Adapt to the changes of 'prefix seek api'

See https://github.com/facebook/rocksdb/wiki/Prefix-Seek-API-Changes

docs/api/database.rst

@@ -72,7 +72,7 @@ Database object
         :param sync: See :py:meth:`rocksdb.DB.put`
         :param disable_wal: See :py:meth:`rocksdb.DB.put`
 
-    .. py:method:: get(key, verify_checksums=False, fill_cache=True, prefix_seek=False, snapshot=None, read_tier="all")
+    .. py:method:: get(key, verify_checksums=False, fill_cache=True, snapshot=None, read_tier="all")
 
         :param bytes key: Name to get
 
@@ -85,10 +85,6 @@ Database object
                 read for this iteration be cached in memory?
                 Callers may wish to set this field to ``False`` for bulk scans.
         
-        :param bool prefix_seek:
-                If this option is set and memtable implementation allows.
-                Seek might only return keys with the same prefix as the seek-key
-
         :param snapshot:
             If not ``None``, read as of the supplied snapshot
             (which must belong to the DB that is being read and which must
@@ -107,7 +103,7 @@ Database object
  
         :returns: ``None`` if not found, else the value for this key
 
-    .. py:method:: multi_get(keys, verify_checksums=False, fill_cache=True, prefix_seek=False, snapshot=None, read_tier="all")
+    .. py:method:: multi_get(keys, verify_checksums=False, fill_cache=True, snapshot=None, read_tier="all")
 
         :param keys: Keys to fetch
         :type keys: list of bytes
@@ -123,7 +119,7 @@ Database object
             keys will not be "de-duplicated".
             Duplicate keys will return duplicate values in order.
 
-    .. py:method:: key_may_exist(key, fetch=False, verify_checksums=False, fill_cache=True, prefix_seek=False, snapshot=None, read_tier="all")
+    .. py:method:: key_may_exist(key, fetch=False, verify_checksums=False, fill_cache=True, snapshot=None, read_tier="all")
 
         If the key definitely does not exist in the database, then this method
         returns ``False``, else ``True``. If the caller wants to obtain value
@@ -142,12 +138,10 @@ Database object
             * ``(True, <data>)`` if key is found and value in memory and ``fetch=True``
             * ``(False, None)`` if key is not found
 
-    .. py:method:: iterkeys(prefix=None, fetch=False, verify_checksums=False, fill_cache=True, prefix_seek=False, snapshot=None, read_tier="all")
+    .. py:method:: iterkeys(fetch=False, verify_checksums=False, fill_cache=True, snapshot=None, read_tier="all")
 
         Iterate over the keys
 
-        :param bytes prefix: Not implemented yet
-
         For other params see :py:meth:`rocksdb.DB.get`
 
         :returns:
@@ -156,12 +150,10 @@ Database object
 
         :rtype: :py:class:`rocksdb.BaseIterator`
 
-    .. py:method:: itervalues(prefix=None, fetch=False, verify_checksums=False, fill_cache=True, prefix_seek=False, snapshot=None, read_tier="all")
+    .. py:method:: itervalues(fetch=False, verify_checksums=False, fill_cache=True, snapshot=None, read_tier="all")
 
         Iterate over the values
 
-        :param bytes prefix: Not implemented yet
-
         For other params see :py:meth:`rocksdb.DB.get`
 
         :returns:
@@ -170,12 +162,10 @@ Database object
 
         :rtype: :py:class:`rocksdb.BaseIterator`
 
-    .. py:method:: iteritems(prefix=None, fetch=False, verify_checksums=False, fill_cache=True, prefix_seek=False, snapshot=None, read_tier="all")
+    .. py:method:: iteritems(fetch=False, verify_checksums=False, fill_cache=True, snapshot=None, read_tier="all")
 
         Iterate over the items
 
-        :param bytes prefix: Not implemented yet
-
         For other params see :py:meth:`rocksdb.DB.get`
 
         :returns:

docs/changelog.rst

@@ -4,6 +4,34 @@ Changelog
 Version 0.3
 -----------
 
+Backward Incompatible Changes:
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+**Prefix Seeks:**
+
+According to this page https://github.com/facebook/rocksdb/wiki/Prefix-Seek-API-Changes,
+all the prefix related parameters on ``ReadOptions`` are removed.
+Rocksdb realizes now if ``Options.prefix_extractor`` is set and uses then
+prefix-seeks automatically. This means the following changes on pyrocksdb.
+
+* DB.iterkeys, DB.itervalues, DB.iteritems have *no* ``prefix`` parameter anymore.
+* DB.get, DB.multi_get, DB.key_may_exist, DB.iterkeys, DB.itervalues, DB.iteritems
+  have *no* ``prefix_seek`` parameter anymore.
+
+Which means all the iterators walk now always to the *end* of the database.
+So if you need to stay within a prefix, write your own code to ensure that.
+For DB.iterkeys and DB.iteritems ``itertools.takewhile`` is a possible solution. ::
+
+    from itertools import takewhile
+
+    it = self.db.iterkeys()
+    it.seek(b'00002')
+    print list(takewhile(lambda key: key.startswith(b'00002'), it))
+
+    it = self.db.iteritems()
+    it.seek(b'00002')
+    print dict(takewhile(lambda item: item[0].startswith(b'00002'), it))
+
 
 Version 0.2
 -----------

docs/tutorial/index.rst

@@ -236,11 +236,13 @@ So always the first 5 bytes are used as the prefix ::
     db.put(b'00003.y', b'y')
     db.put(b'00003.z', b'z')
 
-    it = db.iteritems(prefix=b'00002')
+    prefix = b'00002'
-    it.seek(b'00002')
+
+    it = db.iteritems()
+    it.seek(prefix)
 
     # prints {b'00002.z': b'z', b'00002.y': b'y', b'00002.x': b'x'}
-    print dict(it)
+    print dict(itertools.takewhile(lambda item: item[].startswith(prefix), it))
 
 
 Backup And Restore

rocksdb/_rocksdb.pyx

@@ -1461,40 +1461,36 @@ cdef class DB(object):
 
             return (exists, None)
 
-    def iterkeys(self, prefix=None, *args, **kwargs):
+    def iterkeys(self, *args, **kwargs):
         cdef options.ReadOptions opts
         cdef KeysIterator it
 
         opts = self.build_read_opts(self.__parse_read_opts(*args, **kwargs))
-
         it = KeysIterator(self)
-        it.set_prefix(opts, prefix)
 
         with nogil:
             it.ptr = self.db.NewIterator(opts)
         return it
 
-    def itervalues(self, prefix=None, *args, **kwargs):
+    def itervalues(self, *args, **kwargs):
         cdef options.ReadOptions opts
         cdef ValuesIterator it
 
         opts = self.build_read_opts(self.__parse_read_opts(*args, **kwargs))
 
         it = ValuesIterator(self)
-        it.set_prefix(opts, prefix)
 
         with nogil:
             it.ptr = self.db.NewIterator(opts)
         return it
 
-    def iteritems(self, prefix=None, *args, **kwargs):
+    def iteritems(self, *args, **kwargs):
         cdef options.ReadOptions opts
         cdef ItemsIterator it
 
         opts = self.build_read_opts(self.__parse_read_opts(*args, **kwargs))
 
         it = ItemsIterator(self)
-        it.set_prefix(opts, prefix)
 
         with nogil:
             it.ptr = self.db.NewIterator(opts)
@@ -1541,7 +1537,6 @@ cdef class DB(object):
     def __parse_read_opts(
         verify_checksums=False,
         fill_cache=True,
-        prefix_seek=False,
         snapshot=None,
         read_tier="all"):
 
@@ -1552,7 +1547,6 @@ cdef class DB(object):
         cdef options.ReadOptions opts
         opts.verify_checksums = py_opts['verify_checksums']
         opts.fill_cache = py_opts['fill_cache']
-        opts.prefix_seek = py_opts['prefix_seek']
         if py_opts['snapshot'] is not None:
             opts.snapshot = (<Snapshot?>(py_opts['snapshot'])).ptr
 
@@ -1591,9 +1585,6 @@ cdef class Snapshot(object):
 cdef class BaseIterator(object):
     cdef iterator.Iterator* ptr
     cdef DB db
-    # To keep a reference to the prefix
-    cdef object prefix
-    cdef Slice c_prefix
 
     def __cinit__(self, DB db):
         self.db = db
@@ -1619,14 +1610,6 @@ cdef class BaseIterator(object):
     def __reversed__(self):
         return ReversedIterator(self)
 
-    cdef set_prefix(self, options.ReadOptions& opts, object prefix=None):
-        if prefix is None:
-            return
-
-        self.c_prefix = bytes_to_slice(prefix)
-        self.prefix = prefix
-        opts.prefix = cython.address(self.c_prefix)
-
     cpdef seek_to_first(self):
         with nogil:
             self.ptr.SeekToFirst()

rocksdb/options.pxd

@@ -123,8 +123,6 @@ cdef extern from "rocksdb/options.h" namespace "rocksdb":
     cdef cppclass ReadOptions:
         cpp_bool verify_checksums
         cpp_bool fill_cache
-        cpp_bool prefix_seek
-        const Slice* prefix
         const Snapshot* snapshot
         ReadTier read_tier
 

rocksdb/tests/test_db.py

@@ -3,6 +3,7 @@ import shutil
 import gc
 import unittest
 import rocksdb
+from itertools import takewhile
 
 def int_to_bytes(ob):
     return str(ob).encode('ascii')
@@ -300,7 +301,10 @@ class TestPrefixExtractor(unittest.TestCase, TestHelper):
         self._clean()
         self.db = rocksdb.DB('/tmp/test', opts)
 
-    def test_prefix(self):
+    def tearDown(self):
+        self._close_db()
+
+    def _fill_db(self):
         for x in range(3000):
             keyx = hex(x)[2:].zfill(5).encode('utf8') + b'.x'
             keyy = hex(x)[2:].zfill(5).encode('utf8') + b'.y'
@@ -309,12 +313,26 @@ class TestPrefixExtractor(unittest.TestCase, TestHelper):
             self.db.put(keyy, b'y')
             self.db.put(keyz, b'z')
 
+
+    def test_prefix_iterkeys(self):
+        self._fill_db()
         self.assertEqual(b'x', self.db.get(b'00001.x'))
         self.assertEqual(b'y', self.db.get(b'00001.y'))
         self.assertEqual(b'z', self.db.get(b'00001.z'))
 
-        it = self.db.iterkeys(prefix=b'00002')
+        it = self.db.iterkeys()
         it.seek(b'00002')
 
         ref = [b'00002.x', b'00002.y', b'00002.z']
-        self.assertEqual(ref, list(it))
+        ret = takewhile(lambda key: key.startswith(b'00002'), it)
+        self.assertEqual(ref, list(ret))
+
+    def test_prefix_iteritems(self):
+        self._fill_db()
+
+        it = self.db.iteritems()
+        it.seek(b'00002')
+
+        ref = {'00002.z': 'z', '00002.y': 'y', '00002.x': 'x'}
+        ret = takewhile(lambda item: item[0].startswith(b'00002'), it)
+        self.assertEqual(ref, dict(ret))