git.sesse.net Git - casparcg/blob - common/polling_filesystem_monitor.cpp

   1 /*
   2 * Copyright (c) 2011 Sveriges Television AB <info@casparcg.com>
   3 *
   4 * This file is part of CasparCG (www.casparcg.com).
   5 *
   6 * CasparCG is free software: you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License as published by
   8 * the Free Software Foundation, either version 3 of the License, or
   9 * (at your option) any later version.
  10 *
  11 * CasparCG is distributed in the hope that it will be useful,
  12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 * GNU General Public License for more details.
  15 *
  16 * You should have received a copy of the GNU General Public License
  17 * along with CasparCG. If not, see <http://www.gnu.org/licenses/>.
  18 *
  19 * Author: Helge Norberg, helge.norberg@svt.se
  20 */
  21
  22 #include "stdafx.h"
  23
  24 #include "polling_filesystem_monitor.h"
  25
  26 #include <map>
  27 #include <set>
  28 #include <iostream>
  29 #include <cstdint>
  30
  31 #include <boost/asio.hpp>
  32 #include <boost/thread.hpp>
  33 #include <boost/filesystem/fstream.hpp>
  34 #include <boost/filesystem/convenience.hpp>
  35
  36 #include <tbb/atomic.h>
  37 #include <tbb/concurrent_queue.h>
  38
  39 #include "executor.h"
  40 #include "linq.h"
  41
  42 namespace caspar {
  43
  44 class exception_protected_handler
  45 {
  46         filesystem_monitor_handler handler_;
  47 public:
  48         exception_protected_handler(const filesystem_monitor_handler& handler)
  49                 : handler_(handler)
  50         {
  51         }
  52
  53         void operator()(filesystem_event event, const boost::filesystem::path& file)
  54         {
  55                 try
  56                 {
  57                         handler_(event, file);
  58                 }
  59                 catch (...)
  60                 {
  61                         CASPAR_LOG_CURRENT_EXCEPTION();
  62                 }
  63         }
  64 };
  65
  66 class directory_monitor
  67 {
  68         bool                                                                                    report_already_existing_;
  69         boost::filesystem::path                                                 folder_;
  70         filesystem_event                                                                events_mask_;
  71         filesystem_monitor_handler                                              handler_;
  72         initial_files_handler                                                   initial_files_handler_;
  73         bool                                                                                    first_scan_                                     = true;
  74         std::map<boost::filesystem::path, std::time_t>  files_;
  75         std::map<boost::filesystem::path, uintmax_t>    being_written_sizes_;
  76 public:
  77         directory_monitor(
  78                         bool report_already_existing,
  79                         const boost::filesystem::path& folder,
  80                         filesystem_event events_mask,
  81                         const filesystem_monitor_handler& handler,
  82                         const initial_files_handler& initial_files_handler)
  83                 : report_already_existing_(report_already_existing)
  84                 , folder_(folder)
  85                 , events_mask_(events_mask)
  86                 , handler_(exception_protected_handler(handler))
  87                 , initial_files_handler_(initial_files_handler)
  88         {
  89         }
  90
  91         void reemmit_all(const tbb::atomic<bool>& running)
  92         {
  93                 if (static_cast<int>(events_mask_ & filesystem_event::MODIFIED) == 0)
  94                         return;
  95
  96                 for (auto& file : files_)
  97                 {
  98                         if (!running)
  99                                 return;
 100
 101                         handler_(filesystem_event::MODIFIED, file.first);
 102                 }
 103         }
 104
 105         void reemmit(const boost::filesystem::path& file)
 106         {
 107                 if (static_cast<int>(events_mask_ & filesystem_event::MODIFIED) == 0)
 108                         return;
 109
 110                 if (files_.find(file) != files_.end() && boost::filesystem::exists(file))
 111                         handler_(filesystem_event::MODIFIED, file);
 112         }
 113
 114         void scan(const boost::function<bool ()>& should_abort)
 115         {
 116                 static const std::time_t NO_LONGER_WRITING_AGE = 3; // Assume std::time_t is expressed in seconds
 117                 using namespace boost::filesystem;
 118
 119                 bool interested_in_removed = static_cast<int>(events_mask_ & filesystem_event::REMOVED) > 0;
 120                 bool interested_in_created = static_cast<int>(events_mask_ & filesystem_event::CREATED) > 0;
 121                 bool interested_in_modified = static_cast<int>(events_mask_ & filesystem_event::MODIFIED) > 0;
 122
 123                 auto filenames = cpplinq::from(files_).select(keys());
 124                 std::set<path> removed_files(filenames.begin(), filenames.end());
 125                 std::set<path> initial_files;
 126
 127                 for (boost::filesystem::wrecursive_directory_iterator iter(folder_); iter != boost::filesystem::wrecursive_directory_iterator(); ++iter)
 128                 {
 129                         if (should_abort())
 130                                 return;
 131
 132                         auto& path = iter->path();
 133
 134                         if (is_directory(path))
 135                                 continue;
 136
 137                         auto now = std::time(nullptr);
 138                         std::time_t current_mtime;
 139
 140                         try
 141                         {
 142                                 current_mtime = last_write_time(path);
 143                         }
 144                         catch (...)
 145                         {
 146                                 // Probably removed, will be captured the next round.
 147                                 continue;
 148                         }
 149
 150                         auto time_since_written_to = now - current_mtime;
 151                         bool no_longer_being_written_to = time_since_written_to >= NO_LONGER_WRITING_AGE;
 152                         auto previous_it = files_.find(path);
 153                         bool already_known = previous_it != files_.end();
 154
 155                         if (already_known && no_longer_being_written_to)
 156                         {
 157                                 bool modified = previous_it->second != current_mtime;
 158
 159                                 if (modified && can_read_file(path))
 160                                 {
 161                                         if (interested_in_modified)
 162                                                 handler_(filesystem_event::MODIFIED, path);
 163
 164                                         files_[path] = current_mtime;
 165                                         being_written_sizes_.erase(path);
 166                                 }
 167                         }
 168                         else if (no_longer_being_written_to && can_read_file(path))
 169                         {
 170                                 if (interested_in_created && (report_already_existing_ || !first_scan_))
 171                                         handler_(filesystem_event::CREATED, path);
 172
 173                                 if (first_scan_)
 174                                         initial_files.insert(path);
 175
 176                                 files_.insert(std::make_pair(path, current_mtime));
 177                                 being_written_sizes_.erase(path);
 178                         }
 179
 180                         removed_files.erase(path);
 181                 }
 182
 183                 for (auto& path : removed_files)
 184                 {
 185                         files_.erase(path);
 186                         being_written_sizes_.erase(path);
 187
 188                         if (interested_in_removed)
 189                                 handler_(filesystem_event::REMOVED, path);
 190                 }
 191
 192                 if (first_scan_)
 193                         initial_files_handler_(initial_files);
 194
 195                 first_scan_ = false;
 196         }
 197 private:
 198         bool can_read_file(const boost::filesystem::path& file)
 199         {
 200                 boost::filesystem::wifstream stream(file);
 201
 202                 return stream.is_open();
 203         }
 204 };
 205
 206 class polling_filesystem_monitor : public filesystem_monitor
 207 {
 208         tbb::atomic<bool> running_;
 209         std::shared_ptr<boost::asio::io_service> scheduler_;
 210         directory_monitor root_monitor_;
 211         boost::asio::deadline_timer timer_;
 212         int scan_interval_millis_;
 213         std::promise<void> initial_scan_completion_;
 214         tbb::concurrent_queue<boost::filesystem::path> to_reemmit_;
 215         tbb::atomic<bool> reemmit_all_;
 216         executor executor_;
 217 public:
 218         polling_filesystem_monitor(
 219                         const boost::filesystem::path& folder_to_watch,
 220                         filesystem_event events_of_interest_mask,
 221                         bool report_already_existing,
 222                         int scan_interval_millis,
 223                         std::shared_ptr<boost::asio::io_service> scheduler,
 224                         const filesystem_monitor_handler& handler,
 225                         const initial_files_handler& initial_files_handler)
 226                 : scheduler_(std::move(scheduler))
 227                 , root_monitor_(report_already_existing, folder_to_watch, events_of_interest_mask, handler, initial_files_handler)
 228                 , timer_(*scheduler_)
 229                 , scan_interval_millis_(scan_interval_millis)
 230                 , executor_(L"polling_filesystem_monitor")
 231         {
 232                 running_ = true;
 233                 reemmit_all_ = false;
 234                 executor_.begin_invoke([this]
 235                 {
 236                         scan();
 237                         initial_scan_completion_.set_value();
 238                         schedule_next();
 239                 });
 240         }
 241
 242         ~polling_filesystem_monitor()
 243         {
 244                 running_ = false;
 245                 boost::system::error_code e;
 246                 timer_.cancel(e);
 247         }
 248
 249         std::future<void> initial_files_processed() override
 250         {
 251                 return initial_scan_completion_.get_future();
 252         }
 253
 254         void reemmit_all() override
 255         {
 256                 reemmit_all_ = true;
 257         }
 258
 259         void reemmit(const boost::filesystem::path& file) override
 260         {
 261                 to_reemmit_.push(file);
 262         }
 263 private:
 264         void schedule_next()
 265         {
 266                 if (!running_)
 267                         return;
 268
 269                 timer_.expires_from_now(
 270                         boost::posix_time::milliseconds(scan_interval_millis_));
 271                 timer_.async_wait([this](const boost::system::error_code& e)
 272                 {
 273                         begin_scan();
 274                 });
 275         }
 276
 277         void begin_scan()
 278         {
 279                 if (!running_)
 280                         return;
 281
 282                 executor_.begin_invoke([this]()
 283                 {
 284                         scan();
 285                         schedule_next();
 286                 });
 287         }
 288
 289         void scan()
 290         {
 291                 if (!running_)
 292                         return;
 293
 294                 try
 295                 {
 296                         if (reemmit_all_.fetch_and_store(false))
 297                                 root_monitor_.reemmit_all(running_);
 298                         else
 299                         {
 300                                 boost::filesystem::path file;
 301
 302                                 while (to_reemmit_.try_pop(file))
 303                                         root_monitor_.reemmit(file);
 304                         }
 305
 306                         root_monitor_.scan([=] { return !running_; });
 307                 }
 308                 catch (...)
 309                 {
 310                         CASPAR_LOG_CURRENT_EXCEPTION();
 311                 }
 312         }
 313 };
 314
 315 struct polling_filesystem_monitor_factory::impl
 316 {
 317         std::shared_ptr<boost::asio::io_service> scheduler_;
 318         int scan_interval_millis;
 319
 320         impl(
 321                         std::shared_ptr<boost::asio::io_service> scheduler,
 322                         int scan_interval_millis)
 323                 : scheduler_(std::move(scheduler))
 324                 , scan_interval_millis(scan_interval_millis)
 325         {
 326         }
 327 };
 328
 329 polling_filesystem_monitor_factory::polling_filesystem_monitor_factory(
 330                 std::shared_ptr<boost::asio::io_service> scheduler,
 331                 int scan_interval_millis)
 332         : impl_(new impl(std::move(scheduler), scan_interval_millis))
 333 {
 334 }
 335
 336 polling_filesystem_monitor_factory::~polling_filesystem_monitor_factory()
 337 {
 338 }
 339
 340 filesystem_monitor::ptr polling_filesystem_monitor_factory::create(
 341                 const boost::filesystem::path& folder_to_watch,
 342                 filesystem_event events_of_interest_mask,
 343                 bool report_already_existing,
 344                 const filesystem_monitor_handler& handler,
 345                 const initial_files_handler& initial_files_handler)
 346 {
 347         return spl::make_shared<polling_filesystem_monitor>(
 348                         folder_to_watch,
 349                         events_of_interest_mask,
 350                         report_already_existing,
 351                         impl_->scan_interval_millis,
 352                         impl_->scheduler_,
 353                         handler,
 354                         initial_files_handler);
 355 }
 356
 357 }