Merge pull request python-happybase#1 from TAKEALOT/reverse_table_scans

Reverse table scans

happybase/__init__.py

@@ -8,6 +8,7 @@
 from .connection import DEFAULT_HOST, DEFAULT_PORT, Connection
 from .table import Table
 from .batch import Batch
+from .counter_batch import CounterBatch
 from .pool import ConnectionPool, NoConnectionsAvailable
 
 # TODO: properly handle errors defined in Thrift specification

happybase/_version.py

@@ -5,4 +5,4 @@
 setup.py.
 """
 
-__version__ = '0.9'
+__version__ = '0.9-takealot'

happybase/counter_batch.py

@@ -0,0 +1,51 @@
+from happybase.hbase.ttypes import TIncrement
+
+
+class CounterBatch:
+    def __init__(self, table, batch_size=None):
+        self.table = table
+        self.batch_size = batch_size
+        self.batch = []
+
+    def counter_inc(self, row, column, value=1):
+        self.batch.append({'row': row, 'column': column, 'value': value})
+        self._check_send()
+
+    def counter_dec(self, row, column, value=1):
+        self.batch.append({'row': row, 'column': column, 'value': -value})
+        self._check_send()
+
+    def send(self):
+        increment_rows = []
+        for increment in self.batch:
+            increment_rows.append(
+                TIncrement(
+                    table=self.table.name,
+                    row=increment['row'],
+                    column=increment['column'],
+                    ammount=increment.get('value', 1),
+                )
+            )
+        self.table.connection.client.incrementRows(increment_rows)
+
+    def _check_send(self):
+        if self.batch_size and (len(self.batch) >= self.batch_size):
+            self.send()
+            self.batch = []
+
+    #
+    # Context manager methods
+    #
+
+    def __enter__(self):
+        """Called upon entering a ``with`` block"""
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        """Called upon exiting a ``with`` block"""
+        # TODO: Examine the exception and decide whether or not to send
+        # For now we always send
+        if exc_type is not None:
+            pass
+
+        self.send()

happybase/table.py

@@ -10,6 +10,7 @@
 from .hbase.ttypes import TScan
 from .util import thrift_type_to_dict, str_increment, OrderedDict
 from .batch import Batch
+from .counter_batch import CounterBatch
 
 logger = logging.getLogger(__name__)
 
@@ -215,7 +216,7 @@ def cells(self, row, column, versions=None, timestamp=None,
     def scan(self, row_start=None, row_stop=None, row_prefix=None,
              columns=None, filter=None, timestamp=None,
              include_timestamp=False, batch_size=1000, scan_batching=None,
-             limit=None, sorted_columns=False):
+             limit=None, sorted_columns=False, reversed=False):
         """Create a scanner for data in the table.
 
         This method returns an iterable that can be used for looping over the
@@ -270,6 +271,9 @@ def scan(self, row_start=None, row_stop=None, row_prefix=None,
         * The `sorted_columns` argument is only available when using
           HBase 0.96 (or up).
 
+        * The `reversed` option is only available when using HBase 0.98
+          (or up).
+
         .. versionadded:: 0.8
            `sorted_columns` argument
 
@@ -287,6 +291,7 @@ def scan(self, row_start=None, row_stop=None, row_prefix=None,
         :param bool scan_batching: server-side scan batching (optional)
         :param int limit: max number of rows to return
         :param bool sorted_columns: whether to return sorted columns
+        :param bool reversed: whether or not to reverse the row ordering
 
         :return: generator yielding the rows matching the scan
         :rtype: iterable of `(row_key, row_data)` tuples
@@ -369,6 +374,7 @@ def scan(self, row_start=None, row_stop=None, row_prefix=None,
                 filterString=filter,
                 batchSize=scan_batching,
                 sortColumns=sorted_columns,
+                reversed=reversed,
             )
             scan_id = self.connection.client.scannerOpenWithScan(
                 self.name, scan, {})
@@ -497,6 +503,23 @@ def batch(self, timestamp=None, batch_size=None, transaction=False,
         del kwargs['self']
         return Batch(table=self, **kwargs)
 
+    def counter_batch(self, batch_size=None):
+        """Create a new batch of counter operation for this table.
+
+        This method returns a new :py:class:`CounterBatch` instance that can be used
+        for mass counter manipulation.
+
+        If given, the `batch_size` argument specifies the maximum batch size
+        after which the batch should send the mutations to the server. By
+        default this is unbounded.
+
+        :param int batch_size: batch size (optional)
+
+        :return: CounterBatch instance
+        :rtype: :py:class:`CounterBatch`
+        """
+        return CounterBatch(table=self, batch_size=batch_size)
+
     #
     # Atomic counters
     #