1. 16 Nov, 2021 2 commits
  2. 28 Oct, 2021 4 commits
    • Kirill Smelkov's avatar
      lib/zodb: Teach zconn_at to work on ZODB4 · 1f866c00
      Kirill Smelkov authored
      In 3bd82127 (lib/zodb: Add zconn_at draft (ZODB5 only)) we added
      zconn_at function to find out as of which state a ZODB connection is
      viewing the database. That was ZODB5-only however.
      
      Let's add support for ZODB4 now - by requiring ZODB4-wc2 - a version of
      ZODB4 with MVCC backported from ZODB5: ZODB!1
      
      This makes wendelin.core to work on either ZODB5 or ZODB4-wc2, but not
      plain ZODB4. However as zconn_at will be used only for WCFS-integration,
      non-wcfs mode will continue to work on all ZODB5, ZODB4-wc2 and plain
      ZODB4.
      
      ZBigFile + WCFS client integration will use zconn_at to open WCFS
      connection that corresponds to ZODB connection.
      
      Preliminary history:
      
      kirr/wendelin.core@1c3b7750    X zconn_at for ZODB4
      1f866c00
    • Kirill Smelkov's avatar
      lib/zodb: Add ZODB.Connection.onShutdownCallback · 1dba3a9a
      Kirill Smelkov authored
      Add patch to ZODB.Connection to support callback on after database is
      closed. ZBigFile + WCFS client integration will use this callback to
      close WCFS connection when corresponding ZODB.DB is closed.
      
      Preliminary history:
      
      kirr/wendelin.core@a26d9659    X lib/zodb: Connection += onShutdownCallback
      1dba3a9a
    • Kirill Smelkov's avatar
      lib/zodb: Teach Connection.onResyncCallback to work on ZODB4 · ceadfcc7
      Kirill Smelkov authored
      In 959ae2d0 (lib/zodb: Add patch to ZODB.Connection to support callback
      on connection DB view change) we added patch for ZODB.Connection to
      support callback when database view of the connection changes. At that
      time the patch was working for ZODB5 and ZODB4 was TODO.
      Let's add support for ZODB4 (both ZODB4 and ZODB4-wc2) now.
      
      As a reminder: ZBigFile + WCFS client integration will use this callback
      to keep WCFS connection in sync with ZODB connection.
      
      Preliminary history:
      
      kirr/wendelin.core@533a4cfa     X onResyncCallback for ZODB4
      ceadfcc7
    • Kirill Smelkov's avatar
      lib/zodb: Teach zstor_2zurl about ZEO, NEO and Demo storages · a05db040
      Kirill Smelkov authored
      In 6637d216 (lib/zodb: Add zstor_2zurl - way to convert a ZODB storage
      into URL to access it) we added zstor_2zurl function to convert a ZODB
      storage client object into an URL to access the storage. At that time
      the function knew how to understand FileStorage only. Let's add support
      for other storages that WCFS will need to support now.
      
      NEO URI scheme matches the one currently used on ZODB/go side. It
      semantically needs neoppod!18
      to be also applied to NEO/py side, but we do not care for now that that
      patch is not merged (yet, or forever) because extracted ZURL is used
      only with WCFS which uses NEO/go.
      
      NEO support also depends on custom patch to remember SSL credentials on
      NEO Client:
      
      kirr/neo@a2f192cb
      
      Some preliminary history:
      
      kirr/wendelin.core@5cb39463    fixup! X wcfs/zeo started to work locally
      kirr/wendelin.core@1cf3b228    X zstor_2zurl += NEO
      kirr/wendelin.core@7f8fa32a    X lib/zodb: zstor_2zurl += NEO/SSL support
      kirr/wendelin.core@e26524df    X wcfs, lib/zodb: DemoStorage support
      a05db040
  3. 01 Apr, 2021 1 commit
    • Kirill Smelkov's avatar
      lib/zodb: Add tests for critical ZODB properties that Wendelin.core 2 will depend on · c37a989d
      Kirill Smelkov authored
      The tests verify that there is no concurrency bugs around load,
      Connection.open and invalidations. See e.g.
      
      https://github.com/zopefoundation/ZODB/issues/290
      https://github.com/zopefoundation/ZEO/issues/155
      
      By including the tests into wendelin.core, we will have CI coverage for
      all supported storages (FileStorage, ZEO, NEO), and for all supported
      ZODB (currently ZODB4, ZODB4-wc2 and ZODB5).
      
      ZEO5 is know to currently fail zloadrace.
      However, even though ZODB#290 was fixed, ZEO5 turned out to also fail on zopenrace:
      
              def test_zodb_zopenrace():
                  # exercises ZODB.Connection + particular storage implementation
          >       zopenrace.main()
      
          lib/tests/test_zodb.py:382:
          _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
          <decorator-gen-1>:2: in main
              ???
          ../../tools/go/pygolang/golang/__init__.py:103: in _
              return f(*argv, **kw)
          lib/tests/testprog/zopenrace.py:115: in main
              test(zstor)
          <decorator-gen-2>:2: in test
              ???
          ../../tools/go/pygolang/golang/__init__.py:103: in _
              return f(*argv, **kw)
          lib/tests/testprog/zopenrace.py:201: in test
              wg.wait()
          golang/_sync.pyx:246: in golang._sync.PyWorkGroup.wait
              ???
          golang/_sync.pyx:226: in golang._sync.PyWorkGroup.go.pyrunf
              ???
          lib/tests/testprog/zopenrace.py:165: in T1
              t1()
          _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
      
              def t1():
                  transaction.begin()
                  zconn = db.open()
      
                  root = zconn.root()
                  obj1 = root['obj1']
                  obj2 = root['obj2']
      
                  # obj1 - reload it from zstor
                  # obj2 - get it from zconn cache
                  obj1._p_invalidate()
      
                  # both objects must have the same values
                  i1 = obj1.i
                  i2 = obj2.i
                  if i1 != i2:
          >           raise AssertionError("T1: obj1.i (%d)  !=  obj2.i (%d)" % (i1, i2))
          E           AssertionError: T1: obj1.i (3)  !=  obj2.i (2)
      
          lib/tests/testprog/zopenrace.py:156: AssertionError
      c37a989d
  4. 08 Mar, 2021 1 commit
    • Kirill Smelkov's avatar
      Drop support for ZODB3 · 0802da2b
      Kirill Smelkov authored
      It's been a while since last ZODB3 3.10.7 release in 2016 and the last
      commit in upstream ZODB3 repository (3.10 branch) is from 2017. The
      world switched since then to ZODB4 and to ZODB5 after that.
      
      We were still requiring ZODB3, because ZODB3 3.11 egg was just a
      dependency on newer ZODB, ZEO, BTrees and persistent; and this way we
      could be supporting all ZODB3.10.x and  ZODB4 and ZODB5 via ZODB3.11.
      
      However upcoming Wendelin.core 2, for its proper working, needs MVCC
      semantic as implemented in ZODB5. This forces us, even for ZODB4, to
      backport non-trivial bits from ZODB5 (see [1]). Maintaining ZODB3
      support at this point becomes non-practical, because, to our knowledge,
      there is no wendelin.core user that plans to continue using ZODB3
      without switching to at least ZODB4 in the near future.
      
      So goodbye ZODB3. Even though ZODB still stays with us, it gives a
      feeling similar to [2], because in 2014, when I was myself learning
      ZODB, it was through ZODB3 - still at the time when all ZODB bits were
      living together in one place.
      
      [1] ZODB!1
      [2] https://lists.osuosl.org/pipermail/darcs-users/2008-September/014095.html
      0802da2b
  5. 15 Apr, 2020 3 commits
    • Kirill Smelkov's avatar
      lib/zodb: Add zstor_2zurl - way to convert a ZODB storage into URL to access it · 6637d216
      Kirill Smelkov authored
      Wendelin.core 2 will need to spawn WCFS filesystem server that accesses
      the same ZODB database as the program that spawns it. The database
      argument passed to WCFS is passed in the form of URL[1,2].  Even though
      zodburi provides way to convert an URL into ZODB storage instance, there
      is currently no way for reverse operation - to convert ZODB storage
      instance into URL to access it(*). So we have to build it by our own.
      
      Provide zstor_2zurl stub that currently works for FileStorage only.
      ZEO and NEO support is TODO.
      
      In the future we might want to move this functionality into
      zodbtools/py.
      
      [1] https://lab.nexedi.com/nexedi/zodbtools/blob/a2e4dd23/zodbtools/help.py#L27-53
      [2] https://lab.nexedi.com/kirr/neo/blob/3d909114/go/zodb/zodbtools/help.go#L25-51
      
      (*) contrary to ZODB/go where this functionality is provided out of the box:
          https://godoc.org/lab.nexedi.com/kirr/neo/go/zodb#IStorage
      6637d216
    • Kirill Smelkov's avatar
      lib/zodb: Add patch to ZODB.Connection to support callback on connection DB view change · 959ae2d0
      Kirill Smelkov authored
      Wendelin.core 2 will need to hook into when client ZODB.Connection
      changes its database view and readjust WCFS-level client connection
      accordingly.
      
      ZODB.Connection can change its view on either connection reopen, or even
      without reopen on start of new transaction.
      
      This patch implements ZODB.Connection.onResyncCallback for ZODB5 only.
      
      ZODB4 and ZODB3 support is TODO.
      959ae2d0
    • Kirill Smelkov's avatar
      lib/zodb: Add zconn_at draft (ZODB5 only) · 3bd82127
      Kirill Smelkov authored
      For wendelin.core v2 we need a way to know at which particular database
      state application-level ZODB connection is viewing the database. Knowing
      that state, WCFS client library will interact with WCFS filesystem server
      and, in simple terms, request the server to provide data as of that
      particular database state.
      
      Contrary to ZODB/go[1] ZODB/py does not provide the functionality to
      obtain DB state of connection view, so we have to build it ourselves.
      Let us call the function that for a client ZODB connection returns
      database state corresponding to its database view as zconn_at.
      
      It is relatively easy to implement zconn_at for ZODB5, since ZODB5
      adopted MVCC uniformly and this patch does just that. However even with
      ZODB5 currently all released ZODB5 versions have race in
      Connection.open() vs invalidations[2], and so the first ZODB5 release
      with which zconn_at implemented here will work reliable should be
      upcoming ZODB 5.5.2
      
      It is TODO to implement zconn_at for ZODB4 and ZODB3, which organize
      things differently.
      
      Please note what would happen if zconn_at gives, even a bit, incorrect
      answer: wcfs client will ask wcfs server to provide array data as of
      different database state compared to current on-client ZODB connection.
      This will result in that data accessed via ZBigArray will _not_
      correspond to all other data accessed via regular ZODB mechanism.
      It is, in other words, would be a data corruptions.
      
      [1] https://godoc.org/lab.nexedi.com/kirr/neo/go/zodb#Connection
      [2] https://github.com/zopefoundation/ZODB/issues/290
      3bd82127
  6. 01 Apr, 2020 1 commit
  7. 18 Dec, 2019 1 commit
  8. 12 Jul, 2019 1 commit
    • Kirill Smelkov's avatar
      *: Use defer for dbclose & friends · 5c8340d2
      Kirill Smelkov authored
      For tests this makes sure that if one test fails, it won't make following
      tests fail just because the next test will fail trying to lock test database.
      
      For regular code (demo_zbigarray.py) this is also a good thing to do -
      to always close the database irregardless of whether an exception was
      raised before program reached end of main.
      
      Pygolang becomes regular - not test only - dependency. Being regular
      dependency is currently required only by demo_zbigarray.py, but it will
      be also used in upcoming wcfs, so adding pygolang into wendelin.core
      dependencies aligns with the plan.
      
      dbclose now uses defer almost everywhere - there are still few places in
      tests, where one test function is opening/closing test database multiple
      times - those were not (yet ?) converted.
      5c8340d2
  9. 17 Apr, 2018 1 commit
    • Kirill Smelkov's avatar
      tests: Explicitly close ZODB connections for places with warnings found by previous patch · 01b995a4
      Kirill Smelkov authored
      bigfile/tests/test_filezodb.py ........W: testdb: teardown: <Connection at 7f8fe2b43b90> left not closed by test code; opened by:
        ...
        File "/home/kirr/src/wendelin/wendelin.core/bigfile/tests/test_filezodb.py", line 754, in test_bigfile_zblk1_zdata_reuse
          _test_bigfile_zblk1_zdata_reuse()
        File "/home/kirr/src/wendelin/wendelin.core/bigfile/tests/test_filezodb.py", line 759, in _test_bigfile_zblk1_zdata_reuse
          root = dbopen()
        File "/home/kirr/src/wendelin/wendelin.core/bigfile/tests/test_filezodb.py", line 47, in dbopen
          return testdb.dbopen()
        File "/home/kirr/src/wendelin/wendelin.core/lib/testing.py", line 188, in dbopen
          self.connv.append( (weakref.ref(conn), ''.join(traceback.format_stack())) )
      
      lib/tests/test_zodb.py .W: testdb: teardown: <Connection at 7f8fe26f13d0> left not closed by test code; opened by:
        ...
        File "/home/kirr/src/wendelin/wendelin.core/lib/tests/test_zodb.py", line 49, in test_deactivate_btree
          root = dbopen()
        File "/home/kirr/src/wendelin/wendelin.core/lib/tests/test_zodb.py", line 30, in dbopen
          return testdb.dbopen()
        File "/home/kirr/src/wendelin/wendelin.core/lib/testing.py", line 188, in dbopen
          self.connv.append( (weakref.ref(conn), ''.join(traceback.format_stack())) )
      01b995a4
  10. 24 Oct, 2017 1 commit
    • Kirill Smelkov's avatar
      Relicense to GPLv3+ with wide exception for all Free Software / Open Source... · f11386a4
      Kirill Smelkov authored
      Relicense to GPLv3+ with wide exception for all Free Software / Open Source projects + Business options.
      
      Nexedi stack is licensed under Free Software licenses with various exceptions
      that cover three business cases:
      
      - Free Software
      - Proprietary Software
      - Rebranding
      
      As long as one intends to develop Free Software based on Nexedi stack, no
      license cost is involved. Developing proprietary software based on Nexedi stack
      may require a proprietary exception license. Rebranding Nexedi stack is
      prohibited unless rebranding license is acquired.
      
      Through this licensing approach, Nexedi expects to encourage Free Software
      development without restrictions and at the same time create a framework for
      proprietary software to contribute to the long term sustainability of the
      Nexedi stack.
      
      Please see https://www.nexedi.com/licensing for details, rationale and options.
      f11386a4
  11. 14 Aug, 2016 1 commit
    • Kirill Smelkov's avatar
      bigfile/zodb/ZBlk1: Don't miss to deactivate/free internal .chunktab buckets in loadblkdata() · 542917d1
      Kirill Smelkov authored
      13c0c17c (bigfile/zodb: Format #1 which is optimized for small changes)
      used BTree to organize ZBlk1 block's chunks and for loadblkdata() added
      "TODO we are missing to free internal BTree structures on data load".
      
      #3 besides other
      things showed that even when we deactivate ZData objects, we are still
      keeping them as ghosts occupying memory and the same for IOBucket
      objects.
      
      This all happens because there is no proper way to deactivate whole
      btree - including internal buckets objects. And since internal buckets
      are not deactivated, they stay in picklecache and thus hold a reference
      to ZData objects and ZData objects in turn, even if explicitly
      deactivated, stay in memory.
      
      We can fix this all via implementing whole-btree deactivation procedure.
      
      To do so we need to iterate over all btree buckets recursively, but
      unfortunately there is no BTree API to access/iterate btree's buckets.
      We can however still get reference to first top-level buckets via
      gc.get_referents(btree) and then scan buckets further without hacks.
      
      gc.get_referents(btree) is a hack, but
      
      - it works in O(1)  (we only get pointers from btree, not scanning all
        gcable objects and deducing them)
      - it works reliable if we filter out non-interesting objects.
      
      So in the end it works.
      
      Before the patch loading more and more ZBlk1 data with objgraph
      instrumentation was showing itself like
      
          #                                    Nobj        δ
          wendelin.bigfile.file_zodb.ZData     7168      +512
          BTrees.IOBTree.IOBucket               238       +17
          BTrees.IOBTree.IOBTree                 14        +1
      
      and after this patch we now have
      
          BTrees.IOBTree.IOBTree                 14        +1
      
      we cannot remove that "IOBTree + 1", since ZBlk1 is holding direct
      reference on it (via .chunktab) and we have to keep ZBlk1 live with
      ._v_zfile and ._v_zblk set for invalidation to work. "+1 IOBtree" is
      however small - 144 bytes per 2M (= 0.006%) so we can neglect that the
      same way we neglect keeping ZBlk1 staying live for each block.
      542917d1