// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- 
/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software 
 * Foundation.  See file COPYING.
 * 
 */



#include "BlockDevice.h"

#include "config.h"

#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/file.h>
#include <iostream>
#include <cassert>
#include <errno.h>

#include <sys/uio.h>

#include <sys/ioctl.h>

#ifndef __CYGWIN__
#include <linux/fs.h>
#endif


/*******************************************
 * biovec
 */

inline ostream& operator<<(ostream& out, BlockDevice::biovec &bio)
{
  out << "bio(";
  if (bio.type == BlockDevice::biovec::IO_READ) out << "rd ";
  if (bio.type == BlockDevice::biovec::IO_WRITE) out << "wr ";
  out << bio.start << "~" << bio.length;
  if (bio.note) out << " " << bio.note;
  out << " " << &bio;
  out << ")";
  return out;
}



/*******************************************
 * ElevatorQueue
 */

#undef dout
#define dout(x) if (x <= g_conf.debug_bdev) cout << "bdev(" << dev << ").elevatorq."
#define derr(x) if (x <= g_conf.debug_bdev) cerr << "bdev(" << dev << ").elevatorq."


int BlockDevice::ElevatorQueue::dequeue_io(list<biovec*>& biols, 
                                           block_t& start, block_t& length,
                                           interval_set<block_t>& block_lock)
{
  // queue empty?
  assert(!io_map.empty());

  dout(20) << "dequeue_io el_pos " << el_pos << " dir " << el_dir_forward << endl;

  // find our position: i >= pos
  map<block_t,biovec*>::iterator i;
  
  int tries = g_conf.bdev_el_bidir + 1;
  while (tries > 0) {
    if (el_dir_forward) {
      i = io_map.lower_bound(el_pos);
      if (i != io_map.end()) {
        break;  // not at end.  good.
      }
    } else {
      i = io_map.upper_bound(el_pos);
      if (i != io_map.begin()) {
        i--;   // and back down one (to get i <= pos).  good.
        break;
      }
    }

    // reverse (or initial startup)?
    if (g_conf.bdev_el_bidir || !el_dir_forward) {
      //      dout(20) << "restart reversing" << endl;
      el_dir_forward = !el_dir_forward;
    }
    
    if (el_dir_forward) {
      // forward
      el_pos = 0;
      
      if (g_conf.bdev_el_fw_max_ms) {
        el_stop = g_clock.now();
        utime_t max(0, 1000*g_conf.bdev_el_fw_max_ms);  // (s,us), convert ms -> us!
        el_stop += max;
        //    dout(20) << "restart forward sweep for " << max << endl;
      } else {
        //    dout(20) << "restart fowrard sweep" << endl;
      }
    } else {
      // reverse
      el_pos = bdev->get_num_blocks();
      
      if (g_conf.bdev_el_bw_max_ms) {
        el_stop = g_clock.now();
        utime_t max(0, 1000*g_conf.bdev_el_bw_max_ms);  // (s,us), convert ms -> us!
        el_stop += max;
        //    dout(20) << "restart reverse sweep for " << max << endl;
      } else {
        //    dout(20) << "restart reverse sweep" << endl;
      }
    }

    tries--;
  }
  
  assert(tries > 0);  // this shouldn't happen if the queue is non-empty.

  // get some biovecs
  int num_bio = 0;
  
  dout(20) << "dequeue_io  starting with " << i->first << " " << *i->second << endl;

  // merge contiguous ops
  char type = i->second->type;  // read or write
  int num_iovs = 0;  // count eventual iov's for readv/writev
  
  start = i->first;
  length = 0;

  if (el_dir_forward)
    el_pos = start;
  else
    el_pos = i->first + i->second->length;
  
  // while (contiguous)
  while ((( el_dir_forward && el_pos == i->first) ||
          (!el_dir_forward && el_pos == i->first + i->second->length)) && 
         type == i->second->type) { 
    biovec *bio = i->second;
    
    // allowed?  (not already submitted to kernel?)
    if (block_lock.intersects(bio->start, bio->length)) {
      //      dout(20) << "dequeue_io " << bio->start << "~" << bio->length 
      //               << " intersects block_lock " << block_lock << endl;
      break;  // stop, or go with what we've got so far
    }
    
    // add to biols
    int nv = bio->bl.buffers().size();     // how many iov's in this bio's bufferlist?
    if (num_iovs + nv >= g_conf.bdev_iov_max) break;  // too many!
    num_iovs += nv;
    
    start = MIN(start, bio->start);
    length += bio->length;
    
    if (el_dir_forward) {
      //dout(20) << "dequeue_io fw dequeue io at " << el_pos << " " << *i->second << endl;
      biols.push_back(bio);      // add at back
    } else {
      //  dout(20) << "dequeue_io bw dequeue io at " << el_pos << " " << *i->second << endl;
      biols.push_front(bio);     // add at front
    }
    num_bio++;
    
    // move elevator pointer
    bool at_end = false; 
    map<block_t,biovec*>::iterator prev = i;
    if (el_dir_forward) {
      el_pos += bio->length;                 // cont. next would start right after us
      i++;
      if (i == io_map.end()) {
        at_end = true;
      }
    } else {
      el_pos -= bio->length;
      if (i == io_map.begin()) {
        at_end = true;
      } else {
        i--;
      }
    }
    
    // dequeue
    io_map.erase(prev);
    bio->in_queue = 0;
    
    if (at_end) break;
  }
  
  return num_bio;
}



/*******************************************
 * BarrierQueue
 */
#undef dout
#define dout(x) if (x <= g_conf.debug_bdev) cout << "bdev(" << dev << ").barrierq."

void BlockDevice::BarrierQueue::barrier()
{
  if (!qls.empty() && qls.front()->empty()) {
    assert(qls.size() == 1);
    dout(10) << "barrier not adding new queue, front is empty" << endl;
  } else {
    qls.push_back(new ElevatorQueue(bdev, dev));
    dout(10) << "barrier adding new elevator queue (now " << qls.size() << "), front queue has "
             << qls.front()->size() << " ios left" << endl;
  }
}

bool BlockDevice::BarrierQueue::bump()
{
  assert(!qls.empty());
  
  // is the front queue empty?
  if (qls.front()->empty() &&
      qls.front() != qls.back()) {
    delete qls.front();
    qls.pop_front();
    dout(10) << "dequeue_io front empty, moving to next queue (" << qls.front()->size() << ")" << endl;
    return true;
  }

  return false;
}

int BlockDevice::BarrierQueue::dequeue_io(list<biovec*>& biols, 
                                          block_t& start, block_t& length,
                                          interval_set<block_t>& locked) 
{
  assert(!qls.empty());
  int n = qls.front()->dequeue_io(biols, start, length, locked);
  bump();  // in case we emptied the front queue
  return n;
}




/*******************************************
 * BlockDevice
 */

#undef dout
#define dout(x) if (x <= g_conf.debug_bdev) cout << "bdev(" << dev << ")."



block_t BlockDevice::get_num_blocks() 
{
  if (!num_blocks) {
    assert(fd > 0);

#ifdef BLKGETSIZE64
    // ioctl block device?
    ioctl(fd, BLKGETSIZE64, &num_blocks);
#endif

    if (!num_blocks) {
      // hmm, try stat!
      struct stat st;
      fstat(fd, &st);
      num_blocks = st.st_size;
    }
    
    num_blocks /= (__uint64_t)EBOFS_BLOCK_SIZE;

    if (g_conf.bdev_fake_mb) {
      num_blocks = g_conf.bdev_fake_mb * 256;
      dout(0) << "faking dev size " << g_conf.bdev_fake_mb << " mb" << endl;
    }
    if (g_conf.bdev_fake_max_mb &&
        num_blocks > (block_t)g_conf.bdev_fake_max_mb * 256ULL) {
      dout(0) << "faking dev size " << g_conf.bdev_fake_max_mb << " mb" << endl;
      num_blocks = g_conf.bdev_fake_max_mb * 256;
    }
    
  }
  return num_blocks;
}



/** io thread
 * each worker thread dequeues ios from the root_queue and submits them to the kernel.
 */
void* BlockDevice::io_thread_entry()
{
  lock.Lock();

  int whoami = io_threads_started++;
  io_threads_running++;
  assert(io_threads_running <= g_conf.bdev_iothreads);
  dout(10) << "io_thread" << whoami << " start, " << io_threads_running << " now running" << endl;

  // get my own fd (and file position pointer)
  int fd = open_fd();
  assert(fd > 0);

  while (!io_stop) {
    bool do_sleep = false;
    
    // queue empty?
    if (root_queue.empty()) {
      // sleep
      do_sleep = true;
    } else {
      dout(20) << "io_thread" << whoami << " going" << endl;

      block_t start, length;
      list<biovec*> biols;
      int n = root_queue.dequeue_io(biols, start, length, io_block_lock);

      if (n == 0) {
        // failed to dequeue a do-able op, sleep for now
        dout(20) << "io_thread" << whoami << " couldn't dequeue doable op, sleeping" << endl;
        assert(io_threads_running > 1);   // there must be someone else, if we couldn't dequeue something doable.
        do_sleep = true;
      } 
      else {
        // lock blocks
        assert(start == biols.front()->start);
        io_block_lock.insert(start, length);
          
        // drop lock to do the io
        lock.Unlock();
        do_io(fd, biols);
        lock.Lock();
          
        // unlock blocks
        io_block_lock.erase(start, length);
        
        // someone might have blocked on our block_lock?
        if (io_threads_running < g_conf.bdev_iothreads &&
            (int)root_queue.size() > io_threads_running)   
          io_wakeup.SignalAll();
      }
    }

    if (do_sleep) {
      do_sleep = false;
      
      // sleep
      io_threads_running--;
      dout(20) << "io_thread" << whoami << " sleeping, " << io_threads_running << " threads now running," 
               << " queue has " << root_queue.size()               << endl;

      if (g_conf.bdev_idle_kick_after_ms > 0 &&
          io_threads_running == 0 && 
          idle_kicker) {
        // first wait for signal | timeout
        io_wakeup.WaitInterval(lock, utime_t(0, g_conf.bdev_idle_kick_after_ms*1000));   

        // should we still be sleeping?  (did we get woken up, or did timer expire?
        if (root_queue.empty() && io_threads_running == 0) {
          idle_kicker->kick();          // kick
          io_wakeup.Wait(lock);          // and wait
        }
      } else {
        // normal, just wait.
        io_wakeup.Wait(lock);
      }

      io_threads_running++;
      assert(io_threads_running <= g_conf.bdev_iothreads);
      dout(20) << "io_thread" << whoami << " woke up, " << io_threads_running << " threads now running" << endl;
    }
  }

  // clean up
  ::close(fd);
  io_threads_running--;
  
  lock.Unlock();

  dout(10) << "io_thread" << whoami << " finish" << endl;
  return 0;
}



/** do_io
 * do a single io operation
 * (lock is NOT held, but we own the *biovec)
 */
void BlockDevice::do_io(int fd, list<biovec*>& biols)
{
  int r;
  assert(!biols.empty());

  // get full range, type, bl
  bufferlist bl;
  bl.claim(biols.front()->bl);
  block_t start = biols.front()->start;
  block_t length = biols.front()->length;
  char type = biols.front()->type;

  list<biovec*>::iterator p = biols.begin();
  int numbio = 1;
  for (p++; p != biols.end(); p++) {
    length += (*p)->length;
    bl.claim_append((*p)->bl);
    numbio++;
  }

  // do it
  dout(20) << "do_io start " << (type==biovec::IO_WRITE?"write":"read") 
           << " " << start << "~" << length 
           << " " << numbio << " bits" << endl;
  if (type == biovec::IO_WRITE) {
    r = _write(fd, start, length, bl);
  } else if (type == biovec::IO_READ) {
    r = _read(fd, start, length, bl);
  } else assert(0);
  dout(20) << "do_io finish " << (type==biovec::IO_WRITE?"write":"read") 
           << " " << start << "~" << length << endl;
  
  // set rval
  for (p = biols.begin(); p != biols.end(); p++)
    (*p)->rval = r;

  if (1) {
    // put in completion queue
    complete_lock.Lock();
    complete_queue.splice( complete_queue.end(), biols );
    complete_queue_len += numbio;
    complete_wakeup.Signal();
    complete_lock.Unlock();
  } else {
    // be slow and finish synchronously
    for (p = biols.begin(); p != biols.end(); p++)
      finish_io(*p);
  }
}


/** finish_io
 *
 * finish an io by signaling the cond or performing a callback.
 * called by completion thread, unless that's disabled above.
 */
void BlockDevice::finish_io(biovec *bio)
{
  bio->done = true;
  if (bio->cond) {
    bio->cond->Signal();
  }
  else if (bio->cb) {
    bio->cb->finish((ioh_t)bio, bio->rval);
    delete bio->cb;
    delete bio;
  }
}

/*** completion_thread
 * handle Cond signals or callbacks for completed ios
 */
void* BlockDevice::complete_thread_entry()
{
  complete_lock.Lock();
  dout(10) << "complete_thread start" << endl;

  while (!io_stop) {

    while (!complete_queue.empty()) {
      list<biovec*> ls;
      ls.swap(complete_queue);
      dout(10) << "complete_thread grabbed " << complete_queue_len << " biovecs" << endl;
      complete_queue_len = 0;
      
      complete_lock.Unlock();
      
      // finish
      for (list<biovec*>::iterator p = ls.begin(); 
           p != ls.end(); 
           p++) {
        biovec *bio = *p;
        dout(20) << "complete_thread finishing " << *bio << endl;
        finish_io(bio);
      }
      
      complete_lock.Lock();
    }
    if (io_stop) break;
    
    /*
    if (io_threads_running == 0 && idle_kicker) {
      complete_lock.Unlock();
      idle_kicker->kick();
      complete_lock.Lock();
      if (!complete_queue.empty() || io_stop) 
        continue;
    }
    */

    dout(25) << "complete_thread sleeping" << endl;
    complete_wakeup.Wait(complete_lock);
  }

  dout(10) << "complete_thread finish" << endl;
  complete_lock.Unlock();
  return 0;
}

  


// io queue

void BlockDevice::_submit_io(biovec *b) 
{
  // NOTE: lock must be held
  dout(15) << "_submit_io " << *b << endl;
  
  // wake up io_thread(s)?
  if ((int)root_queue.size() == io_threads_running) 
    io_wakeup.SignalOne();
  else if ((int)root_queue.size() > io_threads_running) 
    io_wakeup.SignalAll();
    
  // queue 
  root_queue.submit_io(b);

  /*
  // [DEBUG] check for overlapping ios
  // BUG: this doesn't detect all overlaps w/ the next queue thing.
  if (g_conf.bdev_debug_check_io_overlap) {
      // BUG: this doesn't catch everything!  eg 1~10000000 will be missed....
      multimap<block_t, biovec*>::iterator p = io_queue.lower_bound(b->start);
      if ((p != io_queue.end() &&
           p->first < b->start+b->length) ||
          (p != io_queue.begin() && 
           (p--, p->second->start + p->second->length > b->start))) {
        dout(1) << "_submit_io new io " << *b 
                << " overlaps with existing " << *p->second << endl;
        cerr << "_submit_io new io " << *b 
             << " overlaps with existing " << *p->second << endl;
      }
    }
  */

}

int BlockDevice::_cancel_io(biovec *bio) 
{
  // NOTE: lock must be held

  if (bio->in_queue == 0) {
    dout(15) << "_cancel_io " << *bio << " FAILED" << endl;
    return -1;
  } else {
    dout(15) << "_cancel_io " << *bio << endl;
    bio->in_queue->cancel_io(bio);
    if (root_queue.bump()) 
      io_wakeup.SignalAll();  // something happened!
    return 0;
  }
}



// low level io

int BlockDevice::_read(int fd, block_t bno, unsigned num, bufferlist& bl) 
{
  dout(10) << "_read " << bno << "~" << num << endl;

  assert(fd > 0);
  
  off_t offset = bno * EBOFS_BLOCK_SIZE;
  off_t actual = lseek(fd, offset, SEEK_SET);
  assert(actual == offset);
  
  size_t len = num*EBOFS_BLOCK_SIZE;
  assert(bl.length() >= len);

  struct iovec iov[ bl.buffers().size() ];
  int n = 0;
  size_t left = len;
  for (list<bufferptr>::const_iterator i = bl.buffers().begin();
       i != bl.buffers().end();
       i++) {
    assert(i->length() % EBOFS_BLOCK_SIZE == 0);
    
    iov[n].iov_base = (void*)i->c_str();
    iov[n].iov_len = MIN(left, i->length());

    left -= iov[n].iov_len;
    n++;
    if (left == 0) break;
  }

  int got = ::readv(fd, iov, n);
  assert(got <= (int)len);
  
  return 0;
}

int BlockDevice::_write(int fd, unsigned bno, unsigned num, bufferlist& bl) 
{
  dout(10) << "_write " << bno << "~" << num << endl;

  assert(fd > 0);
  
  off_t offset = (off_t)bno << EBOFS_BLOCK_BITS;
  assert((off_t)bno * (off_t)EBOFS_BLOCK_SIZE == offset);
  off_t actual = lseek(fd, offset, SEEK_SET);
  assert(actual == offset);
  
  // write buffers
  size_t len = num*EBOFS_BLOCK_SIZE;

  struct iovec iov[ bl.buffers().size() ];

  int n = 0;
  size_t left = len;
  for (list<bufferptr>::const_iterator i = bl.buffers().begin();
       i != bl.buffers().end();
       i++) {
    assert(i->length() % EBOFS_BLOCK_SIZE == 0);

    iov[n].iov_base = (void*)i->c_str();
    iov[n].iov_len = MIN(left, i->length());

    assert((((unsigned long long)iov[n].iov_base) & 4095ULL) == 0);
    assert((iov[n].iov_len & 4095) == 0);
    
    left -= iov[n].iov_len;
    n++;
    if (left == 0) break;
  }

  int r = ::writev(fd, iov, n);

  if (r < 0) {
    dout(1) << "couldn't write bno " << bno << " num " << num 
            << " (" << len << " bytes) in " << n << " iovs,  r=" << r 
            << " errno " << errno << " " << strerror(errno) << endl;
    dout(1) << "bl is " << bl << endl;
    assert(0);
  } else {
    assert(r == (int)len);
  }
  
  return 0;
}



// open/close

int BlockDevice::open_fd()
{
  return ::open(dev.c_str(), O_RDWR|O_SYNC|O_DIRECT, 0);
}

int BlockDevice::open(kicker *idle) 
{
  assert(fd == 0);

  // open?
  fd = open_fd();
  if (fd < 0) {
    dout(1) << "open failed, r = " << fd << " " << strerror(errno) << endl;
    fd = 0;
    return -1;
  }

  // lock
  if (g_conf.bdev_lock) {
    int r = ::flock(fd, LOCK_EX|LOCK_NB);
    if (r < 0) {
      derr(1) << "open " << dev << " failed to get LOCK_EX" << endl;
      assert(0);
      return -1;
    }
  }
               
  // figure size
  __uint64_t bsize = get_num_blocks();
  
  dout(2) << "open " << bsize << " bytes, " << num_blocks << " blocks" << endl;
  
  // start thread
  io_threads_started = 0;
  io_threads.clear();
  for (int i=0; i<g_conf.bdev_iothreads; i++) {
    io_threads.push_back(new IOThread(this));
    io_threads.back()->create();
  }
  complete_thread.create();
 
  // idle kicker?
  idle_kicker = idle;

  return fd;
}


int BlockDevice::close() 
{
  assert(fd>0);
  
  idle_kicker = 0;

  // shut down io thread
  dout(10) << "close stopping io+complete threads" << endl;
  lock.Lock();
  complete_lock.Lock();
  io_stop = true;
  io_wakeup.SignalAll();
  complete_wakeup.SignalAll();
  complete_lock.Unlock();
  lock.Unlock();    
  
  
  for (int i=0; i<g_conf.bdev_iothreads; i++) {
    io_threads[i]->join();
    delete io_threads[i];
  }
  io_threads.clear();

  complete_thread.join();

  io_stop = false;   // in case we start again

  dout(2) << "close " << endl;

  if (g_conf.bdev_lock)
    ::flock(fd, LOCK_UN);

  ::close(fd);
  fd = 0;

  return 0;
}

int BlockDevice::cancel_io(ioh_t ioh) 
{
  biovec *pbio = (biovec*)ioh;
  
  lock.Lock();
  int r = _cancel_io(pbio);
  lock.Unlock();
  
  // FIXME?
  if (r == 0 && pbio->cb) {
    //pbio->cb->finish(ioh, 0);
    delete pbio->cb;
    delete pbio;
  }
  
  return r;
}