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93 lines
2.4 KiB
C++
93 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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long fixedDataSize ,
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long long offset ,
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long 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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long 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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long 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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long m_fixedDataSize;
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char m_useHalfKeys;
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long 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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long long 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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};
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#endif
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