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by brian
clean slate |
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/******************************************************
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Cursor read
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(c) 1997 Innobase Oy
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Created 2/16/1997 Heikki Tuuri
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*******************************************************/
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/*************************************************************************
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Gets the nth trx id in a read view. */
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UNIV_INLINE |
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dulint |
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read_view_get_nth_trx_id(
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/*=====================*/
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/* out: trx id */ |
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read_view_t* view, /* in: read view */ |
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ulint n) /* in: position */ |
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{
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ut_ad(n < view->n_trx_ids); |
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return(*(view->trx_ids + n)); |
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}
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/*************************************************************************
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Sets the nth trx id in a read view. */
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UNIV_INLINE |
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void |
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read_view_set_nth_trx_id(
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/*=====================*/
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read_view_t* view, /* in: read view */ |
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ulint n, /* in: position */ |
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dulint trx_id) /* in: trx id to set */ |
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{
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ut_ad(n < view->n_trx_ids); |
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*(view->trx_ids + n) = trx_id; |
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}
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/*************************************************************************
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Checks if a read view sees the specified transaction. */
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UNIV_INLINE |
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ibool |
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read_view_sees_trx_id(
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/*==================*/
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/* out: TRUE if sees */ |
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read_view_t* view, /* in: read view */ |
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dulint trx_id) /* in: trx id */ |
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{
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ulint n_ids; |
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int cmp; |
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ulint i; |
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if (ut_dulint_cmp(trx_id, view->up_limit_id) < 0) { |
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return(TRUE); |
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} |
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if (ut_dulint_cmp(trx_id, view->low_limit_id) >= 0) { |
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return(FALSE); |
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} |
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/* We go through the trx ids in the array smallest first: this order |
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may save CPU time, because if there was a very long running
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transaction in the trx id array, its trx id is looked at first, and
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the first two comparisons may well decide the visibility of trx_id. */
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n_ids = view->n_trx_ids; |
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for (i = 0; i < n_ids; i++) { |
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cmp = ut_dulint_cmp( |
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trx_id, |
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read_view_get_nth_trx_id(view, n_ids - i - 1)); |
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if (cmp <= 0) { |
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return(cmp < 0); |
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} |
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} |
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return(TRUE); |
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}
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