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
 207                 : public filesystem_monitor
 208                 , public spl::enable_shared_from_this<polling_filesystem_monitor>
 209 {
 210         tbb::atomic<bool>                                                               running_;
 211         std::shared_ptr<boost::asio::io_service>                scheduler_;
 212         directory_monitor                                                               root_monitor_;
 213         boost::asio::deadline_timer                                             timer_;
 214         int                                                                                             scan_interval_millis_;
 215         std::promise<void>                                                              initial_scan_completion_;
 216         tbb::concurrent_queue<boost::filesystem::path>  to_reemmit_;
 217         tbb::atomic<bool>                                                               reemmit_all_;
 218         executor                                                                                executor_;
 219 public:
 220         polling_filesystem_monitor(
 221                         const boost::filesystem::path& folder_to_watch,
 222                         filesystem_event events_of_interest_mask,
 223                         bool report_already_existing,
 224                         int scan_interval_millis,
 225                         std::shared_ptr<boost::asio::io_service> scheduler,
 226                         const filesystem_monitor_handler& handler,
 227                         const initial_files_handler& initial_files_handler)
 228                 : scheduler_(std::move(scheduler))
 229                 , root_monitor_(report_already_existing, folder_to_watch, events_of_interest_mask, handler, initial_files_handler)
 230                 , timer_(*scheduler_)
 231                 , scan_interval_millis_(scan_interval_millis)
 232                 , executor_(L"polling_filesystem_monitor")
 233         {
 234                 running_ = true;
 235                 reemmit_all_ = false;
 236         }
 237
 238         void start()
 239         {
 240                 executor_.begin_invoke([this]
 241                 {
 242                         scan();
 243                         initial_scan_completion_.set_value();
 244                         schedule_next();
 245                 });
 246         }
 247
 248         ~polling_filesystem_monitor()
 249         {
 250                 running_ = false;
 251                 boost::system::error_code e;
 252                 timer_.cancel(e); // Can still have be queued for execution by asio, therefore the task has a weak_ptr to this
 253         }
 254
 255         std::future<void> initial_files_processed() override
 256         {
 257                 return initial_scan_completion_.get_future();
 258         }
 259
 260         void reemmit_all() override
 261         {
 262                 reemmit_all_ = true;
 263         }
 264
 265         void reemmit(const boost::filesystem::path& file) override
 266         {
 267                 to_reemmit_.push(file);
 268         }
 269 private:
 270         void schedule_next()
 271         {
 272                 if (!running_)
 273                         return;
 274
 275                 std::weak_ptr<polling_filesystem_monitor> weak_self = shared_from_this();
 276
 277                 timer_.expires_from_now(boost::posix_time::milliseconds(scan_interval_millis_));
 278                 timer_.async_wait([weak_self](const boost::system::error_code& e)
 279                 {
 280                         auto strong_self = weak_self.lock();
 281
 282                         if (strong_self)
 283                                 strong_self->begin_scan();
 284                 });
 285         }
 286
 287         void begin_scan()
 288         {
 289                 if (!running_)
 290                         return;
 291
 292                 executor_.begin_invoke([this]()
 293                 {
 294                         scan();
 295                         schedule_next();
 296                 });
 297         }
 298
 299         void scan()
 300         {
 301                 if (!running_)
 302                         return;
 303
 304                 try
 305                 {
 306                         if (reemmit_all_.fetch_and_store(false))
 307                                 root_monitor_.reemmit_all(running_);
 308                         else
 309                         {
 310                                 boost::filesystem::path file;
 311
 312                                 while (to_reemmit_.try_pop(file))
 313                                         root_monitor_.reemmit(file);
 314                         }
 315
 316                         root_monitor_.scan([=] { return !running_; });
 317                 }
 318                 catch (...)
 319                 {
 320                         CASPAR_LOG_CURRENT_EXCEPTION();
 321                 }
 322         }
 323 };
 324
 325 struct polling_filesystem_monitor_factory::impl
 326 {
 327         std::shared_ptr<boost::asio::io_service> scheduler_;
 328         int scan_interval_millis;
 329
 330         impl(
 331                         std::shared_ptr<boost::asio::io_service> scheduler,
 332                         int scan_interval_millis)
 333                 : scheduler_(std::move(scheduler))
 334                 , scan_interval_millis(scan_interval_millis)
 335         {
 336         }
 337 };
 338
 339 polling_filesystem_monitor_factory::polling_filesystem_monitor_factory(
 340                 std::shared_ptr<boost::asio::io_service> scheduler,
 341                 int scan_interval_millis)
 342         : impl_(new impl(std::move(scheduler), scan_interval_millis))
 343 {
 344 }
 345
 346 polling_filesystem_monitor_factory::~polling_filesystem_monitor_factory()
 347 {
 348 }
 349
 350 filesystem_monitor::ptr polling_filesystem_monitor_factory::create(
 351                 const boost::filesystem::path& folder_to_watch,
 352                 filesystem_event events_of_interest_mask,
 353                 bool report_already_existing,
 354                 const filesystem_monitor_handler& handler,
 355                 const initial_files_handler& initial_files_handler)
 356 {
 357         auto monitor = spl::make_shared<polling_filesystem_monitor>(
 358                         folder_to_watch,
 359                         events_of_interest_mask,
 360                         report_already_existing,
 361                         impl_->scan_interval_millis,
 362                         impl_->scheduler_,
 363                         handler,
 364                         initial_files_handler);
 365
 366         monitor->start();
 367
 368         return monitor;
 369 }
 370
 371 }