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09de59f026
disk space. added tagdb file cache for better performance, less disk accesses. will help reduce disk load. put file cache sizes in master controls and if they change then update the cache size dynamically.
96 lines
2.4 KiB
C++
96 lines
2.4 KiB
C++
// Matt Wells, copyright Sep 2000
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// . used exculsively by RdbGet
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// . used for scanning a key-range of records
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// . does non-blocking disk reads
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// . set loop to NULL to do blocking disk reads
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// . we set m_errno to a positive value on error, so check it!
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// . originally you could call getNextRecord() before the entire read
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// was complete.
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#ifndef _RDBSCAN_H_
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#define _RDBSCAN_H_
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#include "BigFile.h"
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#include "Loop.h"
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#include "RdbMap.h"
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#include "RdbList.h"
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class RdbScan {
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public:
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// . returns false if blocked, true otherwise
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// . sets errno on error
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// . call this to start the read (sets up your key-range read too)
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// . endKey must be provided
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// . TODO: can we do multiple "simultaneous" non-blocking
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// reads on the same fd?
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// . we need array of files so BigFile::filecb() knows when file nuked
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bool setRead ( BigFile *file ,
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int32_t fixedDataSize ,
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int64_t offset ,
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int32_t bytesToRead ,
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//key_t startKey ,
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//key_t endKey ,
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char *startKey ,
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char *endKey ,
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char keySize ,
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RdbList *list , // we fill this up
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void *state ,
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void (* callback ) ( void *state ) ,
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bool useHalfKeys ,
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char rdbId,
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int32_t niceness , // = MAX_NICENESS ,
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bool allowPageCache , // = true ,
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bool hitDisk ); // = true );
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// RdbGet likes to get our list
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RdbList *getList ( ) { return m_list; };
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// was buffer shifted down 6 bytes to turn first key into a 12 byter?
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bool wasShifted () { return m_shifted; };
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void gotList ( );
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// we set this list with the read buffer on read completion
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RdbList *m_list;
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// for doing non-blocking reads with BigFile::read()
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FileState m_fstate;
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// for dealing with half keys
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int32_t m_off;
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// shifting it
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char m_shifted;
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char m_rdbId;
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// save for call to our gotListWrapper()
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//key_t m_startKey;
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char m_startKey[MAX_KEY_BYTES];
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char m_endKey [MAX_KEY_BYTES];
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int32_t m_fixedDataSize;
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char m_useHalfKeys;
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int32_t m_bytesToRead;
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void (* m_callback ) ( void *state ) ;
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void *m_state;
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// for sanity checking
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BigFile *m_file;
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int64_t m_offset;
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char m_ks;
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// for allowing page cache
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bool m_allowPageCache;
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bool m_hitDisk;
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// this is set by Msg3.cpp
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char m_inPageCache;
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};
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#endif
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