wangle::FilePoller Class Reference

#include <FilePoller.h>

Inheritance diagram for wangle::FilePoller:

Classes
struct	FileData
struct	FileModificationData
class	ThreadProtector

Public Types
using	Cob = std::function< void()>
using	Condition = std::function< bool(const FileModificationData &, const FileModificationData &)>

Public Member Functions
	FilePoller (std::chrono::milliseconds pollInterval=kDefaultPollInterval)
virtual	~FilePoller ()
	FilePoller (const FilePoller &other)=delete
FilePoller &	operator= (const FilePoller &other)=delete
	FilePoller (FilePoller &&other)=delete
FilePoller &&	operator= (FilePoller &&other)=delete
void	addFileToTrack (const std::string &fileName, Cob yCob, Cob nCob=nullptr, Condition condition=fileTouchedCondInternal)
void	removeFileToTrack (const std::string &fileName)
void	stop ()

Static Public Member Functions
static Condition	fileTouchedWithinCond (std::chrono::seconds expireTime)
static Condition	doAlwaysCond ()
static Condition	fileTouchedCond ()

Protected Member Functions
virtual FileModificationData	getFileModData (const std::string &path) noexcept

Private Types
using	FileDatas = std::unordered_map< std::string, FileData >

Private Member Functions
void	checkFiles () noexcept
void	initFileData (const std::string &fName, FileData &fData) noexcept
void	init (std::chrono::milliseconds pollInterval)

Static Private Member Functions
static bool	fileTouchedWithinCondInternal (const FilePoller::FileModificationData &, const FilePoller::FileModificationData &fModData, std::chrono::seconds expireTime)
static bool	doAlwaysCondInternal (const FileModificationData &, const FileModificationData &)
static bool	fileTouchedCondInternal (const FileModificationData &oldModData, const FileModificationData &modData)

Private Attributes
FileDatas	fileDatum_
std::mutex	filesMutex_
uint64_t	pollerId_ {0}
std::shared_ptr< folly::FunctionScheduler >	scheduler_

Static Private Attributes
static constexpr std::chrono::milliseconds	kDefaultPollInterval

Detailed Description

Polls for updates in the files. This poller uses modified times to track changes in the files, so it is the responsibility of the caller to check whether the contents have actually changed. It also assumes that when the file is modified, the modfied time changes. This is a reasonable assumption to make, so it should not be used in situations where files may be modified without changing the modified time.

Definition at line 41 of file FilePoller.h.

Member Typedef Documentation

using wangle::FilePoller::Cob = std::function<void()>

Definition at line 50 of file FilePoller.h.

using wangle::FilePoller::Condition = std::function< bool(const FileModificationData&, const FileModificationData&)>

Definition at line 54 of file FilePoller.h.

using wangle::FilePoller::FileDatas = std::unordered_map<std::string, FileData>

private

Definition at line 113 of file FilePoller.h.

Constructor & Destructor Documentation

wangle::FilePoller::FilePoller ( std::chrono::milliseconds  pollInterval = kDefaultPollInterval )

explicit

Definition at line 65 of file FilePoller.cpp.

References folly::init().

                                                         {
  init(pollInterval);
}

wangle::FilePoller::~FilePoller ( )

virtual

Definition at line 69 of file FilePoller.cpp.

References stop().

{ stop(); }

wangle::FilePoller::FilePoller ( const FilePoller &  other )

delete

wangle::FilePoller::FilePoller ( FilePoller &&  other )

delete

Member Function Documentation

void wangle::FilePoller::addFileToTrack	(	const std::string &	fileName,
		Cob	yCob,
		Cob	nCob = nullptr,
		Condition	condition = fileTouchedCondInternal
	)

Definition at line 115 of file FilePoller.cpp.

Referenced by wangle::MultiFilePoller::registerFiles(), and TEST_F().

                         {
  if (fileName.empty()) {
    // ignore empty file paths
    return;
  }
  if (ThreadProtector::inPollerThread()) {
    LOG(ERROR) << "Adding files from a callback is disallowed";
    return;
  }
  std::lock_guard<std::mutex> lg(filesMutex_);
  fileDatum_[fileName] = FileData(yCob, nCob, condition);
  initFileData(fileName, fileDatum_[fileName]);
}

void wangle::FilePoller::checkFiles ( )

privatenoexcept

Definition at line 92 of file FilePoller.cpp.

References folly::pushmi::__adl::tp.

Referenced by fileTouchedCondInternal().

                                     {
  std::lock_guard<std::mutex> lg(filesMutex_);
  ThreadProtector tp;
  for (auto& fData : fileDatum_) {
    auto modData = getFileModData(fData.first);
    auto& fileData = fData.second;
    if (fileData.condition(fileData.modData, modData) && fileData.yCob) {
      fileData.yCob();
    } else if (fileData.nCob) {
      fileData.nCob();
    }
    fileData.modData = modData;
  }
}

static Condition wangle::FilePoller::doAlwaysCond ( )

inlinestatic

Definition at line 88 of file FilePoller.h.

References doAlwaysCondInternal().

                                  {
    return doAlwaysCondInternal;
  }

static bool wangle::FilePoller::doAlwaysCondInternal ( const FileModificationData &  , const FileModificationData &    )

inlinestaticprivate

Definition at line 123 of file FilePoller.h.

Referenced by doAlwaysCond().

                                   {
    return true;
  }

static Condition wangle::FilePoller::fileTouchedCond ( )

inlinestatic

Definition at line 92 of file FilePoller.h.

References fileTouchedCondInternal(), getFileModData(), folly::pushmi::__adl::noexcept(), and string.

                                     {
    return fileTouchedCondInternal;
  }

static bool wangle::FilePoller::fileTouchedCondInternal ( const FileModificationData &  oldModData, const FileModificationData &  modData  )

inlinestaticprivate

Definition at line 129 of file FilePoller.h.

References checkFiles(), wangle::FilePoller::FileModificationData::exists, init(), initFileData(), wangle::FilePoller::FileModificationData::modTime, folly::pushmi::__adl::noexcept(), and string.

Referenced by fileTouchedCond().

                                           {
    const bool fileStillExists = oldModData.exists && modData.exists;
    const bool fileTouched = modData.modTime != oldModData.modTime;
    const bool fileCreated = !oldModData.exists && modData.exists;
    return (fileStillExists && fileTouched) || fileCreated;
  }

static Condition wangle::FilePoller::fileTouchedWithinCond ( std::chrono::seconds  expireTime )

inlinestatic

Definition at line 80 of file FilePoller.h.

References folly::netops::bind(), and fileTouchedWithinCondInternal().

                                                                      {
    return std::bind(
        fileTouchedWithinCondInternal,
        std::placeholders::_1,
        std::placeholders::_2,
        expireTime);
  }

static bool wangle::FilePoller::fileTouchedWithinCondInternal ( const FilePoller::FileModificationData &  , const FilePoller::FileModificationData &  fModData, std::chrono::seconds  expireTime  )

inlinestaticprivate

Definition at line 115 of file FilePoller.h.

References wangle::FilePoller::FileModificationData::exists, wangle::FilePoller::FileModificationData::modTime, and folly::detail::distributed_mutex::time().

Referenced by fileTouchedWithinCond().

                                   {
    return fModData.exists &&
        (time(nullptr) < fModData.modTime + expireTime.count());
  }

FilePoller::FileModificationData wangle::FilePoller::getFileModData ( const std::string &  path )

protectedvirtualnoexcept

Reimplemented in NoDiskPoller.

Definition at line 146 of file FilePoller.cpp.

References deadlock::info().

Referenced by fileTouchedCond().

                                    {
  struct stat info;
  int ret = stat(path.c_str(), &info);
  if (ret != 0) {
    return FileModificationData{false, 0};
  }
  return FileModificationData{true, info.st_mtime};
}

void wangle::FilePoller::init ( std::chrono::milliseconds  pollInterval )

private

Definition at line 71 of file FilePoller.cpp.

References context.

Referenced by fileTouchedCondInternal().

                                                        {
  auto context = contextSingleton.try_get();
  if (!context) {
    LOG(ERROR) << "Poller context requested after destruction.";
    return;
  }
  pollerId_ = context->getNextId();
  scheduler_ = context->getScheduler();
  scheduler_->addFunction(
      [this] { this->checkFiles(); },
      pollInterval,
      folly::to<std::string>(pollerId_));
}

void wangle::FilePoller::initFileData ( const std::string &  fName, FileData &  fData  )

privatenoexcept

Definition at line 107 of file FilePoller.cpp.

Referenced by fileTouchedCondInternal().

                              {
  auto modData = getFileModData(fName);
  fData.modData.exists = modData.exists;
  fData.modData.modTime = modData.modTime;
}

FilePoller& wangle::FilePoller::operator= ( const FilePoller &  other )

delete

FilePoller&& wangle::FilePoller::operator= ( FilePoller &&  other )

delete

void wangle::FilePoller::removeFileToTrack

(

const std::string &

fileName

)

Definition at line 133 of file FilePoller.cpp.

Referenced by wangle::MultiFilePoller::cancelCallback().

                                                            {
  if (fileName.empty()) {
    // ignore
    return;
  }
  if (ThreadProtector::inPollerThread()) {
    LOG(ERROR) << "Adding files from a callback is disallowed";
    return;
  }
  std::lock_guard<std::mutex> lg(filesMutex_);
  fileDatum_.erase(fileName);
}

void wangle::FilePoller::stop

(

)

Definition at line 85 of file FilePoller.cpp.

                      {
  if (scheduler_) {
    scheduler_->cancelFunctionAndWait(
        folly::to<std::string>(pollerId_));
  }
}

Member Data Documentation

FileDatas wangle::FilePoller::fileDatum_

private

Definition at line 143 of file FilePoller.h.

std::mutex wangle::FilePoller::filesMutex_

private

Definition at line 146 of file FilePoller.h.

constexpr std::chrono::milliseconds wangle::FilePoller::kDefaultPollInterval

staticprivate

Initial value:

=
        std::chrono::milliseconds(10000)

Definition at line 100 of file FilePoller.h.

uint64_t wangle::FilePoller::pollerId_ {0}

private

Definition at line 148 of file FilePoller.h.

std::shared_ptr<folly::FunctionScheduler> wangle::FilePoller::scheduler_

private

Definition at line 153 of file FilePoller.h.

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The documentation for this class was generated from the following files:

• proxygen/wangle/wangle/util/FilePoller.h
• proxygen/wangle/wangle/util/FilePoller.cpp