The official levelDB does not support Cygwin platform, trying to compile it on Cygwin may get the error message:”Unknow platform”. Anyway, levelDB works on Windows Cygwin environment, all you have to do is to manually modify some files.
First, make sure your Cygwin has gcc-4 installed, not gcc-3:
$ gcc -v gcc version 4.5.3 (GCC)
Then, edit build_detect_platform under levelDB source code folder, make it looks like this:
case "$TARGET_OS" in CYGWIN_*) PLATFORM=OS_LINUX COMMON_FLAGS="$MEMCMP_FLAG -lpthread -DOS_LINUX -DCYGWIN" PLATFORM_LDFLAGS="-lpthread" PORT_FILE=port/port_posix.cc ;;
The “CYGWIN_*” codes is added. Then edit port/port_posix.h, make it looks like this:
#if defined(OS_MACOSX) || defined(OS_SOLARIS) || defined(OS_FREEBSD) ||\ defined(OS_NETBSD) || defined(OS_OPENBSD) || defined(OS_DRAGONFLYBSD) ||\ defined(OS_ANDROID) || defined(OS_HPUX) || defined(CYGWIN) // Use fread/fwrite/fflush on platforms without _unlocked variants #define fread_unlocked fread #define fwrite_unlocked fwrite #define fflush_unlocked fflush #endif
The ” || defined(CYGWIN)” is added, or you may got this error if you try to run make:
util/env_posix.cc:50: error: `fread_unlocked' undeclared (first use this function)
Now, you can compile levelDB on Windows Cygwin:
make
If you can find the file libleveldb.a in levelDB source code folder, it’s sucessfull. levelDB is just a library, not a standalone server, so we write a simple CPP code example to test it:
#include <iostream> #include "leveldb/db.h" int main(){ leveldb::DB* db; leveldb::Options options; leveldb::Status status; options.create_if_missing = true; status = leveldb::DB::Open(options, "./testdb", &db); std::string key = "abc"; std::string value = "123"; std::string ret; std::cout << value; status = db->Put(leveldb::WriteOptions(), key, value); status = db->Get(leveldb::ReadOptions(), key, &ret); std::cout << ret; return 0; }
Compile this code(file named a.cpp) and run with command:
g++ a.cpp -Iinclude -L. -lleveldb; ./a