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// @file file_allocator.h
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "../pch.h"
#include <fcntl.h>
#include <errno.h>
#if defined(__freebsd__) || defined(__openbsd__)
#include <sys/stat.h>
#endif
#ifndef O_NOATIME
#define O_NOATIME 0
#endif
namespace mongo {
/* Handles allocation of contiguous files on disk. Allocation may be
requested asynchronously or synchronously.
*/
class FileAllocator {
/* The public functions may not be called concurrently. The allocation
functions may be called multiple times per file, but only the first
size specified per file will be used.
*/
public:
#if !defined(_WIN32)
FileAllocator() : pendingMutex_("FileAllocator"), failed_() {}
#endif
void start() {
#if !defined(_WIN32)
Runner r( *this );
boost::thread t( r );
#endif
}
// May be called if file exists. If file exists, or its allocation has
// been requested, size is updated to match existing file size.
void requestAllocation( const string &name, long &size ) {
/* Some of the system calls in the file allocator don't work in win,
so no win support - 32 or 64 bit. Plus we don't seem to need preallocation
on windows anyway as we don't have to pre-zero the file there.
*/
#if !defined(_WIN32)
scoped_lock lk( pendingMutex_ );
if ( failed_ )
return;
long oldSize = prevSize( name );
if ( oldSize != -1 ) {
size = oldSize;
return;
}
pending_.push_back( name );
pendingSize_[ name ] = size;
pendingUpdated_.notify_all();
#endif
}
// Returns when file has been allocated. If file exists, size is
// updated to match existing file size.
void allocateAsap( const string &name, long &size ) {
#if !defined(_WIN32)
scoped_lock lk( pendingMutex_ );
long oldSize = prevSize( name );
if ( oldSize != -1 ) {
size = oldSize;
if ( !inProgress( name ) )
return;
}
checkFailure();
pendingSize_[ name ] = size;
if ( pending_.size() == 0 )
pending_.push_back( name );
else if ( pending_.front() != name ) {
pending_.remove( name );
list< string >::iterator i = pending_.begin();
++i;
pending_.insert( i, name );
}
pendingUpdated_.notify_all();
while( inProgress( name ) ) {
checkFailure();
pendingUpdated_.wait( lk.boost() );
}
#endif
}
void waitUntilFinished() const {
#if !defined(_WIN32)
if ( failed_ )
return;
scoped_lock lk( pendingMutex_ );
while( pending_.size() != 0 )
pendingUpdated_.wait( lk.boost() );
#endif
}
static void ensureLength( int fd , long size ){
#if defined(_WIN32)
// we don't zero on windows
// TODO : we should to avoid fragmentation
#else
#if defined(__linux__)
int ret = posix_fallocate(fd,0,size);
if ( ret == 0 )
return;
log() << "posix_fallocate failed: " << errnoWithDescription( ret ) << " falling back" << endl;
#endif
off_t filelen = lseek(fd, 0, SEEK_END);
if ( filelen < size ) {
if (filelen != 0) {
stringstream ss;
ss << "failure creating new datafile; lseek failed for fd " << fd << " with errno: " << errnoWithDescription();
massert( 10440 , ss.str(), filelen == 0 );
}
// Check for end of disk.
massert( 10441 , "Unable to allocate file of desired size",
size - 1 == lseek(fd, size - 1, SEEK_SET) );
massert( 10442 , "Unable to allocate file of desired size",
1 == write(fd, "", 1) );
lseek(fd, 0, SEEK_SET);
const long z = 256 * 1024;
const boost::scoped_array<char> buf_holder (new char[z]);
char* buf = buf_holder.get();
memset(buf, 0, z);
long left = size;
while ( left > 0 ) {
long towrite = left;
if ( towrite > z )
towrite = z;
int written = write( fd , buf , towrite );
massert( 10443 , errnoWithPrefix("write failed" ), written > 0 );
left -= written;
}
}
#endif
}
private:
#if !defined(_WIN32)
void checkFailure() {
massert( 12520, "file allocation failure", !failed_ );
}
// caller must hold pendingMutex_ lock. Returns size if allocated or
// allocation requested, -1 otherwise.
long prevSize( const string &name ) const {
if ( pendingSize_.count( name ) > 0 )
return pendingSize_[ name ];
if ( boost::filesystem::exists( name ) )
return boost::filesystem::file_size( name );
return -1;
}
// caller must hold pendingMutex_ lock.
bool inProgress( const string &name ) const {
for( list< string >::const_iterator i = pending_.begin(); i != pending_.end(); ++i )
if ( *i == name )
return true;
return false;
}
mutable mongo::mutex pendingMutex_;
mutable boost::condition pendingUpdated_;
list< string > pending_;
mutable map< string, long > pendingSize_;
bool failed_;
struct Runner {
Runner( FileAllocator &allocator ) : a_( allocator ) {}
FileAllocator &a_;
void operator()() {
while( 1 ) {
{
scoped_lock lk( a_.pendingMutex_ );
if ( a_.pending_.size() == 0 )
a_.pendingUpdated_.wait( lk.boost() );
}
while( 1 ) {
string name;
long size;
{
scoped_lock lk( a_.pendingMutex_ );
if ( a_.pending_.size() == 0 )
break;
name = a_.pending_.front();
size = a_.pendingSize_[ name ];
}
try {
log() << "allocating new datafile " << name << ", filling with zeroes..." << endl;
long fd = open(name.c_str(), O_CREAT | O_RDWR | O_NOATIME, S_IRUSR | S_IWUSR);
if ( fd <= 0 ) {
stringstream ss;
ss << "couldn't open " << name << ' ' << errnoWithDescription();
massert( 10439 , ss.str(), fd <= 0 );
}
#if defined(POSIX_FADV_DONTNEED)
if( posix_fadvise(fd, 0, size, POSIX_FADV_DONTNEED) ) {
log() << "warning: posix_fadvise fails " << name << ' ' << errnoWithDescription() << endl;
}
#endif
Timer t;
/* make sure the file is the full desired length */
ensureLength( fd , size );
log() << "done allocating datafile " << name << ", "
<< "size: " << size/1024/1024 << "MB, "
<< " took " << ((double)t.millis())/1000.0 << " secs"
<< endl;
close( fd );
} catch ( ... ) {
problem() << "Failed to allocate new file: " << name
<< ", size: " << size << ", aborting." << endl;
try {
BOOST_CHECK_EXCEPTION( boost::filesystem::remove( name ) );
} catch ( ... ) {
}
scoped_lock lk( a_.pendingMutex_ );
a_.failed_ = true;
// not erasing from pending
a_.pendingUpdated_.notify_all();
return; // no more allocation
}
{
scoped_lock lk( a_.pendingMutex_ );
a_.pendingSize_.erase( name );
a_.pending_.pop_front();
a_.pendingUpdated_.notify_all();
}
}
}
}
};
#endif
};
FileAllocator &theFileAllocator();
} // namespace mongo
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