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Diffstat (limited to 'mysql-test/include/rpl_generate_sync_chain.inc')
| -rw-r--r-- | mysql-test/include/rpl_generate_sync_chain.inc | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/mysql-test/include/rpl_generate_sync_chain.inc b/mysql-test/include/rpl_generate_sync_chain.inc new file mode 100644 index 00000000000..9104c21c3b8 --- /dev/null +++ b/mysql-test/include/rpl_generate_sync_chain.inc @@ -0,0 +1,122 @@ +# ==== Purpose ==== +# +# Setup $rpl_sync_chain, which is used by rpl_sync.inc. You normally +# don't need to source this file, it should only be sourced by +# rpl_sync.inc. +# +# $rpl_sync_chain is set to a string that specifies in what order +# servers should be synchronized in include/rpl_sync.inc. This has the +# form of a sequence of "chains" (with no separator between two +# chains). Each chain begins with $rpl_server_count_length space +# characters, followed by a sequence of numbers, each number +# whitespace-padded to $rpl_server_count_length characters. Each +# number in the sequence denotes a server, and the N'th server is a +# master of the (N+1)'th server. For example, if $rpl_topology is +# '1->2,2->3,3->1,2->4,5->6', then $rpl_sync_chain is ' 56 123124'. +# +# +# ==== Usage ==== +# +# [--let $rpl_debug= 1] +# --source include/rpl_generate_sync_chain.inc +# +# Parameters: +# $rpl_debug +# See include/rpl_init.inc + + +--let $include_filename= rpl_generate_sync_chain.inc +--source include/begin_include_file.inc + + +# Algorithm: +# 0. Mark all servers as unseen and unsynced. +# 1. Let S be a server that is marked unseen. +# 2. Append S to the list of seen servers. +# 3. Check how S is marked: +# 3.1. If S has no master: append the list of seen servers (in +# order from grand-master to grand-slave) to the end of +# $rpl_sync_chain. Go to 3. +# 3.2. Elseif S is marked as synced: append the list of seen +# servers (in order from grand-master to grand-slave) to the +# end of $rpl_sync_chain. Go to 3. +# 3.3. Elseif S is marked as unsynced but seen: This means that the +# graph of visited servers has a "6-shape": it is a loop with +# a tail, such as 1->2->3->1->4->5. We should first sync the +# loop, and then the tail. To ensure all servers in the loop +# are synced, we must sync the loop two turns minus two +# servers. For example, the loop 1->2->3->4->5->1 is fully +# synced by this sequence of 1-step synchronizations: +# 1->2->3->4->5->1->2->3->4. Hence we do this: in the list of +# traversed servers (in order from grand-master to +# grand-slave), find the first occurrence of S. Take the +# sub-list starting at the 3rd server and ending at the first +# occurrence of S. Append this sub-list it to the end of +# $rpl_sync_chain. Then append the entire list of traversed +# servers (in order from grand-master to grand-slave) to +# $rpl_sync_chain. Go to 3. +# 3.4. Else (i.e., S has a master and is not marked as seen or +# synced): Mark S as seen. Set S=master(S) and go back to 2. +# 4. For each server that is marked as seen, mark it as synced. +# 5. If there are unseen servers, go back to 1. + +# $_rpl_server_marks holds the marks of all servers. The i'th character +# corresponds to the mark of server i: +# '0' = unseen & unmarked, '1' = seen & unsynced, '2' = seen & synced. +--let $_rpl_server_marks= `SELECT REPEAT('0', $rpl_server_count)` +--let $_rpl_start_server= $rpl_server_count +--let $rpl_sync_chain= +while ($_rpl_start_server) +{ + --let $_rpl_server= `SELECT RPAD('$_rpl_start_server', $rpl_server_count_length, ' ')` + --let $_rpl_seen_list= + --let $_rpl_continue_loop= 1 + while ($_rpl_continue_loop) + { + --let $_rpl_master= `SELECT SUBSTRING('$rpl_master_list', 1 + ($_rpl_server - 1) * $rpl_server_count_length, $rpl_server_count_length)` + # We need to delimit elements of $_rpl_seen_list with commas, so + # that LOCATE() below will not find spurious matches that begin in + # the middle of one element and end in the middle of next element. + --let $_rpl_seen_list= $_rpl_server,$_rpl_seen_list + # If server is marked seen or synced, or has no master + if (`SELECT SUBSTRING('$_rpl_server_marks', $_rpl_server, 1) != 0 OR '$_rpl_master' = ''`) + { + # If server is marked seen but not synced. + if (`SELECT SUBSTRING('$_rpl_server_marks', $_rpl_server, 1) = 1`) + { + # Get sub-list of servers to prepend to server list. + # E.g., if topology is 1->2->3->4->1->5, then at this point + # $_rpl_seen_list='1,2,3,4,1,5,' and we have to prepend '4,3,' + # to it. Hence, the sub-list starts at position + # 1+2*($rpl_server_count_length+1) and ends at the first + # occurrence of ',1,' in the list. + --let $_rpl_extra_list= `SELECT SUBSTRING('$_rpl_seen_list', 1 + 2 * ($rpl_server_count_length + 1), LOCATE(',$_rpl_server,', '$_rpl_seen_list') - 2 * ($rpl_server_count_length + 1))` + --let $_rpl_seen_list= $_rpl_extra_list$_rpl_seen_list + } + # Append the seen servers. Only need to append if the list + # contains at least two elements. + if (`SELECT LENGTH('$_rpl_seen_list') > $rpl_server_count_length + 1`) + { + --let $rpl_sync_chain= $rpl_sync_chain$_rpl_no_server$_rpl_seen_list + } + --let $_rpl_continue_loop= 0 + } + --let $_rpl_server_marks= `SELECT INSERT('$_rpl_server_marks', $_rpl_server, 1, '1')` + --let $_rpl_server= $_rpl_master + } + # Mark seen servers as synced + --let $_rpl_server_marks= `SELECT REPLACE('$_rpl_server_marks', '1', '2')` + # Get highest-numbered unmarked server. + --let $_rpl_start_server= `SELECT IFNULL(NULLIF($rpl_server_count + 1 - LOCATE('0', REVERSE('$_rpl_server_marks')), $rpl_server_count + 1), 0)` +} +# Strip commas: they were only needed temporarily. +--let $rpl_sync_chain= `SELECT REPLACE('$rpl_sync_chain', ',', '')` + +if ($rpl_debug) +{ + --echo Generated \$rpl_sync_chain = '$rpl_sync_chain' +} + + +--let $include_filename= rpl_generate_sync_chain.inc +--source include/end_include_file.inc |