- 27 Jan, 2022 1 commit
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Kirill Smelkov authored
Starting from version 0.1 pygolang provides File out of the box: nexedi/pygolang@4690460b https://pypi.org/project/pygolang/#pygolang-change-history -> Use it and remove our custom File implementation that originally served as POC for that pygolang functionality.
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- 26 Jan, 2022 2 commits
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Kirill Smelkov authored
Don't use golang::* namespaces to avoid clashes with pygolang adding something in there and getting compilation error due to conflict, when e.g. nexedi/pygolang!17 lands. -> use xgolang:: as top-level namespace for what was previously living in golang:: shipped in wendelin.core. Inside that xgolang:: namespace don't use the same package names that might be used inside golang:: in pygolang. This avoids ambiguation and compile error in the future on e.g. os::AfterFork - is `using namespace golang` and `using namespace xgolang` were both activated. -> Prefix all namespaces inside xgolang:: also with "x".
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Kirill Smelkov authored
See nexedi/pygolang!17
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- 21 Jan, 2022 8 commits
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Kirill Smelkov authored
The problem is similar to a7bf0311 (wcfs: Fix crash if on invalidation handledδZ needs to access ZODB) - I forgot to put zhead's transaction into context. Without the fix added test fails as: wcfs_test.py::test_wcfs_crash_old_data ---------------- live log call ----------------- WARNING ZODB.FileStorage:FileStorage.py:413 Ignoring index for /tmp/testdb_fs.OV0rS6/1.fs M: commit -> @at0 (03e5a3342bc5ab22) M: commit -> @at1 (03e5a3342bc88899) M: f<0000000000000002> [0] INFO wcfs:__init__.py:293 starting for file:///tmp/testdb_fs.OV0rS6/1.fs ... I0120 17:12:10.274379 704327 wcfs.go:2393] start "/dev/shm/wcfs/556fa61a9f9675f34c6b44e1f978842c37176c59" "file:///tmp/testdb_fs.OV0rS6/1.fs" I0120 17:12:10.274409 704327 wcfs.go:2399] (built with go1.17.6) W0120 17:12:10.274560 704327 storage.go:152] zodb: FIXME: open file:///tmp/testdb_fs.OV0rS6/1.fs: raw cache is not ready for invalidations -> NoCache forced INFO wcfs:__init__.py:334 started pid704327 @ /dev/shm/wcfs/556fa61a9f9675f34c6b44e1f978842c37176c59 C: setup watch f<0000000000000002> @at1 (03e5a3342bc88899) # pinok: {} M: commit -> @at2 (03e5a3342c895777) M: f<0000000000000002> [1] M: commit -> @at3 (03e5a3342ca5ef55) M: f<0000000000000002> [0] C: setup watch f<0000000000000002> @at2 (03e5a3342c895777) # pinok: {0: @at1 (03e5a3342bc88899)} panic: transaction: no current transaction goroutine 88 [running]: lab.nexedi.com/kirr/neo/go/transaction.currentTxn({0x969718, 0xc0000b6240}) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/transaction/transaction.go:59 +0x77 lab.nexedi.com/kirr/neo/go/transaction.Current(...) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/transaction/api.go:206 lab.nexedi.com/kirr/neo/go/zodb.(*Connection).checkTxnCtx(...) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/connection.go:374 lab.nexedi.com/kirr/neo/go/zodb.(*Connection).Get(0xc0000c25a0, {0x969718, 0xc0000b6240}, 0x4) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/connection.go:331 +0x73 lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata.(*ΔFtail).BlkRevAt(0xc00009dd40, {0x969718, 0xc0000b6240}, 0xc000100540, 0x30, 0x3e5a3342c895777) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata/δftail.go:1140 +0x39d main.(*WatchLink).setupWatch(0xc0000120a0, {0x969718, 0xc0000b6240}, 0x2, 0x3e5a3342c895777) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1754 +0xe3f main.(*WatchLink)._handleWatch(0x0, {0x969718, 0xc0000b6240}, {0xc0000a0122, 0x0}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1973 +0x65 main.(*WatchLink).handleWatch(0x0, {0x969718, 0xc0000b6240}, 0x0, {0xc0000a0122, 0x28}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1955 +0x10c main.(*WatchLink)._serve.func3({0x969718, 0xc0000b6240}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1944 +0x3c lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go.func1() /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:86 +0x68 created by lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:83 +0x92 >>> Change history by file: f<0000000000000002>: 0 1 2 3 4 5 6 7 a b c d e f g h @at0 (03e5a3342bc5ab22) @at1 (03e5a3342bc88899) 0 @at2 (03e5a3342c895777) 1 @at3 (03e5a3342ca5ef55) 0 ---------------------------------------- # wcfs was crashing in setting up watch because of "1" and "2" from above, and # 3. setupWatch was calling ΔFtail.BlkRevAt without putting zhead's transaction into ctx. wl2 = t.openwatch() > wl2.watch(zf, at2, {0:at1})
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Kirill Smelkov authored
- put into if block to avoid collision with already-defined-elsewhere blkv - show revisions in symbolic form Noticed while working on recent change to allow ΔFtail/ΔBtail point-queries with at=tail.
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Kirill Smelkov authored
Watching with at=tail is inevitable as explained in the previous patch.
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Kirill Smelkov authored
This is needed because when e.g. wcfs is just started the coverage of ΔFtail is (head,head] i.e. empty, and if user wants to setup a watch with at=head, it becomes watch with at=tail. Then that at is used in a query and if point-queries with at=tail are disallowed it panics with "at out of bounds". This fixes crashes in test_wcfs_watch_setup (see 339f1884 "wcfs: tests: Always start tDB with ZBigFile pre-created before WCFS startup") and in test_wcfs_crash_old_data (see 97ce5105 "wcfs: tests: Add test do demonstrate "at out of bounds" crash on readPinWatchers -> ΔFtail.BlkRevAt") For the reference zodb.ΔTail already allows point queries with at=tail: https://lab.nexedi.com/kirr/neo/blob/1193c44e/go/zodb/δtail.go#L202-206 https://lab.nexedi.com/kirr/neo/blob/1193c44e/go/zodb/δtail.go#L225-228
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Kirill Smelkov authored
The codepath that sends pin messages to watchers on FUSE READ, similarly to what was showed in 339f1884 is also vulnerable to "at out of bounds" panic if at=ΔFtail.tail: wcfs_test.py::test_wcfs_crash_old_data ---------------- live log call ----------------- WARNING ZODB.FileStorage:FileStorage.py:413 Ignoring index for /tmp/testdb_fs.nbSKXu/1.fs M: commit -> @at0 (03e5a31e5e5ef6bb) M: commit -> @at1 (03e5a31e5e63fa77) M: f<0000000000000002> [0] INFO wcfs:__init__.py:293 starting for file:///tmp/testdb_fs.nbSKXu/1.fs ... I0120 16:50:22.136098 697106 wcfs.go:2393] start "/dev/shm/wcfs/93026d44ef96f87df2cc0e2e451c5aabee91b652" "file:///tmp/testdb_fs.nbSKXu/1.fs" I0120 16:50:22.136127 697106 wcfs.go:2399] (built with go1.17.6) W0120 16:50:22.136233 697106 storage.go:152] zodb: FIXME: open file:///tmp/testdb_fs.nbSKXu/1.fs: raw cache is not ready for invalidations -> NoCache forced INFO wcfs:__init__.py:334 started pid697106 @ /dev/shm/wcfs/93026d44ef96f87df2cc0e2e451c5aabee91b652 C: setup watch f<0000000000000002> @at1 (03e5a31e5e63fa77) # pinok: {} panic: at out of bounds: at: @03e5a31e5e63fa77, (tail, head] = (@03e5a31e5e63fa77, @03e5a31e5e63fa77] goroutine 7 [running]: lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata.panicf(...) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata/misc.go:47 lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata.(*ΔFtail).BlkRevAt(0xc0000a5d40, {0x969718, 0xc000076140}, 0xc0001a22a0, 0xc0001c0200, 0x3e5a31e5e63fa77) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata/δftail.go:1077 +0xa45 main.(*BigFile).readPinWatchers(0xc0001d0200, {0x969718, 0xc000076140}, 0x0, 0xffffffffffffffff) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1559 +0x2a5 main.(*BigFile).readBlk(0xc0001d0200, {0x969718, 0xc000076140}, 0x0, {0xc000320000, 0x200000, 0x0}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1281 +0x4d2 main.(*BigFile).Read.func1({0x969718, 0xc000076140}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1223 +0x71 lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go.func1() /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:86 +0x68 created by lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:83 +0x92 >>> Change history by file: f<0000000000000002>: 0 1 2 3 4 5 6 7 a b c d e f g h @at0 (03e5a31e5e5ef6bb) @at1 (03e5a31e5e63fa77) 0 ... @func def test_wcfs_crash_old_data(): # start wcfs with ΔFtail/ΔBtail not covering that initial data. t = tDB(old_data=[{0:'a'}]); zf = t.zfile; at1 = t.head defer(t.close) f = t.open(zf) # ΔFtail coverage is currently (at1,at1] wl = t.openwatch() wl.watch(zf, at1, {}) # wcfs is crashing on readPinWatcher -> ΔFtail.BlkRevAt with # "at out of bounds: at: @at1, (tail,head] = (@at1,@at1] # because BlkRevAt(at=tail) query was disallowed. > f.assertBlk(0, 'a') # [0] becomes tracked Still also crashing in test_wcfs_watch_setup.
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Kirill Smelkov authored
Soon this test will also exercise functionality from isolation protocol as well and so it will stop to be basic. Move plus rename test_wcfs_basic_invalidation_wo_dFtail_coverage -> test_wcfs_crash_old_data. Still crashing in test_wcfs_watch_setup.
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Kirill Smelkov authored
This semantically moves initialization code from test_wcfs_basic_invalidation_wo_dFtail_coverage (see a7bf0311 "wcfs: Fix crash if on invalidation handledδZ needs to access ZODB") to tDB itself, and will be useful to exercise similar scenarios in other tests. Still crashing in test_wcfs_watch_setup.
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Kirill Smelkov authored
This should hopefully exercise codepaths in wcfs.go a bit more for mistakes similar to a7bf0311 (wcfs: Fix crash if on invalidation handledδZ needs to access ZODB) where the code on server side forgets to put zhead's transaction into context. Currently, because watching @tail is disallowed, this leads to panic triggered by test_wcfs_watch_setup: @at0 (03e59e3e606b89bb) -> @at1 (03e59e3e610692bb) -> @at2 (03e59e3e612a5811) -> @at3 (03e59e3e614fa9cc) -> @at4 (03e59e3e6189c3ee) -> @at5 (03e59e3e61af0baa) C: setup watch f<0000000000000002> @at0 (03e59e3e606b89bb) # pinok: {0: @at0 (03e59e3e606b89bb), 2: @at0 (03e59e3e606b89bb), 3: @at0 (03e59e3e606b89bb), 5: @at0 (03e59e3e606b89bb)} panic: at out of bounds: at: @03e59e3e606b89bb, (tail, head] = (@03e59e3e606b89bb, @03e59e3e61af0baa] goroutine 187 [running]: lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata.panicf(...) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata/misc.go:47 lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata.(*ΔFtail).BlkRevAt(0xc000077d40, {0x969718, 0xc000062940}, 0xc0003060c0, 0x4174f4, 0x3e59e3e606b89bb) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata/δftail.go:1077 +0xa45 main.(*WatchLink).setupWatch(0xc000108050, {0x969718, 0xc000062940}, 0x2, 0x3e59e3e606b89bb) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1754 +0xe3f main.(*WatchLink)._handleWatch(0x0, {0x969718, 0xc000062940}, {0xc00001c812, 0xa00000}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1973 +0x65 main.(*WatchLink).handleWatch(0x74039b, {0x969718, 0xc000062940}, 0xc0000a4280, {0xc00001c812, 0x28}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1955 +0x10c main.(*WatchLink)._serve.func3({0x969718, 0xc000062940}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1944 +0x3c lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go.func1() /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:86 +0x68 created by lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:83 +0x92 >>> Change history by file: f<0000000000000002>: 0 1 2 3 4 5 6 7 a b c d e f g h @at0 (03e59e3e606b89bb) @at1 (03e59e3e610692bb) 2 @at2 (03e59e3e612a5811) 2 3 4 5 @at3 (03e59e3e614fa9cc) 0 2 5 @at4 (03e59e3e6189c3ee) 2 4 5 @at5 (03e59e3e61af0baa) 3 5 However next we will anyway need to allow to setup watches @tail, and so we will be fixing this and other errors in followup commits. NOTE: we don't loose coverage for the case when ZBigFile is created after wcfs startup due to test_wcfs_watch_2files, where that scenario is tested. ΔFtail/ΔBtail tests also exercise ZBigFile/BTree epochs (creation/deletion) well.
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- 19 Jan, 2022 4 commits
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Kirill Smelkov authored
tDB.commit always creates only one transaction and so wcfs should be expected to catch up with only that single one -> no need to loop. No need to keep tDB._wc_zheadv as we have information about all committed transactions in t.dFtail.
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Kirill Smelkov authored
.commit is the only caller of ._wcsync. .commit is also the only place via which tests are intended to modify ZODB.
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Kirill Smelkov authored
- .commit performs ZODB commit and synchronizes WCFS to database changes; - ._commit performs ZODB commit without WCFS synchronization. We will soon need ._commit to create initial revisions for ZBigFile while WCFS is not yet started.
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Kirill Smelkov authored
If we do not setup logging explicitly, it will print only No handlers could be found for logger "wcfs" instead of emitting useful details in before e.g. RuntimeError: fuse_unmount /dev/shm/wcfs/<X>: failed: fusermount: failed to unmount /dev/shm/wcfs/<X>: Device or resource busy (more details logged) -> Fix it.
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- 18 Jan, 2022 1 commit
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Kirill Smelkov authored
The invalidation logic is generally right, but invalidateBlk -> ΔFtail.BlkRevAt was being called with ctx without transaction. As the result it was panicking as panic: transaction: no current transaction goroutine 41 [running]: lab.nexedi.com/kirr/neo/go/transaction.currentTxn({0x9696d8, 0xc0000d8080}) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/transaction/transaction.go:59 +0x77 lab.nexedi.com/kirr/neo/go/transaction.Current(...) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/transaction/api.go:206 lab.nexedi.com/kirr/neo/go/zodb.(*Connection).checkTxnCtx(...) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/connection.go:374 lab.nexedi.com/kirr/neo/go/zodb.(*Connection).Get(0xc00010c640, {0x9696d8, 0xc0000d8080}, 0x4) /home/kirr/src/neo/src/lab.nexedi.com/kirr/neo/go/zodb/connection.go:331 +0x73 lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata.(*ΔFtail).BlkRevAt(0xc000077d40, {0x9696d8, 0xc0000d8080}, 0xc000064f60, 0x0, 0x3e5983329bbd100) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/internal/zdata/δftail.go:1140 +0x39d main.(*BigFile).invalidateBlk.func1(0xc000164400, {0x9696d8, 0xc0000d8080}, 0xc0005a0000, 0x200000, 0x200000, {0xc0005a0000, 0x200000, 0x200000}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1089 +0xb8 main.(*BigFile).invalidateBlk(0xc000164400, {0x9696d8, 0xc0000d8080}, 0x0) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:1105 +0x3bb main.(*Root).handleδZ.func3({0x9696d8, 0xc0000d8080}) /home/kirr/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs/wcfs.go:898 +0x34 lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go.func1() /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:86 +0x68 created by lab.nexedi.com/kirr/go123/xsync.(*WorkGroup).Go /home/kirr/src/neo/src/lab.nexedi.com/kirr/go123/xsync/xsync.go:83 +0x92 on any new change to tracked file block whose previous history is not covered by ΔFtail/ΔBtail. Problem reported by @Francois.
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- 26 Nov, 2021 1 commit
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Kirill Smelkov authored
Fixes the following warning that started to appear: kirr@deca:~/src/wendelin/wendelin.core/t$ ./qemu-runlinux -g /home/kirr/src/linux/obj-qemu_debug/arch/x86/boot/bzImage /bin/bash qemu-system-x86_64: warning: 9p: Multiple devices detected in same VirtFS export, which might lead to file ID collisions and severe misbehaviours on guest! You should either use a separate export for each device shared from host or use virtfs option 'multidevs=remap'! See https://wiki.qemu.org/Documentation/9psetup for documentation of multidevs option.
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- 23 Nov, 2021 4 commits
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Kirill Smelkov authored
In 5c8340d2 we said: 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. Let's convert those remaining places now, because when wendelin.core tests are run wrt plain ZODB4 (contrary to ZODB4-wc2), many tests fail at fileh_open time, e.g. @func def test_bigfile_filezodb_fileh_gc(): root1= dbopen() conn1= root1._p_jar db = conn1.db() defer(db.close) root1['zfile4'] = f1 = ZBigFile(blksize) transaction.commit() > fh1 = f1.fileh_open() bigfile/tests/test_filezodb.py:588: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ bigfile/file_zodb.py:603: in fileh_open fileh = _ZBigFileH(self, _use_wcfs) bigfile/file_zodb.py:664: in __init__ self.zfileh = zfile._v_file.fileh_open(use_wcfs) bigfile/_file_zodb.pyx:112: in wendelin.bigfile._file_zodb._ZBigFile.fileh_open pywconn = wczsync.pywconnOf(zconn) wcfs/client/_wczsync.pyx:56: in wendelin.wcfs.client._wczsync.pywconnOf wconn = wc.connect(zconn_at(zconn)) lib/zodb.py:163: in zconn_at "nexedi/ZODB!1") _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ patch = 'conn:MVCC-via-loadBefore-only', details_link = 'nexedi/ZODB!1' def _zassertHasNXDPatch(patch, details_link): if not _zhasNXDPatch(patch): raise AssertionError( "ZODB%s is not patched with required Nexedi patch %r\n\tSee %s for details" % > (zmajor, patch, details_link)) E AssertionError: ZODB4 is not patched with required Nexedi patch 'conn:MVCC-via-loadBefore-only' E See nexedi/ZODB!1 for details and DB is left unclosed. This change should reduce, if not completely fix, the number of leaked /tmp/testdb_* directories for Wendelin.core.UnitTest-ZODB4(xfail) testsuite.
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Kirill Smelkov authored
When WCFS-mmapped memory is accessed, it can get SIGBUS on IO error (and automatically on WCFS crash), and SIGSEGV when accessed client mapping is closed. tFile.assertBlk in wcfs_test.py already converts SIGSEGV into python exception when accessing on-wcfs file's block. However tMapping.assertBlk was not doing so, which, instead of providing proper details, leads to test crashes if something goes wrong. For example when wendelin.core tests are run wrt plain ZODB4 (contrary to ZODB4-wc2, see nexedi/ZODB!1 and nexedi/slapos@e256ed97), it first fails in pinner and then gets SIGSEGV on data access, because, to mimic SIGBUS on EIO, pinner shutdowns all mappings on its failure: https://lab.nexedi.com/nexedi/wendelin.core/blob/49f826b1/wcfs/client/wcfs.cpp#L477-501 https://nexedijs.erp5.net/#/test_result_module/20211118-7C45220A/25 -> Fix it by wrapping test block access with appropriate read_exfault variant. Before this patch: .../wendelin.core$ WENDELIN_CORE_TEST_DB='<zeo>' WENDELIN_CORE_VIRTMEM='r:wcfs+w:uvmm' python -m pytest -vsx wcfs/ -k test_wcfs_client ... wcfs/client/client_test.py::test_wcfs_client -------------------- live log call --------------------- INFO wcfs:__init__.py:293 starting for zeo://localhost:28866 ... I1122 19:17:14.376182 110032 wcfs.go:2384] start "/dev/shm/wcfs/ef87339c054c3e0e48d494fa584bb209518844b2" "zeo://localhost:28866" I1122 19:17:14.376291 110032 wcfs.go:2390] (built with go1.17.3) W1122 19:17:14.380882 110032 storage.go:152] zodb: FIXME: open zeo://localhost:28866: raw cache is not ready for invalidations -> NoCache forced INFO wcfs:__init__.py:334 started pid110032 @ /dev/shm/wcfs/ef87339c054c3e0e48d494fa584bb209518844b2 M: commit -> @at0 (03e452313dddbc00) M: commit -> @at1 (03e452313e0f3b99) M: f<0000000000000002> [2, 3] M: commit -> @at2 (03e452313e1adb55) M: f<0000000000000002> [2] M: commit -> @at3 (03e452313e3be500) M: f<0000000000000002> [3, 4] W1122 19:17:14.597654 110032 wcfs.go:2050] /@03e452313d343c88/bigfile: lookup "0000000000000002": bigfopen 0000000000000002 @03e452313d343c88: invalid argument: Get 0000000000000002: Get 03e452313d343c88:0000000000000002: zeo://localhost:28866: load 03e452313d343c88:0000000000000002: 0000000000000002: no such object E1122 19:17:14.597759 110032 wcfs.go:1220] /head/bigfile/0000000000000002: readblk #4: pin watchers: wlink1: f<0000000000000002>: pin #4 @03e452313d343c88: expect "ack"; got "nak: _remmapblk #4 @03e452313d343c88: open /dev/shm/wcfs/ef87339c054c3e0e48d494fa584bb209518844b2/@03e452313d343c88/bigfile/0000000000000002: Invalid argument" F1122 19:17:14.597803 110050 wcfs/client/wcfs.cpp:487] CRITICAL: pinner: pin f<0000000000000002> #4 @03e452313d343c88: _remmapblk #4 @03e452313d343c88: open /dev/shm/wcfs/ef87339c054c3e0e48d494fa584bb209518844b2/@03e452313d343c88/bigfile/0000000000000002: Invalid argument F1122 19:17:14.597835 110050 wcfs/client/wcfs.cpp:488] CRITICAL: wcfs server will likely kill us soon. CRITICAL: pinner: pin f<0000000000000002> #4 @03e452313d343c88: _remmapblk #4 @03e452313d343c88: open /dev/shm/wcfs/ef87339c054c3e0e48d494fa584bb209518844b2/@03e452313d343c88/bigfile/0000000000000002: Invalid argument CRITICAL: wcfs server will likely kill us soon. Segmentation fault: read @00007ff7b9534000 /home/kirr/src/wendelin/wendelin.core/wcfs/client/./../../bigfile/liblibvirtmem.so(dump_traceback+0x34)[0x7ff7d6b5c279] /home/kirr/src/wendelin/wendelin.core/wcfs/client/./../../bigfile/liblibvirtmem.so(+0x27b0)[0x7ff7d6b577b0] /lib/x86_64-linux-gnu/libpthread.so.0(+0x14140)[0x7ff7da078140] python(PyString_FromStringAndSize+0x228)[0x5627feb96b58] python(PyEval_EvalFrameEx+0x603e)[0x5627febb7a4e] python(PyEval_EvalCodeEx+0x57c)[0x5627febb03cc] ... python(PyObject_Call+0x43)[0x5627feb9d903] python(+0x18a7e1)[0x5627fec5d7e1] python(Py_Main+0x3ad)[0x5627fec4b8ed] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xea)[0x7ff7d9d59d0a] python(_start+0x2a)[0x5627fec4b46a] Ошибка сегментирования (стек памяти сброшен на диск) After this patch: .../wendelin.core$ WENDELIN_CORE_TEST_DB='<zeo>' WENDELIN_CORE_VIRTMEM='r:wcfs+w:uvmm' python -m pytest -vsx wcfs/ -k test_wcfs_client ... wcfs/client/client_test.py::test_wcfs_client -------------------- live log call --------------------- INFO wcfs:__init__.py:293 starting for zeo://localhost:22854 ... I1122 18:17:22.486445 102541 wcfs.go:2384] start "/dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98" "zeo://localhost:22854" I1122 18:17:22.486525 102541 wcfs.go:2390] (built with go1.17.3) W1122 18:17:22.489908 102541 storage.go:152] zodb: FIXME: open zeo://localhost:22854: raw cache is not ready for invalidations -> NoCache forced INFO wcfs:__init__.py:334 started pid102541 @ /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98 M: commit -> @at0 (03e451f560834477) M: commit -> @at1 (03e451f560a2aa77) M: f<0000000000000002> [2, 3] M: commit -> @at2 (03e451f560adafcc) M: f<0000000000000002> [2] M: commit -> @at3 (03e451f560d02111) M: f<0000000000000002> [3, 4] W1122 18:17:22.703710 102541 wcfs.go:2050] /@03e451f55fcc4c77/bigfile: lookup "0000000000000002": bigfopen 0000000000000002 @03e451f55fcc4c77: invalid argument: Get 0000000000000002: Get 03e451f55fcc4c77:0000000000000002: zeo://localhost:22854: load 03e451f55fcc4c77:0000000000000002: 0000000000000002: no such object E1122 18:17:22.703840 102541 wcfs.go:1220] /head/bigfile/0000000000000002: readblk #4: pin watchers: wlink1: f<0000000000000002>: pin #4 @03e451f55fcc4c77: expect "ack"; got "nak: _remmapblk #4 @03e451f55fcc4c77: open /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98/@03e451f55fcc4c77/bigfile/0000000000000002: Invalid argument" F1122 18:17:22.704380 102558 wcfs/client/wcfs.cpp:487] CRITICAL: pinner: pin f<0000000000000002> #4 @03e451f55fcc4c77: _remmapblk #4 @03e451f55fcc4c77: open /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98/@03e451f55fcc4c77/bigfile/0000000000000002: Invalid argument F1122 18:17:22.704639 102558 wcfs/client/wcfs.cpp:488] CRITICAL: wcfs server will likely kill us soon. CRITICAL: pinner: pin f<0000000000000002> #4 @03e451f55fcc4c77: _remmapblk #4 @03e451f55fcc4c77: open /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98/@03e451f55fcc4c77/bigfile/0000000000000002: Invalid argument CRITICAL: wcfs server will likely kill us soon. >>> Change history by file: f<0000000000000002>: 0 1 2 3 4 5 6 7 a b c d e f g h @at0 (03e451f560834477) @at1 (03e451f560a2aa77) 2 3 @at2 (03e451f560adafcc) 2 @at3 (03e451f560d02111) 3 4 INFO wcfs:__init__.py:400 unmount/stop wcfs pid102541 @ /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98 I1122 18:17:22.728452 102541 wcfs.go:2560] stop "/dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98" "zeo://localhost:22854" FAILED ======================= FAILURES ======================= ___________________ test_wcfs_client ___________________ @func def test_wcfs_client(): t = tDB(); zf = t.zfile; at0=t.at0 defer(t.close) pinned = lambda fh: fhpinned(t, fh) at1 = t.commit(zf, {2:'c1', 3:'d1'}) at2 = t.commit(zf, {2:'c2'}) wconn = t.wc.connect(at1) defer(wconn.close) fh = wconn.open(zf._p_oid) defer(fh.close) # create mmap with 1 block beyond file size m1 = fh.mmap(2, 3) defer(m1.unmap) assert m1.blk_start == 2 assert m1.blk_stop == 5 assert len(m1.mem) == 3*zf.blksize tm1 = tMapping(t, m1) assert pinned(fh) == {} # verify initial data reads tm1.assertBlk(2, 'c1', {2:at1}) tm1.assertBlk(3, 'd1', {2:at1}) tm1.assertBlk(4, '', {2:at1}) # commit with growing file size -> verify data read as the same, #3 pinned. # (#4 is not yet pinned because it was not accessed) at3 = t.commit(zf, {3:'d3', 4:'e3'}) assert pinned(fh) == {2:at1} tm1.assertBlk(2, 'c1', {2:at1}) tm1.assertBlk(3, 'd1', {2:at1, 3:at1}) tm1.assertBlk(4, '', {2:at1, 3:at1}) # resync at1 -> at2: #2 must unpin to @head; #4 must stay as zero wconn.resync(at2) assert pinned(fh) == {3:at1} tm1.assertBlk(2, 'c2', { 3:at1}) tm1.assertBlk(3, 'd1', { 3:at1}) > tm1.assertBlk(4, '', { 3:at1, 4:at0}) # XXX at0->ø ? wcfs/client/client_test.py:158: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ wcfs/client/client_test.py:86: in assertBlk _ = read_exfault_withgil(blkview[0:1]) wcfs/internal/wcfs_test.pyx:90: in wendelin.wcfs.internal.wcfs_test.read_exfault_withgil return _read_exfault(mem, withgil=True) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ > raise SegmentationFault() E SegmentationFault wcfs/internal/wcfs_test.pyx:120: SegmentationFault ------------------ Captured log call ------------------- INFO wcfs:__init__.py:293 starting for zeo://localhost:22854 ... INFO wcfs:__init__.py:334 started pid102541 @ /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98 INFO wcfs:__init__.py:400 unmount/stop wcfs pid102541 @ /dev/shm/wcfs/c818c147676f8d6f3b408b02f727aca5e3229e98
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Kirill Smelkov authored
Here wcfs.go should have exited due to either unmount request, _or_ SIGTERM.
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Kirill Smelkov authored
If first unmount fails, e.g. due to "device or resource is busy", we are trying to unmount the filesystem the second time after force kill/FUSE-abort (see 5f684a49 "wcfs: Server.stop: Make sure to remove mount entry even if we had to use FUSE abort"). This way the caller of Server.stop should get an error only if that second unmount fails, not on unmount-1 error, which should be considered as internal to Server.stop implementation. If we don't hide that unmount-1 error and raise it to the caller, from outside it can confusingly look like "the server is successfully stopped, but nevertheless we are raised with an error".
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- 16 Nov, 2021 3 commits
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Kirill Smelkov authored
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Kirill Smelkov authored
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Kirill Smelkov authored
This way on plain ZODB4 the following non-wcfs tests will continue to pass test.py/fs-!wcfs test.py/zeo-!wcfs test.py/neo-!wcfs instead of failing as e.g. in here: https://nexedijs.erp5.net/#/test_result_module/20211116-123A66706 On plain ZODB4 WCFS-related functionality - which uses zconn_at - will continue to raise corresponding assertion in WCFS-related tests, as e.g. in https://nexedijs.erp5.net/#/test_result_module/20211116-123A66706/6
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- 15 Nov, 2021 1 commit
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Kirill Smelkov authored
Server.stop currently tries to unmount, and if that fails invokes FUSE abort and kills wcfs.go . However it does not call unmount the second time after such abort, and this way the filesystem remains mounted (in ENOTCONN state) and rmdir(mountpoint) fails. -> Fix it by calling unmount the second time if we had to abort FUSE connection. In that second try use lazy unmounting, because regular unmount can still fail with "Device or resource busy" since there could be still client file descriptors left pointing to the mounted filesystem. With lazy mode unmounting + followup rmdir, hopefully, always succeeds. Here is example test run where one test timed out, FUSE connection was aborted, but neither the filesystem was unmounted, nor mountpoint directory was deleted, which led to all followup tests failing in setup assert that testmountpoint does not exist: https://nexedijs.erp5.net/#/test_result_module/20211112-1ACEA62D/22 This patch should fix those followup failures + fix another leakage of WCFS mounts in real services.
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- 12 Nov, 2021 4 commits
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Kirill Smelkov authored
By default every WCFS run creates several files in /tmp/wcfs.*.log.* and without explicit cleanup those files are left hanging on testnodes. Over last ~6 months we accumulated ~ 300K such files. Don't allow those files to be leaked by instructing WCFS to log to stderr during test run. This should be also useful to see details in the test output.
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Kirill Smelkov authored
With NEO we were creating test database on /tmp but we were not deleting it in the end. As the result many /tmp/neo_XXXXXX non-empty directories were being leaked. -> Fix it by creating testdb directory outselves and removing it at the end, similarly to FileStorage and ZEO. Fixes: 7fc4ec66 (tests: Allow to test with ZEO & NEO ZODB storages)
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Kirill Smelkov authored
We run tests with different GOMAXPROCS because some WCFS bugs are only likely to trigger when there is only 1 or 2 main OS thread(s) in WCFS. However test.go does not exercise filesystem functionality - it runs unit tests for ZBlk decoding, ΔBtail and similar. At the same time test.go:* currently occupies ~ 50% of whole time to run full testsuite with the main consumer being ΔBtail random testing. -> Run test.go only once. This should save ~ 1000s for each run and lower whole time to run wendelin.core testsuite on testnode from ~60m -> to ~40 minutes.
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Kirill Smelkov authored
Else every time test.py/wcfs is run several empty directories are left in /dev/shm/wcfs - each corresponding to WCFS server that was automatically spawned and stopped at the end of the test. Over time this can accumulate to some big number as e.g. ~20000 of such directories were left on the testnode during last 6 months.
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- 09 Nov, 2021 2 commits
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Kirill Smelkov authored
This are the early days of WCFS - we want full details which in default configuration might not be available to see if WCFS gets stuck for one reason or another. See added comments for details.
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Kirill Smelkov authored
`python setup.py egg_info` stopped working after we added non-ASCII files, e.g. δbtail.go in 2ab4be93 (wcfs: xbtree: ΔBtail) and δftail.go in f980471f (wcfs: zdata: ΔFtail): (neo) (z-dev) (g.env) kirr@deca:~/src/neo/src/lab.nexedi.com/nexedi/wendelin.core$ python setup.py egg_info running egg_info writing requirements to wendelin.core.egg-info/requires.txt writing wendelin.core.egg-info/PKG-INFO writing top-level names to wendelin.core.egg-info/top_level.txt writing dependency_links to wendelin.core.egg-info/dependency_links.txt writing entry points to wendelin.core.egg-info/entry_points.txt package init file '__init__.py' not found (or not a regular file) /usr/lib/python2.7/distutils/filelist.py:64: UnicodeWarning: Unicode equal comparison failed to convert both arguments to Unicode - interpreting them as being unequal sortable_files.sort() Traceback (most recent call last): File "setup.py", line 416, in <module> """.splitlines()] File "/home/kirr/src/tools/go/pygolang/golang/pyx/build.py", line 118, in setup setuptools_dso.setup(**kw) File "/home/kirr/src/wendelin/venv/z-dev/lib/python2.7/site-packages/setuptools_dso/__init__.py", line 37, in setup _setup(**kws) File "/home/kirr/src/wendelin/venv/z-dev/lib/python2.7/site-packages/setuptools/__init__.py", line 162, in setup return distutils.core.setup(**attrs) File "/usr/lib/python2.7/distutils/core.py", line 151, in setup dist.run_commands() File "/usr/lib/python2.7/distutils/dist.py", line 953, in run_commands self.run_command(cmd) File "/usr/lib/python2.7/distutils/dist.py", line 972, in run_command cmd_obj.run() File "/home/kirr/src/wendelin/venv/z-dev/lib/python2.7/site-packages/setuptools/command/egg_info.py", line 296, in run self.find_sources() File "/home/kirr/src/wendelin/venv/z-dev/lib/python2.7/site-packages/setuptools/command/egg_info.py", line 303, in find_sources mm.run() File "/home/kirr/src/wendelin/venv/z-dev/lib/python2.7/site-packages/setuptools/command/egg_info.py", line 538, in run self.filelist.sort() File "/usr/lib/python2.7/distutils/filelist.py", line 64, in sort sortable_files.sort() UnicodeDecodeError: 'ascii' codec can't decode byte 0xce in position 0: ordinal not in range(128) This happens becuase by default setuptools collects filenames as str, not unicode, and our git_lsfiles - also registered into setuptools.file_finders entrypoint - collects filenames as unicode. Previously everything was working because there was no on-ASCII filenames, and so unicode vs str coercion worked automatically. But now, after there is filename like 'δbtail.go', it stopped to work and raises UnicodeDecodeError. -> Fix it by adjusting git_lsfiles to collect filenames as UTF-8 encoded strings instead of unicode.
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- 08 Nov, 2021 4 commits
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Kirill Smelkov authored
Fix last-minute error that crept in during kirr/wendelin.core@4af54da9 : (neo) (z-dev) (g.env) kirr@deca:~/src/neo/src/lab.nexedi.com/nexedi/wendelin.core/wcfs$ go test # lab.nexedi.com/nexedi/wendelin.core/wcfs ./wcfs.go:957:4: Errorf format %s has arg sk of wrong type *lab.nexedi.com/nexedi/wendelin.core/wcfs.FileSock Amends 4430de41.
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Kirill Smelkov authored
Add two functions, that were developed during wendelin.core 2 α, to the package for completeness: - map_zero_into_ro complements map_zero_ro, but mmaps into user-provided buffer. - sync calls msync on the provided memory.
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Kirill Smelkov authored
Remove outdated TODO because test_wcfs_watch_before_create passes this days. It was fixed after ΔFtail was taught about epochs and the fix was reflected in kirr/wendelin.core@63ae8326. Amends 10f7153a.
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Kirill Smelkov authored
Fix how unpatched ZODB4 is reported to lack required patch: Before: Traceback (most recent call last): File "/home/kirr/src/wendelin/wendelin.core/lib/tests/test_zodb.py", line 251, in test_zconn_at assert zconn_at(conn1) == at0 File "/home/kirr/src/wendelin/wendelin.core/lib/zodb.py", line 162, in zconn_at assert 'conn:MVCC-via-loadBefore-only' in ZODB.nxd_patches, \ AttributeError: 'module' object has no attribute 'nxd_patches' After: Traceback (most recent call last): File "/home/kirr/src/wendelin/wendelin.core/lib/tests/test_zodb.py", line 251, in test_zconn_at assert zconn_at(conn1) == at0 File "/home/kirr/src/wendelin/wendelin.core/lib/zodb.py", line 163, in zconn_at "nexedi/ZODB!1") File "/home/kirr/src/wendelin/wendelin.core/lib/zodb.py", line 191, in _zassertHasNXDPatch (zmajor, patch, details_link)) AssertionError: ZODB4 is not patched with required Nexedi patch 'conn:MVCC-via-loadBefore-only' See nexedi/ZODB!1 for details Fixes 1f866c00 (lib/zodb: Teach zconn_at to work on ZODB4).
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- 28 Oct, 2021 5 commits
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Kirill Smelkov authored
It is not possible for WCFS to access data of in-RAM storage of another process. But without explicit explanation the error message is confusing - it was something like: NotImplementedError: don't know how to extract zurl from <ZODB.MappingStorage.MappingStorage object at 0x7f28f04cea10> which suggests it was just not implemented.
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Kirill Smelkov authored
By using WCFS as mmap-overlay for base data(*). WCFS-mode is still opt-in with default remaining to use old full user-space virtual memory manager mode as initially introduced in 2015. Wendelin.core should be draftly usable in WCFS mode now. This patch is organized as follows: - file_zodb.cpp provides mmap-overlay operations for WCFS implemented via WCFS client library. - file_zodb.py is adjusted accordingly to use WCFS if requested. Low-level things specific to gluing to file_zodb.cpp are moved to _file_zodb.pyx. - the rest of the changes are drive-by by main ones. (*) see the following patches for what is mmap-overlay: - fae045cc (bigfile/virtmem: Introduce "mmap overlay" mode) - 23362204 (bigfile/py: Allow PyBigFile backend to expose "mmap overlay" functionality) Some preliminary history: kirr/wendelin.core@01916f09 X Draft demo that reading data through wcfs works kirr/wendelin.core@fd58082a X Fix build on old GCC kirr/wendelin.core@f622e751 X tests: Stop wcfs spawned during tests kirr/wendelin.core@f118617b X tests: Don't try to stop wcfs that is already exited
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Kirill Smelkov authored
Provide integration with virtmem, so that WCFS Mapping can be associated and managed under virtmem VMA. In other words provide support so that WCFS can be used as ZBigFile backend in "mmap overlay" mode (see fae045cc "bigfile/virtmem: Introduce "mmap overlay" mode" for description of mmap-overlay mode). We'll need this functionality for ZBigFile + WCFS client integration. Virtmem integration will be tested via running whole wendelin.core functional testsuite in wcfs-mode after the next patch. Quoting added description: ---- 8< ---- Integration with wendelin.core virtmem layer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This client package can be used standalone, but additionally provides integration with wendelin.core userspace virtual memory manager: when a Mapping is created, it can be associated as serving base layer for a particular virtmem VMA via FileH.mmap(vma=...). In that case, since virtmem itself adds another layer of dirty pages over read-only base provided by Mapping(+) ┌──┐ ┌──┐ │RW│ │RW│ ← virtmem VMA dirty pages └──┘ └──┘ + VMA base = X@at view provided by Mapping: ___ /@revA/bigfile/X __ /@revB/bigfile/X _ /@revC/bigfile/X + ... ─── ───── ────────────────────────── ───── /head/bigfile/X the Mapping will interact with virtmem layer to coordinate updates to mapping virtual memory. How it works ~~~~~~~~~~~~ Wcfs client integrates with virtmem layer to support virtmem handle dirtying pages of read-only base-layer that wcfs client provides via isolated Mapping. For wcfs-backed bigfiles every virtmem VMA is interlinked with Mapping: VMA -> BigFileH -> ZBigFile -----> Z ↑↓ O Mapping -> FileH -> wcfs server --> DB When a page is write-accessed, virtmem mmaps in a page of RAM in place of accessed virtual memory, copies base-layer content provided by Mapping into there, and marks that page as read-write. Upon receiving pin message, the pinner consults virtmem, whether corresponding page was already dirtied in virtmem's BigFileH (call to __fileh_page_isdirty), and if it was, the pinner does not remmap Mapping part to wcfs/@revX/f and just leaves dirty page in its place, remembering pin information in fileh._pinned. Once dirty pages are no longer needed (either after discard/abort or writeout/commit), virtmem asks wcfs client to remmap corresponding regions of Mapping in its place again via calls to Mapping.remmap_blk for previously dirtied blocks. The scheme outlined above does not need to split Mapping upon dirtying an inner page. See bigfile_ops interface (wendelin/bigfile/file.h) that explains base-layer and overlaying from virtmem point of view. For wcfs this interface is provided by small wcfs client wrapper in bigfile/file_zodb.cpp. (+) see bigfile_ops interface (wendelin/bigfile/file.h) that gives virtmem point of view on layering. ---------------------------------------- Some preliminary history: kirr/wendelin.core@f330bd2f X wcfs/client: Overview += interaction with virtmem layer
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Kirill Smelkov authored
For ZBigFile + WCFS client integration we'll need to open WCFS connections that observer database at the same state as current ZODB connection. Later that WCFS connection needs to adjust its on-WCFS view in accordance to how ZODB connection adjusts its one. Wczsync provides a function to do so: pywconnOf(zconn) will open WCFS connection and maintain it in sync with ZODB connection zconn. Some preliminary history: 8bf8f23b X bigfile/_file_zodb: Fix logic around ZSync usage 571cb737 fixup! X bigfile/_file_zodb: Fix logic around ZSync usage a9a82d5a X bigfile/_file_zodb: Fix ZSync to close not only wconn, but also wconn.wc through which wconn was created cf92937f X wcfs: Move wconn<->zconn sync functionality into wcfs.client._wczsync 7203d7ab X wcfs: Fix ZSync to close wconn on zdb.close, even if zconn stays alive
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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: nexedi/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: 1c3b7750 X zconn_at for ZODB4
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