PiperOrigin-RevId: 309110431

leveldb::Env::DeleteFile was replaced with leveldb::Env::RemoveFile in
all tests. This allows us to remove workarounds for windows.h #defining
DeleteFile.
PiperOrigin-RevId: 289121105

The "DeleteFile" method name causes pain for Windows developers, because
<windows.h> #defines a DeleteFile macro to DeleteFileW or DeleteFileA.
Current code uses workarounds, like #undefining DeleteFile everywhere an
Env is declared, implemented, or used.

This CL removes the need for workarounds by renaming Env::DeleteFile to
Env::RemoveFile. For consistency, Env::DeleteDir is also renamed to
Env::RemoveDir. A few internal methods are also renamed for consistency.
Software that supports Windows is expected to migrate any Env
implementations and usage to Remove{File,Dir}, and never use the name
Env::Delete{File,Dir} in its code.

The renaming is done in a backwards-compatible way, at the risk of
making it slightly more difficult to build a new correct Env
implementation. The backwards compatibility is achieved using the
following hacks:

1) Env::Remove{File,Dir} methods are added, with a default
    implementation that calls into Env::Delete{File,Dir}. This makes old
    Env implementations compatible with code that calls into the updated
    API.
2) The Env::Delete{File,Dir} methods are no longer pure virtuals.
    Instead, they gain a default implementation that calls into
    Env::Remove{File,Dir}. This makes updated Env implementations
    compatible with code that calls into the old API.

The cost of this approach is that it's possible to write an Env without
overriding either Rename{File,Dir} or Delete{File,Dir}, without getting
a compiler warning. However, attempting to run the test suite will
immediately fail with an infinite call stack ending in
{Remove,Delete}{File,Dir}, making developers aware of the problem.

PiperOrigin-RevId: 288710907

Env::DeleteFile.

PiperOrigin-RevId: 283607548

PiperOrigin-RevId: 282373286

PiperOrigin-RevId: 281815695

1) Convert iterator-based for loops to C++11 foreach loops.
2) Convert "void operator=" to "T& operator=".
3) Switch from copy operators from private to public deleted.
4) Switch from empty ctors / dtors to "= default" where appropriate.

PiperOrigin-RevId: 246679195

Use clang-format to correct formatting to be in agreement with the [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html). Doing this simplifies the process of accepting changes. Also fixed a few warnings flagged by clang-tidy.

PiperOrigin-RevId: 246350737

This CL moves default values for
leveldb::{Options,ReadOptions,WriteOptions} from constructors to member
declarations, and removes now-redundant comments stating the defaults.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=239271242

ssize_t is not standard C++. It is a POSIX extension. Therefore, it does
not belong in generic code.

This change tweaks the logic in DBIter to remove the need for signed
integers, so ssize_t can be replaced with size_t. The impacted method
and private member are renamed to better express their purpose.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=211471606

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=192365747

After this CL, all classes with Mutex members should be covered by annotations. Exceptions are atomic members, which shouldn't need locking, and DBImpl members that cause errors when annotated, which will be tackled separately.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=190260865

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171708408

(Based on a suggestion by cmumford.)

"open" benchmark on my workstation speeds up significantly since we
can now avoid three fdatasync calls and a compaction per open:

  Before: ~80000 microseconds
  After:    ~130 microseconds

Details:

(1) Added Options::reuse_logs (currently defaults to false) to control
new behavior.  The intention is to change the default to true after some
baking.

(2) Added Env::NewAppendableFile() whose default implementation returns
a not-supported error.

(3) VersionSet::Recovery attempts to reuse the MANIFEST from which
it is recovering.

(4) DBImpl recovery attempts to reuse the last log file and memtable.

(5) db_test.cc now tests a new configuration that sets reuse_logs to true.

(6) fault_injection_test also tests a reuse_logs==true config.

(7) Added a new recovery_test.

This test is intended to ensure leveldb properly detects and recovers from
faults - specifically unwritten file data lost as a result of a system reset.