6844: Do not use inspect.getcallargs: it leaks memory. Passing num_retries as a posit...
[arvados.git] / sdk / python / arvados / arvfile.py
index dd48b99d39f0a1287d686761d5b1c75180ed2c9d..ce0e5e3564559c707825d9acad5717a3a5e42be0 100644 (file)
@@ -2,23 +2,32 @@ import functools
 import os
 import zlib
 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
-from .errors import KeepWriteError, AssertionError
+import re
+import logging
+
+from .errors import KeepWriteError, AssertionError, ArgumentError
 from .keep import KeepLocator
+from ._normalize_stream import normalize_stream
+from ._ranges import locators_and_ranges, replace_range, Range
+from .retry import retry_method
+
+MOD = "mod"
+WRITE = "write"
+
+_logger = logging.getLogger('arvados.arvfile')
 
 def split(path):
-    """Separate the stream name and file name in a /-separated stream path and
-    return a tuple (stream_name, file_name).
+    """split(path) -> streamname, filename
 
-    If no stream name is available, assume '.'.
+    Separate the stream name and file name in a /-separated stream path and
+    return a tuple (stream_name, file_name).  If no stream name is available,
+    assume '.'.
 
     """
     try:
@@ -27,7 +36,7 @@ def split(path):
         stream_name, file_name = '.', path
     return stream_name, file_name
 
-class FileLikeObjectBase(object):
+class _FileLikeObjectBase(object):
     def __init__(self, name, mode):
         self.name = name
         self.mode = mode
@@ -56,16 +65,9 @@ class FileLikeObjectBase(object):
         self.closed = True
 
 
-class ArvadosFileReaderBase(FileLikeObjectBase):
-    class _NameAttribute(str):
-        # The Python file API provides a plain .name attribute.
-        # Older SDK provided a name() method.
-        # This class provides both, for maximum compatibility.
-        def __call__(self):
-            return self
-
+class ArvadosFileReaderBase(_FileLikeObjectBase):
     def __init__(self, name, mode, num_retries=None):
-        super(ArvadosFileReaderBase, self).__init__(self._NameAttribute(name), mode)
+        super(ArvadosFileReaderBase, self).__init__(name, mode)
         self._filepos = 0L
         self.num_retries = num_retries
         self._readline_cache = (None, None)
@@ -80,8 +82,8 @@ class ArvadosFileReaderBase(FileLikeObjectBase):
     def decompressed_name(self):
         return re.sub('\.(bz2|gz)$', '', self.name)
 
-    @FileLikeObjectBase._before_close
-    def seek(self, pos, whence=os.SEEK_CUR):
+    @_FileLikeObjectBase._before_close
+    def seek(self, pos, whence=os.SEEK_SET):
         if whence == os.SEEK_CUR:
             pos += self._filepos
         elif whence == os.SEEK_END:
@@ -91,7 +93,7 @@ class ArvadosFileReaderBase(FileLikeObjectBase):
     def tell(self):
         return self._filepos
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def readall(self, size=2**20, num_retries=None):
         while True:
@@ -100,7 +102,7 @@ class ArvadosFileReaderBase(FileLikeObjectBase):
                 break
             yield data
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def readline(self, size=float('inf'), num_retries=None):
         cache_pos, cache_data = self._readline_cache
@@ -124,15 +126,15 @@ class ArvadosFileReaderBase(FileLikeObjectBase):
         self._readline_cache = (self.tell(), data[nextline_index:])
         return data[:nextline_index]
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def decompress(self, decompress, size, num_retries=None):
-        for segment in self.readall(size, num_retries):
+        for segment in self.readall(size, num_retries=num_retries):
             data = decompress(segment)
             if data:
                 yield data
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def readall_decompressed(self, size=2**20, num_retries=None):
         self.seek(0)
@@ -147,7 +149,7 @@ class ArvadosFileReaderBase(FileLikeObjectBase):
         else:
             return self.readall(size, num_retries=num_retries)
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def readlines(self, sizehint=float('inf'), num_retries=None):
         data = []
@@ -170,8 +172,15 @@ class ArvadosFileReaderBase(FileLikeObjectBase):
 
 
 class StreamFileReader(ArvadosFileReaderBase):
+    class _NameAttribute(str):
+        # The Python file API provides a plain .name attribute.
+        # Older SDK provided a name() method.
+        # This class provides both, for maximum compatibility.
+        def __call__(self):
+            return self
+
     def __init__(self, stream, segments, name):
-        super(StreamFileReader, self).__init__(name, 'rb', num_retries=stream.num_retries)
+        super(StreamFileReader, self).__init__(self._NameAttribute(name), 'rb', num_retries=stream.num_retries)
         self._stream = stream
         self.segments = segments
 
@@ -182,7 +191,7 @@ class StreamFileReader(ArvadosFileReaderBase):
         n = self.segments[-1]
         return n.range_start + n.range_size
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._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"""
@@ -193,14 +202,14 @@ class StreamFileReader(ArvadosFileReaderBase):
         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,
+            data = self._stream.readfrom(lr.locator+lr.segment_offset,
                                           lr.segment_size,
                                           num_retries=num_retries)
 
         self._filepos += len(data)
         return data
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def readfrom(self, start, size, num_retries=None):
         """Read up to 'size' bytes from the stream, starting at 'start'"""
@@ -209,12 +218,11 @@ class StreamFileReader(ArvadosFileReaderBase):
 
         data = []
         for lr in locators_and_ranges(self.segments, start, size):
-            data.append(self._stream._readfrom(lr.locator+lr.segment_offset, lr.segment_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))
@@ -228,9 +236,15 @@ def synchronized(orig_func):
             return orig_func(self, *args, **kwargs)
     return synchronized_wrapper
 
-class BufferBlock(object):
-    """A BufferBlock is a stand-in for a Keep block that is in the process of being
-    written.
+
+class StateChangeError(Exception):
+    def __init__(self, message, state, nextstate):
+        super(StateChangeError, self).__init__(message)
+        self.state = state
+        self.nextstate = nextstate
+
+class _BufferBlock(object):
+    """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:
@@ -252,6 +266,7 @@ class BufferBlock(object):
     WRITABLE = 0
     PENDING = 1
     COMMITTED = 2
+    ERROR = 3
 
     def __init__(self, blockid, starting_capacity, owner):
         """
@@ -269,10 +284,12 @@ class BufferBlock(object):
         self.buffer_block = bytearray(starting_capacity)
         self.buffer_view = memoryview(self.buffer_block)
         self.write_pointer = 0
-        self._state = BufferBlock.WRITABLE
+        self._state = _BufferBlock.WRITABLE
         self._locator = None
         self.owner = owner
         self.lock = threading.Lock()
+        self.wait_for_commit = threading.Event()
+        self.error = None
 
     @synchronized
     def append(self, data):
@@ -282,7 +299,7 @@ class BufferBlock(object):
         buffer, doubling capacity as needed to accomdate all the data.
 
         """
-        if self._state == BufferBlock.WRITABLE:
+        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]
@@ -294,12 +311,30 @@ class BufferBlock(object):
         else:
             raise AssertionError("Buffer block is not writable")
 
-    def set_state(self, nextstate):
-        if ((self._state == BufferBlock.WRITABLE and nextstate == BufferBlock.PENDING) or
-            (self._state == BufferBlock.PENDING and nextstate == BufferBlock.COMMITTED)):
-            self._state = nextstate
-        else:
-            raise AssertionError("Invalid state change from %s to %s" % (self.state, state))
+    STATE_TRANSITIONS = frozenset([
+            (WRITABLE, PENDING),
+            (PENDING, COMMITTED),
+            (PENDING, ERROR),
+            (ERROR, PENDING)])
+
+    @synchronized
+    def set_state(self, nextstate, val=None):
+        if (self._state, nextstate) not in self.STATE_TRANSITIONS:
+            raise StateChangeError("Invalid state change from %s to %s" % (self.state, nextstate), self.state, nextstate)
+        self._state = nextstate
+
+        if self._state == _BufferBlock.PENDING:
+            self.wait_for_commit.clear()
+
+        if self._state == _BufferBlock.COMMITTED:
+            self._locator = val
+            self.buffer_view = None
+            self.buffer_block = None
+            self.wait_for_commit.set()
+
+        if self._state == _BufferBlock.ERROR:
+            self.error = val
+            self.wait_for_commit.set()
 
     @synchronized
     def state(self):
@@ -316,6 +351,20 @@ class BufferBlock(object):
             self._locator = "%s+%i" % (hashlib.md5(self.buffer_view[0:self.write_pointer]).hexdigest(), self.size())
         return self._locator
 
+    @synchronized
+    def clone(self, new_blockid, owner):
+        if self._state == _BufferBlock.COMMITTED:
+            raise AssertionError("Cannot duplicate committed buffer block")
+        bufferblock = _BufferBlock(new_blockid, self.size(), owner)
+        bufferblock.append(self.buffer_view[0:self.size()])
+        return bufferblock
+
+    @synchronized
+    def clear(self):
+        self.owner = None
+        self.buffer_block = None
+        self.buffer_view = None
+
 
 class NoopLock(object):
     def __enter__(self):
@@ -330,37 +379,39 @@ class NoopLock(object):
     def release(self):
         pass
 
-SYNC_READONLY = 1
-SYNC_EXPLICIT = 2
-SYNC_LIVE = 3
 
 def must_be_writable(orig_func):
     @functools.wraps(orig_func)
     def must_be_writable_wrapper(self, *args, **kwargs):
-        if self.sync_mode() == SYNC_READONLY:
-            raise IOError((errno.EROFS, "Collection is read only"))
+        if not self.writable():
+            raise IOError(errno.EROFS, "Collection is read-only.")
         return orig_func(self, *args, **kwargs)
     return must_be_writable_wrapper
 
 
-class BlockManager(object):
-    """BlockManager handles buffer blocks, background block uploads, and background
-    block prefetch for a Collection of ArvadosFiles.
+class _BlockManager(object):
+    """BlockManager handles buffer blocks.
+
+    Also handles background block uploads, and background block prefetch for a
+    Collection of ArvadosFiles.
 
     """
+
+    DEFAULT_PUT_THREADS = 2
+    DEFAULT_GET_THREADS = 2
+
     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
+        self.num_put_threads = _BlockManager.DEFAULT_PUT_THREADS
+        self.num_get_threads = _BlockManager.DEFAULT_GET_THREADS
 
     @synchronized
     def alloc_bufferblock(self, blockid=None, starting_capacity=2**14, owner=None):
@@ -378,14 +429,13 @@ class BlockManager(object):
         """
         if blockid is None:
             blockid = "bufferblock%i" % len(self._bufferblocks)
-        bufferblock = BufferBlock(blockid, starting_capacity=starting_capacity, owner=owner)
+        bufferblock = _BufferBlock(blockid, starting_capacity=starting_capacity, owner=owner)
         self._bufferblocks[bufferblock.blockid] = bufferblock
         return bufferblock
 
     @synchronized
     def dup_block(self, block, owner):
-        """Create a new bufferblock in WRITABLE state, initialized with the content of
-        an existing bufferblock.
+        """Create a new bufferblock initialized with the content of an existing bufferblock.
 
         :block:
           the buffer block to copy.
@@ -395,12 +445,7 @@ class BlockManager(object):
 
         """
         new_blockid = "bufferblock%i" % len(self._bufferblocks)
-        with block.lock:
-            if block._state == BufferBlock.COMMITTED:
-                raise AssertionError("Can only duplicate a writable or pending buffer block")
-
-            bufferblock = BufferBlock(new_blockid, block.size(), owner)
-            bufferblock.append(block.buffer_view[0:block.size()])
+        bufferblock = block.clone(new_blockid, owner)
         self._bufferblocks[bufferblock.blockid] = bufferblock
         return bufferblock
 
@@ -408,6 +453,70 @@ class BlockManager(object):
     def is_bufferblock(self, locator):
         return locator in self._bufferblocks
 
+    def _commit_bufferblock_worker(self):
+        """Background uploader thread."""
+
+        while True:
+            try:
+                bufferblock = self._put_queue.get()
+                if bufferblock is None:
+                    return
+
+                loc = self._keep.put(bufferblock.buffer_view[0:bufferblock.write_pointer].tobytes())
+                bufferblock.set_state(_BufferBlock.COMMITTED, loc)
+
+            except Exception as e:
+                bufferblock.set_state(_BufferBlock.ERROR, e)
+            finally:
+                if self._put_queue is not None:
+                    self._put_queue.task_done()
+
+    @synchronized
+    def start_put_threads(self):
+        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_threads = []
+            for i in xrange(0, self.num_put_threads):
+                thread = threading.Thread(target=self._commit_bufferblock_worker)
+                self._put_threads.append(thread)
+                thread.daemon = False
+                thread.start()
+
+    def _block_prefetch_worker(self):
+        """The background downloader thread."""
+        while True:
+            try:
+                b = self._prefetch_queue.get()
+                if b is None:
+                    return
+                self._keep.get(b)
+            except Exception:
+                pass
+
+    @synchronized
+    def start_get_threads(self):
+        if self._prefetch_threads is None:
+            self._prefetch_queue = Queue.Queue()
+            self._prefetch_threads = []
+            for i in xrange(0, self.num_get_threads):
+                thread = threading.Thread(target=self._block_prefetch_worker)
+                self._prefetch_threads.append(thread)
+                thread.daemon = True
+                thread.start()
+
+
     @synchronized
     def stop_threads(self):
         """Shut down and wait for background upload and download threads to finish."""
@@ -419,7 +528,6 @@ class BlockManager(object):
                 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:
@@ -429,68 +537,60 @@ class BlockManager(object):
         self._prefetch_threads = None
         self._prefetch_queue = None
 
-    def commit_bufferblock(self, block):
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.stop_threads()
+
+    def __del__(self):
+        self.stop_threads()
+
+    def commit_bufferblock(self, block, sync):
         """Initiate a background upload of a bufferblock.
 
-        This will block if the upload queue is at capacity, otherwise it will
-        return immediately.
+        :block:
+          The block object to upload
+
+        :sync:
+          If `sync` is True, upload the block synchronously.
+          If `sync` is False, upload the block asynchronously.  This will
+          return immediately unless the upload queue is at capacity, in
+          which case it will wait on an upload queue slot.
 
         """
 
-        def commit_bufferblock_worker(self):
-            """Background uploader thread."""
-
-            while True:
-                try:
-                    bufferblock = self._put_queue.get()
-                    if bufferblock is None:
-                        return
-                    loc = self._keep.put(bufferblock.buffer_view[0:bufferblock.write_pointer].tobytes())
-                    with bufferblock.lock:
-                        bufferblock._locator = loc
-                        bufferblock.buffer_view = None
-                        bufferblock.buffer_block = None
-                        bufferblock.set_state(BufferBlock.COMMITTED)
-
-                except Exception as e:
-                    print e
-                    self._put_errors.put((bufferblock.locator(), e))
-                finally:
-                    if self._put_queue is not None:
-                        self._put_queue.task_done()
+        try:
+            # Mark the block as PENDING so to disallow any more appends.
+            block.set_state(_BufferBlock.PENDING)
+        except StateChangeError as e:
+            if e.state == _BufferBlock.PENDING and sync:
+                block.wait_for_commit.wait()
+                if block.state() == _BufferBlock.ERROR:
+                    raise block.error
+            return
 
-        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):
-                    thread = threading.Thread(target=commit_bufferblock_worker, args=(self,))
-                    self._put_threads.append(thread)
-                    thread.daemon = True
-                    thread.start()
-
-        # Mark the block as PENDING so to disallow any more appends.
-        with block.lock:
-            block.set_state(BufferBlock.PENDING)
-        self._put_queue.put(block)
+        if sync:
+            try:
+                loc = self._keep.put(block.buffer_view[0:block.write_pointer].tobytes())
+                block.set_state(_BufferBlock.COMMITTED, loc)
+            except Exception as e:
+                block.set_state(_BufferBlock.ERROR, e)
+                raise
+        else:
+            self.start_put_threads()
+            self._put_queue.put(block)
 
     @synchronized
     def get_bufferblock(self, locator):
         return self._bufferblocks.get(locator)
 
+    @synchronized
+    def delete_bufferblock(self, locator):
+        bb = self._bufferblocks[locator]
+        bb.clear()
+        del self._bufferblocks[locator]
+
     def get_block_contents(self, locator, num_retries, cache_only=False):
         """Fetch a block.
 
@@ -501,7 +601,7 @@ class BlockManager(object):
         with self.lock:
             if locator in self._bufferblocks:
                 bufferblock = self._bufferblocks[locator]
-                if bufferblock.state() != BufferBlock.COMMITTED:
+                if bufferblock.state() != _BufferBlock.COMMITTED:
                     return bufferblock.buffer_view[0:bufferblock.write_pointer].tobytes()
                 else:
                     locator = bufferblock._locator
@@ -513,30 +613,33 @@ class BlockManager(object):
     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
-        KeepWriteError() if any blocks failed to upload.
+        This is a synchronous call, and will not return until all buffer blocks
+        are uploaded.  Raises KeepWriteError() 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)
+            if v.state() != _BufferBlock.COMMITTED:
+                v.owner.flush(sync=False)
 
         with self.lock:
             if self._put_queue is not None:
                 self._put_queue.join()
 
-                if not self._put_errors.empty():
-                    err = []
-                    try:
-                        while True:
-                            err.append(self._put_errors.get(False))
-                    except Queue.Empty:
-                        pass
-                    raise KeepWriteError("Error writing some blocks", err)
+                err = []
+                for k,v in items:
+                    if v.state() == _BufferBlock.ERROR:
+                        err.append((v.locator(), v.error))
+                if err:
+                    raise KeepWriteError("Error writing some blocks", err, label="block")
+
+        for k,v in items:
+            # flush again with sync=True to remove committed bufferblocks from
+            # the segments.
+            if v.owner:
+                v.owner.flush(sync=True)
 
     def block_prefetch(self, locator):
         """Initiate a background download of a block.
@@ -551,33 +654,21 @@ class BlockManager(object):
         if not self.prefetch_enabled:
             return
 
-        def block_prefetch_worker(self):
-            """The background downloader thread."""
-            while True:
-                try:
-                    b = self._prefetch_queue.get()
-                    if b is None:
-                        return
-                    self._keep.get(b)
-                except:
-                    pass
+        if self._keep.get_from_cache(locator) is not None:
+            return
 
         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):
-                    thread = threading.Thread(target=block_prefetch_worker, args=(self,))
-                    self._prefetch_threads.append(thread)
-                    thread.daemon = True
-                    thread.start()
+
+        self.start_get_threads()
         self._prefetch_queue.put(locator)
 
 
 class ArvadosFile(object):
-    """ArvadosFile manages the underlying representation of a file in Keep as a
+    """Represent a file in a Collection.
+
+    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.
 
@@ -585,7 +676,7 @@ class ArvadosFile(object):
 
     """
 
-    def __init__(self, parent, stream=[], segments=[]):
+    def __init__(self, parent, name, stream=[], segments=[]):
         """
         ArvadosFile constructor.
 
@@ -596,24 +687,25 @@ class ArvadosFile(object):
           a list of Range objects representing segments
         """
         self.parent = parent
-        self._modified = True
+        self.name = name
+        self._committed = False
         self._segments = []
         self.lock = parent.root_collection().lock
         for s in segments:
             self._add_segment(stream, s.locator, s.range_size)
         self._current_bblock = None
 
-    def sync_mode(self):
-        return self.parent.sync_mode()
+    def writable(self):
+        return self.parent.writable()
 
     @synchronized
     def segments(self):
         return copy.copy(self._segments)
 
     @synchronized
-    def clone(self, new_parent):
+    def clone(self, new_parent, new_name):
         """Make a copy of this file."""
-        cp = ArvadosFile(new_parent)
+        cp = ArvadosFile(new_parent, new_name)
         cp.replace_contents(self)
         return cp
 
@@ -624,20 +716,20 @@ class ArvadosFile(object):
 
         map_loc = {}
         self._segments = []
-        for r in other.segments():
-            new_loc = r.locator
-            if other.parent._my_block_manager().is_bufferblock(r.locator):
-                if r.locator not in map_loc:
-                    bufferblock = other.parent._my_block_manager().get_bufferblock(r.locator)
-                    if bufferblock.state() != BufferBlock.WRITABLE:
-                        map_loc[r.locator] = bufferblock.locator()
+        for other_segment in other.segments():
+            new_loc = other_segment.locator
+            if other.parent._my_block_manager().is_bufferblock(other_segment.locator):
+                if other_segment.locator not in map_loc:
+                    bufferblock = other.parent._my_block_manager().get_bufferblock(other_segment.locator)
+                    if bufferblock.state() != _BufferBlock.WRITABLE:
+                        map_loc[other_segment.locator] = bufferblock.locator()
                     else:
-                        map_loc[r.locator] = self.parent._my_block_manager().dup_block(bufferblock, self).blockid
-                new_loc = map_loc[r.locator]
+                        map_loc[other_segment.locator] = self.parent._my_block_manager().dup_block(bufferblock, self).blockid
+                new_loc = map_loc[other_segment.locator]
 
-            self._segments.append(Range(new_loc, r.range_start, r.range_size, r.segment_offset))
+            self._segments.append(Range(new_loc, other_segment.range_start, other_segment.range_size, other_segment.segment_offset))
 
-        self._modified = True
+        self._committed = False
 
     def __eq__(self, other):
         if other is self:
@@ -673,14 +765,14 @@ class ArvadosFile(object):
         return not self.__eq__(other)
 
     @synchronized
-    def set_unmodified(self):
-        """Clear the modified flag"""
-        self._modified = False
+    def set_committed(self):
+        """Set committed flag to False"""
+        self._committed = True
 
     @synchronized
-    def modified(self):
-        """Test the modified flag"""
-        return self._modified
+    def committed(self):
+        """Get whether this is committed or not."""
+        return self._committed
 
     @must_be_writable
     @synchronized
@@ -700,7 +792,7 @@ class ArvadosFile(object):
                     # 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 = Range(r.locator, r.range_start, size - r.range_start, 0)
                     nr.segment_offset = r.segment_offset
                     new_segs.append(nr)
                     break
@@ -708,34 +800,45 @@ class ArvadosFile(object):
                     new_segs.append(r)
 
             self._segments = new_segs
-            self._modified = True
+            self._committed = False
         elif size > self.size():
-            raise IOError("truncate() does not support extending the file size")
+            raise IOError(errno.EINVAL, "truncate() does not support extending the file size")
+
+    def readfrom(self, offset, size, num_retries, exact=False):
+        """Read up to `size` bytes from the file starting at `offset`.
 
-    def readfrom(self, offset, size, num_retries):
-        """Read upto `size` bytes from the file starting at `offset`."""
+        :exact:
+         If False (default), return less data than requested if the read
+         crosses a block boundary and the next block isn't cached.  If True,
+         only return less data than requested when hitting EOF.
+        """
 
         with self.lock:
             if size == 0 or offset >= self.size():
                 return ''
-            prefetch = locators_and_ranges(self._segments, offset, size + config.KEEP_BLOCK_SIZE)
             readsegs = locators_and_ranges(self._segments, offset, size)
+            prefetch = locators_and_ranges(self._segments, offset + size, config.KEEP_BLOCK_SIZE, limit=32)
 
-        for lr in prefetch:
-            self.parent._my_block_manager().block_prefetch(lr.locator)
-
+        locs = set()
         data = []
         for lr in readsegs:
-            block = self.parent._my_block_manager().get_block_contents(lr.locator, num_retries=num_retries, cache_only=bool(data))
+            block = self.parent._my_block_manager().get_block_contents(lr.locator, num_retries=num_retries, cache_only=(bool(data) and not exact))
             if block:
-                data.append(block[lr.segment_offset:lr.segment_offset+lr.segment_size])
+                blockview = memoryview(block)
+                data.append(blockview[lr.segment_offset:lr.segment_offset+lr.segment_size].tobytes())
+                locs.add(lr.locator)
             else:
                 break
+
+        for lr in prefetch:
+            if lr.locator not in locs:
+                self.parent._my_block_manager().block_prefetch(lr.locator)
+                locs.add(lr.locator)
+
         return ''.join(data)
 
-    def _repack_writes(self):
-        """Test if the buffer block has more data than is referenced by actual
-        segments.
+    def _repack_writes(self, num_retries):
+        """Test if the buffer block has more data than 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
@@ -752,9 +855,10 @@ class ArvadosFile(object):
         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.
+            contents = self.parent._my_block_manager().get_block_contents(self._current_bblock.blockid, num_retries)
             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())
+                new_bb.append(contents[t.segment_offset:t.segment_offset+t.range_size])
                 t.segment_offset = new_bb.size() - t.range_size
 
             self._current_bblock = new_bb
@@ -775,37 +879,80 @@ class ArvadosFile(object):
             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))
+            # Chunk it up into smaller writes
+            n = 0
+            dataview = memoryview(data)
+            while n < len(data):
+                self.writeto(offset+n, dataview[n:n + config.KEEP_BLOCK_SIZE].tobytes(), num_retries)
+                n += config.KEEP_BLOCK_SIZE
+            return
 
-        self._modified = True
+        self._committed = False
 
-        if self._current_bblock is None or self._current_bblock.state() != BufferBlock.WRITABLE:
+        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()
+            self._repack_writes(num_retries)
             if (self._current_bblock.size() + len(data)) > config.KEEP_BLOCK_SIZE:
-                self.parent._my_block_manager().commit_bufferblock(self._current_bblock)
+                self.parent._my_block_manager().commit_bufferblock(self._current_bblock, sync=False)
                 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))
 
+        self.parent.notify(WRITE, self.parent, self.name, (self, self))
+
+        return len(data)
+
+    @synchronized
+    def flush(self, sync=True, num_retries=0):
+        """Flush the current bufferblock to Keep.
+
+        :sync:
+          If True, commit block synchronously, wait until buffer block has been written.
+          If False, commit block asynchronously, return immediately after putting block into
+          the keep put queue.
+        """
+        if self.committed():
+            return
+
+        if self._current_bblock and self._current_bblock.state() != _BufferBlock.COMMITTED:
+            if self._current_bblock.state() == _BufferBlock.WRITABLE:
+                self._repack_writes(num_retries)
+            self.parent._my_block_manager().commit_bufferblock(self._current_bblock, sync=sync)
+
+        if sync:
+            to_delete = set()
+            for s in self._segments:
+                bb = self.parent._my_block_manager().get_bufferblock(s.locator)
+                if bb:
+                    if bb.state() != _BufferBlock.COMMITTED:
+                        self.parent._my_block_manager().commit_bufferblock(self._current_bblock, sync=True)
+                    to_delete.add(s.locator)
+                    s.locator = bb.locator()
+            for s in to_delete:
+               self.parent._my_block_manager().delete_bufferblock(s)
+
+        self.parent.notify(MOD, self.parent, self.name, (self, self))
+
     @must_be_writable
     @synchronized
     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)
+        """Add a segment to the end of the file.
+
+        `pos` and `offset` reference a section of the stream described by
+        `blocks` (a list of Range objects)
 
         """
         self._add_segment(blocks, pos, size)
 
     def _add_segment(self, blocks, pos, size):
         """Internal implementation of add_segment."""
-        self._modified = True
+        self._committed = False
         for lr in locators_and_ranges(blocks, pos, size):
-            last = self._segments[-1] if self._segments else Range(0, 0, 0)
+            last = self._segments[-1] if self._segments else Range(0, 0, 0, 0)
             r = Range(lr.locator, last.range_start+last.range_size, lr.segment_size, lr.segment_offset)
             self._segments.append(r)
 
@@ -818,6 +965,33 @@ class ArvadosFile(object):
         else:
             return 0
 
+    @synchronized
+    def manifest_text(self, stream_name=".", portable_locators=False, normalize=False):
+        buf = ""
+        filestream = []
+        for segment in self.segments:
+            loc = segment.locator
+            if loc.startswith("bufferblock"):
+                loc = self._bufferblocks[loc].calculate_locator()
+            if portable_locators:
+                loc = KeepLocator(loc).stripped()
+            filestream.append(LocatorAndRange(loc, locator_block_size(loc),
+                                 segment.segment_offset, segment.range_size))
+        buf += ' '.join(normalize_stream(stream_name, {stream_name: filestream}))
+        buf += "\n"
+        return buf
+
+    @must_be_writable
+    @synchronized
+    def _reparent(self, newparent, newname):
+        self._committed = False
+        self.flush(sync=True)
+        self.parent.remove(self.name)
+        self.parent = newparent
+        self.name = newname
+        self.lock = self.parent.root_collection().lock
+
+
 class ArvadosFileReader(ArvadosFileReaderBase):
     """Wraps ArvadosFile in a file-like object supporting reading only.
 
@@ -826,25 +1000,44 @@ class ArvadosFileReader(ArvadosFileReaderBase):
 
     """
 
-    def __init__(self, arvadosfile, name, mode="r", num_retries=None):
-        super(ArvadosFileReader, self).__init__(name, mode, num_retries=num_retries)
+    def __init__(self, arvadosfile, num_retries=None):
+        super(ArvadosFileReader, self).__init__(arvadosfile.name, "r", num_retries=num_retries)
         self.arvadosfile = arvadosfile
 
     def size(self):
         return self.arvadosfile.size()
 
-    @FileLikeObjectBase._before_close
+    def stream_name(self):
+        return self.arvadosfile.parent.stream_name()
+
+    @_FileLikeObjectBase._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)
-        self._filepos += len(data)
-        return data
+    def read(self, size=None, num_retries=None):
+        """Read up to `size` bytes from the file and return the result.
 
-    @FileLikeObjectBase._before_close
+        Starts at the current file position.  If `size` is None, read the
+        entire remainder of the file.
+        """
+        if size is None:
+            data = []
+            rd = self.arvadosfile.readfrom(self._filepos, config.KEEP_BLOCK_SIZE, num_retries)
+            while rd:
+                data.append(rd)
+                self._filepos += len(rd)
+                rd = self.arvadosfile.readfrom(self._filepos, config.KEEP_BLOCK_SIZE, num_retries)
+            return ''.join(data)
+        else:
+            data = self.arvadosfile.readfrom(self._filepos, size, num_retries, exact=True)
+            self._filepos += len(data)
+            return data
+
+    @_FileLikeObjectBase._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."""
+        """Read up to `size` bytes from the stream, starting at the specified file offset.
+
+        This method does not change the file position.
+        """
         return self.arvadosfile.readfrom(offset, size, num_retries)
 
     def flush(self):
@@ -859,10 +1052,11 @@ class ArvadosFileWriter(ArvadosFileReader):
 
     """
 
-    def __init__(self, arvadosfile, name, mode, num_retries=None):
-        super(ArvadosFileWriter, self).__init__(arvadosfile, name, mode, num_retries=num_retries)
+    def __init__(self, arvadosfile, mode, num_retries=None):
+        super(ArvadosFileWriter, self).__init__(arvadosfile, num_retries=num_retries)
+        self.mode = mode
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def write(self, data, num_retries=None):
         if self.mode[0] == "a":
@@ -870,13 +1064,15 @@ class ArvadosFileWriter(ArvadosFileReader):
         else:
             self.arvadosfile.writeto(self._filepos, data, num_retries)
             self._filepos += len(data)
+        return len(data)
 
-    @FileLikeObjectBase._before_close
+    @_FileLikeObjectBase._before_close
     @retry_method
     def writelines(self, seq, num_retries=None):
         for s in seq:
-            self.write(s, num_retries)
+            self.write(s, num_retries=num_retries)
 
+    @_FileLikeObjectBase._before_close
     def truncate(self, size=None):
         if size is None:
             size = self._filepos
@@ -884,6 +1080,11 @@ class ArvadosFileWriter(ArvadosFileReader):
         if self._filepos > self.size():
             self._filepos = self.size()
 
+    @_FileLikeObjectBase._before_close
+    def flush(self):
+        self.arvadosfile.flush()
+
     def close(self):
-        if self.arvadosfile.parent.sync_mode() == SYNC_LIVE:
-            self.arvadosfile.parent.root_collection().save()
+        if not self.closed:
+            self.flush()
+            super(ArvadosFileWriter, self).close()