Commit Graph

310 Commits

Author SHA1 Message Date
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
Dmitry Marakasov
f171faa240 Fix printf format for size_t 2015-09-15 15:04:56 +03:00
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
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
agiardullo
aa6eed0c1e Transaction stats
Summary: Added funtions to fetch the number of locked keys in a transaction, the number of pending puts/merge/deletes, and the elapsed time

Test Plan: unit tests

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

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45417
2015-09-09 13:35:53 -07:00
agiardullo
5e94f68f35 TransactionDB Custom Locking API
Summary:
Prototype of API to allow MyRocks to override default Mutex/CondVar used by transactions with their own implementations.  They would simply need to pass their own implementations of Mutex/CondVar to the templated TransactionDB::Open().

Default implementation of TransactionDBMutex/TransactionDBCondVar provided (but the code is not currently changed to use this).

Let me know if this API makes sense or if it should be changed

Test Plan: n/a

Reviewers: yhchiang, rven, igor, sdong, spetrunia

Reviewed By: spetrunia

Subscribers: maykov, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43761
2015-09-08 17:03:57 -07:00
Andres Noetzli
6bdc484fd8 Added Equal method to Comparator interface
Summary:
In some cases, equality comparisons can be done more efficiently than three-way
comparisons. There are quite a few places in the code where we only care about
equality. This patch adds an Equal() method that defaults to using the
Compare() method.

Test Plan: make clean all check

Reviewers: rven, anthony, yhchiang, igor, sdong

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D46233
2015-09-08 15:30:49 -07:00
Mayank Pundir
d9f42aa60d Adding a verifyBackup method to BackupEngine
Summary: This diff adds a verifyBackup method to BackupEngine. The method verifies the name and size of each file in the backup.

Test Plan: Unit test cases created and passing.

Reviewers: igor, benj

Subscribers: zelaine.fong, yhchiang, sdong, lgalanis, dhruba, AaronFeldman

Differential Revision: https://reviews.facebook.net/D46029
2015-09-03 17:27:21 -07:00
Paul Marinescu
50dc5f0c5a Replace BackupRateLimiter with GenericRateLimiter
Summary: BackupRateLimiter removed and uses replaced with the existing GenericRateLimiter

Test Plan:
make all check

make clean
USE_CLANG=1 make all

make clean
OPT=-DROCKSDB_LITE make release

Reviewers: leveldb, igor

Reviewed By: igor

Subscribers: igor, dhruba

Differential Revision: https://reviews.facebook.net/D46095
2015-09-03 17:00:09 -07:00
agiardullo
0f1aab6c12 Add SetLockTimeout for Transactions
Summary: MyRocks wants to be able to change the lock timeout of a transaction that has already started.  Expose existing SetLockTimeout function to users.

Test Plan: unit test

Reviewers: spetrunia, rven, sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45987
2015-09-02 20:07:19 -07:00
Andres Noetzli
3c9cef1eed Unified maps with Comparator for sorting, other cleanup
Summary:
This diff is a collection of cleanups that were initially part of D43179.
Additionally it adds a unified way of defining key-value maps that use a
Comparator for sorting (this was previously implemented in four different
places).

Test Plan: make clean check all

Reviewers: rven, anthony, yhchiang, sdong, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45993
2015-09-02 13:58:22 -07:00
Igor Canadi
b42cd6bed5 Remove the need for LATEST_BACKUP in BackupEngine
Summary:
In the first implementation of BackupEngine, LATEST_BACKUP was the commit point. The backup became committed after the write to LATEST_BACKUP completed.

However, we can avoid the need for LATEST_BACKUP. Instead of write to LATEST_BACKUP, the commit point can be the rename from `meta/<backup_id>.tmp` to `meta/<backup_id>`. Once we see that there exists a file `meta/<backup_id>` (without tmp), we can assume that backup is valid.

In this diff, we still write out the file LATEST_BACKUP. We need to do this so that we can maintain backward compatibility. However, the new version doesn't depend on this file anymore. We get the latest backup by `ls`-ing `meta` directory.

This diff depends on D41925

Test Plan: Adjusted backupable_db_test to this new behavior

Reviewers: benj, yhchiang, sdong, AaronFeldman

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42069
2015-09-02 11:49:49 -07:00
agiardullo
77a28615ec Support static Status messages
Summary: Provide a way to specify a detailed static error message for a Status without incurring a memcpy.  Let me know what people think of this approach.

Test Plan: added simple test

Reviewers: igor, yhchiang, rven, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D44259
2015-08-31 16:13:29 -07:00
Dmitri Smirnov
fbe2c05f59 s/NOEXCEPT/ROCKSDB_NOEXCEPT 2015-08-25 16:34:39 -07:00
Dmitri Smirnov
6924d7582b Address noexcept and const integer lambda capture
VS 2013 does not support noexcept.
   Complains about usage of ineteger constant within lambda requiring explicit capture.
2015-08-25 15:17:14 -07:00
Igor Canadi
53b88784df Add throttling to multi-threaded backups
Summary: See internal task t8056182

Test Plan: Added multi-threading in RateLimiter test

Reviewers: benj, AaronFeldman

Reviewed By: AaronFeldman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45459
2015-08-25 13:32:46 -07:00
agiardullo
20d1e547d1 Common base class for transactions
Summary:
As I keep adding new features to transactions, I keep creating more duplicate code.  This diff cleans this up by creating a base implementation class for Transaction and OptimisticTransaction to inherit from.

The code in TransactionBase.h/.cc is all just copied from elsewhere.  The only entertaining part of this class worth looking at is the virtual TryLock method which allows OptimisticTransactions and Transactions to share the same common code for Put/Get/etc.

The rest of this diff is mostly red and easy on the eyes.

Test Plan: No functionality change.  existing tests pass.

Reviewers: sdong, jkedgar, rven, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D45135
2015-08-24 19:09:43 -07:00
Andres Notzli
f32a572099 Simplify querying of merge results
Summary:
While working on supporting mixing merge operators with
single deletes ( https://reviews.facebook.net/D43179 ),
I realized that returning and dealing with merge results
can be made simpler. Submitting this as a separate diff
because it is not directly related to single deletes.

Before, callers of merge helper had to retrieve the merge
result in one of two ways depending on whether the merge
was successful or not (success = result of merge was single
kTypeValue). For successful merges, the caller could query
the resulting key/value pair and for unsuccessful merges,
the result could be retrieved in the form of two deques of
keys and values. However, with single deletes, a successful merge
does not return a single key/value pair (if merge
operands are merged with a single delete, we have to generate
a value and keep the original single delete around to make
sure that we are not accidentially producing a key overwrite).
In addition, the two existing call sites of the merge
helper were taking the same actions independently from whether
the merge was successful or not, so this patch simplifies that.

Test Plan: make clean all check

Reviewers: rven, sdong, yhchiang, anthony, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43353
2015-08-17 17:34:38 -07:00
Islam AbdelRahman
3bd9db420e [Cleanup] Remove RandomRWFile
Summary: RandomRWFile is not used anywhere in out code base, this patch remove RandomRWFile

Test Plan:
make check -j64
USE_CLANG=1 make all -j64
OPT=-DROCKSDB_LITE make release -j64

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

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D44091
2015-08-12 10:18:59 -07:00
agiardullo
c3466eab07 Have Transactions use WriteBatch::RollbackToSavePoint
Summary:
Clean up transactions to use the new RollbackToSavePoint api in WriteBatchWithIndex.

Note, this diff depends on Pessimistic Transactions diff and ManagedSnapshot diff (D40869 and D43293).

Test Plan: unit tests

Reviewers: rven, yhchiang, kradhakrishnan, spetrunia, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43371
2015-08-11 17:53:30 -07:00
agiardullo
0db807ec28 Transaction error statuses
Summary:
Based on feedback from spetrunia, we should better differentiate error statuses for transaction failures.

https://github.com/MySQLOnRocksDB/mysql-5.6/issues/86#issuecomment-124605954

Test Plan: unit tests

Reviewers: rven, kradhakrishnan, spetrunia, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43323
2015-08-11 17:52:56 -07:00
agiardullo
c2f2cb0214 Pessimistic Transactions
Summary:
Initial implementation of Pessimistic Transactions.  This diff contains the api changes discussed in D38913.  This diff is pretty large, so let me know if people would prefer to meet up to discuss it.

MyRocks folks:  please take a look at the API in include/rocksdb/utilities/transaction[_db].h and let me know if you have any issues.

Also, you'll notice a couple of TODOs in the implementation of RollbackToSavePoint().  After chatting with Siying, I'm going to send out a separate diff for an alternate implementation of this feature that implements the rollback inside of WriteBatch/WriteBatchWithIndex.  We can then decide which route is preferable.

Next, I'm planning on doing some perf testing and then integrating this diff into MongoRocks for further testing.

Test Plan: Unit tests, db_bench parallel testing.

Reviewers: igor, rven, sdong, yhchiang, yoshinorim

Reviewed By: sdong

Subscribers: hermanlee4, maykov, spetrunia, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40869
2015-08-11 17:52:23 -07:00
Poornima Chozhiyath Raman
960d936e83 Add function 'GetInfoLogList()'
Summary: The list of info log files of a db can be obtained using the new function.

Test Plan: New test in db_test.cc passed.

Reviewers: yhchiang, IslamAbdelRahman, sdong

Reviewed By: sdong

Subscribers: IslamAbdelRahman, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D41715
2015-08-05 16:16:46 -07:00
Yueh-Hsuan Chiang
f39cbcb0a5 Merge pull request #654 from adamretter/remove-emptyvalue-compactionfilter
RemoveEmptyValueCompactionFilter
2015-08-04 16:54:14 -07:00
Yueh-Hsuan Chiang
be8621ffaf Fix compile warning in compact_on_deletion_collector in some environment
Summary: Fix compile warning in compact_on_deletion_collector some environment

Test Plan: make

Reviewers: igor, sdong, anthony, IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D43467
2015-08-03 20:53:15 -07:00
Yueh-Hsuan Chiang
26894303c1 Add CompactOnDeletionCollector in utilities/table_properties_collectors.
Summary:
This diff adds CompactOnDeletionCollector in utilities/table_properties_collectors,
which applies a sliding window to a sst file and mark this file as need-compaction
when it observe enough deletion entries within the consecutive keys covered by
the sliding window.

Test Plan: compact_on_deletion_collector_test

Reviewers: igor, anthony, IslamAbdelRahman, kradhakrishnan, yoshinorim, sdong

Reviewed By: sdong

Subscribers: maykov, dhruba

Differential Revision: https://reviews.facebook.net/D41175
2015-08-03 20:42:55 -07:00
agiardullo
8161bdb5a0 WriteBatch Save Points
Summary:
Support RollbackToSavePoint() in WriteBatch and WriteBatchWithIndex.  Support for partial transaction rollback is needed for MyRocks.

An alternate implementation of Transaction::RollbackToSavePoint() exists in D40869.  However, the other implementation is messier because it is implemented outside of WriteBatch.  This implementation is much cleaner and also exposes a potentially useful feature to WriteBatch.

Test Plan: Added unit tests

Reviewers: IslamAbdelRahman, kradhakrishnan, maykov, yoshinorim, hermanlee4, spetrunia, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42723
2015-07-29 16:54:23 -07:00
sdong
85ac65536b Tests to avoid to use TMPDIR directly
Summary: Directly using TMPDIR can cause problems when running tests using parallel option. Fix them.

Test Plan: Run all tests in parallel

Reviewers: kradhakrishnan, yhchiang, IslamAbdelRahman, anthony

Reviewed By: anthony

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D42807
2015-07-21 19:07:34 -07:00
agiardullo
064294081b Improved FileExists API
Summary: Add new CheckFileExists method.  Considered changing the FileExists api but didn't want to break anyone's builds.

Test Plan: unit tests

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42003
2015-07-20 17:20:40 -07:00
Islam AbdelRahman
aa8ac6445b Skip unsupported tests in ROCKSDB_LITE
Summary:
Skipping these tests in ROCKSDB_LITE since they are not supported
json_document_test
wal_manager_test
ttl_test
sst_dump_test
deletefile_test
compact_files_test
prefix_test
checkpoint_test

Test Plan:
json_document_test
wal_manager_test
ttl_test
sst_dump_test
deletefile_test
compact_files_test
prefix_test
checkpoint_test

Reviewers: igor, sdong, yhchiang, kradhakrishnan, anthony

Reviewed By: anthony

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D42573
2015-07-20 11:24:54 -07:00
Islam AbdelRahman
144d2910db Block backupable_db_test_lite in ROCKSDB_LITE
Summary: BackupableDB is not supported in ROCKSDB_LITE, blocking backupable_db_test_lite

Test Plan: backupable_db_test

Reviewers: sdong, igor, yhchiang

Reviewed By: yhchiang

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D42165
2015-07-20 11:15:16 -07:00
sdong
6e9fbeb27c Move rate_limiter, write buffering, most perf context instrumentation and most random kill out of Env
Summary: We want to keep Env a think layer for better portability. Less platform dependent codes should be moved out of Env. In this patch, I create a wrapper of file readers and writers, and put rate limiting, write buffering, as well as most perf context instrumentation and random kill out of Env. It will make it easier to maintain multiple Env in the future.

Test Plan: Run all existing unit tests.

Reviewers: anthony, kradhakrishnan, IslamAbdelRahman, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D42321
2015-07-17 16:58:18 -07:00
Islam AbdelRahman
26ca893198 Block document_db_test in ROCKSDB_LITE
Summary: DocumentDB is not supported in ROCKSDB_LITE

Test Plan: document_db_test

Reviewers: yhchiang

Reviewed By: yhchiang

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D42177
2015-07-17 12:54:30 -07:00
Igor Canadi
35ca59364c Don't let flushes preempt compactions
Summary:
When we first started, max_background_flushes was 0 by default and compaction thread was executing flushes (since there was no flush thread). Then, we switched the default max_background_flushes to 1. However, we still support the case where there is no flush thread and flushes are done in compaction. This is making our code a bit more complicated. By not supporting this use-case we can make our code simpler.

We have a special case that when you set max_background_flushes to 0, we
schedule the flush to execute on the compaction thread.

Test Plan: make check (there might be some unit tests that depend on this behavior)

Reviewers: IslamAbdelRahman, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D41931
2015-07-17 12:02:52 -07:00
Andres Notzli
1d20fa9d0f Fixed and simplified merge_helper
Summary:
MergeUntil was not reporting a success when merging an operand with
a Value/Deletion despite the comments in MergeHelper and CompactionJob
indicating otherwise. This lead to operands being written to the compaction
output unnecessarily:

M1 M2 M3 P M4 M5 --> (P+M1+M2+M3) M2 M3 M4 M5 (before the diff)
M1 M2 M3 P M4 M5 --> (P+M1+M2+M3) M4 M5 (after the diff)

In addition, the code handling Values/Deletion was basically identical.
This patch unifies the code. Finally, this patch also adds testing for
merge_helper.

Test Plan: make && make check

Reviewers: sdong, rven, yhchiang, tnovak, igor

Reviewed By: igor

Subscribers: tnovak, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42351
2015-07-17 09:27:24 -07:00
Dmitri Smirnov
d1a457181d Ensure Windows build w/o port/port.h in public headers
- Remove make file defines from public headers and use _WIN32 because it is compiler defined
 - use __GNUC__ and __clang__ to guard non-portable attributes
 - add #include "port/port.h" to some new .cc files.
 - minor changes in CMakeLists to reflect recent changes
2015-07-16 12:10:16 -07:00
Adam Retter
62dec0e2b7 RemoveEmptyValueCompactionFilter - A compaction filter which removes entries which have an empty value 2015-07-16 11:50:10 +01:00
agiardullo
81d072623c move convenience.h out of utilities
Summary: Moved convenience.h out of utilities to remove a dependency on utilities in db.

Test Plan: unit tests.  Also compiled a link to the old location to verify the _Pragma works.

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42201
2015-07-15 14:51:51 -07:00
Igor Canadi
8a9fca2619 Better error handling in BackupEngine
Summary:
Couple of changes here:
* NewBackupEngine() and NewReadOnlyBackupEngine() are now removed. They were deprecated since RocksDB 3.8. Changing these to new functions should be pretty straight-forward. As a followup, I'll fix all fbcode callsights
* Instead of initializing backup engine in the constructor, we initialize it in a separate function now. That way, we can catch all errors and return appropriate status code.
* We catch all errors during initializations and return them to the client properly.
* Added new tests to backupable_db_test, to make sure that we can't open BackupEngine when there are Env errors.
* Transitioned backupable_db_test to use BackupEngine rather than BackupableDB. From the two available APIs, judging by the current use-cases, it looks like BackupEngine API won. It's much more flexible since it doesn't require StackableDB.

Test Plan: Added a new unit test to backupable_db_test

Reviewers: yhchiang, sdong, AaronFeldman

Reviewed By: AaronFeldman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D41925
2015-07-14 20:51:36 +02:00
agiardullo
18d5e1bf88 Remove db_impl_readonly dependency on utilities
Summary: Seems like the cleanest way to resolve this is to move CompactedDBImpl into db/.  CompactedDBImpl should probably live in the same place as DBImplReadonly since Opening the latter could end up instantiating the former.  Both DBImplReadonly and CompactedDBImpl inherit from DBImpl access protected members of DBImpl( and the latter access friendly private methods).

Test Plan: unit tests

Reviewers: sdong, yhchiang, kradhakrishnan, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42027
2015-07-14 11:32:54 -07:00
Islam AbdelRahman
04d201fa0b Block spatial_db_test in ROCKSDB_LITE
Summary: Block spatial_db_test in ROCKSDB_LITE as SpatialDB is not supported

Test Plan: spatial_db_test

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D41991
2015-07-13 18:35:03 -07:00
Islam AbdelRahman
e8e8c90499 fix compile for optimistic_transaction_test under ROCKSDB_LITE
Summary: Adding a main for optimistic_transaction_test that report that it was skipped when using ROCKSDB_LITE

Test Plan: optimistic_transaction_test

Reviewers: yhchiang, sdong, igor, anthony

Reviewed By: anthony

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D41979
2015-07-13 16:42:40 -07:00
sdong
f9728640f3 "make format" against last 10 commits
Summary: This helps Windows port to format their changes, as discussed. Might have formatted some other codes too becasue last 10 commits include more.

Test Plan: Build it.

Reviewers: anthony, IslamAbdelRahman, kradhakrishnan, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D41961
2015-07-13 13:50:18 -07:00
Dmitri Smirnov
c903ccc4c2 Merge from github/master 2015-07-09 18:01:08 -07:00
Dmitri Smirnov
ef4b87f1b2 Commit both PR and internal code review changes 2015-07-07 16:58:20 -07:00
Aaron Feldman
e12b403991 Initialize threads later in constructor
Summary: This addresses a test failure where an exception occured in the constructor's call to CreateDirIfMissing(). The existence of unjoined threads prevented this exception from propogating properly. See http://stackoverflow.com/questions/7381757/c-terminate-called-without-an-active-exception

Test Plan: Re-run tests from task #7626266

Reviewers: sdong, anthony, igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D41313
2015-07-07 10:49:16 -07:00
Dmitri Smirnov
d2f0912bd3 Merge the latest changes from github/master 2015-07-02 17:23:41 -07:00
Dmitri Smirnov
feb99c31a4 Merge remote-tracking branch 'origin' into ms_win_port 2015-07-02 13:14:18 -07:00
Aaron Feldman
e70115e71b Fix unity build by removing anonymous namespace
Summary: see title

Test Plan: run 'make unity'

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba

Differential Revision: https://reviews.facebook.net/D41079
2015-07-02 12:27:35 -07:00
Aaron Feldman
a69bc91e37 Multithreaded backup and restore in BackupEngineImpl
Summary:
Add a new field: BackupableDBOptions.max_background_copies.
CreateNewBackup() and RestoreDBFromBackup() will use this number of threads to perform copies.
If there is a backup rate limit, then max_background_copies must be 1.
Update backupable_db_test.cc to test multi-threaded backup and restore.
Update backupable_db_test.cc to test backups when the backup environment is not the same as the database environment.

Test Plan:
Run ./backupable_db_test
Run valgrind ./backupable_db_test
Run with TSAN and ASAN

Reviewers: yhchiang, rven, anthony, sdong, igor

Reviewed By: igor

Subscribers: yhchiang, anthony, sdong, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D40725
2015-07-02 11:35:51 -07:00