1.2 branch (failed twice in 5 tries). 

{code}
@Test
    public void testNullCheckAndPut() throws Exception {
         try (Connection conn = DriverManager.getConnection(getUrl())) {
            try (HBaseAdmin admin = conn.unwrap(PhoenixConnection.class).getQueryServices().getAdmin()) {
                Callable<Boolean> c1 = new CheckAndPutCallable();
                Callable<Boolean> c2 = new CheckAndPutCallable();
                ExecutorService e = Executors.newFixedThreadPool(5);
                Future<Boolean> f1 = e.submit(c1);
                Future<Boolean> f2 = e.submit(c2);
                assertTrue(f1.get() || f2.get());
                assertFalse(f1.get() && f2.get());
            }    
        }
    }
    
    
    private static final class CheckAndPutCallable implements Callable<Boolean> {
        @Override
        public Boolean call() throws Exception {
            byte[] rowToLock = "ROW".getBytes();
            byte[] colFamily = "COLUMN_FAMILY".getBytes();
            byte[] column = "COLUMN".getBytes();
            byte[] newValue = "NEW_VALUE".getBytes();
            byte[] oldValue = "OLD_VALUE".getBytes();
            byte[] tableName = "table".getBytes();
            boolean acquired = false;
            try (Connection conn = DriverManager.getConnection(getUrl())) {
                try (HBaseAdmin admin = conn.unwrap(PhoenixConnection.class).getQueryServices().getAdmin()) {
                    HTableDescriptor tableDesc = new HTableDescriptor(TableName.valueOf(tableName));
                    HColumnDescriptor columnDesc = new HColumnDescriptor(colFamily);
                    columnDesc.setTimeToLive(600);
                    tableDesc.addFamily(columnDesc);
                    try {
                        admin.createTable(tableDesc);
                    } catch (TableExistsException e) {
                        // ignore
                    }
                    try (HTableInterface table = admin.getConnection().getTable(tableName)) {
                        Put put = new Put(rowToLock);
                        put.add(colFamily, column, oldValue); // add a row with column set to oldValue
                        table.put(put);
                        put = new Put(rowToLock);
                        put.add(colFamily, column, newValue);
                        // only one of the threads should be able to get return value of true for the expected value of oldValue
                        acquired = table.checkAndPut(rowToLock, colFamily, column, oldValue, put); 
                        if (!acquired) {
                           // if a thread didn't get true before, then it shouldn't get true this time either
                           // because the column DOES exist
                           acquired = table.checkAndPut(rowToLock, colFamily, column, null, put);
                        }
                    }
                }
            }  
            return acquired;
        }
    }
{code}


cc [~apurtell], [~jamestaylor], [~lhofhansl]. 




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