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XrdEcStrmWriter.hh
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XrdEcStrmWriter.hh
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/*
* XrdEcStrmWriter.hh
*
* Created on: 5 May 2020
* Author: simonm
*/
#ifndef SRC_XRDEC_XRDECSTRMWRITER_HH_
#define SRC_XRDEC_XRDECSTRMWRITER_HH_
#include "XrdEc/XrdEcWrtBuff.hh"
#include "XrdEc/XrdEcThreadPool.hh"
#include "XrdCl/XrdClFileOperations.hh"
#include "XrdCl/XrdClParallelOperation.hh"
#include "XrdCl/XrdClZipArchive.hh"
#include <random>
#include <chrono>
#include <future>
#include <atomic>
#include <memory>
#include <vector>
#include <thread>
#include <queue>
#include <condition_variable>
#include <mutex>
#include <iterator>
namespace XrdEc
{
//---------------------------------------------------------------------------
// A class implementing synchronous queue
//---------------------------------------------------------------------------
template<typename Element>
struct sync_queue
{
//-------------------------------------------------------------------------
// An internal exception used for interrupting the `dequeue` method
//-------------------------------------------------------------------------
struct wait_interrupted{ };
//-------------------------------------------------------------------------
// Default constructor
//-------------------------------------------------------------------------
sync_queue() : interrupted( false )
{
}
//-------------------------------------------------------------------------
// Enqueue new element into the queue
//-------------------------------------------------------------------------
inline void enqueue( Element && element )
{
std::unique_lock<std::mutex> lck( mtx );
elements.push( std::move( element ) );
cv.notify_all();
}
//-------------------------------------------------------------------------
// Dequeue an element from the front of the queue
// Note: if the queue is empty blocks until a new element is enqueued
//-------------------------------------------------------------------------
inline Element dequeue()
{
std::unique_lock<std::mutex> lck( mtx );
while( elements.empty() )
{
cv.wait( lck );
if( interrupted ) throw wait_interrupted();
}
Element element = std::move( elements.front() );
elements.pop();
return std::move( element );
}
//-------------------------------------------------------------------------
// Dequeue an element from the front of the queue
// Note: if the queue is empty returns false, true otherwise
//-------------------------------------------------------------------------
inline bool dequeue( Element &e )
{
std::unique_lock<std::mutex> lck( mtx );
if( elements.empty() ) return false;
e = std::move( elements.front() );
elements.pop();
return true;
}
//-------------------------------------------------------------------------
// Checks if the queue is empty
//-------------------------------------------------------------------------
bool empty()
{
std::unique_lock<std::mutex> lck( mtx );
return elements.empty();
}
//-------------------------------------------------------------------------
// Interrupt all waiting `dequeue` routines
//-------------------------------------------------------------------------
inline void interrupt()
{
interrupted = true;
cv.notify_all();
}
private:
std::queue<Element> elements; //< the queue itself
std::mutex mtx; //< mutex guarding the queue
std::condition_variable cv;
std::atomic<bool> interrupted; //< a flag, true if all `dequeue` routines
//< should be interrupted
};
//---------------------------------------------------------------------------
// The Stream Writer objects, responsible for writing erasure coded data
// into selected placement group.
//---------------------------------------------------------------------------
class StrmWriter
{
//-------------------------------------------------------------------------
// Type for queue of buffers to be written
//-------------------------------------------------------------------------
typedef sync_queue<std::future<WrtBuff*>> buff_queue;
public:
//-----------------------------------------------------------------------
// Constructor
//-----------------------------------------------------------------------
StrmWriter( const ObjCfg &objcfg ) : objcfg( objcfg ),
writer_thread_stop( false ),
writer_thread( writer_routine, this ),
next_blknb( 0 ),
global_status( this )
{
}
virtual ~StrmWriter()
{
writer_thread_stop = true;
buffers.interrupt();
writer_thread.join();
}
void Open( XrdCl::ResponseHandler *handler )
{
const size_t size = objcfg.plgr.size();
std::vector<XrdCl::Pipeline> opens;
opens.reserve( size );
// initialize all zip archive objects
for( size_t i = 0; i < size; ++i )
archives.emplace_back( std::make_shared<XrdCl::ZipArchive>() );
for( size_t i = 0; i < size; ++i )
{
std::string url = objcfg.plgr[i] + objcfg.obj + ".zip";
XrdCl::Ctx<XrdCl::ZipArchive> zip( *archives[i] );
opens.emplace_back( XrdCl::OpenArchive( zip, url, XrdCl::OpenFlags::New | XrdCl::OpenFlags::Write ) );
}
XrdCl::Async( XrdCl::Parallel( opens ).AtLeast( objcfg.nbchunks ) >> handler );
}
void Write( uint32_t size, const void *buff, XrdCl::ResponseHandler *handler )
{
//---------------------------------------------------------------------
// First, check the global status, if we are in an error state just
// fail the request.
//---------------------------------------------------------------------
XrdCl::XRootDStatus gst = global_status.get();
if( !gst.IsOK() ) return ScheduleHandler( handler, gst );
//---------------------------------------------------------------------
// Update the number of bytes left to be written
//---------------------------------------------------------------------
global_status.issue_write( size );
const char* buffer = reinterpret_cast<const char*>( buff );
uint32_t wrtsize = size;
while( wrtsize > 0 )
{
if( !wrtbuff ) wrtbuff.reset( new WrtBuff( objcfg ) );
uint64_t written = wrtbuff->Write( wrtsize, buffer );
buffer += written;
wrtsize -= written;
if( wrtbuff->Complete() ) EnqueueBuff( std::move( wrtbuff ) );
}
//---------------------------------------------------------------------
// We can tell the user it's done as we have the date cached in the
// buffer
//---------------------------------------------------------------------
ScheduleHandler( handler );
}
void Close( XrdCl::ResponseHandler *handler )
{
//---------------------------------------------------------------------
// Let the global status handle the close
//---------------------------------------------------------------------
global_status.issue_close( handler );
}
private:
//-----------------------------------------------------------------------
// Global status of the StrmWriter
//-----------------------------------------------------------------------
struct global_status_t
{
//---------------------------------------------------------------------
// Constructor
//---------------------------------------------------------------------
global_status_t( StrmWriter *writer ) : writer( writer ),
bytesleft( 0 ),
stopped_writing( false ),
closeHandler( 0 )
{
}
//---------------------------------------------------------------------
// Report status of write operation
//---------------------------------------------------------------------
void report_wrt( const XrdCl::XRootDStatus &st, uint64_t wrtsize )
{
std::unique_lock<std::mutex> lck( mtx );
//-------------------------------------------------------------------
// Update the global status
//-------------------------------------------------------------------
bytesleft -= wrtsize;
if( !st.IsOK() ) status = st;
//-------------------------------------------------------------------
// check if we are done, and if yes call the close implementation
//-------------------------------------------------------------------
if( bytesleft == 0 && stopped_writing )
{
lck.unlock();
writer->CloseImpl( closeHandler );
}
}
//---------------------------------------------------------------------
// Indicate that the user issued close
//---------------------------------------------------------------------
void issue_close( XrdCl::ResponseHandler *handler )
{
std::unique_lock<std::mutex> lck( mtx );
//-------------------------------------------------------------------
// There will be no more new write requests
//-------------------------------------------------------------------
stopped_writing = true;
//-------------------------------------------------------------------
// If there are no outstanding writes, we can simply call the close
// routine
//-------------------------------------------------------------------
if( bytesleft == 0 ) return writer->CloseImpl( handler );
//-------------------------------------------------------------------
// Otherwise we save the handler for later
//-------------------------------------------------------------------
closeHandler = handler;
}
//---------------------------------------------------------------------
// get the global status value
//---------------------------------------------------------------------
inline const XrdCl::XRootDStatus& get() const
{
std::unique_lock<std::mutex> lck( mtx );
return status;
}
inline void issue_write( uint64_t wrtsize )
{
std::unique_lock<std::mutex> lck( mtx );
bytesleft += wrtsize;
}
private:
mutable std::mutex mtx;
StrmWriter *writer; //> pointer to the StrmWriter
uint64_t bytesleft; //> bytes left to be written
bool stopped_writing; //> true, if user called close
XrdCl::XRootDStatus status; //> the global status
XrdCl::ResponseHandler *closeHandler; //> user close handler
};
inline void EnqueueBuff( std::unique_ptr<WrtBuff> wrtbuff )
{
// the routine to be called in the thread-pool
// - does erasure coding
// - calculates crc32cs
static auto prepare_buff = []( WrtBuff *wrtbuff )
{
std::unique_ptr<WrtBuff> ptr( wrtbuff );
ptr->Encode();
return ptr.release();
};
buffers.enqueue( ThreadPool::Instance().Execute( prepare_buff, wrtbuff.release() ) );
}
inline std::unique_ptr<WrtBuff> DequeueBuff()
{
std::future<WrtBuff*> ftr = buffers.dequeue();
std::unique_ptr<WrtBuff> result( ftr.get() );
return std::move( result );
}
static void writer_routine( StrmWriter *me )
{
try
{
while( !me->writer_thread_stop )
{
std::unique_ptr<WrtBuff> wrtbuff( me->DequeueBuff() );
if( !wrtbuff ) continue;
me->WriteBuff( std::move( wrtbuff ) );
}
}
catch( const buff_queue::wait_interrupted& ){ }
}
void WriteBuff( std::unique_ptr<WrtBuff> buff )
{
//---------------------------------------------------------------------
// Our buffer with the data block, will be shared between all pipelines
// writing to different servers.
//---------------------------------------------------------------------
std::shared_ptr<WrtBuff> wrtbuff( std::move( buff ) );
//---------------------------------------------------------------------
// Shuffle the servers so every block has a different placement
//---------------------------------------------------------------------
static std::default_random_engine random_engine( std::chrono::system_clock::now().time_since_epoch().count() );
std::shared_ptr<sync_queue<size_t>> servers = std::make_shared<sync_queue<size_t>>();
std::vector<size_t> zipid( archives.size() );
std::iota( zipid.begin(), zipid.end(), 0 );
std::shuffle( zipid.begin(), zipid.end(), random_engine );
auto itr = zipid.begin();
for( ; itr != zipid.end() ; ++itr ) servers->enqueue( std::move( *itr ) );
//---------------------------------------------------------------------
// Create the write pipelines for updating stripes
//---------------------------------------------------------------------
const size_t nbchunks = objcfg.nbchunks;
std::vector<XrdCl::Pipeline> writes;
writes.reserve( nbchunks );
size_t blknb = next_blknb++;
uint64_t blksize = 0;
for( size_t strpnb = 0; strpnb < nbchunks; ++strpnb )
{
std::string fn = objcfg.obj + '.' + std::to_string( blknb ) + '.' + std::to_string( strpnb );
uint32_t crc32c = wrtbuff->GetCrc32c( strpnb );
uint64_t strpsize = wrtbuff->GetStrpSize( strpnb );
char* strpbuff = wrtbuff->GetStrpBuff( strpnb );
if( strpnb < objcfg.nbdata ) blksize += strpsize;
//-------------------------------------------------------------------
// Find a server where we can append the next data chunk
//-------------------------------------------------------------------
XrdCl::Ctx<XrdCl::ZipArchive> zip;
XrdCl::XRootDStatus st;
do
{
size_t srvid;
if( !servers->dequeue( srvid ) )
{
XrdCl::XRootDStatus err( XrdCl::stError, XrdCl::errNoMoreReplicas,
0, "No more data servers to try." );
global_status.report_wrt( err, strpsize );
return;
}
zip = *archives[srvid];
st = zip->OpenFile( fn, XrdCl::OpenFlags::New, strpsize, crc32c );
}
while( !st.IsOK() );
//-------------------------------------------------------------------
// Create the Write request
//-------------------------------------------------------------------
XrdCl::Pipeline p = XrdCl::Write( zip, strpsize, strpbuff ) >>
[=]( XrdCl::XRootDStatus &st ) mutable
{
//---------------------------------------------
// Try to recover from error
//---------------------------------------------
if( !st.IsOK() )
{
//-------------------------------------------
// First clean up the ZipArchive object
//-------------------------------------------
zip->CloseFile();
//-------------------------------------------
// Then select another server
//-------------------------------------------
XrdCl::XRootDStatus status;
do
{
size_t srvid;
if( !servers->dequeue( srvid ) ) return; // if there are no more servers we simply fail
zip = *archives[srvid];
st = zip->OpenFile( fn, XrdCl::OpenFlags::New, strpsize, crc32c );
} while( !status.IsOK() );
//-------------------------------------------
// Retry this operation at different server
//-------------------------------------------
XrdCl::Pipeline::Repeat();
}
}
| XrdCl::Final(
[=]( const XrdCl::XRootDStatus &st ) mutable
{
zip->CloseFile();
wrtbuff.reset();
} );
writes.emplace_back( std::move( p ) );
}
XrdCl::Async( XrdCl::Parallel( writes ) >> [=]( XrdCl::XRootDStatus &st ){ global_status.report_wrt( st, blksize ); } );
}
void CloseImpl( XrdCl::ResponseHandler *handler )
{
const size_t size = objcfg.plgr.size();
std::vector<XrdCl::Pipeline> closes;
closes.reserve( size );
for( size_t i = 0; i < size; ++i )
{
closes.emplace_back( XrdCl::CloseArchive( *archives[i] ) );
}
XrdCl::Async( XrdCl::Parallel( closes ).AtLeast( objcfg.nbchunks ) >> handler );
}
const ObjCfg &objcfg;
std::unique_ptr<WrtBuff> wrtbuff;
std::vector<std::shared_ptr<XrdCl::ZipArchive>> archives;
// queue of buffer being prepared (erasure encoded and checksummed) for write
buff_queue buffers;
std::atomic<bool> writer_thread_stop;
std::thread writer_thread;
size_t next_blknb;
global_status_t global_status;
};
}
#endif /* SRC_XRDEC_XRDECSTRMWRITER_HH_ */