open-source-search-engine/RdbScan.cpp

#include "gb-include.h"

#include "RdbScan.h"
#include "DiskPageCache.h"
#include "Rdb.h"

void gotListWrapper ( void *state ) ;

// . readset up for a scan of slots in the RdbScans
// . returns false if blocked, true otherwise
// . sets errno on error
bool RdbScan::setRead ( BigFile  *file         ,
			long      fixedDataSize,
			long long offset       ,
			long      bytesToRead  ,
			//key_t     startKey     , 
			//key_t     endKey       ,
			char     *startKey     , 
			char     *endKey       ,
			char      keySize      ,
			RdbList  *list         , // we fill this up
			void     *state        ,
			void   (* callback) ( void *state ) ,
			bool      useHalfKeys  ,
			char      rdbId ,
			long      niceness     ,
			bool      allowPageCache ,
			bool      hitDisk        ) {
	// remember list
	m_list = list;
	// reset the list
	m_list->reset();
	// save keySize
	m_ks = keySize;
	m_rdbId = rdbId;
	// save allow page cache
	m_allowPageCache = allowPageCache;
	m_hitDisk        = hitDisk;
	// ensure startKey last bit clear, endKey last bit set
	//if ( (startKey.n0 & 0x01) == 0x01 ) 
	//	log("RdbScan::setRead: warning startKey lastbit set"); 
	//if ( (endKey.n0   & 0x01) == 0x00 ) 
	//	log("RdbScan::setRead: warning endKey lastbit clear"); 
	// set list now
	m_list->set ( NULL          , 
		      0             ,
		      NULL          ,
		      0             ,
		      startKey      ,
		      endKey        ,
		      fixedDataSize ,
		      true          , // ownData?
		      useHalfKeys   ,
		      keySize       );
	// . don't do anything if startKey exceeds endKey
	// . often Msg3 will call us with this true because it's page range
	//   is empty because the map knows without having to hit disk. 
	//   therefore, just return silently now.
	// . Msg3 will not merge empty lists so don't worry about setting the
	//   lists startKey/endKey
	//if ( startKey > endKey ) return true;
	if ( KEYCMP(startKey,endKey,m_ks)>0 ) return true;
	//	log("RdbScan::readList: startKey > endKey warning"); 
	//	return true;
	//}
	// don't bother doing anything if nothing needs to be read
	if ( bytesToRead == 0 ) return true;

	// . start reading at m_offset in the file
	// . also, remember this offset for finding the offset of the last key
	//   to set a tighter m_bufEnd in doneReading() so we don't have to
	//   keep checking if the returned record's key falls exactly in
	//   [m_startKey,m_endKey]
	// . set m_bufSize to how many bytes we need to read
	// . m_keyMin is the first key we read, may be < startKey
	// . we won't read any keys strictly greater than "m_keyMax"
	// . m_hint is set to the offset of the BIGGEST key found in the map
	//   that is still <= endKey
	// . we use m_hint so that RdbList::merge() can find the last key
	//   in the startKey/endKey range w/o having to step through
	//   all the records in the read
	// . m_hint will limit the stepping to a PAGE_SIZE worth of records
	// . m_hint is an offset, like m_offset
	// . TODO: what if it returns false?

	// debug msg
	//if ( m_bufSize > 1024 * 1024 * 3 ) {
	//	fprintf(stderr,"BIG READ\n");
	//	sleep(5);
	//}
	// . alloc some read buffer space, m_buf
	// . add 4 extra in case first key is half key and needs to be full
	long bufSize = bytesToRead ;
	// add 6 more if we use half keys
	if ( useHalfKeys ) m_off = 6;
	else               m_off = 0;
	// posdb keys are 18 bytes but can be 12 ot 6 bytes compressed
	if ( m_rdbId == RDB_POSDB || m_rdbId == RDB2_POSDB2  ) m_off = 12;
	// alloc more for expanding the first 6-byte key into 12 bytes,
	// or in the case of posdb, expanding a 6 byte key into 18 bytes
	bufSize += m_off;
	// . and a little extra in case read() reads TOO much
	// . i think a read overflow might be causing a segv in malloc
	// . but try badding under us, maybe read() writes before the buf
	long pad = 16;
	bufSize += pad;
	// get the memory to hold what we read
	//char *buf = (char *) mmalloc ( bufSize , "RdbScan" );
	//if ( ! buf ) { 
	//	log("disk: Could not allocate %li bytes for read of %s.",
	//	    bufSize ,file->getFilename());
	//	return true;
	//}
	// note
	//logf(LOG_DEBUG,"db: list %lu has buf %lu.",(long)m_list,(long)buf);
	// . set up the list
	// . set min/max keys on list if we're done reading
	// . the min/maxKey defines the range of keys we read
	// . m_hint is the offset of the BIGGEST key in the map that is
	//   still <= the m_endKey specified in setRead()
	// . it's used to make it easy to find the actual biggest key that is
	//   <= m_endKey
	/*
	m_list->set ( buf + pad + m_off , 
		      bytesToRead   , 
		      buf           ,
		      bufSize       , 
		      startKey      , 
		      endKey        ,
		      fixedDataSize , 
		      true          ,
		      useHalfKeys   , // ownData?
		      m_ks          );
	*/
	// save caller's callback
	m_callback = callback;
	m_state    = state;
	// save the first key in the list
	//m_startKey = startKey;
	KEYSET(m_startKey,startKey,m_ks);//m_list->m_ks);
	KEYSET(m_endKey,endKey,m_ks);
	m_fixedDataSize = fixedDataSize;
	m_useHalfKeys   = useHalfKeys;
	m_bytesToRead   = bytesToRead;
	// save file and offset for sanity check
	m_file   = file;
	m_offset = offset;
	// ensure we don't mess around
	m_fstate.m_allocBuf = NULL;
	m_fstate.m_buf      = NULL;
	// debug msg
	//log("diskOff=%lli nb=%li",offset,bytesToRead);
	//if ( offset == 16386 && bytesToRead == 16386 )
	//	log("hey");
	// . do a threaded, non-blocking read 
	// . we now pass in a NULL buffer so Threads.cpp will do the
	//   allocation right before launching the thread so we don't waste
	//   memory. i've seen like 19000 unlaunched threads each allocating
	//   32KB for a tfndb read, hogging up all the memory.
	//if ( ! file->read ( buf + pad + m_off ,
	if ( ! file->read ( NULL           ,
			    bytesToRead    ,
			    offset         ,
			    &m_fstate      ,
			    this           ,
			    gotListWrapper ,
			    niceness       ,
			    m_allowPageCache ,
			    m_hitDisk        ,
			    pad + m_off )) // allocOff, buf offset to read into
		return false;

	/*
	// debug point
	log("RDBSCAN: read %li bytes @ %lli",bytesToRead, offset);
	for ( long i = 0 ; i < bytesToRead ; i++ ) {
		if (((offset+i) % 20) == 0 ) 
			fprintf(stderr,"\n%lli) ",offset+i);
		fprintf(stderr,"%02hhx ",(buf+pad+m_off)[i]);
	}
	fprintf(stderr,"\n");

	if ( offset == 49181 && bytesToRead == 98299 ) {
		char *xx = NULL ;*xx = 0; }
	*/

	if ( m_fstate.m_errno && ! g_errno ) { char *xx=NULL;*xx=0; }

	// fix the list if we need to
	gotList();
	// we did not block
	return true;
}

void gotListWrapper ( void *state ) {
	RdbScan *THIS = (RdbScan *)state;
	THIS->gotList ();
	// let caller know we're done
	THIS->m_callback ( THIS->m_state );
}

#include "Threads.h"

void RdbScan::gotList ( ) {
	char *allocBuf  = m_fstate.m_allocBuf;
	long  allocSize = m_fstate.m_allocSize;
	// do not free the allocated buf for when the actual thread
	// does the read and finally completes in this case. we free it
	// in Threads.cpp::ohcrap()
	if ( m_fstate.m_errno == EDISKSTUCK )
		return;
	// just return on error, do nothing
	if ( g_errno ) {
		// free buffer though!! don't forget!
		if ( allocBuf ) 
			mfree ( allocBuf , allocSize , "RdbScan" );
		m_fstate.m_allocBuf = NULL;
		m_fstate.m_allocSize = 0;
		return;
	}
	// . set our list here now since the buffer was allocated in
	//   DiskPageCache.cpp or Threads.cpp to save memory.
	// . only set the list if there was a buffer. if not, it s probably 
	//   due to a failed alloc and we'll just end up using the empty
	//   m_list we set way above.
	if ( m_fstate.m_allocBuf ) {
		// get the buffer info for setting the list
		//char *allocBuf  = m_fstate.m_allocBuf;
		long  allocOff  = m_fstate.m_allocOff; //buf=allocBuf+allocOff
		//long  allocSize = m_fstate.m_allocSize;
		long  bytesDone = m_fstate.m_bytesDone;
		// sanity checks
		if ( bytesDone > allocSize                 ) { 
			char *xx = NULL; *xx = 0; }
		if ( allocOff + m_bytesToRead != allocSize ) { 
			char *xx = NULL; *xx = 0; }
		if ( allocOff != m_off + 16                ) { 
			char *xx = NULL; *xx = 0; }
		// now set this list. this always succeeds.
		m_list->set ( allocBuf + allocOff , // buf + pad + m_off , 
			      m_bytesToRead   , // bytesToRead   , 
			      allocBuf        ,
			      allocSize       ,
			      m_startKey      ,
			      m_endKey        ,
			      m_fixedDataSize ,
			      true            , // ownData?
			      m_useHalfKeys   , 
			      m_ks            );
	}
	// this was bitching a lot when running on a multinode cluster,
	// so i effectively disabled it by changing to _SANITYCHECK2_
#ifdef _SANITYCHECK2_
	// this first test, tests to make sure the read from cache worked
	DiskPageCache *pc = m_file->getDiskPageCache();
	if ( pc && ! g_errno ) {
		// ensure threads disabled
		bool on = ! g_threads.areThreadsDisabled();
		if ( on ) g_threads.disableThreads();
		pc->disableCache();
		FileState fstate;
		// ensure we don't mess around
		fstate.m_allocBuf = NULL;
		fstate.m_buf      = NULL;
		char *bb          = (char *)mmalloc ( m_bytesToRead , "RS" );
		if ( ! bb ) {
			log("db: Failed to alloc mem for page cache verify.");
			goto skip;
		}
		m_file->read ( bb , // NULL, // buf + pad + m_off
			       m_bytesToRead    ,
			       m_offset         ,
			       &fstate          , // &m_fstate
			       NULL             , // callback state
			       gotListWrapper   , // FAKE callback
			       MAX_NICENESS     , // niceness
			       false, // m_allowPageCache ,
			       m_hitDisk  ,
			       16 + m_off );
		//char *allocBuf  = fstate.m_allocBuf;
		//long  allocSize = fstate.m_allocSize;
		//char *bb        = allocBuf + fstate.m_allocOff;
		// if file got unlinked from under us, or whatever, we get
		// an error
		if ( ! g_errno ) {
			char *buf = m_list->getList();
			if ( memcmp ( bb , buf , m_bytesToRead) != 0 ) {
				char *xx = NULL; *xx = 0; }
			if ( m_bytesToRead != m_list->getListSize() ) {
				char *xx = NULL; *xx = 0; }
		}
		//mfree ( allocBuf , allocSize , "RS" );
		mfree ( bb , m_bytesToRead , "RS" );
		if ( on ) g_threads.enableThreads();
		pc->enableCache();
		// . this test tests to make sure the page stores worked
		// . go through each page in page cache and verify on disk
		//pc->verify ( m_file );
	}
 skip:
#endif
	// assume we did not shift it
	m_shifted = 0;//false;
	// if we were doing a cache only read, and got nothing, bail now
	if ( ! m_hitDisk && m_list->isEmpty() ) return;
	// if first key in list is half, make it full
	char *p = m_list->getList();
	// . bitch if we read too much!
	// . i think a read overflow might be causing a segv in malloc
	// . NOTE: BigFile's call to DiskPageCache alters these values
	if ( m_fstate.m_bytesDone != m_fstate.m_bytesToGo && m_hitDisk )
		log(LOG_INFO,"disk: Read %li bytes but needed %li.",
		     m_fstate.m_bytesDone , m_fstate.m_bytesToGo );
	// adjust the list size for biased page cache if necessary
	//if ( m_file->m_pc && m_allowPageCache &&
	//     m_file->m_pc->m_isOverriden &&
	//     m_fstate.m_bytesDone < m_list->m_listSize )
	//	m_list->m_listSize = m_fstate.m_bytesDone;
	// bail if we don't do the 6 byte thing
	if ( m_off == 0 ) return;
	// posdb double compression?
	if ( (m_rdbId == RDB_POSDB || m_rdbId == RDB2_POSDB2)
	     && (p[0] & 0x04) ) {
		// make it full
		m_list->m_list     -= 12;
		m_list->m_listSize += 12;
		p                  -= 12;
		KEYSET(p,m_startKey,m_list->m_ks);
		// clear the compression bits
		*p &= 0xf9;
		// let em know we shifted it so they can shift the hint offset
		// up by 6
		m_shifted = 12;
	}
	// if first key is already full (12 bytes) no need to do anything
	else if ( m_list->isHalfBitOn ( p ) ) {
		// otherwise, make it full
		m_list->m_list     -= 6;
		m_list->m_listSize += 6;
		p                  -= 6;
		//*(key_t *)p = m_startKey;
		KEYSET(p,m_startKey,m_list->m_ks);
		// clear the half bit in case it is set
		*p &= 0xfd;
		// let em know we shifted it so they can shift the hint offset
		// up by 6
		m_shifted = 6; // true;
	}
}