def delete(self, key):
''' Delete the supplied value at the given key.
:param key: The key to delete the value at
'''
LDB.leveldb_writebatch_delete(self.write_batch, key, len(key))
return self
def seek(self, key):
''' Move to the specified key in the database.
:param key: The key in the database to move to.
'''
LDB.leveldb_iter_seek(self.iterator, key, len(key))
self.assert_no_error()
return self
def get_version(self):
''' Retrieve the current version of the underlying library.
:returns: major.minor version of the library
'''
return "{}.{}".format(
LDB.leveldb_minor_version(),
LDB.leveldb_major_version())
def clear(self):
''' Clear the current write batch values written
so far. This current write batch can still be
used, however all operations written up to this
point will be gone.
'''
LDB.leveldb_writebatch_clear(self.write_batch)
return self
def __init__(self, database, options):
''' Initialize a new instance of the DatabaseIterator.
:param options: The read options to operate with.
:param database: The databaes to build an iterator on.
'''
self.iterator = LDB.leveldb_create_iterator(database, options)
if LDB and options: LDB.leveldb_readoptions_destroy(options)
def put(self, key, value):
''' Put the supplied value at the given key.
:param key: The key to store the value at
:param value: The value to store at the key
'''
LDB.leveldb_writebatch_put(self.write_batch, key, len(key), value, len(value))
return self
def compact_range(self, start_key, end_key):
''' Given a start and end key, attempt to compact the
database to save space.
:param start_key: The start key to compat from.
:param end_key: The end to to compat to.
'''
LDB.leveldb_compact_range(self.database, start_key,
len(start_key), end_key, len(end_key))
def commit(self):
''' Commit the total write batch operation. After this
call, this write batch instance may no longer be used.
:throws DatabaseException: If an error has occurred
'''
if LDB and self.write_batch:
self.database.write(self.write_batch, self.synchronous)
LDB.leveldb_writebatch_destroy(self.write_batch)
self.write_batch = None
def get_read_options(self, verify_checksum, fill_cache):
''' Get the options for a read operation on the database.
:param verify_checksum: True to verify the checksum on read, False otherwise
:param fill_cache: True to populate the cache on read, False otherwise
:returns: The read options
'''
options = LDB.leveldb_readoptions_create()
LDB.leveldb_readoptions_set_verify_checksums(options, verify_checksum)
LDB.leveldb_readoptions_set_fill_cache(options, fill_cache)
return options
def assert_no_error(self):
''' Check if there was an error after the last error.
If there was, then throw an exception.
:throws DatabaseException: If there was a problem with the iterator
'''
error = new_native_string()
LDB.leveldb_iter_get_error(error, get_reference_to(error))
message = as_python_string(error)
if message:
raise DatabaseException(message)
def approximate_size(self, ranges):
''' Given a collection of ranges, return the approximate
size of the database between those ranges.
:param ranges: dictionary or list of tuple ranges
:returns: The size of the database between those ranges
'''
if isinstance(ranges, dict):
ranges = ranges.items()
collection = RangeCollection.create(ranges)
LDB.leveldb_approximate_sizes(self.database, collection.count,
collection.start_keys, collection.start_sizes,
collection.end_keys, collection.end_sizes, collection.sizes)
return list(collection.sizes)
def repair(self):
''' Attempt to repair a database after setting paranoid checks
still results in an error.
:throws DatabaseException: If an error has occurred
'''
options = self.get_open_options()
try:
error = new_native_string()
LDB.leveldb_repair_db(options, self.filename, get_reference_to(error))
self.handle_error(error)
finally:
if LDB and options:
LDB.leveldb_options_destroy(options)
self.close()
def destroy(self):
''' Completely blows away the underlying database. This process
is not reversable.
:throws DatabaseException: If an error has occurred
'''
options = self.get_open_options()
try:
error = new_native_string()
LDB.leveldb_destroy_db(options, self.filename, get_reference_to(error))
self.handle_error(error)
finally:
if LDB and options:
LDB.leveldb_options_destroy(options)
self.close()
def get_key(self):
''' Get the current key at the iterator
:returns: The current key at the iterator
'''
size = new_native_size()
pointer = LDB.leveldb_iter_key(self.iterator, get_reference_to(size))
return as_python_string(pointer, size)
def open(self):
''' Creates the neccessary data structures and opens the
underlying database. To tune the underlying options for the
database read the following:
http://docs.basho.com/riak/1.0.0/tutorials/choosing-a-backend/LevelDB/
:throws DatabaseException: If an error has occurred
'''
options = self.get_open_options()
try:
error = new_native_string()
self.database = LDB.leveldb_open(options, self.filename, get_reference_to(error))
self.handle_error(error)
finally:
LDB.leveldb_options_destroy(options)
def __init__(self, database, synchronous=False):
'''
:param database: The database client to issue the write with.
:param synchronous: True to make the put to disk synchronous, False to buffer
'''
self.write_batch = LDB.leveldb_writebatch_create()
self.database = database
self.synchronous = synchronous
def get_value(self):
''' Get the current value at the iterator
:returns: The current value at the iterator
'''
size = new_native_size()
pointer = LDB.leveldb_iter_value(self.iterator, ctypes.byref(length))
return as_python_string(pointer, size)
def get(self, key, verify_checksum=False, fill_cache=True):
''' Delete the supplied value at the given key.
:param key: The key to delete the value at
:throws DatabaseException: If an error has occurred
'''
result = None
options = self.get_read_options(verify_checksum, fill_cache)
try:
error = new_native_string()
size = new_native_size()
value = LDB.leveldb_get(self.database, options, key, len(key),
get_reference_to(size), get_reference_to(error))
self.handle_error(error)
return as_python_string(value, size)
finally:
if LDB and options:
LDB.leveldb_readoptions_destroy(options)
def write(self, write_batch, synchronous=False):
''' Apply the write batch to the datbase.
:param write_batch: The write batch to apply to the database.
:param synchronous: True to make the put to disk synchronous, False to buffer
:throws DatabaseException: If an error has occurred
'''
options = LDB.leveldb_writeoptions_create()
try:
error = new_native_string()
LDB.leveldb_writeoptions_set_sync(options, synchronous)
LDB.leveldb_write(self.database, options, write_batch, get_reference_to(error))
self.handle_error(error)
finally:
if options: LDB.leveldb_writeoptions_destroy(options)
def delete(self, key, synchronous=False):
''' Delete the supplied value at the given key.
:param key: The key to delete the value at
:param synchronous: True to make the put to disk synchronous, False to buffer
:throws DatabaseException: If an error has occurred
'''
options = LDB.leveldb_writeoptions_create()
try:
error = new_native_string()
LDB.leveldb_writeoptions_set_sync(options, synchronous)
LDB.leveldb_delete(self.database, options, key, len(key), get_reference_to(error))
self.handle_error(error)
finally:
if options: LDB.leveldb_writeoptions_destroy(options)
def get_property(self, name):
''' Get an internal property value if it exists. Current
properties that are supported are:
* "leveldb.num-files-at-level<N>"
return the number of files at level <N>, where <N> is an
ASCII representation of a level number (e.g. "0").
* "leveldb.stats"
returns a multi-line string that describes statistics
about the internal operation of the DB.
:param name: The name of the property to retrieve
:returns: The value of the property if it exists, or None
'''
result = None
value = LDB.leveldb_property_value(self.database, name)
return as_python_string(value)
def close(self):
''' Close the database and underlying structures. After
this the database can no longer be used until open is called
again.
'''
if LDB and self.database:
LDB.leveldb_close(self.database)
self.database = None # prevent segfaults
if LDB and self.cache:
LDB.leveldb_cache_destroy(self.cache)
self.cache = None # prevent segfaults
if LDB and self.filter_policy:
LDB.leveldb_filterpolicy_destroy(self.filter_policy)
self.filter_policy = None # prevent segfaults
if LDB and self.environment:
LDB.leveldb_env_destroy(self.environment)
self.environment = None # prevent segfaults
def seek_to_last(self):
''' Move to the last entry in the database.
'''
LDB.leveldb_iter_seek_to_last(self.iterator)
self.assert_no_error()
return self
def __init__(self, name=b'default'):
self.name = get_string_get_callback(lambda _: name)
self.method = get_comparison_callback(self.compare)
self.destructor = get_destructor_callback(self.destruct)
self.comparator = LDB.leveldb_comparator_create(None, self.destructor, self.method, self.name)
def close(self):
''' Close the comparator and free any held resources.
'''
if LDB and self.comparator:
LDB.leveldb_comparator_destroy(self.comparator)
self.comparator = None
def get_open_options(self):
''' Get the options for opening a database as well
as creating all the relevant data-structures needed
for operation.
:returns: The database open options.
'''
options = LDB.leveldb_options_create()
self.cache = LDB.leveldb_cache_create_lru(self.options.get('cache_block_size', 8 * 1024 * 1024))
self.filter_policy = LDB.leveldb_filterpolicy_create_bloom(self.options.get('bloom_filter_size', 10))
self.environment = LDB.leveldb_create_default_env()
LDB.leveldb_options_set_create_if_missing(options, self.options.get('create_if_missing', True))
LDB.leveldb_options_set_error_if_exists(options, self.options.get('error_if_exists', False))
LDB.leveldb_options_set_paranoid_checks(options, self.options.get('paranoid_checks', False))
LDB.leveldb_options_set_write_buffer_size(options, self.options.get('write_buffer_size', 32 * 1024 * 1024))
LDB.leveldb_options_set_max_open_files(options, self.options.get('max_open_files', 256))
LDB.leveldb_options_set_block_size(options, self.options.get('block_size', 4 * 1024))
LDB.leveldb_options_set_block_restart_interval(options, self.options.get('block_restart_interval', 16))
LDB.leveldb_options_set_compression(options, self.options.get('compression', True))
LDB.leveldb_options_set_cache(options, self.cache)
LDB.leveldb_options_set_filter_policy(options, self.filter_policy)
LDB.leveldb_options_set_env(options, self.environment)
#LDB.leveldb_options_set_info_log(options, self.options.get('info_log')) just use default
if self.options.get('comparator', None):
LDB.leveldb_options_set_comparator(options, self.options.get('comparator').comparator)
return options
def is_valid(self):
''' Check if the current iterator is valid.
:returns: True if the iterator is valid, False otherwise
'''
return LDB.leveldb_iter_valid(self.iterator)
def seek_next(self):
''' Move to the next value in the database.
'''
self.assert_is_valid()
LDB.leveldb_iter_next(self.iterator)
return self
def seek_prev(self):
''' Move to the previous value in the database.
'''
self.assert_is_valid()
LDB.leveldb_iter_prev(self.iterator)
return self
def seek_to_first(self):
''' Move to the first element in the database.
'''
LDB.leveldb_iter_seek_to_first(self.iterator)
self.assert_no_error()
return self
