zlob0read.h

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#ifndef zlob0read_h
#define zlob0read_h
 
#include "zlob0index.h"
 
namespace lob {
 
/** Read one data chunk associated with one index entry.
@param[in]      index   The clustered index containing the LOB.
@param[in]      entry   Pointer to the index entry
@param[in]      offset  The offset from which to read the chunk.
@param[in,out]  len     The length of the output buffer. This length can
                        be greater than the chunk size.
@param[in,out]  buf     The output buffer.
@param[in]      mtr     Mini-transaction context.
@return number of bytes copied into the output buffer. */
ulint z_read_chunk(dict_index_t *index, z_index_entry_t &entry, ulint offset,
                   ulint &len, byte *&buf, mtr_t *mtr);
 
/** Read one zlib stream fully, given its index entry.
@param[in]      index      The index dictionary object.
@param[in]      entry      The index entry (memory copy).
@param[in,out]  zbuf       The output buffer
@param[in]      zbuf_size  The size of the output buffer.
@param[in,out]  mtr        Mini-transaction.
@return the size of the zlib stream.*/
ulint z_read_strm(dict_index_t *index, z_index_entry_t &entry, byte *zbuf,
                  ulint zbuf_size, mtr_t *mtr);
 
/** Fetch a compressed large object (ZLOB) from the system.
@param[in] ctx    the read context information.
@param[in] trx    the transaction that is doing the read.
@param[in] ref    the LOB reference identifying the LOB.
@param[in] offset read the LOB from the given offset.
@param[in] len    the length of LOB data that needs to be fetched.
@param[out] buf   the output buffer (owned by caller) of minimum len bytes.
@return the amount of data (in bytes) that was actually read. */
ulint z_read(ReadContext *ctx, trx_t *trx, lob::ref_t ref, ulint offset,
             ulint len, byte *buf);
 
#ifdef UNIV_DEBUG
/** Validate one zlib stream, given its index entry.
@param[in]      index      The index dictionary object.
@param[in]      entry      The index entry (memory copy).
@param[in]      mtr        Mini-transaction.
@return true if validation passed.
@return does not return if validation failed.*/
bool z_validate_strm(dict_index_t *index, z_index_entry_t &entry, mtr_t *mtr);
#endif /* UNIV_DEBUG */
 
} /* namespace lob */
 
#endif /* zlob0read_h */