__declspec(noinline) void makeChunkWritable(size_t chunkno) {
scoped_lock lk(mapViewMutex);
if( writable.get(chunkno) ) // double check lock
return;
// remap all maps in this chunk. common case is a single map, but could have more than one with smallfiles or .ns files
size_t chunkStart = chunkno * MemoryMappedFile::ChunkSize;
size_t chunkNext = chunkStart + MemoryMappedFile::ChunkSize;
scoped_lock lk2(privateViews._mutex());
map<void*,DurableMappedFile*>::iterator i = privateViews.finditer_inlock((void*) (chunkNext-1));
while( 1 ) {
const pair<void*,DurableMappedFile*> x = *(--i);
DurableMappedFile *mmf = x.second;
if( mmf == 0 )
break;
size_t viewStart = (size_t) x.first;
size_t viewEnd = (size_t) (viewStart + mmf->length());
if( viewEnd <= chunkStart )
break;
size_t protectStart = max(viewStart, chunkStart);
dassert(protectStart<chunkNext);
size_t protectEnd = min(viewEnd, chunkNext);
size_t protectSize = protectEnd - protectStart;
dassert(protectSize>0&&protectSize<=MemoryMappedFile::ChunkSize);
DWORD oldProtection;
bool ok = VirtualProtect( reinterpret_cast<void*>( protectStart ),
protectSize,
PAGE_WRITECOPY,
&oldProtection );
if ( !ok ) {
DWORD dosError = GetLastError();
log() << "VirtualProtect for " << mmf->filename()
<< " chunk " << chunkno
<< " failed with " << errnoWithDescription( dosError )
<< " (chunk size is " << protectSize
<< ", address is " << hex << protectStart << dec << ")"
<< " in mongo::makeChunkWritable, terminating"
<< endl;
fassertFailed( 16362 );
}
}
writable.set(chunkno);
}
/** notification on unmapping so we can clear writable bits */
void MemoryMappedFile::clearWritableBits(void *p) {
for( unsigned i = ((size_t)p)/ChunkSize; i <= (((size_t)p)+len)/ChunkSize; i++ ) {
writable.clear(i);
verify( !writable.get(i) );
}
}
__declspec(noinline) void makeChunkWritable(size_t chunkno) {
scoped_lock lk(mapViewMutex);
if( writable.get(chunkno) ) // double check lock
return;
// remap all maps in this chunk. common case is a single map, but could have more than one with smallfiles or .ns files
size_t chunkStart = chunkno * MemoryMappedFile::ChunkSize;
size_t chunkNext = chunkStart + MemoryMappedFile::ChunkSize;
scoped_lock lk2(privateViews._mutex());
map<void*,DurableMappedFile*>::iterator i = privateViews.finditer_inlock((void*) (chunkNext-1));
while( 1 ) {
const pair<void*,DurableMappedFile*> x = *(--i);
DurableMappedFile *mmf = x.second;
if( mmf == 0 )
break;
size_t viewStart = (size_t) x.first;
size_t viewEnd = (size_t) (viewStart + mmf->length());
if( viewEnd <= chunkStart )
break;
size_t protectStart = max(viewStart, chunkStart);
dassert(protectStart<chunkNext);
size_t protectEnd = min(viewEnd, chunkNext);
size_t protectSize = protectEnd - protectStart;
dassert(protectSize>0&&protectSize<=MemoryMappedFile::ChunkSize);
DWORD oldProtection;
bool ok = VirtualProtect( reinterpret_cast<void*>( protectStart ),
protectSize,
PAGE_WRITECOPY,
&oldProtection );
if ( !ok ) {
DWORD dosError = GetLastError();
if (dosError == ERROR_COMMITMENT_LIMIT) {
// System has run out of memory between physical RAM & page file, tell the user
BSONObjBuilder bb;
ProcessInfo p;
p.getExtraInfo(bb);
log() << "MongoDB has exhausted the system memory capacity.";
log() << "Current Memory Status: " << bb.obj().toString();
}
log() << "VirtualProtect for " << mmf->filename()
<< " chunk " << chunkno
<< " failed with " << errnoWithDescription( dosError )
<< " (chunk size is " << protectSize
<< ", address is " << hex << protectStart << dec << ")"
<< " in mongo::makeChunkWritable, terminating"
<< endl;
fassertFailed( 16362 );
}
}
writable.set(chunkno);
}