Commit Graph

4165 Commits

Author SHA1 Message Date
Adam Retter
7d937a0901 Exit with non-zero status if one or more Java tests fail 2015-09-18 15:26:01 +01:00
Andres Noetzli
1b598213aa Check formatting in Travis
Summary:
Check code formatting before running tests. Goal is to make it easier to deal
with external pull requests.

Test Plan: See https://travis-ci.org/facebook/rocksdb/builds/80952963

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47211
2015-09-17 22:02:05 -07:00
agiardullo
c7fba80291 Fix non-deterministic failure in backupable_db_test
Summary: FailOverwritingBackups has unexpected results when auto-compaction runs.

Test Plan: ran test a bunch of times

Reviewers: IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47181
2015-09-17 20:14:51 -07:00
Andres Noetzli
014fd55adc Support for SingleDelete()
Summary:
This patch fixes #7460559. It introduces SingleDelete as a new database
operation. This operation can be used to delete keys that were never
overwritten (no put following another put of the same key). If an overwritten
key is single deleted the behavior is undefined. Single deletion of a
non-existent key has no effect but multiple consecutive single deletions are
not allowed (see limitations).

In contrast to the conventional Delete() operation, the deletion entry is
removed along with the value when the two are lined up in a compaction. Note:
The semantics are similar to @igor's prototype that allowed to have this
behavior on the granularity of a column family (
https://reviews.facebook.net/D42093 ). This new patch, however, is more
aggressive when it comes to removing tombstones: It removes the SingleDelete
together with the value whenever there is no snapshot between them while the
older patch only did this when the sequence number of the deletion was older
than the earliest snapshot.

Most of the complex additions are in the Compaction Iterator, all other changes
should be relatively straightforward. The patch also includes basic support for
single deletions in db_stress and db_bench.

Limitations:
- Not compatible with cuckoo hash tables
- Single deletions cannot be used in combination with merges and normal
  deletions on the same key (other keys are not affected by this)
- Consecutive single deletions are currently not allowed (and older version of
  this patch supported this so it could be resurrected if needed)

Test Plan: make all check

Reviewers: yhchiang, sdong, rven, anthony, yoshinorim, igor

Reviewed By: igor

Subscribers: maykov, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43179
2015-09-17 11:42:56 -07:00
Igor Canadi
f35560d00d Merge pull request #723 from jsteemann/fix-typos
fixed typos in comments of options.h
2015-09-17 11:26:11 -07:00
jsteemann
f8b770a942 fixed typos 2015-09-17 19:58:09 +02:00
Venkatesh Radhakrishnan
51e1c11254 Do not flag error if file to be deleted does not exist
Summary:
Some users have observed errors in the log file when
the log file or sst file is already deleted.

Test Plan:
Make sure that the errors do not appear for already deleted
files.

Reviewers: sdong

Reviewed By: sdong

Subscribers: anthony, kradhakrishnan, yhchiang, rven, igor, IslamAbdelRahman, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47115
2015-09-17 10:21:34 -07:00
Mayank Pundir
a5e312a7a4 Improving condition for bottommost level during compaction
Summary: The diff modifies the condition checked to determine the bottommost level during compaction. Previously, absence of files in higher levels alone was used as the condition. Now, the function additionally evaluates if the higher levels have files which have non-overlapping key ranges, then the level can be safely considered as the bottommost level.

Test Plan: Unit test cases added and passing. However, unit tests of universal compaction are failing as a result of the changes made in this diff. Need to understand why that is happening.

Reviewers: igor

Subscribers: dhruba, sdong, lgalanis, meyering

Differential Revision: https://reviews.facebook.net/D46473
2015-09-16 17:47:50 -07:00
sdong
9aca7cd6d8 DB::Open() to flush info log after printing DB pointer
Summary: Now DB::Open() flushes info log before printing DB pointer, so it may not show up if no activity after DB open. Move log flushing from after printing options to printing DB pointer.

Test Plan: make commit-prereq

Reviewers: igor, IslamAbdelRahman, yhchiang, kradhakrishnan, anthony, rven

Reviewed By: rven

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D47121
2015-09-16 16:33:39 -07:00
Andres Noetzli
cecd903ad9 Fix gflags build in Travis script
Summary:
There were two minor issues with 9566342d28:
- The install command was doing `cmake` instead of `cmake .`
- `LIBRARY_PATH` was not set
Fix both issues.

Test Plan: Run tests on Travis: https://travis-ci.org/facebook/rocksdb/jobs/80699627 (bloom_test works now).

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47103
2015-09-16 13:12:52 -07:00
Andres Noetzli
16934d4959 Fix wrong constants in db_test_util
Summary: Fix two constants in WaitFor() that multiply a value with 000 instead of 1000.

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, aekmekji, sdong, MarkCallaghan, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47091
2015-09-16 13:04:05 -07:00
Yueh-Hsuan Chiang
2e8e7eb391 Fix the verbosity issue in Java makefile
Summary:
When running `make rocksdbjava V=1`, it currently does
not print out the original command but something odd instead:

    mkdir -p jl/db

This patch tries to fix this issue.

Test Plan: make rocksdbjava V=1

Reviewers: igor, sdong, IslamAbdelRahman, meyering

Reviewed By: meyering

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47061
2015-09-16 12:38:17 -07:00
Yueh-Hsuan Chiang
f21c7415a7 Change the log level of DB start-up log from Warn to Header.
Summary: Change the log level of DB start-up log from Warn to Header.

Test Plan: db_bench and observe the LOG header

Reviewers: igor, anthony, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47067
2015-09-16 11:31:45 -07:00
Andres Noetzli
9566342d28 Build gflags from source for Travis
Summary:
Unfortunately it is not easily possible to install gflags as a package on
Travis. Change the Travis script to download and build gflags. This patch
avoids "sudo make install" so that we can continue to use Travis'
container-based infrastructure.

Test Plan: Run tests on Travis.

Reviewers: sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47037
2015-09-16 11:10:24 -07:00
Alexey Maykov
3ebf11ed16 Adding the increment for a counter for a number of WAL syncs
Summary: This will unblock the corresponding change in MyRocks

Test Plan: ran rocksdb.write_sync test

Reviewers: sdong, kolmike

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46911
2015-09-16 11:00:49 -07:00
Igor Canadi
81a61d75dc Skipped tests shouldn't be failures [part 2]
Summary: Missed one file in the previous commit

Test Plan: compiles

Reviewers: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47055
2015-09-15 22:59:53 -07:00
Igor Canadi
1b7ea8ce81 Skipped tests shouldn't be failures
Summary: If we skip a test, we shouldn't mark `make check` as failure. This fixes travis CI test.

Test Plan: Travis CI

Reviewers: noetzli, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47031
2015-09-15 18:10:36 -07:00
Ari Ekmekji
5ba3297d0d Add compaction time to log output
Summary:
Although compaction time is recorded in the statistics,
it is helpful to include this value in the log output corresponding
to the end of compaction.

Test Plan: make all && make check

Reviewers: yhchiang, sdong, igor, noetzli, MarkCallaghan

Reviewed By: MarkCallaghan

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D47007
2015-09-15 17:11:44 -07:00
Dmytro Okhonko
31a27a3606 Callback for informing backup downloading added
Summary:
In case of huge db backup infromation about progress of downloading would help.
New callback parameter in CreateNewBackup() function will trigger whenever a some amount of data downloaded.
Task: 8057631

Test Plan:
ProgressCallbackDuringBackup test that cover new functionality added to BackupableDBTest tests.
other test succeed as well.

Reviewers: Guenena, benj, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46575
2015-09-15 17:08:30 -07:00
Igor Canadi
d93a9f2aaf [travis CI] Run ulimit -n 2000
Summary: This should let us pass tests on OS X.

Test Plan: none yet

Reviewers: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46989
2015-09-15 12:12:24 -07:00
Ari Ekmekji
2b683d4972 Add DBOption.max_subcompaction to option dump
Summary:
RocksDB options can be dumped to the log file, and
up to this point the max_subcompactions option was not included
in this dump. This fixes that.

Test Plan: makek all && make check

Reviewers: MarkCallaghan, igor, noetzli, anthony, yhchiang, sdong

Reviewed By: yhchiang, sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46971
2015-09-15 11:41:46 -07:00
Igor Canadi
0e50a3fcc0 Merge issue with D46773
Summary: There was a merge issue with SleepingBackgroundTask

Test Plan: compiles now

Reviewers: sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46977
2015-09-15 11:35:23 -07:00
Igor Canadi
a7e80379b0 LogAndApply() should fail if the column family has been dropped
Summary:
This patch finally fixes the ColumnFamilyTest.ReadDroppedColumnFamily test. The test has been failing very sporadically and it was hard to repro. However, I managed to write a new tests that reproes the failure deterministically.

Here's what happens:
1. We start the flush for the column family
2. We check if the column family was dropped here: a3fc49bfdd/db/flush_job.cc (L149)
3. This check goes through, ends up in InstallMemtableFlushResults() and it goes into LogAndApply()
4. At about this time, we start dropping the column family. Dropping the column family process gets to LogAndApply() at about the same time as LogAndApply() from flush process
5. Drop column family goes through LogAndApply() first, marking the column family as dropped.
6. Flush process gets woken up and gets a chance to write to the MANIFEST. However, this is where it gets stuck: a3fc49bfdd/db/version_set.cc (L1975)
7. We see that the column family was dropped, so there is no need to write to the MANIFEST. We return OK.
8. Flush gets OK back from LogAndApply() and it deletes the memtable, thinking that the data is now safely persisted to sst file.

The fix is pretty simple. Instead of OK, we return ShutdownInProgress. This is not really true, but we have been using this status code to also mean "this operation was canceled because the column family has been dropped".

The fix is only one LOC. All other code is related to tests. I added a new test that reproes the failure. I also moved SleepingBackgroundTask to util/testutil.h (because I needed it in column_family_test for my new test). There's plenty of other places where we reimplement SleepingBackgroundTask, but I'll address that in a separate commit.

Test Plan:
1. new test
2. make check
3. Make sure the ColumnFamilyTest.ReadDroppedColumnFamily doesn't fail on Travis: https://travis-ci.org/facebook/rocksdb/jobs/79952386

Reviewers: yhchiang, anthony, IslamAbdelRahman, kradhakrishnan, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46773
2015-09-15 11:28:44 -07:00
krad
2819a1db32 Minor fix to CI job definition
Summary: Timeout needs to be set for command and job for it to work.

Test Plan: Manual

Reviewers: sdong igor

CC: levledb@

Task ID: #6968635

Blame Rev:
2015-09-15 10:56:48 -07:00
Andres Noetzli
df22e2fb71 Relax memory order for faster tickers
Summary:
The default behavior for atomic operations is sequentially consistent ordering
which is not needed for simple counters (see:
http://en.cppreference.com/w/cpp/atomic/memory_order). Change the memory order
to std::memory_order_relaxed for better performance.

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, aekmekji, sdong, MarkCallaghan, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46953
2015-09-15 10:52:00 -07:00
Yoshinori Matsunobu
4886073174 Adding Slice::difference_offset() function
Summary:
There are some use cases in MyRocks to compare two slices
and to return the first byte where they differ. It may be
useful to add it as a RocksDB Slice function.

Test Plan: db_test

Reviewers: sdong, rven, igor

Reviewed By: igor

Subscribers: jkedgar, dhruba

Differential Revision: https://reviews.facebook.net/D46935
2015-09-15 10:32:42 -07:00
Igor Canadi
5ce63e30ea Merge pull request #720 from AMDmi3/fix-constant-overflow
Fix `integer overflow in expression' error
2015-09-15 09:54:37 -07:00
Igor Canadi
925babc761 Merge pull request #721 from AMDmi3/printf-size_t
Fix printf format for size_t
2015-09-15 09:09:01 -07:00
Dmitry Marakasov
f171faa240 Fix printf format for size_t 2015-09-15 15:04:56 +03:00
Dmitry Marakasov
4b0b0201c9 Fix `integer overflow in expression' error 2015-09-15 14:41:00 +03:00
sdong
f3170b6f6c DBImpl::FindObsoleteFiles() shouldn't release mutex between getting min_pending_output and scanning files
Summary:
Releasing mutex between getting min_pending_output and scanning files may cause min_pending_output to be max but some non-final files are found in file scanning, ending up with deleting wrong files.
As a recent regression, mutex can be released while waiting for log sync. We move it to after file scanning.

Test Plan: Run all existing tests. Don't think it is easy to write a unit test. Maybe we should find a way to assert lock not released so that we can have some test verification for similar cases.

Reviewers: igor, anthony, IslamAbdelRahman, kradhakrishnan, yhchiang, kolmike, rven

Reviewed By: rven

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D46899
2015-09-14 23:39:30 -07:00
Islam AbdelRahman
e467bf0de0 Fix valgrind error
Summary:
Valgrind is complaining because we are using hard_rate_limit (when serializing the options) without being initialized
http://our.intern.facebook.com/intern/sandcastle/3962140295/77533971/

Test Plan: run the test under valgrind

Reviewers: kradhakrishnan, yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46929
2015-09-14 17:41:40 -07:00
Islam AbdelRahman
7cb314b9e6 Skip some tests in ROCKSD_LITE
Summary:
Skip these tests under ROCKSDB_LITE

compaction_job_stats_test
corruption_test
transactions/transaction_test

Test Plan: compile using ROCKSDB_LITE

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46923
2015-09-14 16:44:35 -07:00
Andres Noetzli
0bfe0573e8 Add gflags dependency to Travis script
Summary:
Travis is failing due to missing gflags
(https://travis-ci.org/facebook/rocksdb/jobs/80307921). Adding libgflags-dev
should help.

Test Plan: Run tests on Travis.

Reviewers: rven, anthony, yhchiang, aekmekji, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46905
2015-09-14 14:30:17 -07:00
sdong
5de807ac16 Add options.hard_pending_compaction_bytes_limit to stop writes if compaction lagging behind
Summary: Add an option to stop writes if compaction lefts behind. If estimated pending compaction bytes is more than threshold specified by options.hard_pending_compaction_bytes_liimt, writes will stop until compactions are cleared to under the threshold.

Test Plan: Add unit test DBTest.HardLimit

Reviewers: rven, kradhakrishnan, anthony, IslamAbdelRahman, yhchiang, igor

Reviewed By: igor

Subscribers: MarkCallaghan, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D45999
2015-09-14 12:51:16 -07:00
Islam AbdelRahman
7143242d12 Fix compaction_job_stats under ROCKSDB_LITE
Summary: Fix compaction_job_stats under ROCKSDB_LITE

Test Plan: compile using ROCKSDB_LITE

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46887
2015-09-14 12:42:06 -07:00
Siying Dong
592f6bf782 Merge pull request #716 from yuslepukhin/refactor_file_reader_writer_win
Refactor to support file_reader_writer on Windows.
2015-09-14 12:29:01 -07:00
krad
e2d6011f47 Minor fix to CI job definition
Summary: Command level timeouts are not working. Moving it to step level.

Test Plan: Manual testing sending commands

Reviewers: sdong igor

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-14 12:10:18 -07:00
Andres Noetzli
ad0d70ca1e Relax asserts in arena_test
Summary:
Commit c67d206898 did not fix all test conditions
which use Arena::MemoryAllocatedBytes() (see Travis failure
https://travis-ci.org/facebook/rocksdb/jobs/79957700). The assumption of that
commit was that aligned allocations do not call Arena::AllocateNewBlock(), so
malloc_usable_block_size() would not be used for Arena::MemoryAllocatedBytes().
However, there is a code path where Arena::AllocateAligned() calls
AllocateFallback() which in turn calls Arena::AllocateNewBlock(), so
Arena::MemoryAllocatedBytes() may return a greater value than expected even for
aligned requests.

Test Plan: make arena_test && ./arena_test

Reviewers: rven, anthony, yhchiang, aekmekji, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46869
2015-09-14 11:54:47 -07:00
Ari Ekmekji
03ddce9a01 Add counters for L0 stall while L0-L1 compaction is taking place
Summary:
Although there are currently counters to keep track of the
stall caused by having too many L0 files, there is no distinction as
to whether when that stall occurs either (A) L0-L1 compaction is taking
place to try and mitigate it, or (B) no L0-L1 compaction has been scheduled
at the moment. This diff adds a counter for (A) so that the nature of L0
stalls can be better understood.

Test Plan: make all && make check

Reviewers: sdong, igor, anthony, noetzli, yhchiang

Reviewed By: yhchiang

Subscribers: MarkCallaghan, dhruba

Differential Revision: https://reviews.facebook.net/D46749
2015-09-14 11:03:37 -07:00
agiardullo
a3fc49bfdd Transactions: Release Locks when rolling back to a savepoint
Summary: Transaction::RollbackToSavePoint() will now release any locks that were taken since the previous SavePoint.  To do this cleanly, I moved tracked_keys_ management into TransactionBase.

Test Plan: New Transaction test.

Reviewers: igor, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, spetrunia, leveldb

Differential Revision: https://reviews.facebook.net/D46761
2015-09-11 18:10:50 -07:00
Dmitri Smirnov
ddc8b44998 Address code review comments both GH and internal
Fix compilation issues on GCC/CLANG
 Address Windows Release test build issues due to Sync
2015-09-11 17:36:48 -07:00
krad
9f3a66a936 Improvements to CI jobs
Summary: Fixed
- Added timeouts for crash tests. They take around 9hrs.
- Added oncall so we can get notifications for timeout etc.
- Fixed a bug in the valgrind script
- Cosmetic fix

Test Plan: Manual run

Reviewers: sdong igor

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-11 16:09:01 -07:00
krad
7db1471cc1 Minor fix to CI job
Summary: Fix the issue where compilation error will not result in log file not
found error

Test Plan: None

Reviewers: sdong igor

CC: leveldb@

Task ID: #6968635

Blame Rev:
2015-09-11 13:00:55 -07:00
Andres Noetzli
c67d206898 Fixed arena_test failure due to malloc_usable_size()
Summary:
ArenaTest.MemoryAllocatedBytes on Travis failed:
https://travis-ci.org/facebook/rocksdb/jobs/79887849 . This is probably due to
malloc_usable_size() returning a value greater than the requested size. From
the man page:

   The value returned by malloc_usable_size() may be greater than the requested
   size of the allocation because of alignment and minimum size constraints.
   Although the excess bytes can be overwritten by the application without ill
   effects, this is not good programming practice: the number of excess bytes
   in an allocation depends on the underlying implementation.

Test Plan: make arena_test && ./arena_test

Reviewers: rven, anthony, yhchiang, aekmekji, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46743
2015-09-11 12:32:59 -07:00
Andres Noetzli
34cedaff66 Initialize variable to avoid warning
Summary:
RocksDB debug version failed to build under gcc-4.8.1 on sandcastle with the following error:

```
db/db_compaction_filter_test.cc:570:33: error: ‘snapshot’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
```

Test Plan: make db_compaction_filter_test && ./db_compaction_filter_test

Reviewers: rven, anthony, yhchiang, aekmekji, igor, sdong

Reviewed By: igor, sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46725
2015-09-11 12:07:54 -07:00
Manuel Ung
aeb4612685 Add counters for seek/next/prev
Summary:
There are currently no statistics on seeks, only on gets. This adds the following counters:

rocksdb.number.db.seek
rocksdb.number.db.next
rocksdb.number.db.prev
(number of calls)

rocksdb.db.iterate.bytes.read
(number of bytes read from key + value using seek/next/prev)

rocksdb.number.keys.seek.found
rocksdb.number.keys.next.found
rocksdb.number.keys.prev.found
(number of calls where seek/next/prev found a value)

Test Plan:
./db_bench -statistics -benchmarks fillrandom,seekrandom -seek_nexts 5
./db_bench -statistics -benchmarks fillrandom,seekrandom -seek_nexts 5 -reverse_iterator

Reviewers: yhchiang, rven, kradhakrishnan, IslamAbdelRahman, MarkCallaghan, sdong, igor

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46605
2015-09-11 11:37:44 -07:00
Islam AbdelRahman
45e9e4f0bb Refactor NewTableReader to accept TableReaderOptions
Summary:
Refactoring NewTableReader to accept TableReaderOptions
This will make it easier to add new options in the future, for example in this diff https://reviews.facebook.net/D46071

Test Plan: run existing tests

Reviewers: igor, yhchiang, anthony, rven, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D46179
2015-09-11 11:36:33 -07:00
Andres Noetzli
ddb950f83f Fixed bug in compaction iterator
Summary:
During the refactoring, the condition that makes sure that compaction
filters are only applied to records newer than the latest snapshot
got butchered. This patch fixes the condition and adds a test case.

Test Plan: make db_compaction_filter_test && ./db_compaction_filter_test

Reviewers: rven, anthony, yhchiang, sdong, aekmekji, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46707
2015-09-11 10:13:49 -07:00
Dmitri Smirnov
30e82d5c41 Refactor to support file_reader_writer on Windows.
Summary. A change https://reviews.facebook.net/differential/diff/224721/
  Has attempted to move common functionality out of platform dependent
  code to a new facility called file_reader_writer.
  This includes:
  - perf counters
  - Buffering
  - RateLimiting

  However, the change did not attempt to refactor Windows code.
  To mitigate, we introduce new quering interfaces such as UseOSBuffer(),
  GetRequiredBufferAlignment() and ReaderWriterForward()
  for pure forwarding where required.
  Introduce WritableFile got a new method Truncate(). This is to communicate
  to the file as to how much data it has on close.
   - When space is pre-allocated on Linux it is filled with zeros implicitly,
    no such thing exist on Windows so we must truncate file on close.
   - When operating in unbuffered mode the last page is filled with zeros but we still want to truncate.

   Previously, Close() would take care of it but now buffer management is shifted to the wrappers and the file has
   no idea about the file true size.

   This means that Close() on the wrapper level must always include
   Truncate() as well as wrapper __dtor should call Close() and
   against double Close().
   Move buffered/unbuffered write logic to the wrapper.
   Utilize Aligned buffer class.
   Adjust tests and implement Truncate() where necessary.
   Come up with reasonable defaults for new virtual interfaces.
   Forward calls for RandomAccessReadAhead class to avoid double
   buffering and locking (double locking in unbuffered mode on WIndows).
2015-09-11 09:57:02 -07:00