Update to leveldb upstream using subtree merge

Author: laanwj

src/leveldb/.appveyor.yml

@@ -0,0 +1,35 @@
+# Build matrix / environment variables are explained on:
+# https://www.appveyor.com/docs/appveyor-yml/
+# This file can be validated on: https://ci.appveyor.com/tools/validate-yaml
+
+version: "{build}"
+
+environment:
+  matrix:
+    # AppVeyor currently has no custom job name feature.
+    # http://help.appveyor.com/discussions/questions/1623-can-i-provide-a-friendly-name-for-jobs
+    - JOB: Visual Studio 2017
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      CMAKE_GENERATOR: Visual Studio 15 2017
+
+platform:
+  - x86
+  - x64
+
+configuration:
+  - RelWithDebInfo
+  - Debug
+
+build_script:
+  - git submodule update --init --recursive
+  - mkdir build
+  - cd build
+  - if "%platform%"=="x64" set CMAKE_GENERATOR=%CMAKE_GENERATOR% Win64
+  - cmake --version
+  - cmake .. -G "%CMAKE_GENERATOR%"
+      -DCMAKE_CONFIGURATION_TYPES="%CONFIGURATION%"
+  - cmake --build . --config "%CONFIGURATION%"
+  - cd ..
+
+test_script:
+  - cd build && ctest --verbose --build-config "%CONFIGURATION%" && cd ..

src/leveldb/.clang-format

@@ -0,0 +1,18 @@
+# Run manually to reformat a file:
+# clang-format -i --style=file <file>
+# find . -iname '*.cc' -o -iname '*.h' -o -iname '*.h.in' | xargs clang-format -i --style=file
+BasedOnStyle: Google
+DerivePointerAlignment: false
+
+# Public headers are in a different location in the internal Google repository.
+# Order them so that when imported to the authoritative repository they will be
+# in correct alphabetical order.
+IncludeCategories:
+  - Regex:           '^(<|"(benchmarks|db|helpers)/)'
+    Priority:        1
+  - Regex:           '^"(leveldb)/'
+    Priority:        2
+  - Regex:           '^(<|"(issues|port|table|third_party|util)/)'
+    Priority:        3
+  - Regex:           '.*'
+    Priority:        4

src/leveldb/.gitignore

@@ -1,13 +1,8 @@
-build_config.mk
-*.a
-*.o
-*.dylib*
-*.so
-*.so.*
-*_test
-db_bench
-leveldbutil
-Release
-Debug
-Benchmark
-vs2010.*
+# Editors.
+*.sw*
+.vscode
+.DS_Store
+
+# Build directory.
+build/
+out/

src/leveldb/.travis.yml

@@ -1,13 +1,82 @@
+# Build matrix / environment variables are explained on:
+# http://about.travis-ci.org/docs/user/build-configuration/
+# This file can be validated on: http://lint.travis-ci.org/
+
 language: cpp
+dist: bionic
+osx_image: xcode10.3
+
 compiler:
-- clang
 - gcc
+- clang
 os:
 - linux
 - osx
-sudo: false
-before_install:
-- echo $LANG
-- echo $LC_ALL
+
+env:
+- BUILD_TYPE=Debug
+- BUILD_TYPE=RelWithDebInfo
+
+addons:
+  apt:
+    sources:
+    - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
+      key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+    - sourceline: 'ppa:ubuntu-toolchain-r/test'
+    packages:
+    - clang-9
+    - cmake
+    - gcc-9
+    - g++-9
+    - libgoogle-perftools-dev
+    - libkyotocabinet-dev
+    - libsnappy-dev
+    - libsqlite3-dev
+    - ninja-build
+  homebrew:
+    packages:
+    - cmake
+    - crc32c
+    - gcc@9
+    - gperftools
+    - kyoto-cabinet
+    - llvm@9
+    - ninja
+    - snappy
+    - sqlite3
+    update: true
+
+install:
+# The following Homebrew packages aren't linked by default, and need to be
+# prepended to the path explicitly.
+- if [ "$TRAVIS_OS_NAME" = "osx" ]; then
+    export PATH="$(brew --prefix llvm)/bin:$PATH";
+  fi
+# /usr/bin/gcc points to an older compiler on both Linux and macOS.
+- if [ "$CXX" = "g++" ]; then export CXX="g++-9" CC="gcc-9"; fi
+# /usr/bin/clang points to an older compiler on both Linux and macOS.
+#
+# Homebrew's llvm package doesn't ship a versioned clang++ binary, so the values
+# below don't work on macOS. Fortunately, the path change above makes the
+# default values (clang and clang++) resolve to the correct compiler on macOS.
+- if [ "$TRAVIS_OS_NAME" = "linux" ]; then
+    if [ "$CXX" = "clang++" ]; then export CXX="clang++-9" CC="clang-9"; fi;
+  fi
+- echo ${CC}
+- echo ${CXX}
+- ${CXX} --version
+- cmake --version
+
+before_script:
+- mkdir -p build && cd build
+- cmake .. -G Ninja -DCMAKE_BUILD_TYPE=$BUILD_TYPE
+    -DCMAKE_INSTALL_PREFIX=$HOME/.local
+- cmake --build .
+- cd ..
+
 script:
-- make -j 4 check
+- cd build && ctest --verbose && cd ..
+- "if [ -f build/db_bench ] ; then build/db_bench ; fi"
+- "if [ -f build/db_bench_sqlite3 ] ; then build/db_bench_sqlite3 ; fi"
+- "if [ -f build/db_bench_tree_db ] ; then build/db_bench_tree_db ; fi"
+- cd build && cmake --build . --target install