mongodb C++ Driver安裝

前言

mongocxx官網地址 http://mongocxx.org/?jmp=docs

本文的安裝版本是：mongocxx-r3.2.0.tar.gz 。

參考文檔安裝過程 http://mongocxx.org/mongocxx-v3/installation/ 。根據文檔過程安裝，因爲系統不一致，可能會遇到各類問題，筆者就一路坎坷。

Linux系統信息：Linux 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2 (2016-04-08) x86_64 GNU/Linux

 

1 開始安裝

1.1 安裝最新版的mongoDB C driver

mongocxx是基於mongo-c-driver的，因此須要先下載安裝最新版本的 mongo-c-driver。此時最新版本是 1.13.0.tar.gz 。

參考連接：http://mongoc.org/libmongoc/current/installing.html 。本文全部內容都是採用源碼安裝的方式。

根據文檔要求，cmake須要是3.2或以後的版本。camke --version發現系統的cmake還停留在2.x版本。先升級一下cmake。

 1.1.1 升級cmake到最近版本

wget https://cmake.org/files/v3.12/cmake-3.12.3.tar.gz
tar -xzf cmake-3.12.3.tar.gz
cd cmake-3.12.3
./configure
sudo make && make install
cmake --version    

其中，cmake --version檢查一下最終的cmake版本。

mongo-c-driver的cmake過程：

wget https://github.com/mongodb/mongo-c-driver/releases/download/1.13.0/mongo-c-driver-1.13.0.tar.gz
tar -xzf mongo-c-driver-1.13.0.tar.gz
mkdir cmake-build
cd cmake-build
cmake -DENABLE_AUTOMATIC_INIT_AND_CLEANUP=OFF -DCMAKE_BUILD_TYPE=Release ..

NOTE：這裏要特別注意cmake的輸出，會提示你係統還缺乏什麼庫（NOT FOUND），請不要無視。筆者的mongo-c-driver就安裝了兩遍。

例如，openssl和snappy沒有安裝正確。雖然最終cmake和make不會報錯，可是最後面用mongocxx的時候會提示ssl錯誤，不能鏈接mongodb。

附上cmake的部分輸出：

-- Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the system variable OPENSSL_ROOT_DIR (missing: OPENSSL_CRYPTO_LIBRARY OPENSSL_INCLUDE_DIR) 
-- Searching for sasl/sasl.h
--   Found in /usr/include
-- Searching for libsasl2
--   Found /usr/lib/x86_64-linux-gnu/libsasl2.so
-- Detected parameters: accept (int, struct sockaddr *, socklen_t *)
-- Searching for compression library header snappy-c.h
-- Not found (specify -DCMAKE_INCLUDE_PATH=/path/to/snappy/include for Snappy compression)
-- No ICU library found, SASLPrep disabled for SCRAM-SHA-256 authentication.
-- If ICU is installed in a non-standard directory, define ICU_ROOT as the ICU installation path.
-- SSL disabled -- Compiling against Cyrus SASL
-- Configuring done
-- Generating done
-- Build files have been written to: /home/yyln2745/studyplace/mongo-c-driver-1.13.0/cmake-build

 若是SSL disabled的話，後面你寫的代碼應該會報錯：The SCRAM_SHA_1 authentication mechanism requires libmongoc built with ENABLE_SSL: generic server error 。

1.1.2 openssl問題

先肯定是否安裝了openssl。直接在shell輸入openssl命令，或者查看目錄：/usr/local/ssl 是否有東西。肯定沒有則須要安裝一下了。

按照cmake的提示，須要設置OPENSSL_ROOT_DIR、OPENSSL_CRYPTO_LIBRARY、OPENSSL_INCLUDE_DIR到系統路徑才能找到，可能放在cmake文件也能夠，可是對cmake不太熟。先按照上面的提示設置到 system variable中。直接設置到profile文件中，編輯vim /etc/profile，添加如下三行。

export OPENSSL_ROOT_DIR=/usr/local/ssl
export OPENSSL_CRYPTO_LIBRARY=/usr/local/ssl/lib
export OPENSSL_INCLUDE_DIR=/usr/local/ssl/include/

1.1.4 安裝snappy

snappy用來壓縮的。雖然不知道不安裝會有什麼問題，可是不想像SSL同樣，遇到問題了再回頭來修，將上面cmake提到的not found的都解決。安裝命令：

wget https://github.com/google/snappy/tarball/master
tar -xzf master
cd google-snappy-ea660b5/cmake
cmake ..
// 暫停一下 make
sudo make install

在make前，咱們須要先編輯一下CMakeCache.txt，修改CMAKE_CXX_FLAGS:STRING=-fPIC 。爲何要加 -fPIC 呢？由於不這樣的話，待會mongo-c-driver執行make時，應該會報如下錯誤：

/usr/bin/ld: /usr/local/lib/libsnappy.a(snappy.cc.o): relocation R_X86_64_32 against `.rodata' can not be used when making a shared object; recompile with -fPIC /usr/local/lib/libsnappy.a: error adding symbols: Bad value
collect2: error: ld returned 1 exit status
src/libmongoc/CMakeFiles/mongoc_shared.dir/build.make:1277: recipe for target 'src/libmongoc/libmongoc-1.0.so.0.0.0' failed
make[2]: *** [src/libmongoc/libmongoc-1.0.so.0.0.0] Error 1
CMakeFiles/Makefile2:1678: recipe for target 'src/libmongoc/CMakeFiles/mongoc_shared.dir/all' failed
make[1]: *** [src/libmongoc/CMakeFiles/mongoc_shared.dir/all] Error 2
Makefile:151: recipe for target 'all' failed
make: *** [all] Error 2

 關於更多 fPIC 的知識，可另行學習，建議瞭解一下。

1.1.5 安裝ICU

官網：http://www.icu-project.org/download/4.2.html 安裝步驟：

wget http://download.icu-project.org/files/icu4c/4.2.1/icu4c-4_2_1-src.tgz
tar -xzf icu4c-4_2_1-src.tgz 
cd source
./configure
make
sudo make install

 

1.1.6 最後make

最後一步，接着make & make install mongo-c-driver。

make
sudo make install

若是還出現以下錯誤：

[66%]Linking C executable test-libmongoc /usr/bin/ld: /usr/local/ssl/lib/libcrypto.a(dso_dlfcn.o): undefined reference to symbol 'dlclose@@GLIBC_2.2.5'
//lib/x86_64-linux-gnu/libdl.so.2: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
src/libmongoc/CMakeFiles/test-libmongoc.dir/build.make:1563: recipe for target 'src/libmongoc/test-libmongoc' failed
make[2]: *** [src/libmongoc/test-libmongoc] Error 1
CMakeFiles/Makefile2:1376: recipe for target 'src/libmongoc/CMakeFiles/test-libmongoc.dir/all' failed
make[1]: *** [src/libmongoc/CMakeFiles/test-libmongoc.dir/all] Error 2
Makefile:151: recipe for target 'all' failed
make: *** [all] Error 2

這是mongo-c-driver測試樣例編譯錯誤，咱們能夠選擇直接幹掉，方法爲編輯mongo-c-driver的CMakeCache.txt文件，修改ENABLE_TESTS:BOOL=OFF，或者在cmake的時候修改，命令以下，注意TEST後面有S：

cmake -DENABLE_AUTOMATIC_INIT_AND_CLEANUP=OFF -DCMAKE_BUILD_TYPE=Release -DENABLE_TESTS=OFF ..

 

安裝mongocxx

wget -OL https://github.com/mongodb/mongo-cxx-driver/archive/r3.3.1.tar.gz
tar -xzf r3.3.1.tar.gz
cd mongo-cxx-driver-r3.3.1/build
cmake -DCMAKE_BUILD_TYPE=Release -DBSONCXX_POLY_USE_MNMLSTC=1 -DCMAKE_INSTALL_PREFIX=/usr/local ..    
make EP_mnmlstc_core
make
sudo make install

其中，/usr/local是與前面的mongodb c driver同目錄， DBSONCXX_POLY_USE_MNMLSTC=1 or DBSONCXX_POLY_USE_BOOST=1

 這裏問題不大。

 

代碼測試

測試代碼以下：

#include <iostream>
#include <bsoncxx/builder/stream/document.hpp>
#include <bsoncxx/json.hpp>

#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>


int main(int, char**)
{
    mongocxx::instance inst{};
    //下面uri 請替換成真實數值。
    mongocxx::uri yace_uri{"mongodb://test_username:test_pwd@test_ip:test_port/?authSource=test_db"}; 

    mongocxx::options::client client_options;
    if (yace_uri.ssl()) {
        std::cout << "ssl-----------\n";
    }
    else {
        std::cout << "no-ssl\n";
    }

    mongocxx::client conn{yace_uri};

    mongocxx::database db = conn["test_db"];
    mongocxx::collection gift_test = db["gift_test"];

    bsoncxx::stdx::optional<bsoncxx::document::value> res = gift_test.find_one({});
    if (res)
        std::cout << bsoncxx::to_json(*res) << std::endl;
    
    return 0;
}

編譯命令：

c++ --std=c++11 test.cpp \
-I/usr/local/include/mongocxx/v_noabi -I/usr/local/include/libmongoc-1.0 \
-I/usr/local/include/bsoncxx/v_noabi -I/usr/local/include/libbson-1.0 \
-L/usr/local/lib -lmongocxx -lbsoncxx -Wl,-rpath,/usr/local/lib  

添加「-Wl,-rpath,/usr/local/lib」 是由於運行時報錯：error while loading shared libraries: libmongocxx.so._noabi。

參考連接：

https://jira.mongodb.org/browse/CXX-1425 for preior question. http://blog.51cto.com/elephantliu/563298 https://blog.csdn.net/furzoom/article/details/70843664 https://stackoverflow.com/questions/6562403/i-dont-understand-wl-rpath-wl

總結

本文介紹了mongocxx的安裝過程，主要記錄其中可能遇到的問題和解決過程。