text: /*
    Copyright (c) 2016, Antonio SJ Musumeci <trapexit@spawn.link>
  
    Permission to use, copy, modify, and/or distribute this software for any
    purpose with or without fee is hereby granted, provided that the above
    copyright notice and this permission notice appear in all copies.
  
    THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
    MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
    ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
    ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
  
  #include "errno.hpp"
  #include "fs_exists.hpp"
  #include "fs_info.hpp"
  #include "fs_path.hpp"
  #include "fs_statvfs_cache.hpp"
  #include "policy.hpp"
  #include "policy_eppfrd.hpp"
  #include "policy_error.hpp"
  #include "rnd.hpp"
  #include "rwlock.hpp"
  #include "strvec.hpp"
  
  #include <string>
  #include <vector>
  
  using std::string;
  using std::vector;
  
  struct BranchInfo
  {
    uint64_t      spaceavail;
    const string *basepath;
  };
  
  typedef vector<BranchInfo> BranchInfoVec;
  
  namespace eppfrd
  {
    static
    int
    get_branchinfo_create(const Branches::CPtr &branches_,
                          const char           *fusepath_,
                          BranchInfoVec        *branchinfo_,
                          uint64_t             *sum_)
    {
      int rv;
      int error;
      BranchInfo bi;
      fs::info_t info;
  
      *sum_ = 0;
      error = ENOENT;
      for(auto &branch : *branches_)
        {
          if(branch.ro_or_nc())
            error_and_continue(error,EROFS);
          if(!fs::exists(branch.path,fusepath_))
            error_and_continue(error,ENOENT);
          rv = fs::info(branch.path,&info);
          if(rv == -1)
            error_and_continue(error,ENOENT);
          if(info.readonly)
            error_and_continue(error,EROFS);
          if(info.spaceavail < branch.minfreespace())
            error_and_continue(error,ENOSPC);
  
          *sum_ += info.spaceavail;
  
          bi.spaceavail = info.spaceavail;
          bi.basepath   = &branch.path;
          branchinfo_->push_back(bi);
        }
  
      return error;
    }
  
    static
    int
    get_branchinfo_action(const Branches::CPtr &branches_,
                          const char           *fusepath_,
                          BranchInfoVec        *branchinfo_,
                          uint64_t             *sum_)
    {
      int rv;
      int error;
      BranchInfo bi;
      fs::info_t info;
  
      *sum_ = 0;
      error = ENOENT;
      for(auto &branch : *branches_)
        {
          if(branch.ro())
            error_and_continue(error,EROFS);
          if(!fs::exists(branch.path,fusepath_))
            error_and_continue(error,ENOENT);
          rv = fs::info(branch.path,&info);
          if(rv == -1)
            error_and_continue(error,ENOENT);
          if(info.readonly)
            error_and_continue(error,EROFS);
  
          *sum_ += info.spaceavail;
  
          bi.spaceavail = info.spaceavail;
          bi.basepath   = &branch.path;
          branchinfo_->push_back(bi);
        }
  
      return error;
    }
  
    static
    int
    get_branchinfo_search(const Branches::CPtr &branches_,
                          const char           *fusepath_,
                          BranchInfoVec        *branchinfo_,
                          uint64_t             *sum_)
    {
      int rv;
      BranchInfo bi;
      uint64_t spaceavail;
  
      *sum_ = 0;
      for(auto &branch : *branches_)
        {
          if(!fs::exists(branch.path,fusepath_))
            continue;
          rv = fs::statvfs_cache_spaceavail(branch.path,&spaceavail);
          if(rv == -1)
            continue;
  
          *sum_ += spaceavail;
  
          bi.spaceavail = spaceavail;
          bi.basepath   = &branch.path;
          branchinfo_->push_back(bi);
        }
  
      return ENOENT;
    }
  
    static
    const
    string*
    get_branch(const BranchInfoVec &branchinfo_,
               const uint64_t       sum_)
    {
      uint64_t idx;
      uint64_t threshold;
  
      idx = 0;
      threshold = RND::rand64(sum_);
      for(size_t i = 0; i < branchinfo_.size(); i++)
        {
          idx += branchinfo_[i].spaceavail;
  
          if(idx < threshold)
            continue;
  
          return branchinfo_[i].basepath;
        }
  
      return NULL;
    }
  
    static
    int
    create(const Branches::CPtr &branches_,
           const char           *fusepath_,
           StrVec               *paths_)
    {
      int error;
      uint64_t sum;
      const string *basepath;
      BranchInfoVec branchinfo;
  
      error    = eppfrd::get_branchinfo_create(branches_,fusepath_,&branchinfo,&sum);
      basepath = eppfrd::get_branch(branchinfo,sum);
      if(basepath == NULL)
        return (errno=error,-1);
  
      paths_->push_back(*basepath);
  
      return 0;
    }
  
    static
    int
    action(const Branches::CPtr &branches_,
           const char           *fusepath_,
           StrVec               *paths_)
    {
      int error;
      uint64_t sum;
      const string *basepath;
      BranchInfoVec branchinfo;
  
      error    = eppfrd::get_branchinfo_action(branches_,fusepath_,&branchinfo,&sum);
      basepath = eppfrd::get_branch(branchinfo,sum);
      if(basepath == NULL)
        return (errno=error,-1);
  
      paths_->push_back(*basepath);
  
      return 0;
    }
  
    static
    int
    search(const Branches::CPtr &branches_,
           const char           *fusepath_,
           StrVec               *paths_)
    {
      int error;
      uint64_t sum;
      const string *basepath;
      BranchInfoVec branchinfo;
  
      error    = eppfrd::get_branchinfo_search(branches_,fusepath_,&branchinfo,&sum);
      basepath = eppfrd::get_branch(branchinfo,sum);
      if(basepath == NULL)
        return (errno=error,-1);
  
      paths_->push_back(*basepath);
  
      return 0;
    }
  }
  
  int
  Policy::EPPFRD::Action::operator()(const Branches::CPtr &branches_,
                                     const char           *fusepath_,
                                     StrVec               *paths_) const
  {
    return ::eppfrd::action(branches_,fusepath_,paths_);
  }
  
  int
  Policy::EPPFRD::Create::operator()(const Branches::CPtr &branches_,
                                     const char           *fusepath_,
                                     StrVec               *paths_) const
  {
    return ::eppfrd::create(branches_,fusepath_,paths_);
  }
  
  int
  Policy::EPPFRD::Search::operator()(const Branches::CPtr &branches_,
                                     const char           *fusepath_,
                                     StrVec               *paths_) const
  {
    return ::eppfrd::search(branches_,fusepath_,paths_);
  }
  