Line data    Source code

       1              : //!
       2              : //! Common utilities for dealing with PostgreSQL non-relation files.
       3              : //!
       4              : use crate::pg_constants;
       5              : use crate::transaction_id_precedes;
       6              : use bytes::BytesMut;
       7              : 
       8              : use super::bindings::MultiXactId;
       9              : 
      10            0 : pub fn transaction_id_set_status(xid: u32, status: u8, page: &mut BytesMut) {
      11            0 :     tracing::trace!(
      12            0 :         "handle_apply_request for RM_XACT_ID-{} (1-commit, 2-abort, 3-sub_commit)",
      13              :         status
      14              :     );
      15              : 
      16            0 :     let byteno: usize =
      17            0 :         ((xid % pg_constants::CLOG_XACTS_PER_PAGE) / pg_constants::CLOG_XACTS_PER_BYTE) as usize;
      18              : 
      19            0 :     let bshift: u8 =
      20            0 :         ((xid % pg_constants::CLOG_XACTS_PER_BYTE) * pg_constants::CLOG_BITS_PER_XACT as u32) as u8;
      21              : 
      22            0 :     page[byteno] =
      23            0 :         (page[byteno] & !(pg_constants::CLOG_XACT_BITMASK << bshift)) | (status << bshift);
      24            0 : }
      25              : 
      26            0 : pub fn transaction_id_get_status(xid: u32, page: &[u8]) -> u8 {
      27            0 :     let byteno: usize =
      28            0 :         ((xid % pg_constants::CLOG_XACTS_PER_PAGE) / pg_constants::CLOG_XACTS_PER_BYTE) as usize;
      29              : 
      30            0 :     let bshift: u8 =
      31            0 :         ((xid % pg_constants::CLOG_XACTS_PER_BYTE) * pg_constants::CLOG_BITS_PER_XACT as u32) as u8;
      32              : 
      33            0 :     (page[byteno] >> bshift) & pg_constants::CLOG_XACT_BITMASK
      34            0 : }
      35              : 
      36              : // See CLOGPagePrecedes in clog.c
      37            0 : pub const fn clogpage_precedes(page1: u32, page2: u32) -> bool {
      38            0 :     let mut xid1 = page1 * pg_constants::CLOG_XACTS_PER_PAGE;
      39            0 :     xid1 += pg_constants::FIRST_NORMAL_TRANSACTION_ID + 1;
      40            0 :     let mut xid2 = page2 * pg_constants::CLOG_XACTS_PER_PAGE;
      41            0 :     xid2 += pg_constants::FIRST_NORMAL_TRANSACTION_ID + 1;
      42              : 
      43            0 :     transaction_id_precedes(xid1, xid2)
      44            0 :         && transaction_id_precedes(xid1, xid2 + pg_constants::CLOG_XACTS_PER_PAGE - 1)
      45            0 : }
      46              : 
      47              : // See SlruMayDeleteSegment() in slru.c
      48            0 : pub fn slru_may_delete_clogsegment(segpage: u32, cutoff_page: u32) -> bool {
      49            0 :     let seg_last_page = segpage + pg_constants::SLRU_PAGES_PER_SEGMENT - 1;
      50              : 
      51            0 :     assert_eq!(segpage % pg_constants::SLRU_PAGES_PER_SEGMENT, 0);
      52              : 
      53            0 :     clogpage_precedes(segpage, cutoff_page) && clogpage_precedes(seg_last_page, cutoff_page)
      54            0 : }
      55              : 
      56              : // Multixact utils
      57              : 
      58           40 : pub fn mx_offset_to_flags_offset(xid: MultiXactId) -> usize {
      59           40 :     ((xid / pg_constants::MULTIXACT_MEMBERS_PER_MEMBERGROUP as u32)
      60           40 :         % pg_constants::MULTIXACT_MEMBERGROUPS_PER_PAGE as u32
      61           40 :         * pg_constants::MULTIXACT_MEMBERGROUP_SIZE as u32) as usize
      62           40 : }
      63              : 
      64           20 : pub fn mx_offset_to_flags_bitshift(xid: MultiXactId) -> u16 {
      65           20 :     (xid as u16) % pg_constants::MULTIXACT_MEMBERS_PER_MEMBERGROUP
      66           20 :         * pg_constants::MXACT_MEMBER_BITS_PER_XACT
      67           20 : }
      68              : 
      69              : /* Location (byte offset within page) of TransactionId of given member */
      70           20 : pub fn mx_offset_to_member_offset(xid: MultiXactId) -> usize {
      71           20 :     mx_offset_to_flags_offset(xid)
      72           20 :         + (pg_constants::MULTIXACT_FLAGBYTES_PER_GROUP
      73           20 :             + (xid as u16 % pg_constants::MULTIXACT_MEMBERS_PER_MEMBERGROUP) * 4) as usize
      74           20 : }
      75              : 
      76           40 : fn mx_offset_to_member_page(xid: u32) -> u32 {
      77           40 :     xid / pg_constants::MULTIXACT_MEMBERS_PER_PAGE as u32
      78           40 : }
      79              : 
      80           20 : pub fn mx_offset_to_member_segment(xid: u32) -> i32 {
      81           20 :     (mx_offset_to_member_page(xid) / pg_constants::SLRU_PAGES_PER_SEGMENT) as i32
      82           20 : }
      83              : 
      84              : #[cfg(test)]
      85              : mod tests {
      86              :     use super::*;
      87              : 
      88              :     #[test]
      89            4 :     fn test_multixid_calc() {
      90              :         // Check that the mx_offset_* functions produce the same values as the
      91              :         // corresponding PostgreSQL C macros (MXOffsetTo*). These test values
      92              :         // were generated by calling the PostgreSQL macros with a little C
      93              :         // program.
      94            4 :         assert_eq!(mx_offset_to_member_segment(0), 0);
      95            4 :         assert_eq!(mx_offset_to_member_page(0), 0);
      96            4 :         assert_eq!(mx_offset_to_flags_offset(0), 0);
      97            4 :         assert_eq!(mx_offset_to_flags_bitshift(0), 0);
      98            4 :         assert_eq!(mx_offset_to_member_offset(0), 4);
      99            4 :         assert_eq!(mx_offset_to_member_segment(1), 0);
     100            4 :         assert_eq!(mx_offset_to_member_page(1), 0);
     101            4 :         assert_eq!(mx_offset_to_flags_offset(1), 0);
     102            4 :         assert_eq!(mx_offset_to_flags_bitshift(1), 8);
     103            4 :         assert_eq!(mx_offset_to_member_offset(1), 8);
     104            4 :         assert_eq!(mx_offset_to_member_segment(123456789), 2358);
     105            4 :         assert_eq!(mx_offset_to_member_page(123456789), 75462);
     106            4 :         assert_eq!(mx_offset_to_flags_offset(123456789), 4780);
     107            4 :         assert_eq!(mx_offset_to_flags_bitshift(123456789), 8);
     108            4 :         assert_eq!(mx_offset_to_member_offset(123456789), 4788);
     109            4 :         assert_eq!(mx_offset_to_member_segment(u32::MAX - 1), 82040);
     110            4 :         assert_eq!(mx_offset_to_member_page(u32::MAX - 1), 2625285);
     111            4 :         assert_eq!(mx_offset_to_flags_offset(u32::MAX - 1), 5160);
     112            4 :         assert_eq!(mx_offset_to_flags_bitshift(u32::MAX - 1), 16);
     113            4 :         assert_eq!(mx_offset_to_member_offset(u32::MAX - 1), 5172);
     114            4 :         assert_eq!(mx_offset_to_member_segment(u32::MAX), 82040);
     115            4 :         assert_eq!(mx_offset_to_member_page(u32::MAX), 2625285);
     116            4 :         assert_eq!(mx_offset_to_flags_offset(u32::MAX), 5160);
     117            4 :         assert_eq!(mx_offset_to_flags_bitshift(u32::MAX), 24);
     118            4 :         assert_eq!(mx_offset_to_member_offset(u32::MAX), 5176);
     119            4 :     }
     120              : }