system_wrappers/source/data_log.cc - src/webrtc - Git at Google

 /*
  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */

 #include "webrtc/system_wrappers/interface/data_log.h"

 #include <assert.h>

 #include <algorithm>
 #include <list>

 #include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
 #include "webrtc/system_wrappers/interface/event_wrapper.h"
 #include "webrtc/system_wrappers/interface/file_wrapper.h"
 #include "webrtc/system_wrappers/interface/rw_lock_wrapper.h"
 #include "webrtc/system_wrappers/interface/thread_wrapper.h"

 namespace webrtc {

 DataLogImpl::CritSectScopedPtr DataLogImpl::crit_sect_(
   CriticalSectionWrapper::CreateCriticalSection());

 DataLogImpl* DataLogImpl::instance_ = NULL;

 // A Row contains cells, which are indexed by the column names as std::string.
 // The string index is treated in a case sensitive way.
 class Row {
  public:
   Row();
   ~Row();

   // Inserts a Container into the cell of the column specified with
   // column_name.
   // column_name is treated in a case sensitive way.
   int InsertCell(const std::string& column_name,
                  const Container* value_container);

   // Converts the value at the column specified by column_name to a string
   // stored in value_string.
   // column_name is treated in a case sensitive way.
   void ToString(const std::string& column_name, std::string* value_string);

  private:
   // Collection of containers indexed by column name as std::string
   typedef std::map<std::string, const Container*> CellMap;

   CellMap                   cells_;
   CriticalSectionWrapper*   cells_lock_;
 };

 // A LogTable contains multiple rows, where only the latest row is active for
 // editing. The rows are defined by the ColumnMap, which contains the name of
 // each column and the length of the column (1 for one-value-columns and greater
 // than 1 for multi-value-columns).
 class LogTable {
  public:
   LogTable();
   ~LogTable();

   // Adds the column with name column_name to the table. The column will be a
   // multi-value-column if multi_value_length is greater than 1.
   // column_name is treated in a case sensitive way.
   int AddColumn(const std::string& column_name, int multi_value_length);

   // Buffers the current row while it is waiting to be written to file,
   // which is done by a call to Flush(). A new row is available when the
   // function returns
   void NextRow();

   // Inserts a Container into the cell of the column specified with
   // column_name.
   // column_name is treated in a case sensitive way.
   int InsertCell(const std::string& column_name,
                  const Container* value_container);

   // Creates a log file, named as specified in the string file_name, to
   // where the table will be written when calling Flush().
   int CreateLogFile(const std::string& file_name);

   // Write all complete rows to file.
   // May not be called by two threads simultaneously (doing so may result in
   // a race condition). Will be called by the file_writer_thread_ when that
   // thread is running.
   void Flush();

  private:
   // Collection of multi_value_lengths indexed by column name as std::string
   typedef std::map<std::string, int> ColumnMap;
   typedef std::list<Row*> RowList;

   ColumnMap               columns_;
   RowList                 rows_[2];
   RowList*                rows_history_;
   RowList*                rows_flush_;
   Row*                    current_row_;
   FileWrapper*            file_;
   bool                    write_header_;
   CriticalSectionWrapper* table_lock_;
 };

 Row::Row()
   : cells_(),
     cells_lock_(CriticalSectionWrapper::CreateCriticalSection()) {
 }

 Row::~Row() {
   for (CellMap::iterator it = cells_.begin(); it != cells_.end();) {
     delete it->second;
     // For maps all iterators (except the erased) are valid after an erase
     cells_.erase(it++);
   }
   delete cells_lock_;
 }

 int Row::InsertCell(const std::string& column_name,
                     const Container* value_container) {
   CriticalSectionScoped synchronize(cells_lock_);
   assert(cells_.count(column_name) == 0);
   if (cells_.count(column_name) > 0)
     return -1;
   cells_[column_name] = value_container;
   return 0;
 }

 void Row::ToString(const std::string& column_name,
                    std::string* value_string) {
   CriticalSectionScoped synchronize(cells_lock_);
   const Container* container = cells_[column_name];
   if (container == NULL) {
     *value_string = "NaN,";
     return;
   }
   container->ToString(value_string);
 }

 LogTable::LogTable()
   : columns_(),
     rows_(),
     rows_history_(&rows_[0]),
     rows_flush_(&rows_[1]),
     current_row_(new Row),
     file_(FileWrapper::Create()),
     write_header_(true),
     table_lock_(CriticalSectionWrapper::CreateCriticalSection()) {
 }

 LogTable::~LogTable() {
   for (RowList::iterator row_it = rows_history_->begin();
        row_it != rows_history_->end();) {
     delete *row_it;
     row_it = rows_history_->erase(row_it);
   }
   for (ColumnMap::iterator col_it = columns_.begin();
        col_it != columns_.end();) {
     // For maps all iterators (except the erased) are valid after an erase
     columns_.erase(col_it++);
   }
   if (file_ != NULL) {
     file_->Flush();
     file_->CloseFile();
     delete file_;
   }
   delete current_row_;
   delete table_lock_;
 }

 int LogTable::AddColumn(const std::string& column_name,
                         int multi_value_length) {
   assert(multi_value_length > 0);
   if (!write_header_) {
     // It's not allowed to add new columns after the header
     // has been written.
     assert(false);
     return -1;
   } else {
     CriticalSectionScoped synchronize(table_lock_);
     if (write_header_)
       columns_[column_name] = multi_value_length;
     else
       return -1;
   }
   return 0;
 }

 void LogTable::NextRow() {
   CriticalSectionScoped sync_rows(table_lock_);
   rows_history_->push_back(current_row_);
   current_row_ = new Row;
 }

 int LogTable::InsertCell(const std::string& column_name,
                          const Container* value_container) {
   CriticalSectionScoped synchronize(table_lock_);
   assert(columns_.count(column_name) > 0);
   if (columns_.count(column_name) == 0)
     return -1;
   return current_row_->InsertCell(column_name, value_container);
 }

 int LogTable::CreateLogFile(const std::string& file_name) {
   if (file_name.length() == 0)
     return -1;
   if (file_->Open())
     return -1;
   file_->OpenFile(file_name.c_str(),
                   false,  // Open with read/write permissions
                   false,  // Don't wraparound and write at the beginning when
                           // the file is full
                   true);  // Open as a text file
   if (file_ == NULL)
     return -1;
   return 0;
 }

 void LogTable::Flush() {
   ColumnMap::iterator column_it;
   bool commit_header = false;
   if (write_header_) {
     CriticalSectionScoped synchronize(table_lock_);
     if (write_header_) {
       commit_header = true;
       write_header_ = false;
     }
   }
   if (commit_header) {
     for (column_it = columns_.begin();
          column_it != columns_.end(); ++column_it) {
       if (column_it->second > 1) {
         file_->WriteText("%s[%u],", column_it->first.c_str(),
                          column_it->second);
         for (int i = 1; i < column_it->second; ++i)
           file_->WriteText(",");
       } else {
         file_->WriteText("%s,", column_it->first.c_str());
       }
     }
     if (columns_.size() > 0)
       file_->WriteText("\n");
   }

   // Swap the list used for flushing with the list containing the row history
   // and clear the history. We also create a local pointer to the new
   // list used for flushing to avoid race conditions if another thread
   // calls this function while we are writing.
   // We don't want to block the list while we're writing to file.
   {
     CriticalSectionScoped synchronize(table_lock_);
     RowList* tmp = rows_flush_;
     rows_flush_ = rows_history_;
     rows_history_ = tmp;
     rows_history_->clear();
   }

   // Write all complete rows to file and delete them
   for (RowList::iterator row_it = rows_flush_->begin();
        row_it != rows_flush_->end();) {
     for (column_it = columns_.begin();
          column_it != columns_.end(); ++column_it) {
       std::string row_string;
       (*row_it)->ToString(column_it->first, &row_string);
       file_->WriteText("%s", row_string.c_str());
     }
     if (columns_.size() > 0)
       file_->WriteText("\n");
     delete *row_it;
     row_it = rows_flush_->erase(row_it);
   }
 }

 int DataLog::CreateLog() {
   return DataLogImpl::CreateLog();
 }

 void DataLog::ReturnLog() {
   return DataLogImpl::ReturnLog();
 }

 std::string DataLog::Combine(const std::string& table_name, int table_id) {
   std::stringstream ss;
   std::string combined_id = table_name;
   std::string number_suffix;
   ss << "_" << table_id;
   ss >> number_suffix;
   combined_id += number_suffix;
   std::transform(combined_id.begin(), combined_id.end(), combined_id.begin(),
                  ::tolower);
   return combined_id;
 }

 int DataLog::AddTable(const std::string& table_name) {
   DataLogImpl* data_log = DataLogImpl::StaticInstance();
   if (data_log == NULL)
     return -1;
   return data_log->AddTable(table_name);
 }

 int DataLog::AddColumn(const std::string& table_name,
                        const std::string& column_name,
                        int multi_value_length) {
   DataLogImpl* data_log = DataLogImpl::StaticInstance();
   if (data_log == NULL)
     return -1;
   return data_log->DataLogImpl::StaticInstance()->AddColumn(table_name,
                                                             column_name,
                                                             multi_value_length);
 }

 int DataLog::NextRow(const std::string& table_name) {
   DataLogImpl* data_log = DataLogImpl::StaticInstance();
   if (data_log == NULL)
     return -1;
   return data_log->DataLogImpl::StaticInstance()->NextRow(table_name);
 }

 DataLogImpl::DataLogImpl()
   : counter_(1),
     tables_(),
     flush_event_(EventWrapper::Create()),
     file_writer_thread_(NULL),
     tables_lock_(RWLockWrapper::CreateRWLock()) {
 }

 DataLogImpl::~DataLogImpl() {
   StopThread();
   Flush();  // Write any remaining rows
   delete file_writer_thread_;
   delete flush_event_;
   for (TableMap::iterator it = tables_.begin(); it != tables_.end();) {
     delete static_cast<LogTable*>(it->second);
     // For maps all iterators (except the erased) are valid after an erase
     tables_.erase(it++);
   }
   delete tables_lock_;
 }

 int DataLogImpl::CreateLog() {
   CriticalSectionScoped synchronize(crit_sect_.get());
   if (instance_ == NULL) {
     instance_ = new DataLogImpl();
     return instance_->Init();
   } else {
     ++instance_->counter_;
   }
   return 0;
 }

 int DataLogImpl::Init() {
   file_writer_thread_ = ThreadWrapper::CreateThread(
                           DataLogImpl::Run,
                           instance_,
                           kHighestPriority,
                           "DataLog");
   if (file_writer_thread_ == NULL)
     return -1;
   unsigned int thread_id = 0;
   bool success = file_writer_thread_->Start(thread_id);
   if (!success)
     return -1;
   return 0;
 }

 DataLogImpl* DataLogImpl::StaticInstance() {
   return instance_;
 }

 void DataLogImpl::ReturnLog() {
   CriticalSectionScoped synchronize(crit_sect_.get());
   if (instance_ && instance_->counter_ > 1) {
     --instance_->counter_;
     return;
   }
   delete instance_;
   instance_ = NULL;
 }

 int DataLogImpl::AddTable(const std::string& table_name) {
   WriteLockScoped synchronize(*tables_lock_);
   // Make sure we don't add a table which already exists
   if (tables_.count(table_name) > 0)
     return -1;
   tables_[table_name] = new LogTable();
   if (tables_[table_name]->CreateLogFile(table_name + ".txt") == -1)
     return -1;
   return 0;
 }

 int DataLogImpl::AddColumn(const std::string& table_name,
                            const std::string& column_name,
                            int multi_value_length) {
   ReadLockScoped synchronize(*tables_lock_);
   if (tables_.count(table_name) == 0)
     return -1;
   return tables_[table_name]->AddColumn(column_name, multi_value_length);
 }

 int DataLogImpl::InsertCell(const std::string& table_name,
                             const std::string& column_name,
                             const Container* value_container) {
   ReadLockScoped synchronize(*tables_lock_);
   assert(tables_.count(table_name) > 0);
   if (tables_.count(table_name) == 0)
     return -1;
   return tables_[table_name]->InsertCell(column_name, value_container);
 }

 int DataLogImpl::NextRow(const std::string& table_name) {
   ReadLockScoped synchronize(*tables_lock_);
   if (tables_.count(table_name) == 0)
     return -1;
   tables_[table_name]->NextRow();
   if (file_writer_thread_ == NULL) {
     // Write every row to file as they get complete.
     tables_[table_name]->Flush();
   } else {
     // Signal a complete row
     flush_event_->Set();
   }
   return 0;
 }

 void DataLogImpl::Flush() {
   ReadLockScoped synchronize(*tables_lock_);
   for (TableMap::iterator it = tables_.begin(); it != tables_.end(); ++it) {
     it->second->Flush();
   }
 }

 bool DataLogImpl::Run(void* obj) {
   static_cast<DataLogImpl*>(obj)->Process();
   return true;
 }

 void DataLogImpl::Process() {
   // Wait for a row to be complete
   flush_event_->Wait(WEBRTC_EVENT_INFINITE);
   Flush();
 }

 void DataLogImpl::StopThread() {
   if (file_writer_thread_ != NULL) {
     file_writer_thread_->SetNotAlive();
     flush_event_->Set();
     // Call Stop() repeatedly, waiting for the Flush() call in Process() to
     // finish.
     while (!file_writer_thread_->Stop()) continue;
   }
 }

 }  // namespace webrtc
	/*
	* Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
	*
	* Use of this source code is governed by a BSD-style license
	* that can be found in the LICENSE file in the root of the source
	* tree. An additional intellectual property rights grant can be found
	* in the file PATENTS. All contributing project authors may
	* be found in the AUTHORS file in the root of the source tree.
	*/

	#include "webrtc/system_wrappers/interface/data_log.h"

	#include <assert.h>

	#include <algorithm>
	#include <list>

	#include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
	#include "webrtc/system_wrappers/interface/event_wrapper.h"
	#include "webrtc/system_wrappers/interface/file_wrapper.h"
	#include "webrtc/system_wrappers/interface/rw_lock_wrapper.h"
	#include "webrtc/system_wrappers/interface/thread_wrapper.h"

	namespace webrtc {

	DataLogImpl::CritSectScopedPtr DataLogImpl::crit_sect_(
	CriticalSectionWrapper::CreateCriticalSection());

	DataLogImpl* DataLogImpl::instance_ = NULL;

	// A Row contains cells, which are indexed by the column names as std::string.
	// The string index is treated in a case sensitive way.
	class Row {
	public:
	Row();
	~Row();

	// Inserts a Container into the cell of the column specified with
	// column_name.
	// column_name is treated in a case sensitive way.
	int InsertCell(const std::string& column_name,
	const Container* value_container);

	// Converts the value at the column specified by column_name to a string
	// stored in value_string.
	// column_name is treated in a case sensitive way.
	void ToString(const std::string& column_name, std::string* value_string);

	private:
	// Collection of containers indexed by column name as std::string
	typedef std::map<std::string, const Container*> CellMap;

	CellMap cells_;
	CriticalSectionWrapper* cells_lock_;
	};

	// A LogTable contains multiple rows, where only the latest row is active for
	// editing. The rows are defined by the ColumnMap, which contains the name of
	// each column and the length of the column (1 for one-value-columns and greater
	// than 1 for multi-value-columns).
	class LogTable {
	public:
	LogTable();
	~LogTable();

	// Adds the column with name column_name to the table. The column will be a
	// multi-value-column if multi_value_length is greater than 1.
	// column_name is treated in a case sensitive way.
	int AddColumn(const std::string& column_name, int multi_value_length);

	// Buffers the current row while it is waiting to be written to file,
	// which is done by a call to Flush(). A new row is available when the
	// function returns
	void NextRow();

	// Inserts a Container into the cell of the column specified with
	// column_name.
	// column_name is treated in a case sensitive way.
	int InsertCell(const std::string& column_name,
	const Container* value_container);

	// Creates a log file, named as specified in the string file_name, to
	// where the table will be written when calling Flush().
	int CreateLogFile(const std::string& file_name);

	// Write all complete rows to file.
	// May not be called by two threads simultaneously (doing so may result in
	// a race condition). Will be called by the file_writer_thread_ when that
	// thread is running.
	void Flush();

	private:
	// Collection of multi_value_lengths indexed by column name as std::string
	typedef std::map<std::string, int> ColumnMap;
	typedef std::list<Row*> RowList;

	ColumnMap columns_;
	RowList rows_[2];
	RowList* rows_history_;
	RowList* rows_flush_;
	Row* current_row_;
	FileWrapper* file_;
	bool write_header_;
	CriticalSectionWrapper* table_lock_;
	};

	Row::Row()
	: cells_(),
	cells_lock_(CriticalSectionWrapper::CreateCriticalSection()) {
	}

	Row::~Row() {
	for (CellMap::iterator it = cells_.begin(); it != cells_.end();) {
	delete it->second;
	// For maps all iterators (except the erased) are valid after an erase
	cells_.erase(it++);
	}
	delete cells_lock_;
	}

	int Row::InsertCell(const std::string& column_name,
	const Container* value_container) {
	CriticalSectionScoped synchronize(cells_lock_);
	assert(cells_.count(column_name) == 0);
	if (cells_.count(column_name) > 0)
	return -1;
	cells_[column_name] = value_container;
	return 0;
	}

	void Row::ToString(const std::string& column_name,
	std::string* value_string) {
	CriticalSectionScoped synchronize(cells_lock_);
	const Container* container = cells_[column_name];
	if (container == NULL) {
	*value_string = "NaN,";
	return;
	}
	container->ToString(value_string);
	}

	LogTable::LogTable()
	: columns_(),
	rows_(),
	rows_history_(&rows_[0]),
	rows_flush_(&rows_[1]),
	current_row_(new Row),
	file_(FileWrapper::Create()),
	write_header_(true),
	table_lock_(CriticalSectionWrapper::CreateCriticalSection()) {
	}

	LogTable::~LogTable() {
	for (RowList::iterator row_it = rows_history_->begin();
	row_it != rows_history_->end();) {
	delete *row_it;
	row_it = rows_history_->erase(row_it);
	}
	for (ColumnMap::iterator col_it = columns_.begin();
	col_it != columns_.end();) {
	// For maps all iterators (except the erased) are valid after an erase
	columns_.erase(col_it++);
	}
	if (file_ != NULL) {
	file_->Flush();
	file_->CloseFile();
	delete file_;
	}
	delete current_row_;
	delete table_lock_;
	}

	int LogTable::AddColumn(const std::string& column_name,
	int multi_value_length) {
	assert(multi_value_length > 0);
	if (!write_header_) {
	// It's not allowed to add new columns after the header
	// has been written.
	assert(false);
	return -1;
	} else {
	CriticalSectionScoped synchronize(table_lock_);
	if (write_header_)
	columns_[column_name] = multi_value_length;
	else
	return -1;
	}
	return 0;
	}

	void LogTable::NextRow() {
	CriticalSectionScoped sync_rows(table_lock_);
	rows_history_->push_back(current_row_);
	current_row_ = new Row;
	}

	int LogTable::InsertCell(const std::string& column_name,
	const Container* value_container) {
	CriticalSectionScoped synchronize(table_lock_);
	assert(columns_.count(column_name) > 0);
	if (columns_.count(column_name) == 0)
	return -1;
	return current_row_->InsertCell(column_name, value_container);
	}

	int LogTable::CreateLogFile(const std::string& file_name) {
	if (file_name.length() == 0)
	return -1;
	if (file_->Open())
	return -1;
	file_->OpenFile(file_name.c_str(),
	false, // Open with read/write permissions
	false, // Don't wraparound and write at the beginning when
	// the file is full
	true); // Open as a text file
	if (file_ == NULL)
	return -1;
	return 0;
	}

	void LogTable::Flush() {
	ColumnMap::iterator column_it;
	bool commit_header = false;
	if (write_header_) {
	CriticalSectionScoped synchronize(table_lock_);
	if (write_header_) {
	commit_header = true;
	write_header_ = false;
	}
	}
	if (commit_header) {
	for (column_it = columns_.begin();
	column_it != columns_.end(); ++column_it) {
	if (column_it->second > 1) {
	file_->WriteText("%s[%u],", column_it->first.c_str(),
	column_it->second);
	for (int i = 1; i < column_it->second; ++i)
	file_->WriteText(",");
	} else {
	file_->WriteText("%s,", column_it->first.c_str());
	}
	}
	if (columns_.size() > 0)
	file_->WriteText("\n");
	}

	// Swap the list used for flushing with the list containing the row history
	// and clear the history. We also create a local pointer to the new
	// list used for flushing to avoid race conditions if another thread
	// calls this function while we are writing.
	// We don't want to block the list while we're writing to file.
	{
	CriticalSectionScoped synchronize(table_lock_);
	RowList* tmp = rows_flush_;
	rows_flush_ = rows_history_;
	rows_history_ = tmp;
	rows_history_->clear();
	}

	// Write all complete rows to file and delete them
	for (RowList::iterator row_it = rows_flush_->begin();
	row_it != rows_flush_->end();) {
	for (column_it = columns_.begin();
	column_it != columns_.end(); ++column_it) {
	std::string row_string;
	(*row_it)->ToString(column_it->first, &row_string);
	file_->WriteText("%s", row_string.c_str());
	}
	if (columns_.size() > 0)
	file_->WriteText("\n");
	delete *row_it;
	row_it = rows_flush_->erase(row_it);
	}
	}

	int DataLog::CreateLog() {
	return DataLogImpl::CreateLog();
	}

	void DataLog::ReturnLog() {
	return DataLogImpl::ReturnLog();
	}

	std::string DataLog::Combine(const std::string& table_name, int table_id) {
	std::stringstream ss;
	std::string combined_id = table_name;
	std::string number_suffix;
	ss << "_" << table_id;
	ss >> number_suffix;
	combined_id += number_suffix;
	std::transform(combined_id.begin(), combined_id.end(), combined_id.begin(),
	::tolower);
	return combined_id;
	}

	int DataLog::AddTable(const std::string& table_name) {
	DataLogImpl* data_log = DataLogImpl::StaticInstance();
	if (data_log == NULL)
	return -1;
	return data_log->AddTable(table_name);
	}

	int DataLog::AddColumn(const std::string& table_name,
	const std::string& column_name,
	int multi_value_length) {
	DataLogImpl* data_log = DataLogImpl::StaticInstance();
	if (data_log == NULL)
	return -1;
	return data_log->DataLogImpl::StaticInstance()->AddColumn(table_name,
	column_name,
	multi_value_length);
	}

	int DataLog::NextRow(const std::string& table_name) {
	DataLogImpl* data_log = DataLogImpl::StaticInstance();
	if (data_log == NULL)
	return -1;
	return data_log->DataLogImpl::StaticInstance()->NextRow(table_name);
	}

	DataLogImpl::DataLogImpl()
	: counter_(1),
	tables_(),
	flush_event_(EventWrapper::Create()),
	file_writer_thread_(NULL),
	tables_lock_(RWLockWrapper::CreateRWLock()) {
	}

	DataLogImpl::~DataLogImpl() {
	StopThread();
	Flush(); // Write any remaining rows
	delete file_writer_thread_;
	delete flush_event_;
	for (TableMap::iterator it = tables_.begin(); it != tables_.end();) {
	delete static_cast<LogTable*>(it->second);
	// For maps all iterators (except the erased) are valid after an erase
	tables_.erase(it++);
	}
	delete tables_lock_;
	}

	int DataLogImpl::CreateLog() {
	CriticalSectionScoped synchronize(crit_sect_.get());
	if (instance_ == NULL) {
	instance_ = new DataLogImpl();
	return instance_->Init();
	} else {
	++instance_->counter_;
	}
	return 0;
	}

	int DataLogImpl::Init() {
	file_writer_thread_ = ThreadWrapper::CreateThread(
	DataLogImpl::Run,
	instance_,
	kHighestPriority,
	"DataLog");
	if (file_writer_thread_ == NULL)
	return -1;
	unsigned int thread_id = 0;
	bool success = file_writer_thread_->Start(thread_id);
	if (!success)
	return -1;
	return 0;
	}

	DataLogImpl* DataLogImpl::StaticInstance() {
	return instance_;
	}

	void DataLogImpl::ReturnLog() {
	CriticalSectionScoped synchronize(crit_sect_.get());
	if (instance_ && instance_->counter_ > 1) {
	--instance_->counter_;
	return;
	}
	delete instance_;
	instance_ = NULL;
	}

	int DataLogImpl::AddTable(const std::string& table_name) {
	WriteLockScoped synchronize(*tables_lock_);
	// Make sure we don't add a table which already exists
	if (tables_.count(table_name) > 0)
	return -1;
	tables_[table_name] = new LogTable();
	if (tables_[table_name]->CreateLogFile(table_name + ".txt") == -1)
	return -1;
	return 0;
	}

	int DataLogImpl::AddColumn(const std::string& table_name,
	const std::string& column_name,
	int multi_value_length) {
	ReadLockScoped synchronize(*tables_lock_);
	if (tables_.count(table_name) == 0)
	return -1;
	return tables_[table_name]->AddColumn(column_name, multi_value_length);
	}

	int DataLogImpl::InsertCell(const std::string& table_name,
	const std::string& column_name,
	const Container* value_container) {
	ReadLockScoped synchronize(*tables_lock_);
	assert(tables_.count(table_name) > 0);
	if (tables_.count(table_name) == 0)
	return -1;
	return tables_[table_name]->InsertCell(column_name, value_container);
	}

	int DataLogImpl::NextRow(const std::string& table_name) {
	ReadLockScoped synchronize(*tables_lock_);
	if (tables_.count(table_name) == 0)
	return -1;
	tables_[table_name]->NextRow();
	if (file_writer_thread_ == NULL) {
	// Write every row to file as they get complete.
	tables_[table_name]->Flush();
	} else {
	// Signal a complete row
	flush_event_->Set();
	}
	return 0;
	}

	void DataLogImpl::Flush() {
	ReadLockScoped synchronize(*tables_lock_);
	for (TableMap::iterator it = tables_.begin(); it != tables_.end(); ++it) {
	it->second->Flush();
	}
	}

	bool DataLogImpl::Run(void* obj) {
	static_cast<DataLogImpl*>(obj)->Process();
	return true;
	}

	void DataLogImpl::Process() {
	// Wait for a row to be complete
	flush_event_->Wait(WEBRTC_EVENT_INFINITE);
	Flush();
	}

	void DataLogImpl::StopThread() {
	if (file_writer_thread_ != NULL) {
	file_writer_thread_->SetNotAlive();
	flush_event_->Set();
	// Call Stop() repeatedly, waiting for the Flush() call in Process() to
	// finish.
	while (!file_writer_thread_->Stop()) continue;
	}
	}

	} // namespace webrtc