import bz2
from .ranges import *
from arvados.retry import retry_method
+import config
+import hashlib
+import hashlib
+import threading
+import Queue
+import copy
+import errno
def split(path):
"""split(path) -> streamname, filename
self.closed = True
-class StreamFileReader(ArvadosFileBase):
+class ArvadosFileReaderBase(ArvadosFileBase):
class _NameAttribute(str):
# The Python file API provides a plain .name attribute.
# Older SDK provided a name() method.
def __call__(self):
return self
-
- def __init__(self, stream, segments, name):
- super(StreamFileReader, self).__init__(self._NameAttribute(name), 'rb')
- self._stream = stream
- self.segments = segments
+ def __init__(self, name, mode, num_retries=None):
+ super(ArvadosFileReaderBase, self).__init__(self._NameAttribute(name), mode)
self._filepos = 0L
- self.num_retries = stream.num_retries
+ self.num_retries = num_retries
self._readline_cache = (None, None)
def __iter__(self):
def decompressed_name(self):
return re.sub('\.(bz2|gz)$', '', self.name)
- def stream_name(self):
- return self._stream.name()
-
@ArvadosFileBase._before_close
def seek(self, pos, whence=os.SEEK_CUR):
if whence == os.SEEK_CUR:
pos += self._filepos
elif whence == os.SEEK_END:
pos += self.size()
- self._filepos = min(max(pos, 0L), self._size())
+ self._filepos = min(max(pos, 0L), self.size())
def tell(self):
return self._filepos
- def _size(self):
- n = self.segments[-1]
- return n[OFFSET] + n[BLOCKSIZE]
-
- def size(self):
- return self._size()
-
- @ArvadosFileBase._before_close
- @retry_method
- def read(self, size, num_retries=None):
- """Read up to 'size' bytes from the stream, starting at the current file position"""
- if size == 0:
- return ''
-
- data = ''
- available_chunks = locators_and_ranges(self.segments, self._filepos, size)
- if available_chunks:
- locator, blocksize, segmentoffset, segmentsize = available_chunks[0]
- data = self._stream._readfrom(locator+segmentoffset, segmentsize,
- num_retries=num_retries)
-
- self._filepos += len(data)
- return data
-
- @ArvadosFileBase._before_close
- @retry_method
- def readfrom(self, start, size, num_retries=None):
- """Read up to 'size' bytes from the stream, starting at 'start'"""
- if size == 0:
- return ''
-
- data = []
- for locator, blocksize, segmentoffset, segmentsize in locators_and_ranges(self.segments, start, size):
- data.append(self._stream._readfrom(locator+segmentoffset, segmentsize,
- num_retries=num_retries))
- return ''.join(data)
-
@ArvadosFileBase._before_close
@retry_method
def readall(self, size=2**20, num_retries=None):
break
return ''.join(data).splitlines(True)
- def as_manifest(self):
- manifest_text = ['.']
- manifest_text.extend([d[LOCATOR] for d in self._stream._data_locators])
- manifest_text.extend(["{}:{}:{}".format(seg[LOCATOR], seg[BLOCKSIZE], self.name().replace(' ', '\\040')) for seg in self.segments])
- return arvados.CollectionReader(' '.join(manifest_text) + '\n').manifest_text(normalize=True)
+ def size(self):
+ raise NotImplementedError()
+
+ def read(self, size, num_retries=None):
+ raise NotImplementedError()
+
+ def readfrom(self, start, size, num_retries=None):
+ raise NotImplementedError()
-class StreamFileWriter(StreamFileReader):
+class StreamFileReader(ArvadosFileReaderBase):
def __init__(self, stream, segments, name):
- super(StreamFileWriter, self).__init__(stream, segments, name)
- self.mode = 'wb'
+ super(StreamFileReader, self).__init__(name, 'rb', num_retries=stream.num_retries)
+ self._stream = stream
+ self.segments = segments
- # wrap superclass methods in mutex
- def _proxy_method(name):
- method = getattr(StreamFileReader, name)
- @functools.wraps(method, ('__name__', '__doc__'))
- def wrapper(self, *args, **kwargs):
- with self._stream.mutex:
- return method(self, *args, **kwargs)
- return wrapper
+ def stream_name(self):
+ return self._stream.name()
- for _method_name in ['__iter__', 'seek', 'tell', 'size', 'read', 'readfrom', 'readall', 'readline', 'decompress', 'readall_decompressed', 'readlines', 'as_manifest']:
- locals()[_method_name] = _proxy_method(_method_name)
+ def size(self):
+ n = self.segments[-1]
+ return n.range_start + n.range_size
- def truncate(self, size=None):
- with self._stream.mutex:
- if size is None:
- size = self._filepos
-
- segs = locators_and_ranges(self.segments, 0, size)
-
- newstream = []
- self.segments = []
- streamoffset = 0L
- fileoffset = 0L
-
- for seg in segs:
- for locator, blocksize, segmentoffset, segmentsize in locators_and_ranges(self._stream._data_locators, seg[LOCATOR]+seg[OFFSET], seg[SEGMENTSIZE]):
- newstream.append([locator, blocksize, streamoffset])
- self.segments.append([streamoffset+segmentoffset, segmentsize, fileoffset])
- streamoffset += blocksize
- fileoffset += segmentsize
- if len(newstream) == 0:
- newstream.append(config.EMPTY_BLOCK_LOCATOR)
- self.segments.append([0, 0, 0])
- self._stream._data_locators = newstream
- if self._filepos > fileoffset:
- self._filepos = fileoffset
-
- def _writeto(self, offset, data):
- self._stream._append(data)
- replace_range(self.segments, self._filepos, len(data), self._stream._size()-len(data))
-
- def writeto(self, offset, data):
- with self._stream.mutex:
- self._writeto(offset, data)
-
- def write(self, data):
- with self._stream.mutex:
- self._writeto(self._filepos, data)
- self._filepos += len(data)
+ @ArvadosFileBase._before_close
+ @retry_method
+ def read(self, size, num_retries=None):
+ """Read up to 'size' bytes from the stream, starting at the current file position"""
+ if size == 0:
+ return ''
+
+ data = ''
+ available_chunks = locators_and_ranges(self.segments, self._filepos, size)
+ if available_chunks:
+ lr = available_chunks[0]
+ data = self._stream._readfrom(lr.locator+lr.segment_offset,
+ lr.segment_size,
+ num_retries=num_retries)
- def writelines(self, seq):
- with self._stream.mutex:
- for s in seq:
- self._writeto(self._filepos, s)
- self._filepos += len(s)
+ self._filepos += len(data)
+ return data
+
+ @ArvadosFileBase._before_close
+ @retry_method
+ def readfrom(self, start, size, num_retries=None):
+ """Read up to 'size' bytes from the stream, starting at 'start'"""
+ if size == 0:
+ return ''
+
+ data = []
+ for lr in locators_and_ranges(self.segments, start, size):
+ data.append(self._stream._readfrom(lr.locator+lr.segment_offset, lr.segment_size,
+ num_retries=num_retries))
+ return ''.join(data)
+
+ def as_manifest(self):
+ from stream import normalize_stream
+ segs = []
+ for r in self.segments:
+ segs.extend(self._stream.locators_and_ranges(r.locator, r.range_size))
+ return " ".join(normalize_stream(".", {self.name: segs})) + "\n"
+
+
+class BufferBlock(object):
+ """
+ A BufferBlock is a stand-in for a Keep block that is in the process of being
+ written. Writers can append to it, get the size, and compute the Keep locator.
+
+ There are three valid states:
+
+ WRITABLE
+ Can append to block.
+
+ PENDING
+ Block is in the process of being uploaded to Keep, append is an error.
+
+ COMMITTED
+ The block has been written to Keep, its internal buffer has been
+ released, fetching the block will fetch it via keep client (since we
+ discarded the internal copy), and identifiers referring to the BufferBlock
+ can be replaced with the block locator.
+ """
+ WRITABLE = 0
+ PENDING = 1
+ COMMITTED = 2
+
+ def __init__(self, blockid, starting_capacity, owner):
+ """
+ :blockid:
+ the identifier for this block
+
+ :starting_capacity:
+ the initial buffer capacity
+
+ :owner:
+ ArvadosFile that owns this block
+ """
+ self.blockid = blockid
+ self.buffer_block = bytearray(starting_capacity)
+ self.buffer_view = memoryview(self.buffer_block)
+ self.write_pointer = 0
+ self.state = BufferBlock.WRITABLE
+ self._locator = None
+ self.owner = owner
+
+ def append(self, data):
+ """
+ Append some data to the buffer. Only valid if the block is in WRITABLE
+ state. Implements an expanding buffer, doubling capacity as needed to
+ accomdate all the data.
+ """
+ if self.state == BufferBlock.WRITABLE:
+ while (self.write_pointer+len(data)) > len(self.buffer_block):
+ new_buffer_block = bytearray(len(self.buffer_block) * 2)
+ new_buffer_block[0:self.write_pointer] = self.buffer_block[0:self.write_pointer]
+ self.buffer_block = new_buffer_block
+ self.buffer_view = memoryview(self.buffer_block)
+ self.buffer_view[self.write_pointer:self.write_pointer+len(data)] = data
+ self.write_pointer += len(data)
+ self._locator = None
+ else:
+ raise AssertionError("Buffer block is not writable")
+
+ def size(self):
+ """Amount of data written to the buffer"""
+ return self.write_pointer
+
+ def locator(self):
+ """The Keep locator for this buffer's contents."""
+ if self._locator is None:
+ self._locator = "%s+%i" % (hashlib.md5(self.buffer_view[0:self.write_pointer]).hexdigest(), self.size())
+ return self._locator
+
+
+class AsyncKeepWriteErrors(Exception):
+ """
+ Roll up one or more Keep write exceptions (generated by background
+ threads) into a single one.
+ """
+ def __init__(self, errors):
+ self.errors = errors
+
+ def __repr__(self):
+ return "\n".join(self.errors)
+
+def _synchronized(orig_func):
+ @functools.wraps(orig_func)
+ def wrapper(self, *args, **kwargs):
+ with self.lock:
+ return orig_func(self, *args, **kwargs)
+ return wrapper
+
+class NoopLock(object):
+ def __enter__(self):
+ return self
+
+ def __exit__(self, exc_type, exc_value, traceback):
+ pass
+
+ def acquire(self, blocking=False):
+ pass
+
+ def release(self):
+ pass
+
+SYNC_READONLY = 1
+SYNC_EXPLICIT = 2
+SYNC_LIVE = 3
+
+def _must_be_writable(orig_func):
+ # Decorator for methods that read actual Collection data.
+ @functools.wraps(orig_func)
+ def wrapper(self, *args, **kwargs):
+ if self.sync_mode() == SYNC_READONLY:
+ raise IOError((errno.EROFS, "Collection is read only"))
+ return orig_func(self, *args, **kwargs)
+ return wrapper
+
+
+class BlockManager(object):
+ """
+ BlockManager handles buffer blocks, background block uploads, and
+ background block prefetch for a Collection of ArvadosFiles.
+ """
+ def __init__(self, keep):
+ """keep: KeepClient object to use"""
+ self._keep = keep
+ self._bufferblocks = {}
+ self._put_queue = None
+ self._put_errors = None
+ self._put_threads = None
+ self._prefetch_queue = None
+ self._prefetch_threads = None
+ self.lock = threading.Lock()
+ self.prefetch_enabled = True
+ self.num_put_threads = 2
+ self.num_get_threads = 2
+
+ @_synchronized
+ def alloc_bufferblock(self, blockid=None, starting_capacity=2**14, owner=None):
+ """
+ Allocate a new, empty bufferblock in WRITABLE state and return it.
+
+ :blockid:
+ optional block identifier, otherwise one will be automatically assigned
+
+ :starting_capacity:
+ optional capacity, otherwise will use default capacity
+
+ :owner:
+ ArvadosFile that owns this block
+ """
+ if blockid is None:
+ blockid = "bufferblock%i" % len(self._bufferblocks)
+ bb = BufferBlock(blockid, starting_capacity=starting_capacity, owner=owner)
+ self._bufferblocks[bb.blockid] = bb
+ return bb
+
+ @_synchronized
+ def dup_block(self, blockid, owner):
+ """
+ Create a new bufferblock in WRITABLE state, initialized with the content of an existing bufferblock.
+
+ :blockid:
+ the block to copy. May be an existing buffer block id.
+
+ :owner:
+ ArvadosFile that owns the new block
+ """
+ new_blockid = "bufferblock%i" % len(self._bufferblocks)
+ block = self._bufferblocks[blockid]
+ bb = BufferBlock(new_blockid, len(block), owner)
+ bb.append(block)
+ self._bufferblocks[bb.blockid] = bb
+ return bb
+
+ @_synchronized
+ def is_bufferblock(self, id):
+ return id in self._bufferblocks
+
+ @_synchronized
+ def stop_threads(self):
+ """
+ Shut down and wait for background upload and download threads to finish.
+ """
+ if self._put_threads is not None:
+ for t in self._put_threads:
+ self._put_queue.put(None)
+ for t in self._put_threads:
+ t.join()
+ self._put_threads = None
+ self._put_queue = None
+ self._put_errors = None
+
+ if self._prefetch_threads is not None:
+ for t in self._prefetch_threads:
+ self._prefetch_queue.put(None)
+ for t in self._prefetch_threads:
+ t.join()
+ self._prefetch_threads = None
+ self._prefetch_queue = None
+
+ def commit_bufferblock(self, block):
+ """
+ Initiate a background upload of a bufferblock. This will block if the
+ upload queue is at capacity, otherwise it will return immediately.
+ """
+
+ def worker(self):
+ """
+ Background uploader thread.
+ """
+ while True:
+ try:
+ b = self._put_queue.get()
+ if b is None:
+ return
+ b._locator = self._keep.put(b.buffer_view[0:b.write_pointer].tobytes())
+ b.state = BufferBlock.COMMITTED
+ b.buffer_view = None
+ b.buffer_block = None
+ except Exception as e:
+ print e
+ self._put_errors.put(e)
+ finally:
+ if self._put_queue is not None:
+ self._put_queue.task_done()
+
+ with self.lock:
+ if self._put_threads is None:
+ # Start uploader threads.
+
+ # If we don't limit the Queue size, the upload queue can quickly
+ # grow to take up gigabytes of RAM if the writing process is
+ # generating data more quickly than it can be send to the Keep
+ # servers.
+ #
+ # With two upload threads and a queue size of 2, this means up to 4
+ # blocks pending. If they are full 64 MiB blocks, that means up to
+ # 256 MiB of internal buffering, which is the same size as the
+ # default download block cache in KeepClient.
+ self._put_queue = Queue.Queue(maxsize=2)
+ self._put_errors = Queue.Queue()
+
+ self._put_threads = []
+ for i in xrange(0, self.num_put_threads):
+ t = threading.Thread(target=worker, args=(self,))
+ self._put_threads.append(t)
+ t.daemon = True
+ t.start()
+
+ # Mark the block as PENDING so to disallow any more appends.
+ block.state = BufferBlock.PENDING
+ self._put_queue.put(block)
+
+ def get_block(self, locator, num_retries, cache_only=False):
+ """
+ Fetch a block. First checks to see if the locator is a BufferBlock and
+ return that, if not, passes the request through to KeepClient.get().
+ """
+ with self.lock:
+ if locator in self._bufferblocks:
+ bb = self._bufferblocks[locator]
+ if bb.state != BufferBlock.COMMITTED:
+ return bb.buffer_view[0:bb.write_pointer].tobytes()
+ else:
+ locator = bb._locator
+ return self._keep.get(locator, num_retries=num_retries, cache_only=cache_only)
+
+ def commit_all(self):
+ """
+ Commit all outstanding buffer blocks. Unlike commit_bufferblock(), this
+ is a synchronous call, and will not return until all buffer blocks are
+ uploaded. Raises AsyncKeepWriteErrors() if any blocks failed to
+ upload.
+ """
+ with self.lock:
+ items = self._bufferblocks.items()
+
+ for k,v in items:
+ if v.state == BufferBlock.WRITABLE:
+ self.commit_bufferblock(v)
+
+ with self.lock:
+ if self._put_queue is not None:
+ self._put_queue.join()
+ if not self._put_errors.empty():
+ e = []
+ try:
+ while True:
+ e.append(self._put_errors.get(False))
+ except Queue.Empty:
+ pass
+ raise AsyncKeepWriteErrors(e)
+
+ def block_prefetch(self, locator):
+ """
+ Initiate a background download of a block. This assumes that the
+ underlying KeepClient implements a block cache, so repeated requests
+ for the same block will not result in repeated downloads (unless the
+ block is evicted from the cache.) This method does not block.
+ """
+
+ if not self.prefetch_enabled:
+ return
+
+ def worker(self):
+ """Background downloader thread."""
+ while True:
+ try:
+ b = self._prefetch_queue.get()
+ if b is None:
+ return
+ self._keep.get(b)
+ except:
+ pass
+
+ with self.lock:
+ if locator in self._bufferblocks:
+ return
+ if self._prefetch_threads is None:
+ self._prefetch_queue = Queue.Queue()
+ self._prefetch_threads = []
+ for i in xrange(0, self.num_get_threads):
+ t = threading.Thread(target=worker, args=(self,))
+ self._prefetch_threads.append(t)
+ t.daemon = True
+ t.start()
+ self._prefetch_queue.put(locator)
+
+
+class ArvadosFile(object):
+ """
+ ArvadosFile manages the underlying representation of a file in Keep as a sequence of
+ segments spanning a set of blocks, and implements random read/write access.
+ """
+
+ def __init__(self, parent, stream=[], segments=[]):
+ """
+ :stream:
+ a list of Range objects representing a block stream
+
+ :segments:
+ a list of Range objects representing segments
+ """
+ self.parent = parent
+ self._modified = True
+ self._segments = []
+ for s in segments:
+ self._add_segment(stream, s.locator, s.range_size)
+ self._current_bblock = None
+ if parent.sync_mode() == SYNC_READONLY:
+ self.lock = NoopLock()
+ else:
+ self.lock = threading.Lock()
+
+ def sync_mode(self):
+ return self.parent.sync_mode()
+
+ @_synchronized
+ def segments(self):
+ return copy.copy(self._segments)
+
+ @_synchronized
+ def clone(self, new_parent):
+ """Make a copy of this file."""
+ cp = ArvadosFile(new_parent)
+ cp._modified = False
+
+ map_loc = {}
+ for r in self._segments:
+ new_loc = r.locator
+ if self.parent._my_block_manager().is_bufferblock(r.locator):
+ if r.locator not in map_loc:
+ map_loc[r.locator] = self.parent._my_block_manager().dup_block(r.locator, cp).blockid
+ new_loc = map_loc[r.locator]
+
+ cp._segments.append(Range(new_loc, r.range_start, r.range_size, r.segment_offset))
+
+ return cp
+
+ @_synchronized
+ def __eq__(self, other):
+ if type(other) != ArvadosFile:
+ return False
+ return self._segments == other.segments()
+
+ def __neq__(self, other):
+ return not self.__eq__(other)
+
+ @_synchronized
+ def set_unmodified(self):
+ """Clear the modified flag"""
+ self._modified = False
+
+ @_synchronized
+ def modified(self):
+ """Test the modified flag"""
+ return self._modified
+
+ @_must_be_writable
+ @_synchronized
+ def truncate(self, size):
+ """
+ Adjust the size of the file. If `size` is less than the size of the file,
+ the file contents after `size` will be discarded. If `size` is greater
+ than the current size of the file, an IOError will be raised.
+ """
+ if size < self._size():
+ new_segs = []
+ for r in self._segments:
+ range_end = r.range_start+r.range_size
+ if r.range_start >= size:
+ # segment is past the trucate size, all done
+ break
+ elif size < range_end:
+ nr = Range(r.locator, r.range_start, size - r.range_start)
+ nr.segment_offset = r.segment_offset
+ new_segs.append(nr)
+ break
+ else:
+ new_segs.append(r)
+
+ self._segments = new_segs
+ self._modified = True
+ elif size > self._size():
+ raise IOError("truncate() does not support extending the file size")
+
+ @_synchronized
+ def readfrom(self, offset, size, num_retries):
+ """
+ read upto `size` bytes from the file starting at `offset`.
+ """
+ if size == 0 or offset >= self._size():
+ return ''
+ data = []
+
+ for lr in locators_and_ranges(self._segments, offset, size + config.KEEP_BLOCK_SIZE):
+ self.parent._my_block_manager().block_prefetch(lr.locator)
+
+ for lr in locators_and_ranges(self._segments, offset, size):
+ d = self.parent._my_block_manager().get_block(lr.locator, num_retries=num_retries, cache_only=bool(data))
+ if d:
+ data.append(d[lr.segment_offset:lr.segment_offset+lr.segment_size])
+ else:
+ break
+ return ''.join(data)
+
+ def _repack_writes(self):
+ """
+ Test if the buffer block has more data than is referenced by actual segments
+ (this happens when a buffered write over-writes a file range written in
+ a previous buffered write). Re-pack the buffer block for efficiency
+ and to avoid leaking information.
+ """
+ segs = self._segments
+
+ # Sum up the segments to get the total bytes of the file referencing
+ # into the buffer block.
+ bufferblock_segs = [s for s in segs if s.locator == self._current_bblock.blockid]
+ write_total = sum([s.range_size for s in bufferblock_segs])
+
+ if write_total < self._current_bblock.size():
+ # There is more data in the buffer block than is actually accounted for by segments, so
+ # re-pack into a new buffer by copying over to a new buffer block.
+ new_bb = self.parent._my_block_manager().alloc_bufferblock(self._current_bblock.blockid, starting_capacity=write_total, owner=self)
+ for t in bufferblock_segs:
+ new_bb.append(self._current_bblock.buffer_view[t.segment_offset:t.segment_offset+t.range_size].tobytes())
+ t.segment_offset = new_bb.size() - t.range_size
+
+ self._current_bblock = new_bb
+
+ @_must_be_writable
+ @_synchronized
+ def writeto(self, offset, data, num_retries):
+ """
+ Write `data` to the file starting at `offset`. This will update
+ existing bytes and/or extend the size of the file as necessary.
+ """
+ if len(data) == 0:
+ return
+
+ if offset > self._size():
+ raise ArgumentError("Offset is past the end of the file")
+
+ if len(data) > config.KEEP_BLOCK_SIZE:
+ raise ArgumentError("Please append data in chunks smaller than %i bytes (config.KEEP_BLOCK_SIZE)" % (config.KEEP_BLOCK_SIZE))
+
+ self._modified = True
+
+ if self._current_bblock is None or self._current_bblock.state != BufferBlock.WRITABLE:
+ self._current_bblock = self.parent._my_block_manager().alloc_bufferblock(owner=self)
+
+ if (self._current_bblock.size() + len(data)) > config.KEEP_BLOCK_SIZE:
+ self._repack_writes()
+ if (self._current_bblock.size() + len(data)) > config.KEEP_BLOCK_SIZE:
+ self.parent._my_block_manager().commit_bufferblock(self._current_bblock)
+ self._current_bblock = self.parent._my_block_manager().alloc_bufferblock(owner=self)
+
+ self._current_bblock.append(data)
+
+ replace_range(self._segments, offset, len(data), self._current_bblock.blockid, self._current_bblock.write_pointer - len(data))
+
+ @_must_be_writable
+ @_synchronized
+ def add_segment(self, blocks, pos, size):
+ # Synchronized public api, see _add_segment
+ self._add_segment(blocks, pos, size)
+
+ def _add_segment(self, blocks, pos, size):
+ """
+ Add a segment to the end of the file, with `pos` and `offset` referencing a
+ section of the stream described by `blocks` (a list of Range objects)
+ """
+ self._modified = True
+ for lr in locators_and_ranges(blocks, pos, size):
+ last = self._segments[-1] if self._segments else Range(0, 0, 0)
+ r = Range(lr.locator, last.range_start+last.range_size, lr.segment_size, lr.segment_offset)
+ self._segments.append(r)
+
+ def _size(self):
+ """Get the file size"""
+ if self._segments:
+ n = self._segments[-1]
+ return n.range_start + n.range_size
+ else:
+ return 0
+
+ @_synchronized
+ def size(self):
+ """Get the file size"""
+ return self._size()
+
+class ArvadosFileReader(ArvadosFileReaderBase):
+ def __init__(self, arvadosfile, name, mode="r", num_retries=None):
+ super(ArvadosFileReader, self).__init__(name, mode, num_retries=num_retries)
+ self.arvadosfile = arvadosfile
+
+ def size(self):
+ return self.arvadosfile.size()
+
+ @ArvadosFileBase._before_close
+ @retry_method
+ def read(self, size, num_retries=None):
+ """Read up to `size` bytes from the stream, starting at the current file position"""
+ data = self.arvadosfile.readfrom(self._filepos, size, num_retries=num_retries)
+ self._filepos += len(data)
+ return data
+
+ @ArvadosFileBase._before_close
+ @retry_method
+ def readfrom(self, offset, size, num_retries=None):
+ """Read up to `size` bytes from the stream, starting at the current file position"""
+ return self.arvadosfile.readfrom(offset, size, num_retries)
def flush(self):
pass
+
+
+class ArvadosFileWriter(ArvadosFileReader):
+ def __init__(self, arvadosfile, name, mode, num_retries=None):
+ super(ArvadosFileWriter, self).__init__(arvadosfile, name, mode, num_retries=num_retries)
+
+ @ArvadosFileBase._before_close
+ @retry_method
+ def write(self, data, num_retries=None):
+ if self.mode[0] == "a":
+ self.arvadosfile.writeto(self.size(), data)
+ else:
+ self.arvadosfile.writeto(self._filepos, data, num_retries)
+ self._filepos += len(data)
+
+ @ArvadosFileBase._before_close
+ @retry_method
+ def writelines(self, seq, num_retries=None):
+ for s in seq:
+ self.write(s)
+
+ def truncate(self, size=None):
+ if size is None:
+ size = self._filepos
+ self.arvadosfile.truncate(size)
+ if self._filepos > self.size():
+ self._filepos = self.size()
projects / arvados.git / blobdiff