New read-only system variables (set at startup, need --log-error):
* log_error_file_buffer_size: error log buffer size, default 0 (off)
* log_error_file_rotate_size: rotate the error log above this size,
default 1073741824
* log_error_file_rotations: number of rotated files kept, default 0
Changes:
* Write the error log through the logger service, which batches writes
in an in-memory buffer, when log_error_file_buffer_size is set.
* print_buffer_to_file() uses one static buffer, allocated on first use
(MAX_LOG_BUFFER_SIZE+1), grown as needed and freed at shutdown.
* vprint_msg_to_log() writes lines longer than 1024 bytes in full, up
to 1 MB.
* Galera messages use the same error log path. Debug messages are
written only if wsrep_debug is set.
* Add mtr tests for the three variables, buffered logging, rotation and
long lines.
Assisted-by: https://mariadb.org/governance/governance-ai-policy/
df2582990d