upload: use WriteBucketProxy_v2 when uploading a large file (with shares larger than 4GiB). This finally closes #346. I think we can now handle immutable files up to 48EiB.

src/allmydata/immutable/layout.py

@@ -66,17 +66,25 @@ limitations described in #346.
     : rest of share is the same as v1, above
 ...   ...
 ?   : start of uri_extension_length (eight-byte big-endian value)
+?   : start of uri_extension
 """
 
-# Footnote 1: as of Tahoe v1.3.0 these fields are not used when reading, but they are still
-# provided when writing so that older versions of Tahoe can read them.
+# Footnote 1: as of Tahoe v1.3.0 these fields are not used when reading, but
+# they are still provided when writing so that older versions of Tahoe can
+# read them.
 
-def allocated_size(data_size, num_segments, num_share_hashes,
-                   uri_extension_size_max):
-    wbp = WriteBucketProxy(None, data_size, 0, num_segments, num_share_hashes,
-                           uri_extension_size_max, None)
-    uri_extension_starts_at = wbp._offsets['uri_extension']
-    return uri_extension_starts_at + wbp.fieldsize + uri_extension_size_max
+def make_write_bucket_proxy(rref, data_size, block_size, num_segments,
+                            num_share_hashes, uri_extension_size_max, nodeid):
+    # Use layout v1 for small files, so they'll be readable by older versions
+    # (<tahoe-1.3.0). Use layout v2 for large files; they'll only be readable
+    # by tahoe-1.3.0 or later.
+    try:
+        wbp = WriteBucketProxy(rref, data_size, block_size, num_segments,
+                               num_share_hashes, uri_extension_size_max, nodeid)
+    except FileTooLargeError:
+        wbp = WriteBucketProxy_v2(rref, data_size, block_size, num_segments,
+                                  num_share_hashes, uri_extension_size_max, nodeid)
+    return wbp
 
 class WriteBucketProxy:
     implements(IStorageBucketWriter)
@@ -101,6 +109,10 @@ class WriteBucketProxy:
 
         self._create_offsets(block_size, data_size)
 
+    def get_allocated_size(self):
+        return (self._offsets['uri_extension'] + self.fieldsize +
+                self._uri_extension_size_max)
+
     def _create_offsets(self, block_size, data_size):
         if block_size >= 2**32 or data_size >= 2**32:
             raise FileTooLargeError("This file is too large to be uploaded (data_size).")

src/allmydata/immutable/upload.py

@@ -77,11 +77,13 @@ class PeerTracker:
         self._storageserver = storage_server # to an RIStorageServer
         self.buckets = {} # k: shareid, v: IRemoteBucketWriter
         self.sharesize = sharesize
-        self.allocated_size = layout.allocated_size(sharesize,
-                                                    num_segments,
-                                                    num_share_hashes,
-                                                    EXTENSION_SIZE)
 
+        wbp = layout.make_write_bucket_proxy(None, sharesize,
+                                             blocksize, num_segments,
+                                             num_share_hashes,
+                                             EXTENSION_SIZE, peerid)
+        self.wbp_class = wbp.__class__ # to create more of them
+        self.allocated_size = wbp.get_allocated_size()
         self.blocksize = blocksize
         self.num_segments = num_segments
         self.num_share_hashes = num_share_hashes
@@ -110,7 +112,7 @@ class PeerTracker:
         #log.msg("%s._got_reply(%s)" % (self, (alreadygot, buckets)))
         b = {}
         for sharenum, rref in buckets.iteritems():
-            bp = layout.WriteBucketProxy(rref, self.sharesize,
+            bp = self.wbp_class(rref, self.sharesize,
                                 self.blocksize,
                                 self.num_segments,
                                 self.num_share_hashes,
@@ -171,10 +173,11 @@ class Tahoe2PeerSelector:
         num_share_hashes = len(ht.needed_hashes(0, include_leaf=True))
 
         # figure out how much space to ask for
-        allocated_size = layout.allocated_size(share_size,
-                                               num_segments,
-                                               num_share_hashes,
-                                               EXTENSION_SIZE)
+        wbp = layout.make_write_bucket_proxy(None, share_size, 0, num_segments,
+                                             num_share_hashes, EXTENSION_SIZE,
+                                             None)
+        allocated_size = wbp.get_allocated_size()
+
         # filter the list of peers according to which ones can accomodate
         # this request. This excludes older peers (which used a 4-byte size
         # field) from getting large shares (for files larger than about

src/allmydata/test/test_upload.py

@@ -241,17 +241,17 @@ class GoodServer(unittest.TestCase, ShouldFailMixin):
         return DATA[:size]
 
     def test_too_large(self):
-        # we currently impose a sizelimit on uploaded files, because of
-        # limitations in the share format (see ticket #346 for details). The
-        # limit is set to ensure that no share is larger than 4GiB. Make sure
-        # that we reject files larger than that.
+        # we've removed the 4GiB share size limit (see ticket #346 for
+        # details), but still have an 8-byte field, so the limit is now
+        # 2**64, so make sure we reject files larger than that.
         k = 3; happy = 7; n = 10
         self.set_encoding_parameters(k, happy, n)
-        data1 = GiganticUploadable(k*4*1024*1024*1024)
+        big = k*(2**64)
+        data1 = GiganticUploadable(big)
         d = self.shouldFail(FileTooLargeError, "test_too_large-data1",
                             "This file is too large to be uploaded (data_size)",
                             self.u.upload, data1)
-        data2 = GiganticUploadable(k*4*1024*1024*1024-3)
+        data2 = GiganticUploadable(big-3)
         d.addCallback(lambda res:
                       self.shouldFail(FileTooLargeError,
                                       "test_too_large-data2",