ARROW-3440: [Gandiva] fix readme for builds

- also use thirdy-party protobuf install for gandiva

cpp/README.md

@@ -225,6 +225,37 @@ The optional arrow reader for the Apache ORC format (found in the
 This is currently not supported on windows. Note that this functionality is
 still in Alpha stages, and subject to API changes without deprecation warnings.
 
+### Building and developing Gandiva (optional)
+
+In addition to the arrow dependancies, gandiva requires :
+* On linux, gcc 4.9 or higher C++11-enabled compiler.
+* LLVM
+
+On Ubuntu/Debian you can install these requirements with:
+
+```shell
+sudo apt-get install llvm-6.0-dev
+```
+
+On macOS, you can use [Homebrew][1]:
+
+```shell
+brew install llvm@6
+```
+
+The optional `gandiva` libraries and tests can be built by passing
+`-DARROW_GANDIVA=on`.
+
+```shell
+cmake .. -DARROW_GANDIVA=on
+make
+ctest -L unitest
+ctest -L integ
+```
+
+This library is still in Alpha stages, and subject to API changes without
+deprecation warnings.
+
 ### API documentation
 
 To generate the (html) API documentation, run the following command in the apidoc
@@ -398,4 +429,4 @@ both of these options would be used rarely. Current known uses-cases when they a
 [2]: https://github.com/apache/arrow/blob/master/cpp/apidoc/Windows.md
 [3]: https://google.github.io/styleguide/cppguide.html
 [4]: https://github.com/include-what-you-use/include-what-you-use
-[5]: https://github.com/apache/arrow/blob/master/cpp/thirdparty/README.md
+[5]: https://github.com/apache/arrow/blob/master/cpp/thirdparty/README.md

cpp/cmake_modules/ThirdpartyToolchain.cmake

@@ -1126,12 +1126,13 @@ if (ARROW_ORC OR ARROW_FLIGHT OR ARROW_GANDIVA)
     set (PROTOBUF_HOME "${PROTOBUF_PREFIX}")
     set (PROTOBUF_INCLUDE_DIR "${PROTOBUF_PREFIX}/include")
     set (PROTOBUF_STATIC_LIB "${PROTOBUF_PREFIX}/lib/${CMAKE_STATIC_LIBRARY_PREFIX}protobuf${CMAKE_STATIC_LIBRARY_SUFFIX}")
+    set (PROTOBUF_EXECUTABLE "${PROTOBUF_PREFIX}/bin/protoc")
 
     ExternalProject_Add(protobuf_ep
       CONFIGURE_COMMAND "./configure" "--disable-shared" "--prefix=${PROTOBUF_PREFIX}" "CXXFLAGS=${EP_CXX_FLAGS}"
       BUILD_IN_SOURCE 1
       URL ${PROTOBUF_SOURCE_URL}
-      BUILD_BYPRODUCTS "${PROTOBUF_STATIC_LIB}"
+      BUILD_BYPRODUCTS "${PROTOBUF_STATIC_LIB}" "${PROTOBUF_EXECUTABLE}"
       ${EP_LOG_OPTIONS})
 
     set (PROTOBUF_VENDORED 1)

cpp/src/gandiva/README.md

@@ -1,88 +0,0 @@
-<!---
-  Licensed to the Apache Software Foundation (ASF) under one
-  or more contributor license agreements.  See the NOTICE file
-  distributed with this work for additional information
-  regarding copyright ownership.  The ASF licenses this file
-  to you under the Apache License, Version 2.0 (the
-  "License"); you may not use this file except in compliance
-  with the License.  You may obtain a copy of the License at
-
-    http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing,
-  software distributed under the License is distributed on an
-  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
-  KIND, either express or implied.  See the License for the
-  specific language governing permissions and limitations
-  under the License.
--->
-
-# Gandiva C++
-
-## System setup
-
-Gandiva uses CMake as a build configuration system. Currently, it supports
-out-of-source builds only.
-
-Build Gandiva requires:
-
-* A C++11-enabled compiler. On Linux, gcc 4.8 and higher should be sufficient.
-* CMake
-* LLVM
-* Arrow
-* Boost
-* Protobuf
-* re2
-
-On macOS, you can use [Homebrew][1]:
-
-```shell
-brew install cmake llvm boost protobuf re2
-```
-
-To install arrow, follow the steps in the [arrow Readme][2].
-## Building Gandiva
-
-Debug build :
-
-```shell
-git clone https://github.com/apache/arrow.git
-cd cpp/src/gandiva
-mkdir debug
-cd debug
-cmake ..
-make
-ctest
-```
-
-Release build :
-
-```shell
-git clone https://github.com/apache/arrow.git
-cd cpp/src/gandiva
-mkdir release
-cd release
-cmake .. -DCMAKE_BUILD_TYPE=Release
-make
-ctest
-```
-
-## Validating code style
-
-We follow the [google cpp code style][3]. To validate compliance,
-
-```shell
-cd debug
-make stylecheck
-```
-
-## Fixing code style
-
-```shell
-cd debug
-make stylefix
-```
-
-[1]: https://brew.sh/
-[2]: https://github.com/apache/arrow/tree/master/cpp
-[3]: https://google.github.io/styleguide/cppguide.html

cpp/src/gandiva/jni/CMakeLists.txt

@@ -17,9 +17,7 @@
 
 project(gandiva_jni)
 
-# Find protobuf
 set(Protobuf_USE_STATIC_LIBS "ON")
-find_package(Protobuf REQUIRED)
 
 # Find JNI
 find_package(JNI REQUIRED)
@@ -35,7 +33,7 @@ get_filename_component(ABS_GANDIVA_PROTO ${CMAKE_SOURCE_DIR}/src/gandiva/proto/T
 add_custom_command(
   OUTPUT ${PROTO_OUTPUT_FILES}
   COMMAND ${PROTOBUF_EXECUTABLE} --proto_path ${CMAKE_SOURCE_DIR}/src/gandiva/proto --cpp_out ${PROTO_OUTPUT_DIR} ${CMAKE_SOURCE_DIR}/src/gandiva/proto/Types.proto
-  DEPENDS ${ABS_GANDIVA_PROTO}
+  DEPENDS ${ABS_GANDIVA_PROTO} protobuf
   COMMENT "Running PROTO compiler on Types.proto"
   VERBATIM
 )

java/README.md

@@ -25,13 +25,25 @@ install:
  - java 7 or later
  - maven 3.3 or later
 
-## Building running tests
+## Building and running tests
 
 ```
 cd java
 mvn install
 ```
 
+## Building and running tests for gandiva (optional)
+
+[Gandiva cpp][2] must be built before this step.
+
+```
+cd java
+mvn install -P gandiva -pl gandiva -am
+```
+
+This library is still in Alpha stages, and subject to API changes without
+deprecation warnings.
+
 ## Test Logging Configuration
 
 When running tests, Arrow Java uses the Logback logger with SLF4J. By default,
@@ -51,3 +63,4 @@ mvn -Dlogback.configurationFile=file:`pwd`/dev/logback.xml
 See [Logback Configuration][1] for more details.
 
 [1]: https://logback.qos.ch/manual/configuration.html
+[2]: https://github.com/apache/arrow/blob/master/cpp/README.md