rstudio/src/cpp/session/SessionSourceDatabaseSupervisor.cpp at master · usersbin/rstudio · GitHub

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* SessionSourceDatabaseSupervisor.cpp

* This program is licensed to you under the terms of version 3 of the

* GNU Affero General Public License. This program is distributed WITHOUT

* ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING THOSE OF NON-INFRINGEMENT,

* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Please refer to the

* AGPL (http://www.gnu.org/licenses/agpl-3.0.txt) for more details.

#include "SessionSourceDatabaseSupervisor.hpp"

#include <vector>

#include <boost/foreach.hpp>

#include <boost/scope_exit.hpp>

#include <boost/algorithm/string/predicate.hpp>

#include <core/Error.hpp>

#include <core/FilePath.hpp>

#include <core/FileSerializer.hpp>

#include <core/FileLock.hpp>

#include <core/BoostErrors.hpp>

#include <core/system/System.hpp>

#include <session/SessionModuleContext.hpp>

#include "session/SessionSourceDatabase.hpp"

using namespace core;

namespace session {

namespace source_database {

namespace supervisor {

namespace {

const char * const kSessionDirPrefix = "session-";

FilePath oldSourceDatabaseRoot()

{

return

module_context::scopedScratchPath().complete("source_database");

}

FilePath sourceDatabaseRoot()

{

return

module_context::scopedScratchPath().complete("source_database_v2");

}

FilePath persistentTitledDir()

{

return sourceDatabaseRoot().complete("persistent/titled");

}

FilePath persistentUntitledDir()

{

return sourceDatabaseRoot().complete("persistent/untitled");

}

FilePath sessionLockFilePath(const FilePath& sessionDir)

{

return sessionDir.complete("lock_file");

}

// session dir lock (initialized by attachToSourceDatabase)

FileLock s_sessionDirLock;

Error removeSessionDir(const FilePath& sessionDir)

{

// first remove children

std::vector<FilePath> children;

Error error = sessionDir.children(&children);

if (error)

LOG_ERROR(error);

BOOST_FOREACH(const FilePath& filePath, children)

{

error = filePath.remove();

if (error)

LOG_ERROR(error);

}

// then remove dir

return sessionDir.remove();

}

FilePath generateSessionDirPath()

{

return sourceDatabaseRoot().complete(kSessionDirPrefix +

core::system::generateUuid());

}

bool isNotSessionDir(const FilePath& filePath)

{

return !filePath.isDirectory() || !boost::algorithm::starts_with(

filePath.filename(),

kSessionDirPrefix);

}

Error enumerateSessionDirs(std::vector<FilePath>* pSessionDirs)

{

// get the directories

Error error = sourceDatabaseRoot().children(pSessionDirs);

if (error)

return error;

// clean out non session dirs

pSessionDirs->erase(std::remove_if(pSessionDirs->begin(),

pSessionDirs->end(),

isNotSessionDir),

pSessionDirs->end());

// return success

return Success();

}

void attemptToMoveSourceDbFiles(const FilePath& fromPath,

const FilePath& toPath)

{

// enumerate the from path

std::vector<FilePath> children;

Error error = fromPath.children(&children);

if (error)

LOG_ERROR(error);

// move the files

BOOST_FOREACH(const FilePath& filePath, children)

{

Error error = filePath.move(toPath.complete(filePath.filename()));

if (error)

LOG_ERROR(error);

}

// NOTE: the supervisor needs to return a session dir in order for the process

// to start. therefore, in the createSessionDir family of functions below

// once we successfully create and lock the session dir other errors (such

// as trying to move files into the session dir) are simply logged

Error createSessionDir(FilePath* pSessionDir)

{

*pSessionDir = generateSessionDirPath();

Error error = pSessionDir->ensureDirectory();

if (error)

return error;

return s_sessionDirLock.acquire(sessionLockFilePath(*pSessionDir));

}

Error createSessionDirFromOldSourceDatabase(FilePath* pSessionDir)

{

// move properties (if any) into new source database root

FilePath propsPath = oldSourceDatabaseRoot().complete("properties");

if (propsPath.exists())

{

FilePath newPropsPath = sourceDatabaseRoot().complete("properties");

Error error = propsPath.move(newPropsPath);

if (error)

LOG_ERROR(error);

}

// move the old source database into a new dir

*pSessionDir = generateSessionDirPath();

Error error = oldSourceDatabaseRoot().move(*pSessionDir);

if (error)

LOG_ERROR(error);

// if that failed we might still need to call ensureDirectory

error = pSessionDir->ensureDirectory();

if (error)

return error;

// acquire the lock

return s_sessionDirLock.acquire(sessionLockFilePath(*pSessionDir));

}

Error createSessionDirFromPersistent(FilePath* pSessionDir)

{

// create new session dir

Error error = createSessionDir(pSessionDir);

if (error)

return error;

// move persistent titled files

if (persistentTitledDir().exists())

attemptToMoveSourceDbFiles(persistentTitledDir(), *pSessionDir);

// move persistent untitled files

if (persistentUntitledDir().exists())

attemptToMoveSourceDbFiles(persistentUntitledDir(), *pSessionDir);

// return success

return Success();

}

bool reclaimOrphanedSession(const std::vector<FilePath>& sessionDirs,

FilePath* pSessionDir)

{

BOOST_FOREACH(const FilePath& sessionDir, sessionDirs)

{

FilePath lockFilePath = sessionLockFilePath(sessionDir);

if (!FileLock::isLocked(lockFilePath))

{

Error error = s_sessionDirLock.acquire(lockFilePath);

if (!error)

{

*pSessionDir = sessionDir;

return true;

}

else

{

LOG_ERROR(error);

}

return false;

}

bool noLockedSessionsExist(const std::vector<FilePath>& sessionDirs)

{

BOOST_FOREACH(const FilePath& sessionDir, sessionDirs)

{

FilePath lockFilePath = sessionLockFilePath(sessionDir);

if (FileLock::isLocked(lockFilePath))

return false;

}

return true;

}

} // anonymous namespace

Error attachToSourceDatabase(FilePath* pSessionDir)

{

// check whether we will need to migrate -- ensure we do this only

// one time so that if for whatever reason we can't migrate the

// old source database we don't get stuck trying to do it every

// time we start up

bool needToMigrate = !sourceDatabaseRoot().exists() &&

oldSourceDatabaseRoot().exists();

// ensure the root path exists

Error error = sourceDatabaseRoot().ensureDirectory();

if (error)

return error;

// check for existing sessions (use this to decide how to startup below)

std::vector<FilePath> sessionDirs;

error = enumerateSessionDirs(&sessionDirs);

if (error)

LOG_ERROR(error);

// attempt to migrate if necessary

if (needToMigrate)

return createSessionDirFromOldSourceDatabase(pSessionDir);

// if there is an orphan (crash) then reclaim it

else if (reclaimOrphanedSession(sessionDirs, pSessionDir))

return Success();

// if there are no existing locked sessions then create from persistent

else if (noLockedSessionsExist(sessionDirs))

return createSessionDirFromPersistent(pSessionDir);

// otherwise startup with a brand new session dir

else

return createSessionDir(pSessionDir);

}

Error detachFromSourceDatabase()

{

// confirm that we are attached

if (s_sessionDirLock.lockFilePath().empty())

return core::pathNotFoundError(ERROR_LOCATION);

// list all current source docs

std::vector<boost::shared_ptr<SourceDocument> > sourceDocs;

Error error = source_database::list(&sourceDocs);

if (error)

return error;

// get references to persistent subdirs

FilePath titledDir = persistentTitledDir();

FilePath untitledDir = persistentUntitledDir();

// first blow away the existing persistent titled dir

error = titledDir.removeIfExists();

if (error)

LOG_ERROR(error);

// ensure both directories exist -- if they don't it is a fatal error

error = titledDir.ensureDirectory();

if (error)

return error;

error = untitledDir.ensureDirectory();

if (error)

return error;

// now write the source database entries to the appropriate places

BOOST_FOREACH(boost::shared_ptr<SourceDocument> pDoc, sourceDocs)

{

if (pDoc->isUntitled())

{

error = pDoc->writeToFile(untitledDir.complete(pDoc->id()));

if (error)

LOG_ERROR(error);

}

else

{

error = pDoc->writeToFile(titledDir.complete(pDoc->id()));

if (error)

LOG_ERROR(error);

}

// record session dir (parent of lock file)

FilePath sessionDir = s_sessionDirLock.lockFilePath().parent();

// give up our lock

error = s_sessionDirLock.release();

if (error)

LOG_ERROR(error);

// remove the session directory

return removeSessionDir(sessionDir);

}

} // namespace supervisor

} // namespace source_database

} // namespace session

rstudio/src/cpp/session/SessionSourceDatabaseSupervisor.cpp at master · usersbin/rstudio · GitHub

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