0518-如何在Impala中使用UDF获取SessionId

context->impl()->state()->session_id();

https://github.com/cloudera/Impala/blob/cdh5-2.9.0_5.12.2/be/src/udf/udf.h#L234
https://github.com/cloudera/Impala/blob/cdh5-2.9.0_5.12.2/be/src/runtime/runtime-state.h#L112

wget http://mirror.cogentco.com/pub/apache/maven/maven-3/3.6.0/binaries/apache-maven-3.6.0-bin.tar.gz

tar  -zxvf  apache-maven-3.6.0-bin.tar.gz
mv apache-maven-3.6.0 /usr/local/

export MAVEN_HOME=/usr/local/apache-maven-3.6.0

yum -y install cmake-3.3.2-1.gf.el7.x86_64

sudo yum -y install centos-release-scl
sudo yum -y install devtoolset-7
scl enable devtoolset-7 bash

wget https://codeload.github.com/cloudera/Impala/zip/cdh5-trunk

unzip Impala-cdh5-trunk.zip

export IMPALA_HOME=/data/Impala-cdh5-trunk

source /etc/profile

yum install -y redhat-lsb.x86_64
yum -y group install "Development Tools"
yum -y install git ant libevent-devel automake libtool flex bison gcc-c++ 
yum -y install openssl-devel make
yum -y install doxygen.x86_64 glib-devel python-devel bzip2-devel svn libevent-devel krb5-workstation
yum -y install openldap-devel db4-devel python-setuptools python-pip cyrus-sasl* postgresql postgresql-server ant-nodeps lzo-devel lzop
yum -y install boost boost-devel

./buildall.sh -notests(该命令将编译整个工程，耗时较长)
或者执行：
./buildall.sh -cmake_only

mkdir -p /root/impala-udf
mkdir -p /root/impala-udf/include

cp -r toolchain/gflags-2.2.0-p1/include/gflags/ /root/impala-udf/include
cp -r toolchain/glog-0.3.4-p3/include/glog/ /root/impala-udf/include
cp -r toolchain/rapidjson-0.11/include/rapidjson/ /root/impala-udf/include
cp -r toolchain/thrift-0.9.0-p11/include/thrift/ /root/impala-udf/include
cp -r be/generated-sources/gen-cpp /root/impala-udf/include
cp -r be/src/* /root/impala-udf/include

#ifndef SAMPLES_UDF_H
#define SAMPLES_UDF_H
#include <udf/udf.h>
#include <udf/udf-internal.h>
using namespace impala_udf;

StringVal GetSessionId(FunctionContext* context);
#endif

#define __STDC_FORMAT_MACROS

#include <stdlib.h>
#include "getSessionId.h"
#include <udf/udf.h>
#include <udf/udf-internal.h>
#include <runtime/runtime-state.h>
#include <string.h>
#include <vector>

#include <stdio.h>
#include <inttypes.h>
#include<iostream>  


using namespace std; 
namespace impala{
 class TUniqueId;
}
using namespace impala_udf;

string DecIntToHexStr(unsigned long long num)
{
    string str;
    long long Temp = num / 16;
    int left = num % 16;
    if (Temp > 0)
        str += DecIntToHexStr(Temp);
    if (left < 10)
        str += (left + '0');
    else
        str += ('A' + left - 10);
    return str;
}

StringVal getSessionId(FunctionContext* context) {
 impala::TUniqueId id = context->impl()->state()->session_id();
 string idhi = DecIntToHexStr(id.hi);
 string idlo = DecIntToHexStr(id.lo);
 string sessionid = idhi +":"+ idlo;
 return *(new StringVal(sessionid.data()));
}

cmake_minimum_required(VERSION 3.2.3)
# where to put generated libraries
set(LIBRARY_OUTPUT_PATH "build")
# where to put generated binaries
set(EXECUTABLE_OUTPUT_PATH "build")

find_program(CLANG_EXECUTABLE clang++)

SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g -ggdb")

include_directories("include")

# Function to generate rule to cross compile a source file to an IR module.
# This should be called with the .cc src file and it will generate a
# src-file-ir target that can be built.
# e.g. COMPILE_TO_IR(test.cc) generates the "test-ir" make target.
set(IR_COMPILE_FLAGS "-emit-llvm" "-O3" "-c" "-Iinclude")
function(COMPILE_TO_IR SRC_FILE)
  get_filename_component(BASE_NAME ${SRC_FILE} NAME_WE)
  set(OUTPUT_FILE "build/${BASE_NAME}.ll")
  add_custom_command(
    OUTPUT ${OUTPUT_FILE}
    COMMAND ${CLANG_EXECUTABLE} ${IR_COMPILE_FLAGS} ${SRC_FILE} -o ${OUTPUT_FILE}
    DEPENDS ${SRC_FILE})
  add_custom_target(${BASE_NAME}-ir ALL DEPENDS ${OUTPUT_FILE})
endfunction(COMPILE_TO_IR)

# Build the UDA/UDFs into a shared library.
add_library(getSessionId SHARED getSessionId.cc)

# Custom targest to cross compile UDA/UDF to ir
if (CLANG_EXECUTABLE)
COMPILE_TO_IR(getSessionId.cc )
endif(CLANG_EXECUTABLE)

# This is an example of how to use the test harness to help develop UDF and UDAs.
target_link_libraries(getSessionId ImpalaUdf)

cmake .

make

hdfs dfs -put libgetSessionId.so /tmp

CREATE FUNCTION getSessionId() RETURNS string location '/tmp/libgetSessionId.so' symbol='getSessionId';

select *,getSessionId() from test_table;

CREATE FUNCTION getQueryId() RETURNS string location '/tmp/libgetQueryId.so' symbol='getQueryId';

select *,getQueryId() from test_table;